The Late Pleistocene Extinction in North America: An Investigation of

Transcription

UNIVERSITY OF CALGARY
The Late Pleistocene Extinction in North America: An Investigation of Horse and
Bison Fossil Material and Its Implication for Nutritional Extinction Models
by
Christian Raúl Barrón-Ortiz
A THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
GRADUATE PROGRAM IN BIOLOGICAL SCIENCES
CALGARY, ALBERTA
JANUARY, 2016
© Christian Raúl Barrón-Ortiz 2016
Abstract
Approximately 50,000 – 11,000 years ago many species around the world became extinct
or were extirpated at a continental scale. The causes of the late Pleistocene extinctions
have been extensively debated and are poorly understood. This dissertation focuses on
testing two nutritional extinction models (coevolutionary disequilibrium and mosaicnutrient models) through the study of dental wear and enamel hypoplasia of equid and
bison specimens from the Western Interior of North America. In order to undertake this
task it was first necessary to determine the number of equid species that inhabited this
region during the late Pleistocene. Notable findings of this research include the
identification of four equid taxa based on molecular and morphometric analyses of the
cheek teeth. Two non-caballine species and two caballine subspecies were identified
which, pending further study of North American Pleistocene Equus, are referred as:
Equus cedralensis, E. conversidens (which corresponds to the New World stilt-legged
group of previous molecular analyses), E. ferus scotti, and E. ferus lambei. The
separation into caballine and non-caballine equids was revealed in both the Bayesian
phylogenetic analysis of mitochondrial ancient DNA and the geometric morphometric
analyses of the upper and lower premolars. Investigation of the dental wear (microwear
and mesowear) of the equid and bison samples studied yielded results which are
consistent with predictions established for the coevolutionary disequilibrium extinction
model, but not for the mosaic-nutrient model. These ungulate species show statistically
different dental wear patterns, suggesting dietary resource partitioning, prior to the
postglacial, but not during this time interval in accordance to predictions of the
coevolutionary disequilibrium model. In addition to changes in diet, these ungulates,
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specifically the equid species, show increased levels of enamel hypoplasia during the
postglacial indicating higher levels of systemic stress, a result which is consistent with
the models tested as well as other climate-based extinction models that have been
proposed. The extent to which the increase in systemic stress was detrimental to equid
populations remains to be further investigated, but it is suggestive that environmental
changes might have played an important role in the extinction of equids and perhaps
other Pleistocene ungulates.
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Acknowledgments
This dissertation would not have been possible without the help and support of a number
of people. First, I want to thank my supervisor, Jessica Theodor, for guiding me through
the whole process. Her thoughtful questions and insight allowed me to develop and refine
my research ideas. I thank the rest of my supervisory committee, Anthony Russell and
Sean Rogers, for their expert council and direction. I also extend my gratitude to my
external thesis examiners, Brian Kooyman and Ernest Lundelius, for carefully reviewing
the completed version of the dissertation. The administrative staff of the Department of
Biological Sciences, Karen Barron and Sophia George, were always quick to answer my
questions related to the program.
Over the course of my research I visited several institutions and I would like to
thank the curators and collection managers who provided access to specimens in their
care: Stacey Girling-Christie (CMH), Joaquín Arroyo-Cabrales and Ana Fabiola Guzmán
(INAH), Desui Miao (KU), Xioming Wang, Sam McLeod, and Vanessa Rhue, (LACM),
Chris Jass and Peter Milot (Department of Quaternary Palaeontology, RAM), Jack Brink
and Karen Giering (Department of Archaeology, RAM), Tim Rowe and Chris Sagebiel
(TMM), and Art Harris (UTEP).
I am indebted to a number of people at the University of Calgary for the
stimulating discussions and support they provided me over the course of my dissertation.
I especially thank Brian Rankin and the rest of my lab mates: Dani Fraser, Josh Ludtke,
Tasha Cammidge, and Chelsey Zurowski. Thanks also to present and past members of the
J. Anderson, S. Rogers, A. Russell, and D. Zelenitsky labs. I gratefully acknowledge the
expert insight and training on ancient DNA provided by Camilla Speller. Tyler Murchie
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and Ana Morales provided valuable discussions and helped maintain the ancient DNA
lab. Sean Rogers kindly allowed me access to his lab for PCR amplification and sample
preparation for sequencing. Mason Kulbaba and Stevi Vanderzwan provided helpful
assistance at the PCR lab. Larry Powell, Jordan Mallon, and Sian Wilson offered
insightful discussions on morphometrics. Jason Anderson allowed me access to his lab
and the micro CT-scanner under his care. Jason Pardo and Alex Tinius provided technical
assistance with the use of the CT-scanner and the software AMIRA. Summer Yalda and
Tasha Cammidge helped CT-scan some of the specimens studied and Shanna Walkert
assisted with processing of the reconstructed images.
I also appreciate the assistance provided Benoit Thériault and Sarah Prower who
facilitated access to documentation on the Bluefish Caves on file at the Archives of the
Canadian Museum of History. Ariane Burke and Lauriane Bourgeon kindly allowed me
to study specimens from Bluefish Caves that were temporarily on loan at the Université
de Montréal. Andrew Nelson, University of Western Ontario, CT-scanned equid
mandibles from the Wally’s Beach site. I extend my gratitude to Chris Jass, Royal
Alberta Museum, for allowing me to occasionally take time off work to finish writing this
dissertation and for many stimulating discussions.
This research was supported by a scholarship from the Consejo Nacional de
Ciencia y Tecnología de México (CONACYT scholarship No. 310423), a Graduate
Student Research Grant from the Geological Society of America, scholarships from the
University of Calgary (Eyes High Leadership Doctoral Scholarship, Eyes High
International Doctoral Scholarship, Chancellor’s Challenge Graduate Scholarship,
Graeme Bell and Norma Kay Sullivan-Bell Graduate Scholarship in Biology, and Dr.
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Anthony P. Russell Distinguished Faculty Achievement Graduate Scholarship in
Zoology), and a Natural Sciences and Engineering Research Council of Canada (NSERC)
Discovery Grant to Jessica Theodor.
I extend a special thank you to Mr. Salvatore Schillaci, my eight grade science
teacher, for fostering my passion for paleontology and to my friend Jesús for the many
useful discussions about my research and help in navigating the unexpected
circumstances that came up along the way.
Last, but definitely not least, I would like to express my gratitude to my family for
their constant love and support. My parents, Raúl and Graciela, have always encouraged
me to follow my dreams and over the course of this dissertation they provided me with
moral and sometimes technical support (thank you Dad for your help with MATLAB).
My sisters, Jaqueline and Lupita, have been cheering me on from the beginning. Finally, I
specially want to thank my wife, Liz, for taking this journey with me—I love you.
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Dedication
For my parents and my wife,
Gracias por su constante apoyo y amor
And for Christina,
¡Lo lograste!
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Table of contents
Abstract .…..…………………………………………………………………………………i
Acknowledgments ................................................................................................................. iii
Dedication . ........................................................................................................................... vi
Table of contents .................................................................................................................. vii
List of Tables ..........................................................................................................................x
List of Figures ..................................................................................................................... xiii
List of Abbreviations ......................................................................................................... xvii
Chapter 1. Introduction ..........................................................................................................1
1.1 The Pleistocene epoch and the Wisconsinan glacial stage ...........................................3
1.2 Non-analog communities and Wisconsinan paleoenvironments ..................................6
1.3 The late Pleistocene megafaunal extinction in North America ....................................9
1.4 Dissertation Chapters and Objectives .........................................................................15
1.5 Literature Cited ...........................................................................................................17
Chapter 2. Determination of equid species in the late Pleistocene of the Western Interior
of North America: A molecular and morphometric analysis of the cheek tooth
dentition ..................................................................................................................29
2.1 Introduction ................................................................................................................29
2.1.1 Northeastern Mexico: San Josecito Cave and Cedral fossil sites ....................32
2.1.2 The American Southwest: New Mexico, western Texas and northern
Chihuahua, Mexico ..........................................................................................34
2.1.3 Natural Trap Cave, Wyoming ..........................................................................38
2.1.4 Alberta, Canada: the Edmonton area gravel pits and Wally’s Beach site........39
2.1.5 Eastern Beringia: Bluefish Caves ....................................................................39
2.2 Materials and Methods ...............................................................................................44
2.2.1 Linear morphometrics ......................................................................................46
2.2.2 Geometric morphometrics of the occlusal enamel pattern ..............................51
2.2.3 Mitochondrial ancient DNA.............................................................................59
2.3 Results ........................................................................................................................63
2.3.1 Linear morphometrics ......................................................................................63
2.3.2 Geometric morphometrics of the enamel pattern of upper premolars .............97
2.3.3 Geometric morphometrics of the enamel pattern of lower premolars ...........106
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2.3.4 Mitochondrial aDNA .....................................................................................115
2.4 Discussion.................................................................................................................122
2.4.1 Interpretation and synthesis of morphometric and molecular analyses .........122
2.4.2 Taxonomic nomenclature of late Pleistocene equids from the Western
Interior of North America ..............................................................................126
2.5 Conclusions ..............................................................................................................134
2.6 Literature Cited .........................................................................................................135
Chapter 3. Dental microwear and mesowear in late Pleistocene equids and bison: testing
predictions of nutritional extinction models .........................................................148
3.1 Introduction ..............................................................................................................148
3.2.1 The coevolutionary disequilibrium extinction model.....................................150
3.2.2 The mosaic-nutrient extinction model ...........................................................152
3.2.3 Nutritional stress ............................................................................................154
3.3 Limitations and Assumptions ...................................................................................154
3.4 Materials and Methods .............................................................................................158
3.4.1 Analysis of dental wear ..................................................................................161
3.5 Results ......................................................................................................................171
3.5.1 Microwear ......................................................................................................171
3.5.2 Mesowear .......................................................................................................179
3.6 Discussion.................................................................................................................188
3.6.1 Diets of late Pleistocene equids and bison .....................................................197
3.7 Conclusions ..............................................................................................................199
Chapter 4. Enamel hypoplasia in late Pleistocene equids and bison: insights into early
systemic stress of two herbivorous mammals.......................................................216
4.1 Introduction ..............................................................................................................216
4.1.1 Tooth development and enamel hypoplasia ...................................................218
4.2 Limitations and Assumptions ...................................................................................222
4.3 Materials and Methods .............................................................................................223
4.4 Results ......................................................................................................................236
4.5 Discussion.................................................................................................................243
4.6 Conclusions ..............................................................................................................249
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Chapter 5. Conclusions ......................................................................................................262
Appendix.…………………………………………………………………………………274i
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List of Tables
Table 2.1. Eigenvalues, percentage variance, and factor loadings for the principal
components resulting from PCA of the linear measurements of the upper teeth. ........ 84
Table 2.2. Eigenvalues, percentage variance, and factor loadings for the principal
components resulting from PCA of the linear measurements of the lower teeth. ........ 84
Table 2.3. Results of Shapiro-Wilk test for normal distribution of principal component 1
scores for each tooth category from Cedral and San Josecito Cave, Mexico.. ............. 95
scores for each tooth category from the American Southwest.. ................................... 95
scores for each tooth category from Natural Trap Cave, Wyoming.. ........................... 96
scores for each tooth category from the Edmonton area and Wally’s Beach, Alberta..96
scores for each tooth category from Bluefish Caves, Yukon........................................ 97
Table 2.8. Eigenvalues, percentage variance, and cumulative percentage variance of the
first five Canonical Variates resulting from CVA of 24 landmark coordinates of the
occlusal enamel pattern of the upper premolars (P3/P4). ............................................. 99
Table 2.9. Procrustes distances among groups for the upper premolars.. .......................... 104
Table 2.10. P-values from permutation tests (10,000 permutation rounds) for Procrustes
distances among groups for the upper premolars.. ..................................................... 105
first five Canonical Variates resulting from CVA of 50 semilandmark coordinates of
the double knot (metaconid-metastylid-entoconid complex) of the lower premolars
(p3/p4). ........................................................................................................................ 108
Table 2.12. Procrustes distances among groups for the lower premolars.. ........................ 113
distances among groups for the lower premolars.. ..................................................... 114
Table 2.14. Ancient DNA extraction and amplification success rate by locality.. ............ 118
Table 2.15. Summary of the results of the morphometric analyses of the cheek tooth
dentition and the Bayesian phylogenetic analyses of mitochondrial aDNA............... 133
x
Table 3.1. Summary statistics of microwear variables of late Pleistocene equid and bison
samples studied.. ......................................................................................................... 173
Table 3.2. Results of NP-MANOVA tests (10,000 replications and using the Mahalanobis
distance measure) used to evaluate the hypotheses of the coevolutionary
disequilibrium extinction model. ................................................................................ 174
Table 3.3. Results of bootstrap statistical analyses conducted to test the hypotheses of the
mosaic-nutrient extinction model using four counted microwear variables. .............. 175
Table 3.4. Summary statistics of microwear variables of late Pleistocene equid and bison
samples studied following the methodology of Solounias and Sembrebon (2002).. .. 176
Table 3.5. Results of discriminant function analysis (DFA) of the Solounias and
Semprebon (2002) microwear dataset of extant ungulate species.. ............................ 177
Table 3.6. Classification functions derived from a discriminant function analysis of the
microwear data of extant ungulate species published by Solounias and Semprebon
(2002), assuming equal prior classification probabilities for all dietary groups......... 177
Table 3.7. Classification posterior probabilities of the samples studied based on a
discriminant function analysis of the microwear data of extant ungulates published
by Solounias and Semprebon (2002), assuming equal prior classification
probabilities for all dietary groups. ............................................................................. 178
Table 3.8. Summary statistics of the mesowear variables of late Pleistocene equid and
bison samples studied.. ............................................................................................... 181
Table 3.9. Results of Kruskall-Wallis tests used to evaluate the hypotheses of the
coevolutionarty disequilibrium extinction model using the mesowear score ............. 182
Table 3.10. Results of bootstrap statistical analyses conducted to test the hypotheses of
the mosaic-nutrient extinction model using the mesowear score. .............................. 183
Table 3.11. Results of discriminant function analysis (DFA) of the dataset of extant
ungulates published by Fortelius and Solounias (2000), with the exclusion of the
minute abraded brachydont species and species with a sample size lower than ten
specimens.. .................................................................................................................. 184
mesowear data of extant ungulate species published by Fortelius and Solounias
(2000), assuming equal prior classification probabilities for all dietary groups......... 184
Table 3.13. Classification posterior probabilities of the equid and bison samples studied
based on a discriminant function analysis of the mesowear data of extant ungulate
species published by Fortelius and Solounias (2000), assuming equal prior
classification probabilities for all dietary groups. ....................................................... 185
xi
Table 4.1. Summary statistics of enamel hypoplasia data for the equid and bison samples
studied.. ....................................................................................................................... 238
Table 4.2. Results of one-tailed Z-tests of proportions used to determine whether the
incidence of enamel hypoplasia significantly increased during the postglacial relative
to the previous time interval(s).. ................................................................................. 240
Table 4.3. Results of one-tailed bootstrap t-tests to determine whether the number of
stress events per affected specimen increased during the postglacial relative to the
previous time interval(s).. ........................................................................................... 242
xii
List of Figures
Figure 1.1. Global chronostratigraphical correlation table for the last 2.7 million years
showing the paleomagnetic record, marine isotope stages, and North American
stages. .............................................................................................................................. 5
Figure 1.2. Generalized vegetation formations of North America during the Last Glacial
Maximum (A) and the Holocene (B). ............................................................................. 8
Figure 1.3. Important events during the terminal Pleistocene in North America.. .............. 14
Figure 2.1. Geographic location of the fossil localities considered in this study. ............... 43
Figure 2.2. Upper (A) and lower (B) fourth premolars showing the dental structures
referred to in the text, based on the dental nomenclature of Evander (2004)... ............ 45
Figure 2.3. Lower (A and B) and upper (C and D) third premolars showing the
measurements that were taken with a caliper for upper and lower cheek teeth... ......... 49
Figure 2.4. Occlusal surface of a P3 (LACM 192/18109) showing the landmarks used in
the analysis. ................................................................................................................... 55
Figure 2.5. Digitized double knot of a lower p4 (KU 50629) showing the 50
semilandmarks used in the analysis. ............................................................................. 57
Figure 2.6. Plot of principal components for P2 specimens.. .............................................. 66
Figure 2.7. Plot of principal components for P3/P4 specimens.. ......................................... 67
Figure 2.8. Plot of principal components for M1/M2 specimens.. ...................................... 68
Figure 2.9. Plot of principal components for M3 specimens.. ............................................. 69
Figure 2.10. Plot of principal components for p2 specimens.. ............................................ 70
Figure 2.11. Plot of principal components for p3/p4 specimens.. ....................................... 71
Figure 2.12 Plot of principal components for m1/m2 specimens.. ...................................... 72
Figure 2.13. Plot of principal components for m3 specimens.. ........................................... 73
Figure 2.14. Principal component plots showing upper teeth from Cedral and San Josecito
Cave, Mexico.. .............................................................................................................. 74
Figure 2.15. Principal component plots showing lower teeth from Cedral and San Josecito
Cave, Mexico. ............................................................................................................... 75
Figure 2.16. Principal component plots showing upper teeth from the American
Southwest.. .................................................................................................................... 76
xiii
Figure 2.17. Principal component plots showing lower teeth from the American
Southwest.. .................................................................................................................... 77
Figure 2.18. Principal component plots showing upper teeth from Natural Trap Cave,
Wyoming....................................................................................................................... 78
Figure 2.19. Principal component plots showing lower teeth from Natural Trap Cave,
Wyoming....................................................................................................................... 79
Figure 2.20. Principal component plots showing upper teeth from the Edmonton area and
Wally’s Beach, Alberta.. ............................................................................................... 80
Figure 2.21. Principal component plots showing lower teeth from the Edmonton area and
Wally’s Beach, Alberta.. ............................................................................................... 81
Figure 2.22. Principal component plots showing upper teeth from Bluefish Caves, Yukon.
....................................................................................................................................... 82
Figure 2.23. Principal component plots showing lower teeth from Bluefish Caves, Yukon.
....................................................................................................................................... 83
Figure 2.24. Histograms showing the distribution of PC 1 scores of upper teeth from
Cedral and San Josecito Cave, Mexico. ........................................................................ 85
Figure 2.25. Histograms showing the distribution of PC 1 scores of lower teeth from
Cedral and San Josecito Cave, Mexico. ........................................................................ 86
different localities of the American Southwest. ............................................................ 87
different localities of the American Southwest. ............................................................ 88
Natural Trap Cave, Wyoming. ...................................................................................... 89
Natural Trap Cave, Wyoming. ...................................................................................... 90
Figure 2.30. Histograms showing the distribution of PC 1 scores of upper teeth from the
Edmonton area and Wally’s Beach, Alberta. ................................................................ 91
Figure 2.31. Histograms showing the distribution of PC 1 scores of lower teeth from the
Edmonton area and Wally’s Beach, Alberta. ................................................................ 92
Bluefish Caves, Yukon. ................................................................................................ 93
xiv
Bluefish Caves, Yukon. ................................................................................................ 94
Figure 2.34. Plot of the first two Canonical Variates resulting from CVA of 24 landmark
coordinates of the occlusal enamel pattern of the upper premolars (P3/P4)............... 100
Figure 2.35. Plot of the first and third Canonical Variates resulting from CVA of 24
landmark coordinates of the occlusal enamel pattern of the upper premolars
(P3/P4)... ..................................................................................................................... 102
Figure 2.36. Plot of the first two Canonical Variates resulting from CVA of the
semilandmarks of the double knot (metaconid-metastylid-entoconid complex) of the
lower teeth.. ................................................................................................................. 109
Figure 2.37. Plot of the first and third Canonical Variates resulting from CVA of the
semilandmarks of the double knot (metaconid-metastylid-entoconid complex) of the
lower teeth.. ................................................................................................................. 111
Figure 2.38. Consensus tree of Bayesian (Markov chain Monte Carlo) phylogenetic
analysis displaying relationships between mitochondrial control region (HVR 1)
haplotypes of extinct and extant equids constructed using 583 bp fragments of the
HVR I.. ........................................................................................................................ 119
HVR I.. ........................................................................................................................ 120
HVR I.. ........................................................................................................................ 121
Figure 3.1. Geographic location of the fossil sites considered in this study. ..................... 161
Figure 3.2. High dynamic range image of the postfossette lingual enamel band (upper
M2) of an equid tooth showing one of the 0.4 X 0.4 mm counting areas................... 168
Figure 3.3. Buccal view of the apices of three equid upper cheek teeth showing the
different cusps morphologies examined with the mesowear method.. ....................... 170
Figure 3.4. Average mesowear score for the late Pleistocene bison and equid samples
studied and extant ungulate species reported in Kaiser et al. (2013)... ....................... 186
Figure 4.1. A) Diagram of a human molar cross section showing perikymata, striae of
Retzius, and cross-striations. B) Microphotograph of imbricational enamel.. ........... 221
Figure 4.2. Different types of enamel hypoplasia.. ............................................................ 222
xv
Figure 4.3. Geographic location of the fossil sites considered in this study. ..................... 233
Figure 4.4. The timing of tooth mineralization of the dentary cheek tooth dentition in
modern horses (Equus ferus caballus), based on data reported by Hoppe et al.
(2004).. ........................................................................................................................ 234
modern bison (Bison bison), based on data reported by Niven et al. (2004). ............. 234
Figure 4.6. Example of CT-scan data that was used to determine the presence of enamel
hypoplasia in three equid mandibles from Wally’s Beach, Alberta. .......................... 235
Figure 4.7. Incidence of enamel hypoplasia in the equid and bison samples studied.. ...... 239
Figure 4.8. Mean number of hypoplastic events per affected specimen in the equid and
bison samples studied.. ............................................................................................... 241
xvi
List of Abbreviations
Institutional Abbreviations
CMH
INAH
KU
LACM
RAM
TMM
UTEP
Canadian Museum of History
Instituto Nacional de Antropología e Historia
University of Kansas
Los Angeles County Museum of Natural History
Royal Alberta Museum
Vertebrate Paleontology Laboratory, University of Texas at Austin.
University of Texas at El Paso
Fossil localities
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
Q
R
S
U
V
X
W
Algerita Blossom Cave, New Mexico, U. S. A.
Bluefish Caves, Yukon Territory, Canada
Cedral, San Luis Potosí, Mexico
Dry Cave, New Mexico, U. S. A.
Edmonton area gravel pits, Alberta, Canada
Fresnal Canyon, New Mexico, U. S. A.
Highway 45, Chihuahua, Mexico
Nash Draw, New Mexico, U. S. A.
Isleta Cave No. 2, New Mexico, U. S. A.
San Josecito Cave, Nuevo León, Mexico
Dark Canyon Cave, New Mexico, U. S. A.
Blackwater Draw Loc. 1, New Mexico, U. S. A.
Big Manhole Cave, New Mexico, U. S. A.
Natural Trap Cave, Wyoming
Lubbock Lake site, Texas, U. S. A.
Quitaque Creek, Texas, U. S. A.
Scharbauer Ranch, Texas, U. S. A.
Salt Creek, Texas, U. S. A.
U-Bar Cave, New Mexico, U. S. A.
Villa Ahumada, Chihuahua, Mexico
El Barreal, Chihuahua, Mexico
Wally’s Beach site, Alberta, Canada
Statistical abbreviations
CVA
PCA
MANOVA
Canonical Variate Analysis
Principal Component Analysis
Multivariate Analysis of Variance
xvii
CHAPTER 1. INTRODUCTION
The late Pleistocene was a dynamic time in Earth’s history. The planet experienced major
climatic and biological changes, which played a significant role in shaping current
biodiversity patterns (Koch and Barnosky, 2006; Hofreiter and Stewart, 2009).
Approximately 50,000 – 11,000 cal BP (calibrated radiocarbon years before the present)
many species around the world suffered extinctions or were extirpated at a continental
scale (Koch and Barnosky, 2006). In North America south of the ice sheets, the vast
majority of the extinctions and extirpations may have occurred as a synchronous event
during the terminal Pleistocene, approximately 13,800 – 11,400 cal BP (Faith and
Surovell, 2009). Horses, mammoths, and saber-tooth cats are examples of some of the
mammals that disappeared from the continent during the late Pleistocene extinction,
which represents the second most severe extinction event in North America in the past 55
million years (Alroy, 1999). There were survivors of course, such as bison and whitetailed deer, but the continent was left with a much lower diversity (Stuart, 2015).
Notably, the late Pleistocene extinction primarily affected large animals, referred to in the
literature as megafauna (animals with a body mass ≥ 44 kg), and species with low
reproductive rates, regardless of body size (Johnson, 2002; Koch and Barnosky, 2006).
Mammals were among the most adversely affected groups and it is estimated that over 30
genera disappeared from North America, including approximately 70 % of the
continent’s megafauna (Grayson, 1991, 2007; Koch and Barnosky, 2006; Faith and
Surovell, 2009; Stuart, 2015). South America and Australia were also hard hit and it is
estimated that over 80 % of the megafaunal genera in these continents went extinct; 52
1
genera in South America and 14 in Australia (Koch and Barnosky, 2006; Barnosky and
Lindsey, 2010).
The late Pleistocene extinction roughly coincided with environmental changes
associated with the most recent glacial-interglacial transition and/or with the dispersal (or
population increases) of anatomically modern humans, Homo sapiens sapiens (Barnosky
et al., 2004; Koch and Barnosky, 2006). Thus, some extinction models identify climate
change as the primary causal factor (e.g., Kiltie, 1984; King and Saunders, 1984; Graham
and Lundelius, 1984; Guthrie, 1984; Barnosky, 1986; Ficcarelli et al., 2003; Forster,
2004; Scott, 2010), while others place a greater emphasis on overhunting (e.g., Martin,
1967, 1984; Mosimann and Martin, 1975) or a combination of slow hunting rates and
habitat alteration by early human populations (e.g., Diamond, 1989). A third set of
extinction models invokes catastrophic events, such as a bolide impact (Firestone et al.,
2007) or a hyperdisease (MacPhee and Marx, 1997).
Despite decades of research, the cause or causes for the late Pleistocene extinction
continue to be unresolved. One important problem with late Pleistocene extinction
models is that they have yet to connect particular variables with particular species in
convincing ways. In order to better understand extinction mechanisms some researchers
have suggested that comprehensive species-by-species analyses are required (Grayson
and Meltzer 2003; Koch and Barnosky, 2006; Grayson, 2007). On that account, this
dissertation investigates late Pleistocene equid and bison specimens from different
localities along the Western Interior of North America, with the objective of testing
assumptions and predictions formulated for two climate-based extinction models. In order
to accomplish this task, it was necessary to determine the number of equid species that
2
inhabited this region of North America during the late Pleistocene, using morphological
and mitochondrial ancient DNA data derived from the cheek tooth dentition. To begin
this discussion, I present a brief overview of Pleistocene glaciations, non-analog
ecological communities, and the late Pleistocene extinction in North America.
1.1
The Pleistocene epoch and the Wisconsinan glacial stage
The Pleistocene is the penultimate epoch in the geologic time scale; it preceded the
Holocene epoch, in which we live, and occurred after the Pliocene epoch (Figure 1.1).
The lower boundary of the Pleistocene is currently placed at approximately 2.6 million
years ago (Ma) and the upper boundary is considered at 10,000 yr RCBP (radiocarbon
years before the present) or 11,700 cal BP (calibrated radiocarbon years before the
present) (Walker et al., 2009, Gibbard et al., 2010).
The Pleistocene is characterized by great climatic oscillations at different
amplitudes that gave rise to several glacial and interglacial periods. Traditionally, four or
five glacial periods have been identified for North America (Boellstorff, 1978; Roy et al.,
2006). Currently several additional glacial periods are recognized (Gibbard and Cohen,
2008), each marking a cooling event and an expansion of the polar and mountain ice
sheets over the continent. Each of these glacial periods is separated by intervals of
warmer temperatures, similar to the present day, known as interglacials. Moreover, within
each glacial and interglacial there were short term climatic fluctuations. Brief cooling
events are termed stadials or stades, whereas short periods of warm temperatures are
known as interstadials or interstades. The last glacial period started approximately
100,000 yr RCBP and ended roughly 10,000 yr RCBP and is called, in North America,
3
the Wisconsin or Wisconsinan stage (Johnson et al. 1997). This stage is bracketed by the
Sangamonian interglacial and the Holocene epoch (Figure 1.1). The Wisconsinan
contained several interstadials and stadials (Johnson et al. 1997). The last maximum
extent of the ice sheets over the continents is known as the Last Glacial Maximum
(LGM); this terminated around 18,000 cal BP (Denton et al. 2010). These cycles of
warming and cooling events were the climatic setting in which the fauna of the
Pleistocene, including modern humans, evolved.
4
Figure 1.1. Global chronostratigraphical correlation table for the last 2.7 million years
showing the paleomagnetic record, marine isotope stages, and North American stages;
time scale is in millions of years (Ma) (Modified from Gibbard and Cohen, 2008).
5
1.2
Non-analog communities and Wisconsinan paleoenvironments
Beside the great climatic fluctuations, the Pleistocene differs from the Holocene epoch in
regard to the composition of biological communities; this is true even for species that did
not become extinct at the end of the Pleistocene. During both glacial and interglacial
periods, Pleistocene communities around the world show an unusual association of plants
and animals, many of which today are only found in allopatry (e.g., Graham, 1985a,b;
Williams and Jackson, 2007; Stewart, 2008). For example, Wisconsinan assemblages in
the mid-Appalachian region show a mixture of tropical species such as tapir (Tapirus cf.
veroensis) and jaguar (Panthera onca) alongside subarctic species such as caribou
(Rangifer tarandus) (Guilday, 1984). These types of associations have been referred to as
disharmonious, intermingled, mixed, and non-analog communities (Semken et al., 2010).
When first observed in the fossil record, non-analog communities were thought to
be the result of mixing of deposits of different ages (Grayson, 1984); however, several
studies have demonstrated that many of these associations represented actual ecological
communities (e.g., Grayson, 1984; Graham, 1985a,b; Williams and Jackson, 2007;
Stewart, 2008; Semken et al., 2010). Different explanations for non-analog communities
have been proposed (e.g., Kerney, 1963; Coope and Angus, 1975; Bramwell, 1984;
Graham and Grimm, 1990; Graham et al., 1996; Stafford et al., 1999), but the most
widely accepted is that populations of species respond individualistically to climate
change and not as part of communities (Graham, 1985a,b; Graham et al., 1996). The
individualistic response of species results in mixing of biotas in each subsequent climatic
oscillation. This process can potentially have important implications for evolutionary
ecology, especially in regard to processes such as diffuse coevolution and character
6
displacement (Stewart, 2009). Some climate-based extinction models, such as
coevolutionary disequilibrium (Graham and Lundelius, 1984) and mosaic-nutrient
(Guthrie, 1984) models draw upon the individualistic response of plant species to climate
change to present plausible mechanisms for the late Pleistocene extinction. These models
are discussed further in the next section.
The unusual association of extant plants and animals along with the species that
became extinct made North American ecosystems, and those in other parts around the
world, look quite different from how they are today (Figure 1.2). During the LGM,
Beringia (i.e., Alaska, parts of the Yukon, and eastern Siberia) and an area of several
kilometres south of the ice sheets, were covered by a complex mixture of tundra and
steppe elements that has come to be known as the mammoth steppe (McDonald, 1984;
Guthrie, 2001). The mammoth steppe at this time is reconstructed as a cold, windy, and
dry habitat (Szpak et al., 2010) in which the dominant large herbivores were woolly
mammoth (Mammuthus primigenius), horse (Equus ferus) and bison (Bison priscus),
together with other ungulates such as caribou (Rangifer tarandus) and helmeted
muskoxen (Bootherium bombifrons) (Guthrie, 2001). The Great Plains consisted
primarily of woodland and forested areas where the abundant large herbivores were
different species of equids (Equus spp.), Columbian mammoth (Mammuthus columbi),
bison (Bison antiquus), and camels (e.g., Camelops hesternus) (Graham, 1986; Wells and
Stewart, 1987). The currently dry American Southwest was more mesic during the LGM
and supported, in addition to the large herbivores found in the Great Plains, significant
populations of ground sloths (e.g., Nothrotheriops shastensis) in a woodland/shrubland
habitat (Harris, 1989). The eastern part of North America south of the ice sheets consisted
7
primarily of coniferous forest and a mixed forest with deciduous elements to the
southeast (McDonald, 1984). Mastodon (Mammut americanum) was one of the most
abundant large herbivores that roamed these forested areas, along with tapir (Tapirus
veroensis) and white-tailed deer (Odocoileus virginianus) (Graham, 1986, Webb and
Simons, 2006). The presence of equids, mammoth, and bison, though not as common as
in other regions of the continent (the ratio of mastodon to mammoth is approximately 4:1
[Webb and Simons, 2006]), indicates that these forests where not as closed as those found
during the Holocene.
A
B
Figure 1.2. Generalized vegetation formations of North America during the Last Glacial
Maximum (A) and the Holocene (B) (Modified from McDonald, 1984).
8
1.3
The late Pleistocene megafaunal extinction in North America
The late Pleistocene extinction is the second largest extinction event in North America in
the past 55 million years (Alroy, 1999). This extinction event is also remarkable because
it is strongly biased towards large (i.e., body mass ≥ 44 kg) as well as slow-breeding
animals (Johnson, 2002; Koch and Barnosky, 2006). Mammals were among the most
adversely affected groups and it is estimated that over 30 genera disappeared from North
America, including approximately 70 % of the continent’s megafauna (Grayson, 1991,
2007; Koch and Barnosky, 2006; Faith and Surovell, 2009; Stuart, 2015). In North
America south of the ice sheets the late Pleistocene extinction roughly coincided with
environmental changes associated with the most recent glacial-interglacial transition and
the arrival of humans (Figure 1.3) (Barnosky et al., 2004; Koch and Barnosky, 2006).
Some studies suggest that the extinction was a synchronous event that occurred
approximately 12,000 – 10,000 yr RCBP (~13,800 – 11,400 cal BP) (Faith and Surovell,
2009). Recent genetic evidence indicates that the population which gave rise to all Native
Americans (with the exclusion of Eskimo-Aleuts who dispersed later during the
Holocene) diverged from East Asian ancestors during the LGM, no earlier than ~23,000
cal BP, and possibly remained isolated in Siberia or Beringia for~8,000 cal BP
(Raghavan et al., 2015). This group of people is thought to have spread into the midcontinent, south of the continental ice sheets, sometime after ~16,500 cal BP, probably
dispersing along the recently deglaciated Pacific coastline (Goebel et al., 2008).
In eastern Beringia (unglaciated Alaska and the Yukon Territory) the extinction
appears to have been a two pulse event, with the extirpation of some warm-adapted
species (e.g., stilt-legged horses, camels, mastodons, and short-faced bears) before the
9
LGM, approximately 20,000 – 50,000 yr RCBP (Barnes et al., 2002; Guthrie, 2003,
2006; Zazula et al., 2014). The disappearance of these mammals occurred apparently in
the absence of human populations, as it pre-dates any undisputable archaeological sites in
eastern Beringia (Goebel et al., 2008) as well as the divergence times mentioned above
based on modern and ancient human genetic data (Raghavan et al., 2015). Most coldadapted megafauna characteristic of the mammoth steppe (e.g., woolly mammoths,
caballoid horses, and helmeted muskoxen) disappeared from eastern Beringia
approximately 12,000 – 9,000 yr RCBP (Barnosky et al., 2004).
The causes of the late Pleistocene megafaunal extinction have been extensively
debated and several extinction models have been proposed. Some models identify climate
change as the primary causal factor (e.g., Kiltie, 1984; King and Saunders, 1984; Graham
and Lundelius, 1984; Guthrie, 1984; Barnosky, 1986; Ficcarelli et al., 2003; Forster,
2004; Scott, 2010), while others place a greater emphasis on overhunting (e.g., Martin,
1967, 1984; Mosimann and Martin, 1975; Belovsky, 1988) or a combination of slow
hunting rates and habitat alteration by early human populations (e.g., Diamond, 1989). A
third set of extinction models invokes catastrophic events, such as a bolide impact
(Firestone et al., 2007) or a hyperdisease (MacPhee and Marx, 1997).
Currently, there is weak support for the catastrophic extinction models (e.g.,
Lyons et al., 2004; Koch and Barnosky, 2006; Surovell et al., 2009; Holliday et al., 2014;
Meltzer et al., 2014) and much of the debate regarding the late Pleistocene extinction has
focused on the relative importance of climate change versus human hunting. Under
overhunting (more commonly known as overkill) extinction models, prey species go
extinct because hunting, in addition to deaths from natural causes, result in death rates
10
exceeding birth rates. Probably the most debated and tested of the overkill extinction
models is the blitzkrieg model (Martin, 1967, 1973,1984; Mosimann and Martin, 1975).
The mode of extinction depicted in the blitzkrieg model is the active and intensive
hunting of large herbivores by expanding populations of anatomically modern humans,
with extinction occurring within 500 or 1000 years after human contact (Martin, 1973;
Mosimann and Martin, 1975). It is proposed that the intense hunting resulted in a drastic
decline in large herbivore populations, triggering their extinction and, as a consequence,
fostering the concomitant extinction of large carnivores and scavengers that depended on
them for survival (Martin, 1984). The blitzkrieg overkill model has been rejected on the
basis of simulation studies that have employed optimal foraging theory as well as
archaeological evidence which suggest that humans were present in North America
thousands of years before the megafaunal extinction (Koch and Barnosky, 2006).
Other overkill extinction models propose a more protracted extinction of
megafauna through the agency of human populations who did not exclusively target large
herbivores, but rather had more omnivorous diets. In these models human populations
take large herbivores when encountered, but otherwise are sustained by fast-breeding
“fall-back” prey such as small animals and plants (Belovsky, 1988; Alroy, 2001). Other
extinction models have proposed that the killing might have been done slowly and
primarily by indirect means, such as the burning and alteration of natural habitats, in
addition to lower intensity hunting (“sitzkrieg”) (e.g., Diamond, 1989), or the
overhunting of keystone species (Owen-Smith, 1987).
Climate change has also been suggested to be the most important factor in the late
Pleistocene extinction. Oxygen isotope records from ice-cores in Greenland (e.g., Alley,
11
2000), tropical corals (e.g., Guilderson et al., 2001), and deep sea sediments (e.g., Hodell
et al., 2010) show drastic climatic fluctuations during the terminal Pleistocene. At about
the same time, the fossil record shows significant reorganization of the flora and fauna
throughout North America and in many regions around the world (Graham et al., 1996).
Moreover, the fossil record demonstrates that species responded individualistically to
these climatic changes and not as part of communities (Graham et al. 1996, Stewart,
2009). There are different models that try to explain how climate-induced vegetation
changes may have been the driving force behind the late Pleistocene extinction, including
habitat loss (e.g., King and Saunders, 1984; Barnosky, 1986; Ficcarelli et al., 2003),
coevolutionary disequilibrium (Graham and Lundelius, 1984), and the mosaic-nutrient
model (Guthrie, 1984). Both coevolutionary disequilibrium and mosaic-nutrient models
draw upon the individualistic response of plant species to climate change to present a
plausible scenario whereby nutritional stress is considered one of the primary drivers of
extinction.
The coevolutionary disequilibrium model (Graham and Lundelius, 1984) assumes
that Pleistocene mammals partitioned available food resources through well-defined
niche differentiation. It is further proposed that climate-induced environmental changes
towards the end of the Pleistocene restructured vegetation patterns, resulting in
coevolutionary disequilibrium, which caused a reduction in niche differentiation,
increased competition, and resulted in the extinction of several species (Graham and
Lundelius, 1984). Alternatively, the mosaic-nutrient model (Guthrie, 1984) suggests that
the mosaic vegetation pattern present throughout the Pleistocene allowed ungulates,
especially large hindgut fermenters (e.g., horses and mammoths), to obtain the right mix
12
of nutrients needed for survival. This model proposes that the shift from a mosaic
vegetation pattern to a more zonal, low diversity, vegetation pattern during the terminal
Pleistocene had a detrimental effect, particularly on the hind-gut fermenters (Guthrie,
1984). Thus, the coevolutionary disequilibrium model emphasizes competition for food
resources between species, whereas the mosaic-nutrient model highlights constraints
imposed on organisms by specific nutritional requirements.
Some researchers believe that human impacts, such as hunting and perhaps habitat
alteration, were crucial in precipitating the late Pleistocene extinction, but that climate
change also played an important role in determining the spatial and temporal expression
and impact of this extinction event (Barnosky et al., 2004). This seems plausible for the
Americas where the three events (climate change, first appearance of humans, and
extinction) largely overlap (Barnosky et al. 2004). If this was indeed the case, the relative
contribution of climate change versus human impacts remains to be determined. Were
large mammals experiencing significant stress as a result of environmental changes
during the terminal Pleistocene at the time humans entered the continent? This is one of
the questions that this research seeks to investigate, focusing specifically on equid and
bison species.
13
Figure 1.3. Important events during the terminal Pleistocene in North America.
Temperature is plotted against age in calibrated radiocarbon years before the present,
derived from oxygen isotope records from Greenland ice-cores (data from Alley, 2000).
The blue shaded overlay indicates the Last Glacial Maximum (LGM) (Denton, 2010).
The solid line represents the oldest reliable archaeological sites in North America
(Goebel et al., 2008). The estimated time of extinction for most megafauna south of the
Canadian ice sheets (Faith and Surovell, 2009) is indicated by the red shaded overlay.
14
1.4
Dissertation Chapters and Objectives
This dissertation aims to provide new insights into two contentious areas of Quaternary
paleontology: the systematics of North American late Pleistocene equids and the late
Pleistocene extinction. It is comprised of three quantitative studies, each one representing
a separate chapter. The first study (Chapter 2) has the objective of determining the
number of equid species that inhabited the Western Interior of North America during the
late Pleistocene. More than 40 species of North American Pleistocene equids have been
named (Winans, 1985). Despite several attempts at revising the taxonomy of this group
(e.g., Gidley, 1901; Savage, 1951; Hibbard, 1955; Dalquest, 1978, 1979; Winans, 1985,
1989; Azzaroli, 1995, 1998), there is still considerable disagreement on the number of
species that inhabited the continent and on the taxonomic nomenclature employed. Using
morphological and molecular data derived from the cheek tooth dentition, I studied equid
remains ranging from northeastern Mexico to northern Yukon Territory, Canada. The
morphological analysis consisted of measurement-based morphometrics of overall tooth
dimensions as well as geometric morphometrics of the occlusal enamel pattern. These
studies allowed the identification of morphological groups which were further assessed
by employing Bayesian phylogenetic analyses of mitochondrial ancient DNA of a subset
of specimens, integrated in a dataset with published DNA sequences of extant (e.g.,
Achilli et al., 2012) and extinct equids (e.g., Weinstock et al., 2005; Orlando et al., 2008;
Orlando et al., 2013; Vilstrup et al., 2013).
Subsequent to my identification of the equid species present during the late
Pleistocene of the Western Interior of North America, Chapters 3 and 4 focus on the
15
bison and equid species from three geographic regions: the American Southwest (eastern
New Mexico and western Texas), Alberta (Wally’s Beach Site and the Edmonton area
gravel pits), and eastern Beringia (Bluefish Caves, Yukon Territory). In Chapter 3, I
investigate two nutritional extinction models (coevolutionary disequilibrium [Graham
and Lundelius, 1984] and the mosaic-nutrient model [Guthrie, 1984]) that have been
proposed to explain the late Pleistocene extinctions by testing predictions of dental wear
patterns in bison and equid species formulated for each extinction model. Low
magnification dental microwear (Solounias and Semprebon, 2002) and extended
mesowear methods (Franz-Odendaal and Kaiser, 2003; Kaiser and Solounias, 2003) were
used to characterize dental wear at micro- and macroscopic scales.
Chapter 4 presents a study of enamel hypoplasia to permit inferences about early
physiological stress in bison and equid species during the latest Pleistocene (~50,000 –
10,000 yr RCBP). The primary objective of this study was to test whether these ungulates
experienced increased levels of systemic stress, as predicted by the two nutritional
extinction models here investigated, as well as other climate-based extinction models.
Enamel hypoplasia is a developmental tooth defect that results from a physical disruption
of the amelobasts that secrete enamel (Goodman and Rose, 1990). This defect most
commonly occurs as a result of systemic stress and results in a thinning of the enamel
(Goodman and Rose, 1990). I examined changes in the incidence of enamel hypoplasia as
well as whether the occurrence of enamel hypoplasia increased in frequency during the
terminal Pleistocene.
16
The final chapter (Chapter 5) provides a summary of the central findings of this
research, discussing some of the broader implications and outlining areas for further
study.
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CHAPTER 2. DETERMINATION OF EQUID SPECIES IN THE LATE
PLEISTOCENE OF THE WESTERN INTERIOR OF NORTH AMERICA: A
MOLECULAR AND MORPHOMETRIC ANALYSIS OF THE CHEEK
TOOTH DENTITION
2.1
Introduction
Horses were a dominant component of North American Pleistocene land mammal
communities and their remains are well represented in the fossil record (FAUNMAP,
1994). Despite the abundant material available for study, there is still considerable
disagreement over the number of species that inhabited the continent and on the
taxonomic nomenclature. More than 40 species of Equus have been named from the
Pleistocene of North America (Winans, 1985). Different authors have attempted to revise
the taxonomy of this group (e.g., Gidley, 1901; Savage, 1951; Hibbard, 1955; Dalquest,
1978, 1979; Winans, 1985, 1989; Azzaroli, 1995, 1998), but no consensus has been
reached. The morphological revisions by Winans (1985, 1989) and Azzaroli (1995,
1998), as well as the recent molecular study by Weinstock et al. (2005), exemplify the
diversity of opinions regarding the taxonomy of North American Pleistocene equids.
One of the first large-scale quantitative studies of the genus Equus in North
America was undertaken by Winans (1985, 1989). She conducted a multivariate analysis
using linear measurements of cranial and metapodial remains, identifying five
morphological groups, which she named according to the most senior type specimen
included in each group. Winans (1985) originally treated these groups as actual species,
but later referred to them as species groups, indicating that some groups may include
29
more than one species (Winans, 1989). Three of these five species groups have temporal
ranges that extend into the late Pleistocene: Equus alaskae (Hay), 1913b (small and stoutlegged species group), E. francisci Hay, 1915 (small and stilt-legged species group), and
E. laurentius Hay, 1913a (large and stout-legged species group) (Winans, 1989). The two
other species groups identified by Winans (1989) are E. simplicidens Cope, 1892 and E.
scotti Gidley, 1900.
In another study, Azzaroli (1995, 1998) identified ten taxa of Equus as being valid
for North America during the Irvingtonian and Rancholabrean North American Land
Mammal Ages (middle and late Pleistocene). He based his taxonomic assignments on a
primarily qualitative study of the morphology of the skull, dentition, and limb bones as
well as size. Nine of the species proposed to be valid by Azzaroli (1998) have been found
in late Pleistocene localities: E. ferus Boddaert, 1785, E. niobrarensis Hay, 1913a, E.
lambei Hay, 1917, E. francisci Hay, 1915, E. fraternus Leidy, 1860, E. conversidens
Owen, 1869, E. mexicanus (Hibbard), 1955, E. excelsus Leidy, 1858, and E. occidentalis
sensu Merriam, 1913. The other taxon identified by Azzaroli (1998), E. semiplicatus
Cope, 1892, is restricted to the early and middle Pleistocene.
More recently, Weinstock et al. (2005) conducted a mitochondrial ancient DNA
study and a basic analysis of metapodial dimensions of Eurasian, North American, and
South American late Pleistocene equids. These authors concluded that only two lineages
of equids were present in North America, a stout-legged (including Eurasian and modern
caballines) and a stilt-legged lineage (endemic to North America), possibly each
representing a distinct species. Weinstock et al. (2005) did not assign species names to
these two potential equid species. The geographic and temporal coverage of this study
30
was small compared to the studies by Winans (1989) and Azzaroli (1998), as it was
restricted to late Pleistocene sites located primarily in northern North America. It remains
to be seen if the pattern identified by Weinstock et al. (2005) holds for the rest of the
continent.
The contrasting views presented in the three studies summarized above highlight
the need for further investigations into the taxonomy of North American late Pleistocene
equids. The discrepancy between the results of the molecular study and the
morphological revisions is intriguing and merits further investigation. In contrast to
previous studies, here I undertake a dual approach that includes a comprehensive
morphometric analysis of the cheek teeth, using both linear and geometric
morphometrics, and a study of mitochondrial ancient DNA obtained from a subsample of
the teeth I studied. The study of the cheek teeth is important for two reasons. First, the
use of the cheek teeth has been limited in the latest morphological revisions, even though
they are well represented in the fossil record and, secondly, the dentition is one of the
skeletal elements that best preserve ancient DNA and is less susceptible to contamination
by exogenous DNA (Pilli et al., 2013), allowing the opportunity for the recovery of
molecular data for specimens from localities in southern North America. Furthermore,
elucidating the number of valid species using the cheek teeth is of particular relevance
because teeth are archives of paleobiological and paleoclimatic information. Often,
techniques used to extract this information (e.g., stable isotope analysis) are destructive
and are performed on isolated teeth, which are regularly identified only as Equus sp. (e.g.,
Connin et al., 1998; Feranec, 2004; Kohn et al., 2005; DeSantis et al., 2009; Perez-Crespo
et al., 2012), limiting the full potential of these studies. Refining the taxonomic
31
assignment of isolated cheek teeth will allow for in depth investigations into the
paleobiology and extinction of Pleistocene North American equids.
My study concentrates on fossil material retrieved from five geographic regions
approximately arranged in a north-south transect along the Western Interior of North
America, from northern Yukon Territory to northeastern Mexico (Figure 2.1). Below, I
provide a summary of research conducted on horse remains from these fossil localities
and discuss the species that have been identified. Two issues will become apparent in this
summary: the lack of consensus regarding the number of equid species that existed in
each geographic region and the confused nomenclature of Pleistocene Equus.
2.1.1
Northeastern Mexico: San Josecito Cave and Cedral fossil sites
The fossil localities of San Josecito Cave (Nuevo León) and Cedral (San Luis Potosí) are
two of the most studied late Pleistocene sites in northeastern Mexico. Stock (1950, 1953)
considered all of the horse remains from San Josecito Cave to belong to a single species
of Equus, which he thought was most similar to Equus conversidens Owen, 1869, but
with sufficient morphological differences to be identified as a new subspecies: E.
conversidens leoni. As pointed out by Dalquest (1979) and Winans (1985; 1989), Stock
did not select a type nor publish a formal description, thus, the name should be regarded
as a nomen nudum. Moreover, Winans (1985) proposed E. conversidens to be nomen
dubium, because she considered, in accordance to Hibbard (1955), that the convergence
of the cheek tooth rows toward the rostrum in the holotype (the main diagnostic character
for this species) was the result of a distorted restoration. Winans (1985, 1989) assigned
the specimens from San Josecito Cave to her species group E. alaskae (Hay), 1913b.
Contrary to Winans (1985), Azzaroli (1998) regarded E. conversidens as a valid species
32
distinct from E. niobrarensis alaskae Hay, 1913b, which he considered to be a synonym
of E. ferus Boddaert, 1785. He figured and described a partial skull from central Mexico,
in which the two tooth rows converge toward the rostrum, suggesting that the holotype of
E. conversidens was correctly mounted. In addition, Azzaroli (1998) referred the fossil
material from San Josecito Cave to E. conversidens, further stating that this species was
closely related to South American horses (Azzaroli, 1998), a relationship that has been
suggested by other researchers (e.g., Dalquest, 1978; Harris and Porter, 1980). Eisenmann
(2013a) agreed with Winans (1985) in considering the holotype of E. conversidens to be
inadequate. She indicated that the upper cheek teeth of the holotype of E. conversidens
are similar in morphology to those referred to E. semiplicatus Cope, 1893 and that
because of the lack of associated lower cheek teeth and limb bones, it is better to abolish
the use of this name for more complete material that has traditionally been referred to this
species (Eisenmann, 2013a). Eisenmann (2013a) proposed referring the specimens from
San Josecito Cave to the South American genus Amerhippus Hoffstetter, 1950, under the
name Amerhippus leoni (Eisenmann, 2013a), but a formal description has not been
published.
Three equid species have been recognized from the late Pleistocene deposits of
Cedral, San Luis Potosí, Mexico, based on differences in size (Alberdi et al., 2003;
Melgarejo-Damian and Montellano-Ballesteros, 2008; Barrón-Ortiz and Theodor, 2011;
Marin Leyva, 2011; Alberdi et al., 2014), metapodial proportions (Melgarejo-Damian and
Montellano-Ballesteros, 2008; Marin Leyva, 2011), and features of the occlusal enamel
pattern of the third and fourth upper premolars (Barrón-Ortiz and Theodor, 2011). The
large and medium-sized species have been tentatively identified as E. mexicanus
33
(Hibbard), 1955 (originally described by Hibbard [1955] as E. (Hesperohippus)
mexicanus), and E. conversidens, respectively (Alberdi et al., 2003; Melgarejo-Damian
and Montellano-Ballesteros, 2008; Marin Leyva, 2011; Alberdi et al., 2014). The
taxonomic identification of the smaller equid has been more problematic. Alberdi et al.,
(2003) originally identified it as Equus sp. A, whereas Melgarejo-Damian and
Montellano-Ballesteros (2008) assigned it to Equus tau Owen, 1869. Recently, Alberdi et
al. (2014) have designated a new species, Equus cedralensis, for this material.
2.1.2
The American Southwest: New Mexico, western Texas and northern
Chihuahua, Mexico
A number of important late Pleistocene fossil localities are known from New Mexico and
western Texas, all of which have yielded large numbers of equid specimens, including
Blackwater Draw Loc. 1, Dry Cave, Dark Canyon Cave, and U-bar Cave in New Mexico
as well as Scharbauer Ranch and Quitaque Creek in Texas. Blackwater Draw Loc. 1,
New Mexico, is the type locality of the Clovis cultural complex and a large collection of
bones as well as lithic artifacts and other cultural remains have been retrieved from this
site (Haynes, 1995). The equid material from Blackwater Draw has been assigned to a
variety of species. Stock and Bode (1937) considered that only one species, E. excelsus
Leidy, 1858, was represented in the material they studied. In contrast, Quinn (1957)
identified four taxa from this locality: Asinus conversidens, Equus caballus caballus
Linnaeus, 1758, E. caballus laurentius Hay 1913a, (originally described by Hay [1913a]
as E. laurentius), and E. midlandensis Quinn, 1957, a new species he named based on
specimens from Scharbauer Ranch, Texas. Quinn (1957) adhered to the proposal of
dividing modern and fossil species of Equus into four genera, which consists of Equus for
34
horses, Asinus for African asses and the domestic donkey, Onager for Asiatic asses, and
Hippotigris for zebras. Lundelius (1972), working with a larger sample from the Gray
Sand unit of Blackwater Draw, agreed with Quinn (1957) in identifying A. conversidens,
but following a broader definition of the genus Equus he referred it to E. conversidens. In
addition, Lundelius (1972) reassigned the material identified by Quinn (1957) as E.
caballus laurentius to E. niobrarensis Hay 1913a, whereas he reassigned the specimens
identified as E. midlandensis and E. caballus caballus to E. scotti Gidley, 1900. A few
years later, Harris and Porter (1980) concluded that the specimens studied by Stock and
Bode (1937), Quinn (1957), and Lundelus (1972), with the exception of E. conversidens,
appear to be assignable to E. niobrarensis. Recently, Harris (2015) has revised his
opinion and now considers E. niobrarensis a junior synonym of E. scotti.
In his study of fossil Equidae from Texas, Quinn (1957) also examined, among
other material, specimens from Scharbauer Ranch. Like Blackwater Draw Loc. 1, this
locality has also yielded lithic artifacts and other cultural remains (Holliday and Meltzer,
1996). Quinn (1957) identified some of the equid specimens he studied as A.
conversidens and proposed a new species of large and stout-legged equid which he
named E. midlandensis (Quinn, 1957). This latter species is not considered to be valid by
various authors. Lundelius (1972) regarded E. midlandensis a synonym of E. scotti,
Harris and Porter (1980) proposed that it was synonymous with E. niobrarensis, whereas
Winans (1985) considered it a synonym of E. mexicanus, a species she thought was
distinct from E. scotti. Winans (1989) later proposed the name E. laurentius for the
species group of E. mexicanus; however, it was recently shown that the holotype of E.
laurentius belongs to a historic domestic horse and it is therefore a junior synonym of this
35
species (Scott et al., 2010), a conclusion that had previously been expressed in the
literature (e.g., Matthew, 1926; Savage, 1951; Winans, 1985; Azzaroli, 1995, 1998).
Dalquest (1964) described an assemblage of fossils from a small tributary of
Quitaque Creek, western Texas. Most of the equid remains collected were from a species
of small horse, which Dalquest (1964) identified as E. cf. conversidens based on
similarities with specimens from the Valley of Mexico referred to E. conversidens by
Hibbard (1955). There were also some remains of a larger horse slightly smaller than the
average size of comparable elements identified as E. scotti from the Seymour formation
of Knox County, Texas, which Dalquest (1964) reported as Equus sp.
In one of the first studies that applied multivariate morphometrics to fossil equids,
Harris and Porter (1980) studied the equid remains from Dry Cave, southeastern New
Mexico. They concluded that E. conversidens and E. niobrarensis were represented in the
material they studied and also referred some specimens to E. occidentalis sensu Merriam,
(1913), E. scotti, and a small zebrine species, which they called E. sp. A. Winans (1989)
studied specimens from Dry Cave and assigned them to the small, stout-legged species
group of E. alaskae and the large, stout-legged species group of E. laurentius. Harris
(2015) has revised his interpretation of the equid remains from Dry Cave and currently
recognizes E. conversidens, E. scotti (which he now considers the senior synonym of E.
niobrarensis), E. occidentalis (sensu Merriam, [1913]; for the largest specimens in the
fauna), E. sp. A (a small zebrine species), and a single partial upper tooth identified as E.
francisci.
In addition to Dry Cave, there are several other cave sites from the American
Southwest that have yielded equid remains. Two of these are U-Bar Cave, located in
36
southwestern New Mexico, and Dark Canyon Cave, found south of Dry Cave, in
southeastern New Mexico. Harris (1987, 1989) studied the fossil material collected from
U-Bar Cave, separating it into mid-Wisconsinan and late Wisconsinan ages. He listed
three equid species for the mid-Wisconsinan of U-Bar Cave, namely E. conversidens, E.
cf. niobrarensis, and E. cf. occidentalis (Harris, 1987), whereas for the late Wisconsinan
he considered that only E. conversidens and E. cf. niobrarensis were represented in the
fauna (Harris, 1987). Harris (2015) maintains the same interpretation of the equid
material from U-Bar Cave, with the exception that he now considers E. niobrarensis to be
a junior synonym of E. scotti. Regarding Dark Canyon Cave, Lundelius (1973)
tentatively identified E. conversidens and E. scotii from this site, whereas Harris and
Porter (1980) referred to E. conversidens a small collection of equid remains from this
locality housed at the University of Texas at El Paso. In his dissertation, Tebedge (1988)
described the fauna collected from excavations undertaken in the East Side Pocket of
Dark Canyon Cave. He decided to identify the equid material as Equus sp. because of the
confused nomenclature of Pleistocene equids (Tebedge, 1988).
The Vertebrate Paleobiology Collection of the University of Texas at El Paso
houses specimens from different parts of Chihuahua, Mexico. Among these is a small
collection of fossils from the ranch of Santa Barbara, located 9 km north of Villa
Ahumada, northern Chihuahua (1992). In their report of this fossil locality, Comaduran et
al. (1992) identified the presence of Mammuthus sp. and Equus sp. Harris (2015)
examined the fossil material from this locality and identified the equid remains as Equus
francisci.
37
2.1.3
The Natural Trap Cave fossil locality, Wyoming, has yielded thousands of vertebrate
remains, with a temporal range that extends from historical times to >100,000 years ago
(Wang and Martin, 1993). In a report of the excavations at Natural Trap Cave, Martin and
Gilbert (1978) mentioned the presence of three horse species for the equid material
known at the time. They remarked that the most common species was a small, stilt-legged
equid likely referrable to Hemionus (Martin and Gilbert, 1978), a group which has been
treated as a genus or subgenus of Equus, and which includes the extant Asiatic asses.
Martin and Gilbert (1978) indicated that the other two species were less abundant and
that one of them is assignable to the subgenus Amerhippus. Winans (1989) studied
several specimens from Natural Trap Cave and assigned them to the species group of E.
alaskae, which generally includes small, stout-legged horses. In a recent study using
mitochondrial aDNA, Weinstock et al. (2005) concluded that two clades were present at
this fossil site, a caballine and a stilt-legged clade, each possibly representing a single
species. The study by Weinstock et al. (2005) further indicated that the stilt-legged clade
is phylogenetically closer to caballines than it is to Asiatic asses and that the presence of
slender metapodials is, therefore, a convergent feature. In contrast, Eisenmann et al.
(2008) proposed that four equid species are represented in the material from Natural Trap
Cave: a caballine, E. cf. conversidens, and a large and small Amerhippus, both with
slender metapodials. According to Eisenmann et al. (2008), the small Amerhippus is the
most common species in the fauna. Subsequently, Eisenmann (2013b) assigned this
species to Amerhippus cf. pseudaltidens (Hulbert), 1995, and she assigned the specimens
of E. cf. conversidens to Amerhippus conversidens.
38
2.1.4
Alberta, Canada: the Edmonton area gravel pits and Wally’s Beach site
The equid material from the Edmonton area gravel pits has not been described in detail.
Burns (1994) listed two types of horses, which he referred to Equus cf. conversidens and
E. cf. niobrarensis. Weinstock et al. (2005) obtained mitochondrial aDNA from a large
sample of specimens from the gravel pits around the Edmonton area. All of the specimens
they studied were found to belong to the caballine clade, suggesting that only one species
was represented in the sample they studied (Weinstock et al., 2005).
The archaeological-paleontological site of Wally’s Beach located in southern
Alberta is remarkable in that it is the only known late Pleistocene horse and camel kill
and butchering locality in North America (Kooyman et al., 2006; Kooyman et al., 2012;
Waters et al., 2015). Seven butchered horses were recovered associated with lithic
artifacts (Kooyman et al., 2006). McNeil (2009) compared the equid material collected
from Wally’s Beach to specimens from the Yukon Territory identified as E. lambei, as
well as a skull from Papago Springs Cave, Arizona, identified by Skinner (1942) as E.
conversidens. McNeil (2009) assigned the equid material from Wally’s Beach to E.
conversidens and noted several differences between the Wally’s Beach sample and the
sample of E. lambei, particularly in skull morphology and dentition.
2.1.5
Eastern Beringia: Bluefish Caves
The Bluefish Caves are located in northern Yukon Territory above the Arctic circle and
have yielded, in addition to a large collection of vertebrate remains, some lithic artifacts,
a few butchered bones, and other cultural evidence that arguably extends from the late
glacial to the LGM or even earlier (Cinq-Mars, 1990; Goebel et al., 2008; Bourgeon,
2015). Burke and Cinq-Mars (1996, 1998) studied the horse remains from Bluefish Caves
39
identified as E. lambei Hay, 1917. These authors documented the range of variation in
cheek tooth morphology (Burke and Cinq-Mars, 1996) and also constructed mortality
profiles for each of the three caves (Burke and Cinq-Mars, 1998). Equus lambei has been
identified as an onager (Quinn, 1957), as a member of the genus Asinus (Groves and
Mazak, 1967; Harington, 1977), and as a caballine equid (Savage, 1951, Harington, 1980;
Eisenmann, 1980, 1986; Forsten, 1988). This species has also been considered a junior
synonym of E. ferus caballus (Savage, 1951; Winans, 1985) or E. asinus (Winans, 1985),
has also been assigned to the E. alaskae species group of Winans (1989), and has been
regarded as a possible subspecies of E. niobrarensis (Azarroli, 1995, 1998). Burke and
Cinq-Mars (1996) concluded that E. lambei was a caballine horse, based on the
morphology of the cheek tooth dentition. Weinstock et al. (2005) successfully extracted,
amplified, and sequenced, mitochondrial aDNA from one horse metatarsal from Bluefish
Cave III. Although the specimen was only identified as Equus sp., the sequence obtained
by Weinstock et al. (2005) placed it within the caballine group. Other late Pleistocene
sites in Beringia have yielded fossil material of a horse with slender metapodials
(Guthrie, 2003, 2006), a feature that is present in extant hemione (Asiatic ass) species.
However, molecular analysis of slender metapodials from the Yukon by Weinstock et al.
(2005) have placed this equid outside of the modern hemiones as a distinct species, more
closely related to caballine horses than to any other modern group of equids. These
studies suggest that at least two species of Equus where present in Beringia during the
late Pleistocene.
40
The summary presented above highlights the unstable and confused status of
Pleistocene equid taxonomy. This can be attributed to a number of factors, including the
existence of fragmentary holotypes (Winans, 1985, 1989; Eisenmann, 2013a), differences
in the methodology used by taxonomists (e.g., qualitative vs. quantitative analyses), and
emphasis on some characters over others (e.g., Skinner, 1972; Dalquest 1978, 1988;
Eisenmann, 1981, Forsten, 1986). Probably the best avenue to follow for clarifying
Pleistocene equid taxonomy is to conduct comprehensive morphological and molecular
studies on the same set of specimens in order to contrast morphological and molecular
variation. To accomplish this, I conducted a morphometric analysis, using both linear and
geometric morphometrics, and a molecular study using the cheek tooth dentition.
This approach brings us to the consideration of species concepts. Determination
of species based on morphometric analyses is done under the morphological species
concept, whereas determination of species based on phylogenetic analyses of molecular
data makes use of the phylogenetic species concept. Under the morphological species
concept, species are recognized based on morphological characters. It is assumed that
species display a certain definable variability and are sufficiently distinct from other
samples (Rose and Bown, 1986; Benton and Pearson, 2001). The morphological species
concept is ahistorical, that is, it does not consider ancestor-descendant relationships in the
identification of species (Mayden, 1999; Richards, 2010; Wiley and Liebermann, 2011).
On the other hand, the phylogenetic species concept is historical and under the more
common version of this species concept, a species is “a diagnosable cluster of individuals
with which there is a parental pattern of ancestry and descent, beyond which there is not,
and which exhibits a pattern of phylogenetic ancestry and descent among unit of like
41
kind” (Eldredge and Cracraft, 1980, p. 92). In this study, I gave priority to the results
obtained in the phylogenetic analyses when encountering discrepancies between these
analyses and the morphometric study. Nevertheless, as it will be seen below, the results
of these two sets of analyses are mostly congruent with each other.
42
Figure 2.1. Geographic location of the fossil sites considered in this study. Northeastern
Mexico: C = Cedral, J = San Josecito Cave; American Southwest: A = Algerita Blossom
Cave, M = Big Manhole Cave, L = Blackwater Draw, K = Dark Canyon Cave, D = Dry
Cave, X = El Barreal, F = Fresnal Canyon, G = Highway 45, Chihuahua, I = Isleta Cave
No. 2, O = Lubbock Lake, H = Nash Draw, Q = Quitaque Creek, S = Salt Creek, R =
Scharbauer Ranch, U = U-Bar Cave, V = Villa Ahumada; Wyoming: N = Natural Trap
Cave; Alberta: E = Edmonton area gravel pits, W = Wally’s Beach; Eastern Beringia: B =
Bluefish Caves
.
43
2.2
Materials and Methods
All of the specimens studied are housed at one of the following institutions, with
corresponding institutional acronyms indicated in parentheses: Archaeology Collection
(Bluefish Caves; MgVo-1, 2, and 3) of the Canadian Museum of History (CMH),
Gatineau, Quebec, Canada; Quaternary Paleontology (P) and Archaeology collections
(Wally’s Beach site; DhPg-8) of the Royal Alberta Museum (RAM), Edmonton, Alberta,
Canada; paleontology collection (DP) of the Archeozoology Laboratory ‘M. en C. Ticul
Álvarez Solórzano’, Instituto Nacional de Antropología e Historia (INAH), Mexico City,
Mexico; Vertebrate Paleontology collection of the Natural History Museum of Los
Angeles County (LACM), Los Angeles, California, USA; Vertebrate Paleontology
collection of the University of Kansas (KU), Lawrence, Kansas, USA; Vertebrate
Paleontology collection, Laboratory for Environmental Biology, University of Texas at
El Paso (UTEP), El Paso, Texas, USA; and the Vertebrate Paleontology collection of the
Vertebrate Paleontology Laboratory, University of Texas at Austin (TMM), Austin,
Texas, USA.
Throughout this study, I use the revised dental nomenclature proposed by Evander
(2004). The primary structures for upper and lower cheek teeth referred to in the text are
shown in Figure 2.2.
44
Figure 2.2. Upper (A) and lower (B) fourth premolars showing the dental structures
referred to in the text, based on the dental nomenclature of Evander (2004). Computed
tomography (CT-scan) images of LACM 192/156497 (A) and TMM 937-169 (B). The
anterior side of both teeth is located to the right. The lingual side is located at the bottom
of panel A and the top of panel B.
45
2.2.1
Linear morphometrics
2.2.1.1 Measurements and sample size
The cheek tooth dentition of equids consists of three upper (P2, P3, and P4) and three
lower (p2, p3, and p4) premolars, as well as three upper (M1, M2, and M3) and three
lower (m1, m2, and m3) molars on each side of the dentition. I gathered linear
measurements of the tooth crown dimensions of upper and lower cheek teeth using a
Mitutoyo digital caliper with a measuring range of 0 – 150 mm, a resolution of 0.01 mm,
and an accuracy of 0.003 mm. To account for measurement error, I took every
measurement three times and used the mean of these measurements in all statistical
analyses. The measurements collected are partially based on the methodology published
by Eisenmann et al. (1988). For the p3 to m3 lower teeth, I measured the crown height on
the buccal side of the tooth along the protoconid, from the occlusal surface down to the
point at which the protoconid and hypoconid columns separate (Figure 2.3A). For the p2
I measured the crown height along the buccal side of the hypoconid, from the occlusal
surface down to the point at which the protoconid and hypoconid columns separate. I also
measured the length and width of each tooth (Figure 2.3B) at a crown height of 2 cm (i.e.,
2 cm above from the point at which the protoconid and hypoconid columns separate). For
the upper teeth, I measured the crown height on the buccal side of the tooth along the
mesostyle, from the occlusal surface down to the point at which the mesostyle ends
(Figure 2.3C). I then measured the length and width of the tooth crown (Figure 2.3D) at a
crown height of 2 cm (i.e., 2 cm above from the point at which the mesostyle ends). The
occlusal dimensions of a tooth change as it wears down (e.g., Gidley, 1901; Howe, 1970)
46
and taking measurements at a set tooth height partially compensates for this ontogenetic
variation, especially for teeth with similar size and degree of hypsodonty. However, this
is not the case for teeth that differ in these two parameters, but I decided to follow this
approach because it allowed for the acquisition of larger sample sizes than dividing the
specimens by wear classes and taking the measurements at the occlusal surface of the
tooth. This also meant that depending on the developmental stage of the tooth (and its
state of preservation) sometimes cementum covered the area where the measurements
were taken. Nevertheless, this extra source of variation does not appear to confound the
variation observed in the different samples, as is evident in the results section.
I measured a total of 1,454 cheek teeth (738 upper and 716 lower teeth) (Table A
1 of the Appendix). Most of the specimens that I measured were isolated teeth, although
there were some tooth series and some complete or partial dentaries and maxillaries. I
determined the side and tooth position for every individual tooth using the criteria
presented by Bode (1931) and Eisenmann et al. (1988). The upper and lower third and
fourth premolars (P3/p3 and P4/p4) are sometimes difficult to distinguish, as is the case
for upper and lower first and second molars (M1/m1 and M2/m2). As a result, Eisenmann
et al. (1988) suggest combining upper P3 and P4 as well as lower p3 and p4 into a single
category, respectively. The same suggestion applies to the upper M1 and M2 as well as
the lower m1 and m2 teeth (Eisenmann et al., 1988). Combining these tooth positions
also increases the sample size available for study, improving statistical power.
Consequently, I arranged the data into eight tooth categories: Upper P2, P3/P4, M1/M2,
and M3; and lower p2, p3/p4, m1/m2, and m3. For cases in which different tooth
positions of the same tooth category were associated (i.e., they belong to the same
47
individual), for instance the left p3 and left p4, I selected one of the two specimens at
random and excluded the other from the analysis. For situations in which the left and
right sides of the same tooth position were associated, for example right P2 and left P2, I
obtained the average of the two specimens and used it in the statistical analysis. The final
dataset for each of the five geographic regions and each tooth category studied are shown
in Table A 1 of the Appendix.
48
A
C
H
B
H
D
Figure 2.3. Lower (A and B) and upper (C and D) third premolars showing the
measurements that were taken with a caliper for upper and lower cheek teeth. Photograph
in labial view (A) and transversal section of a CT-scan reconstruction (B) of a left p3
(DhPg-8 3437.1) indicating the measurements for tooth height (H), transverse width (Tr),
and anteroposterior length (Ap) (these last two measurements were taken at a crown
height of 2 cm). The same set of measurements are shown for a right P3 (DP 3850) in a
photograph of the labial side of the tooth (C) and a transversal section of a CT-scan
reconstruction (D) of the specimen.
49
2.2.1.2 Statistical analyses
I conducted a Principal Components Analysis (PCA) of the variance-covariance matrix
for each of the eight tooth categories. For both the upper and lower teeth, I used the
length and width of the tooth crown measured at a tooth height of 2 cm. Because of the
possibility of a non-linear allometric relationship between these variables in the sample
studied, I log-transformed the data prior to conducting the PCA. This transformation
linearizes the data making it possible to use PCA and other statistical methods which
assume linear relationships between variables (Hammer and Harper, 2006). For each
tooth category, I first conducted a PCA for the five geographic regions combined, in
order to place all of the specimens into the same multivariate space (i.e., morphospace). I
then dissected the variation in the data by geographic region, by plotting the PC scores
for specimens from each geographic region separately. This facilitated the identification
of different clusters in the morphospace, which were primarily arranged along the first
principal component (PC1). However, it should be noted that PCA is a statistical
exploratory technique that facilitates the identification of patterns in the data and it is not
a statistical test (Hammer and Harper, 2006). Therefore, to test for heterogeneity in the
data that would indicate the presence of more than one population, I conducted a ShapiroWilk test for normal distribution for the PC1 scores. The null hypothesis is that the
observations are drawn at random from a single population with a normal distribution.
All statistical tests were conducted in PAST 2.17 (Hammer et al., 2001) and
STATISTICA v. 9 (StatSoft, 2009) software packages. The significance level for all tests
was set to a p-value of 0.05.
50
2.2.2
Geometric morphometrics of the occlusal enamel pattern
The occlusal enamel pattern of equids is complex and has been used to varying degrees in
the taxonomy of these ungulates. It was heavily used, along with other tooth characters
such as the bucco-lingual curvature of the tooth, in early studies of equid paleontology.
However, it was soon recognized that the enamel pattern is extremely variable. Gidley
(1901) was one of the first researchers to caution against the use of tooth characters,
including the enamel pattern, in equid taxonomy. He sectioned cheek teeth of the modern
horse to demonstrate that the enamel pattern changes as the tooth wears down (Gidley,
1901). Other researchers have also pointed out that the occlusal surface and dimensions
of hypsodont equid cheek teeth change with age as the teeth wear down (e.g., Howe,
1970; Carranza-Castañeda and Ferrusquía-Villafranca, 1979, Woodburne, 2003). This
large ontogenetic variation has brought into question the utility of the cheek teeth in the
determination of equid species. However, when comparing specimens at similar stages of
wear, the enamel pattern can be taxonomically informative (Barrón-Ortiz et al., 2008;
Barrón-Ortiz and Theodor, 2011). In this study, I examined teeth with a tooth height
representing 30 – 40 % of the maximum crown height, which approximately corresponds
to a crown height equivalent to the width of the tooth (or the length of the tooth for the
lower teeth) measured at a tooth height of 2 cm.
I photographed specimens showing the selected stage of wear using a SONY
Cyber-shot DSC-H9 digital camera. When taking the photograph, the occlusal surface of
the tooth was oriented perpendicular to the camera lens. In addition, I placed a scale bar
oriented parallel to the occlusal surface on the lingual side of the tooth for the upper teeth
(Figure 2.4) and on the buccal side for the lower teeth.
51
2.2.2.1 Acquisition of CT-scan data
Typically, fossil assemblages present teeth with varying degrees of wear; therefore,
restricting the analysis to teeth with equivalent stages of wear reduces the effective
sample size. In order to increase the sample size available for study I relied on X-ray
Computed Tomography to digitally section specimens at the selected stage of wear. Due
to limitations in CT-scanning time and monetary resources, I did not scan all of the tooth
positions, but rather concentrated on the third and fourth premolars, as these tooth
positions had proven to be taxonomically useful in a previous study of the occlusal
enamel pattern (Barrón-Ortiz et al., 2008). In total, 139 specimens were CT-scanned, 64
upper P3/P4 and 75 lower p3/p4. All of the specimens were scanned using a SkyScan
1173 high-resolution micro-CT scanner at the Department of Comparative Biology and
Experimental Medicine, University of Calgary. The scanner was set to 100 – 130 kV, 61
µA, 250 – 600 ms of exposure, 0.40 – 0.50° rotation step, and a resolution of 38.91 –
60.35 µm. An aluminum filter of 1.0 mm or a brass filter of 0.25 mm was used according
to the specimen being CT-scanned. Each slice was averaged from two frames and every
specimen was rotated either 180 o or 360o during scanning. The software NRecon 1.4 was
used to reconstruct the virtual slices through each tooth.
Subsequently, 3-D surface models of the teeth were created in AMIRA 5.3.3. The
3-D models were sectioned at the selected tooth height using the “ObliqueSlice” module.
The specimens were not sectioned perpendicular to the long axis of the tooth, but rather
the cutting plane was aligned with the occlusal surface of the tooth. Thus, the cutting
plane was inclined lingually and mesially to varying degrees for the upper teeth and
52
buccally and (generally) mesially on the lower teeth. The sectioned 3-D models were then
oriented with the enamel pattern perpendicular to the screen and an image along with a
scale bar was obtained. Further processing of the images is detailed in the sections below.
2.2.2.2 Upper cheek teeth landmark acquisition and sample size
I used the computer software tpsDig 2.16 (Rohlf, 2010) to digitize 24 landmarks on the
images, including both photographs and images of the sectioned 3-D surface models, of
the upper P3 and P4 teeth. The landmarks used in this analysis are presented in Figure 2.4
and are based on a study reported by Barrón-Ortiz and Theodor (2011). The first 18
landmarks are considered type II landmarks under Bookstein’s (1991) classification of
landmarks. Type II landmarks are points located at local maxima and minima of
curvature. The remaining six landmarks are considered type III landmarks. Type III
landmarks are defined by their relative position to other landmarks. In this case,
landmarks 19, 20, and 21 are defined by their relative position to landmarks 1 and 2,
whereas landmarks 22, 23, and 24 are defined by their relative position to landmarks 3
and 5. Landmark 19 is placed at the mid-point between landmarks 1 and 2 and at the
intersection with the enamel band of the metastyle-mesostyle valley. Landmarks 20 and
21 are placed at the mid-point between landmarks 1 and 2 and at the intersection with the
buccal and lingual enamel bands of the postfossette, respectively, following the
orientation of the distal margin of the tooth. Landmark 22 is placed at the mid-point
between landmarks 3 and 5 and at the intersection with the enamel band of the mesostyleparastyle valley. Landmarks 23 and 24 are placed at the mid-point between landmarks 3
and 5 and at the intersection with the buccal and lingual enamel bands of the prefossette,
53
respectively, following the orientation of the distal margin of the tooth. I used these six
type III landmarks to obtain a better characterization of the fossettes and the ectoloph (the
buccal enamel band of the tooth). I originally placed a type II landmark on the pli
hypostyle of the postfossette and on the pli protoloph of the prefossette, but decided to
exclude these landmarks because these plications are not present in all of the specimens
imaged. The pli hypostyle is absent from 18 specimens and the pli protoloph is absent
from four teeth.
In cases where there were images of associated specimens, for example left and
right P3 of the same individual, I chose one of the two specimens at random for
digitization. I also reflected all of the left teeth in the dataset in order to have all of the
specimens in the same orientation. I then renamed every image with a four digit identifier
generated at random, with the objective of mixing the sample of images and removing the
identity of each image to minimize any biases during digitization. The final dataset
consisted of 144 specimens (including both photographed and CT-scanned specimens)
(Table A 2 of the Appendix).
54
Figure 2.4. Occlusal surface of a P3 (LACM 192/18109) showing the landmarks used in
the analysis.
2.2.2.3 Lower cheek teeth landmark acquisition and sample size
For the lower cheek teeth, I focused my study on what some researchers call the doubleknot (e.g., Eisenmann et al., 1988), which consist of the metaconid, linguaflexid, and
metastylid (Figure 2.2). The linguaflexid, in particular, has been considered
taxonomically important by different researchers (e.g., Skinner, 1972; Dalquest 1978,
1988; Eisenmann, 1981, Forsten, 1986). These researchers indicate that horses, including
the Mongolian wild horse (E. ferus przewalskii), tend to have a deep U-shaped
linguaflexid, whereas zebrines have a V-shaped linguaflexid, and hemiones have a
shallow V- or U-shaped linguaflexid. One methodological complication with this
categorization of the linguaflexid is that it is subjective, that is, whether a linguaflexid is
categorized as U-shaped or V-shaped depends on the judgment of the researcher
55
(Dalquest, 1988). A further potential complication is that this character may be variable
within the same species; at least this has been reported in populations of the extant
hemione Equus kiang, in which northern populations tend to have a U-shaped
linguaflexid, whereas southern populations tend to present a V-shaped linguaflexid
(Groves and Willoughby, 1981). The first complication can be addressed with the use of
outline-based geometric morphometrics. This technique allows for the characterization of
outlines or curves in a more objective manner. Regarding the second complication, what
can be concluded at the moment is that further studies are needed to better assess the
morphological plasticity of this trait and the present study attempts to shed some light on
this issue.
I prepared the images for digitization in two different ways. For the images of the
sections of the 3-D surface models, I first converted the image into a binary image and
adjusted the threshold (I used values between 190 and 230) to highlight the enamel band.
I conducted this operation using the Outlines tab under Image Tools in the software
tpsDig 2.16 (Rohlf, 2010). Subsequently, I opened the converted image in ImageJ 1.48v
(Rasband, 2014), cropped it, converted it once again to a binary image, and used the
operation called erode to smooth the enamel band and remove any fuzziness produced by
the CT-scanner. For the digital photographs, I cropped the images in ImageJ 1.48v
(Rasband, 2014) and traced the outline of the double knot with a dark blue color using a
line width of 20 pixels. I then processed both sets of images in MATLAB 7.8
(MathWorks, 2009) using a modified version of the program developed by Barrón-Ortiz
et al. (2008) to obtain 50 equally spaced semilandmarks along the double knot (Figure
2.5).
56
As for the upper cheek teeth, in cases where there were images of associated
specimens, for example left and right p4 of the same individual, I chose one of the two
specimens at random for digitization. I also reflected all of the left teeth in the dataset in
order to have all of the specimens in the same orientation. I then renamed every image
with a four digit identifier generated at random, with the objective of mixing the sample
of images and removing the identity of each image to minimize any biases during
digitization. The final dataset consisted of 128 specimens (including both photographed
and CT-scanned specimens) (Table A 3 of the Appendix).
Figure 2.5. Digitized double knot (metaconid, linguaflexid, and metastylid) of a lower p4
(KU 50629) showing the 50 semilandmarks used in the analysis. The arrow points to the
first semilandmark.
2.2.2.4 Statistical analyses
The primary goal of the geometric morphometric analysis was to determine whether the
groups that I identified in the analysis of the linear measurements, which were based on
differences in size, statistically differed in shape for both the upper and the lower
57
premolars. Shape refers to the geometric features of an object after accounting for
differences in size, position, and orientation (Kendal, 1977). Congruence between the
linear and geometric morphometric analyses would provide support for the consideration
of these groups as candidates for the recognition of different species under the
morphological species concept. To this end, I organized the landmark data by size group
(according to groups identified in the linear morphometric analysis) and geographic
region. The groups considered in the analysis are: large, medium, and small specimens
from northeastern Mexico; large, medium, and small specimens from the American
Southwest; large and medium specimens from Natural Trap Cave, Wyoming; large and
medium specimens from Alberta; and the specimens from Bluefish Caves, Yukon.
For both the upper and the lower teeth, I superimposed the configuration of
landmarks using the generalized least squares Procrustes superimposition algorithm in
MorphoJ 1.05f (Klingenberg, 2011). This superimposition technique translates the
configurations of landmarks to the origin, scales them to unit centroid size, and rotates
them to minimize the summed square distances between homologous landmarks
(Zelditch et al., 2004). A consensus (mean) configuration is obtained and the deviation of
each configuration of landmarks from the consensus yields the Procrustees coordinates,
which are subsequently used for statistical analyses.
I performed a pooled within subgroups multivariate regression of log centroid size
on the Procrustes coordinates to test for allometry; covariation between size and shape
(e.g., Loy et al., 1998; Monteiro, 1999; Frost et al., 2003; Drake and Klingenberg, 2008).
As will be seen in the results, the regression for both the upper and lower premolars
yielded a statistically significant relationship. I used the regression residuals to control for
58
the variation of shape due to size and conducted a Canonical Variate Analysis (CVA). To
test for significant differences between groups, I carried out pair-wise permutation tests,
using10,000 permutation rounds, for the Procrustes distances among groups.
2.2.3
Mitochondrial ancient DNA
2.2.3.1 Samples
I processed a subsample of 50 late Pleistocene equid teeth from 12 North American
localities for ancient DNA (aDNA) analysis (Table A 5 of the Appendix). These
specimens were used in the linear and/or geometric morphometric analyses described
above. I also extracted, amplified, and sequenced aDNA from an archaeological domestic
horse (Equus ferus caballus) which served as the positive control (Table A 5 of the
Appendix).
2.2.3.2 DNA extraction, amplification, and sequencing
I processed all of the samples at the Ancient DNA Laboratory located in the Department
of Anthropology and Archaeology at the University of Calgary. This laboratory has been
designed exclusively for ancient DNA (aDNA) work and no modern samples have ever
been processed there. Furthermore, prior to this study, ancient equid samples had not
been processed at the Ancient DNA Laboratory. The laboratory is equipped with UV
filtered ventilation and positive airflow, as well as UV sources for decontamination. All
equipment in the laboratory is dedicated for aDNA use. Strict contamination protocols are
followed including: 1) the use of protective clothing such as Tyvex suits, masks, and
disposable gloves; 2) separation of the aDNA lab into bone preparation, DNA extraction,
59
and PCR set-up rooms, with dedicated equipment for each room; 3) Separation of preand post-PCR work: extraction of aDNA and set-up of PCR reactions take place at the
Ancient DNA Laboratory, whereas aDNA amplification is conducted at the PCR
Laboratory in the Department of Biological Sciences, University of Calgary (the two
buildings are physically separated from each other and have separate ventilation
systems); 4) the inclusion of multiple blank DNA extractions (one for every six to seven
samples processed) and negative PCR controls.
2.2.3.3 Sampling, decontamination, and DNA extraction
For every tooth in this subsample, I obtained a sample from one of the roots in order to
avoid damaging the tooth crown. I cut a fragment of approximately 10 mm in length from
the tip of the root using a small hacksaw, which had previously been cleaned with 6 %
sodium hypochlorite. Approximately 0.3 – 0.6 g of sample were subjected to chemical
and UV decontamination. First, each sample was placed in a new 15 ml test tube and
immersed in a 6 % sodium hypochlorite for 7 minutes, before rinsing it twice in ultrapure water to remove any residue of sodium hypochlorite. Subsequently, I placed the
samples on clean weighing trays and UV irradiated them in a crosslinker for 30 minutes
on two sides.
I used a modified silica-spin column technique (Yang et al., 1998; Yang et al.
2004), to extract DNA from the decontaminated tooth samples. The samples were
crushed into powder using a small hammer and incubated overnight in a new 15 ml test
tube with 5 ml of lysis solution (0.5 M EDTA pH 8.0, 0.5% SDS, and 0.5 mg/mL
proteinase K) in a rotating hybridization oven at 50 oC. The 15 ml tubes were centrifuged
60
for 25 minutes and 4 ml of supernatant was transferred to an Amicon 10K column
(Millipore, Billerica, MA, USA) in order to concentrate the DNA. After concentration,
approximately 50 – 100 µl of supernatant was purified using Qiagen Nucleotide Removal
Kits (Qiagen, Valencia, California, USA). For each sample, approximately 200 µl of
DNA extract were obtained in two separate elutions of 100 µl each.
2.2.3.4 Primer design and PCR amplifications
Primers were designed to target portions of the hypervariable region I (HVR I) of equid
mitochondrial control region. In order to accomplish this task, I downloaded from
GenBank (www.ncbi.nlm.nih.gov) DNA sequences of the mitochondrial control region of
extant and extinct equids (Table A 6 of the Appendix). All of the sequences were aligned
in BioEdit 7.0.5.3 (Hall, 1999). I designed eight primer sets (Table A 4 of the Appendix)
to amplify a 621 bp fragment of the HVR I by visually examining the aligned DNA
sequences. The primers were designed on conserved regions of the sequences
interspersed between regions with varying degrees of DNA sequence variation. The
targeted fragments spanned positions 15,443 – 16,063 of the Equus ferus caballus
mtDNA genome (Genbank accession: X79547.1).
I conducted PCR reactions using an Eppendorf Mastercycler® in a 30 µl reaction
volume containing 50 mmol/L KCl, 10 mmol/L Tris-HCl, 2.5 mmol/L MgCl2,
0.2mmol/L dNTP, 1.0 mg/mL BSA, 0.3 µmol/L each primer, 3.0 – 4.0 µl DNA sample,
and 2 U (1 U ≈ 16.67 nkat) AmpliTaq Gold LD (Life Technologies Corporation,
Carlsbad, California, USA). PCR started with an initial 12 min denaturation period at 95
o
C, followed by 60 cycles at 95 oC denaturation for 30 s, 50-52 oC annealing for 30 s, and
61
72 oC extension for 40 s. I included blank extracts and negative controls in each of the
PCR sets. PCR products were sequenced using forward and reverse primers at Eurofins
MWG Operon, Inc., Huntsville, Alabama, USA. For all of the samples that yielded DNA
I attempted repeat amplifications and sequencing and for five specimens (EQ29, EQ39,
EQ43, EQ50, and EQ53) I conducted repeat extractions to ensure the reproducibility of
the results and to detect any base pair misincorporations due to DNA damage.
Contigs of the obtained DNA sequences were produced using ChromasPro
software (http://technelysium.com.au/). The aligned DNA fragments were checked for
consistency and were visually edited where necessary. Subsequently, I truncated the
contig sequences to remove primer sequences and to make them comparable with
previously published equid reference sequences from GenBank.
2.2.3.5 Data analysis
I compiled DNA sequences of the mitochondrial control region of extant and extinct
equids (Table A 6 of the Appendix) from GenBank, including sequences from the
modern horse haplogroups identified by Achilli et al. (2012), ancient horse sequences
obtained by Weinstock et al. (2005), sequences of stilt-legged horses reported by Vilstrup
et al. (2013), and sequences of specimens identified as Equus (Amerhippus) neogeus
obtained by Orlando et al. (2008). I also included in the dataset the mitochondrial control
region of the fossil specimens from Thistle Creek, Yukon, and Taymyr peninsula,
Siberia, reported by Orlando et al. (2013). I used sequences of the domestic and African
donkeys as outgroups (Table A 6 of the Appendix). The sequences from the literature and
the ones obtained in this study were arranged into two datasets depending on their degree
62
of completeness. One dataset consisted of 75 sequences of a 583 bp fragment of the HVR
I. The second dataset was comprised by 126 sequences of a 348 bp of the HVR I.
I aligned each of the datasets by way of a ClustalW Multiple alignment in BioEdit
7.0.5.3 (Hall, 1999). Subsequently, I used MrModeltest 2.3 (Nylander, 2004) in PAUP
4.0b10 (Swofford, 2001) to determine the best nucleotide substitution model. Based on
the Akaike Information Criterion, this analysis determined that the best model of
nucleotide substitution for the three datasets is the general time reversible model with
gamma-distributed rate variation across sites and a proportion of invariable sites
(GTR+G+I). I then conducted a Bayesian phylogenetic analysis integrating Markov chain
Monte Carlo algorithms in MrBayes 3.2 (Ronquist et al., 2012) for each dataset. The
posterior probability distribution of trees was approximated by drawing a sample every
1,000 steps over 10,000,000 generations, after discarding a burn-in of 1,000,000
generations.
2.3
2.3.1
Results
Linear morphometrics
In all analyses for both the upper and the lower cheek teeth, the first principal component
(PC 1) accounted for over 87 % of the variation in the data (Tables 2.1 and 2.2). The
factor loadings indicate that this component reflects variation in size, with larger
specimens showing more positive scores (Tables 2.1 and 2.2). The scatter plot of the two
principal components shows that the specimens grade from smallest to largest with few
appreciable breaks (Figures 2.6 – 2.13); however, plotting the PC scores by geographic
region reveals better-defined size clusters.
63
The upper and lower cheek teeth from northeastern Mexico tend to plot into three
size groups: large, medium, and small (Figures 2.14 and 2.15). Moreover, the distribution
of the specimens along PC 1 (Figures 2.24 and 2.25) statistically departs from normality
in all tooth categories, except M3 and p2 (Table 2.3).
The specimens from the American Southwest tend to plot into large and medium
size clusters, except for the p3/p4 tooth category where there are three small sized
specimens that plot in the same region of the morphospace as the small sized specimens
from northeastern Mexico (Figures 2.16 and 2.17). Sample sizes for this geographic
region are small for four of the eight tooth categories, namely P2, M3, p2, and m3 (Table
2.4). As a result, greater weight was given to the remaining tooth categories in the
interpretation of the Shapiro-Wilk test of normality. The distribution of PC1 scores for
P3/P4 and p3/p4 cheek teeth (Figures 2.26B and 2.27B) is statistically different from the
expected normal distribution, whereas normality is not rejected for the M1/M2 and
m1/m2 tooth categories (Table 2.4); although, the p-value for the M1/M2 category is
marginally greater than 0.05.
The vast majority of the specimens from Natural Trap Cave plot into one cluster
that falls in the same region of the morphospace as the medium sized cluster from
northeastern Mexico and the American Southwest (Figures 2.18 and 2.19). There are,
however, a few specimens that are of larger size, producing a right-skewed distribution of
specimens along PC1 for all of the tooth categories except p2 and p3/p4 (Figures 2.28
and 2.29). Accordingly, the Shapiro-Wilk test is not significant for these two tooth
categories (Table 2.5). The test is also not significant for the m3 tooth category.
64
Significant departures from normality are detected for the remaining five tooth categories
(Table 2.5).
The specimens from Alberta tend to plot on the right side of the graph in the same
region of the morphospace as the large specimens from the American Southwest and
northeastern Mexico (Figures 2.20 and 2.21). However, this does not apply to all of the
tooth positions, and there are four specimens (one p2, two p3/p4, and one m1) that are
smaller in size and that fall in the same region of the morphospace as the medium sized
specimens from Natural Trap Cave, the American Southwest, and northeastern Mexico.
The sample size in four of the eight tooth categories (P2, M3, p2, and m3) is small and,
therefore, greater weight was given to the interpretation of the Shapiro-Wilk test for the
other tooth categories. Normality cannot be rejected for the distribution of specimens
along PC1 in the P3/P4, M1/M2, and m1/m2 tooth categories, and the test is marginally
not significant for the p3/p4 tooth category (Figures 2.30 and 2.31; Table 2.6).
The specimens from Bluefish Caves form one cluster for all tooth categories. The
specimens tend to plot in the lower range of the large specimens from the other
geographic regions (Figures 2.22 and 2.23). The Shapiro-Wilk test is not significant for
any tooth categories, although it is only marginally not significant for the p2 and m3
tooth categories (Figures 2.32 and 2.33; Table 2.7).
65
Figure 2.6. Plot of principal components for P2 specimens. Letters indicate specimens according to locality provenance (Figure 2.1).
Teeth that yielded aDNA are identified by “a” beside the letter and “*” indicates teeth associated with specimens that yielded aDNA.
66
Figure 2.7. Plot of principal components for P3/P4 specimens. Letters indicate specimens according to locality provenance (Fig. 2.1).
67
Figure 2.8. Plot of principal components for M1/M2 specimens. Letters indicate specimens according to locality provenance (Figure
2.1). Teeth that yielded aDNA are identified by “a” beside the letter; “*” indicates teeth associated with specimens that yielded aDNA.
68
Figure 2.9. Plot of principal components for M3 specimens. Letters indicate specimens according to locality provenance (Figure 2.1).
Teeth associated with specimens that yielded aDNA are identified by “*” beside the letter.
69
Figure 2.10. Plot of principal components for p2 specimens. Letters indicate specimens according to locality provenance (Figure 2.1).
70
Figure 2.11. Plot of principal components for p3/p4 specimens. Letters indicate specimens according to locality provenance (Fig. 2.1).
71
Figure 2.12 Plot of principal components for m1/m2 specimens. Letters indicate specimens according to locality provenance (Figure
2.1). Teeth that yielded aDNA are identified by “a” beside the letter; “*” indicates teeth associated with specimens that yielded aDNA.
72
Figure 2.13. Plot of principal components for m3 specimens. Letters indicate specimens according to locality provenance (Figure 2.1).
73
P2
P3/P4
M1/M2
M3
Figure 2.14. Principal component plots showing upper teeth from Cedral (C) and San Josecito Cave (J), Mexico. The P2 specimen that
yielded aDNA is identified by “a” and corresponds to EQ30 of the aDNA analysis.
74
p2
p3/p4
m1/m2
m3
Figure 2.15. Principal component plots showing lower teeth from Cedral (C) and San Josecito Cave (J), Mexico.
75
P2
P3/P4
M1/M2
M3
Figure 2.16. Principal component plots showing upper teeth from the American Southwest. Refer to Fig. 2.1 for locality abbreviations.
Specimens that yielded aDNA (EQ3 and EQ16) and teeth associated with these specimens are identified by “a” and “*”, respectively.
76
p2
p3/p4
m1/m2
m3
Figure 2.17. Principal component plots showing lower teeth from the American Southwest. Letters indicate specimens according to
locality provenance (Figure 2.1). Specimens that yielded aDNA (EQ1 and EQ2) are identified by “a”.
77
P2
P3/P4
M1/M2
M3
Figure 2.18. Principal component plots showing upper teeth from Natural Trap Cave, Wyoming. The P2 specimen that yielded aDNA
(EQ9) and teeth associated with it are identified by “a” and “*”, respectively.
78
p2
p3/p4
m1/m2
m3
Figure 2.19. Principal component plots showing lower teeth from Natural Trap Cave, Wyoming. Specimens that yielded aDNA
(EQ13, EQ22, and EQ41) are identified by “a”.
79
P2
P3/P4
M1/M2
M3
Figure 2.20. Principal component plots showing upper teeth from the Edmonton area (E) and Wally’s Beach (W), Alberta. Specimens
associated with teeth that yielded aDNA (EQ43) are identified by “*”.
80
p2
p3/p4
m1/m2
m3
Figure 2.21. Principal component plots showing lower teeth from the Edmonton area (E) and Wally’s Beach (W), Alberta. Specimens
that yielded aDNA (EQ4 and EQ43) and teeth associated with these specimens are identified by “a” and “*”, respectively.
81
P2
P3/P4
M1/M2
M3
Figure 2.22. Principal component plots showing upper teeth from Bluefish Caves, Yukon. Specimens that yielded aDNA (EQ38,
EQ44, EQ45, and EQ47) and teeth associated with these specimens are identified by “a” and “*”, respectively.
82
p2
p3/p4
m1/m2
m3
Figure 2.23. Principal component plots showing lower teeth from Bluefish Caves, Yukon. Specimens that yielded aDNA (EQ39,
EQ42, EQ47, EQ48, EQ50, EQ51, and EQ53) and teeth associated with these specimens are identified by “a” and “*”, respectively.
83
Table 2.1. Eigenvalues, percentage variance, and factor loadings for the principal components resulting from PCA of the linear
measurements of the upper teeth (Ap = anteroposterior length; Tr = transversal width), taken at a crown height of 2 cm.
Upper P2
Upper P3/P4
Upper M1/M2
Upper M3
PC1
PC2
PC1
PC2
PC1
PC2
PC1
PC2
Eigenvalue
0.0031
0.0003
0.0044
0.0002
0.0041
0.0002
0.0051
0.0004
% variance
92.49
7.51
94.62
5.38
96.18
3.82
93.04
6.96
Ap
0.7773
-0.6291
0.7680
-0.6405
0.7401
-0.6725
0.7905
-0.6125
Tr
0.6291
0.7773
0.6405
0.7680
0.6725
0.7401
0.6125
0.7905
Factor loadings
Table 2.2. Eigenvalues, percentage variance, and factor loadings for the principal components resulting from PCA of the linear
measurements of the lower teeth (Ap = anteroposterior length; Tr = transversal width), taken at a crown height of 2 cm.
Lower p2
Lower p3/p4
Lower m1/m2
Lower m3
PC1
PC2
PC1
PC2
PC1
PC2
PC1
PC2
Eigenvalue
0.0042
0.0006
0.0037
0.0004
0.0043
0.0005
0.0055
0.0005
% variance
87.34
12.66
89.81
10.19
90.01
9.99
91.90
8.10
Ap
0.6873
0.7264
0.7036
0.7105
0.6411
0.7675
0.7230
-0.6909
Tr
0.7264
-0.6873
0.7105
-0.7036
0.7675
-0.6411
0.6909
0.7230
Factor
loadings
84
P2
P3/P4
M1/M2
M3
Figure 2.24. Histograms showing the distribution of PC 1 scores of upper teeth from Cedral and San Josecito Cave, Mexico, resulting
from PCA of the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
85
p2
p3/p4
m1/m2
m3
Figure 2.25. Histograms showing the distribution of PC 1 scores of lower teeth from Cedral and San Josecito Cave, Mexico, resulting
from PCA of the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
86
P2
P3/P4
M1/M2
M3
Figure 2.26. Histograms showing the distribution of PC 1 scores of upper teeth from localities in the American Southwest (Figure 2.1),
resulting from PCA of the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
87
p2
p3/p4
m1/m2
m3
Figure 2.27. Histograms showing the distribution of PC 1 scores of lower teeth from localities in the American Southwest (Figure 2.1),
88
P2
P3/P4
M1/M2
M3
Figure 2.28. Histograms showing the distribution of PC 1 scores of upper teeth from Natural Trap Cave, Wyoming, resulting from
PCA of the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
89
p2
p3/p4
m1/m2
m3
Figure 2.29. Histograms showing the distribution of PC 1 scores of lower teeth from Natural Trap Cave, Wyoming, resulting from
PCA of the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
90
P2
P3/P4
M1/M2
M3
Figure 2.30. Histograms showing the distribution of PC 1 scores of upper teeth from the Edmonton area and Wally’s Beach, Alberta,
91
p2
p3/p4
m1/m2
m3
Figure 2.31. Histograms showing the distribution of PC 1 scores of lower teeth from the Edmonton area and Wally’s Beach, Alberta,
92
P2
P3/P4
M1/M2
M3
Figure 2.32. Histograms showing the distribution of PC 1 scores of upper teeth from Bluefish Caves, Yukon, resulting from PCA of
the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
93
p2
p3/p4
m1/m2
m3
Figure 2.33. Histograms showing the distribution of PC 1 scores of lower teeth from Bluefish Caves, Yukon, resulting from PCA of
the linear measurements (anteroposterior length and transversal width), taken at a crown height of 2 cm.
94
scores for each tooth category from Cedral and San Josecito Cave, Mexico. n = sample
size. Statistically significant p-values are shown in bold.
Tooth category
n
Shapiro-Wilk W
p-value
P2
33
0.9313
0.0382
P3/P4
71
0.9332
0.0010
M1/M2
103
0.9716
0.0256
M3
37
0.9496
0.0937
p2
44
0.9512
0.0608
p3/p4
77
0.9607
0.0177
m1/m2
134
0.9712
0.0061
m3
33
0.9323
0.0407
scores for each tooth category from the American Southwest. n = sample size.
Statistically significant p-values are shown in bold.
Tooth category
n
Shapiro-Wilk W
p-value
P2
10
0.9153
0.3190
P3/P4
26
0.9156
0.0356
M1/M2
34
0.9417
0.0695
M3
12
0.9322
0.4035
p2
14
0.9510
0.5765
p3/p4
34
0.8884
0.0023
m1/m2
56
0.9654
0.1079
m3
11
0.8826
0.1122
95
scores for each tooth category from Natural Trap Cave, Wyoming. n = sample size.
Tooth category
n
Shapiro-Wilk W
p-value
P2
27
0.8857
0.0064
P3/P4
66
0.9533
0.0144
M1/M2
72
0.9390
0.0017
M3
35
0.9040
0.0051
p2
25
0.9490
0.2383
p3/p4
46
0.9749
0.4147
m1/m2
56
0.9533
0.0298
m3
32
0.9440
0.0971
scores for each tooth category from the Edmonton area and Wally’s Beach, Alberta. n =
sample size. Statistically significant p-values are shown in bold.
Tooth category
n
Shapiro-Wilk W
p-value
P2
5
0.9067
0.4481
P3/P4
26
0.9715
0.6633
M1/M2
41
0.9835
0.8039
M3
11
0.9524
0.6752
p2
9
0.8189
0.0335
p3/p4
20
0.9136
0.0747
m1/m2
22
0.9686
0.6781
m3
5
0.8523
0.2020
96
scores for each tooth category from Bluefish Caves, Yukon. n = sample size.
2.3.2
Tooth category
n
Shapiro-Wilk W
p-value
P2
23
0.9641
0.5504
P3/P4
45
0.9815
0.6820
M1/M2
41
0.9819
0.7471
M3
20
0.9270
0.1354
p2
21
0.9132
0.0634
p3/p4
30
0.9681
0.4879
m1/m2
28
0.9860
0.9613
m3
19
0.9075
0.0665
Geometric morphometrics of the enamel pattern of upper premolars
There is a statistically significant relationship between shape (as defined by the
Procrustes coordinates) and log centroid size (p-value < 0.0001). The regression on
centroid size accounts for 6.045 % of the total shape variation. Thus, it was necessary to
standardize the data by computing the residuals from the regression to remove the shape
variation due to allometry. The residuals were then used in further statistical analyses.
The first three Canonical Variates (CV 1 to CV 3) account for 81.84 % of the
relative between-group variation (Table 2.8). The different groups are arranged from
small to large along CV 1, largely reflecting the pattern seen in the PCA of the linear
measurements (Figure 2.34). The transformation grids show that negative scores on CV 1
correspond to shallow parastyle-mesostyle and mesostyle-metastyle valleys, buccolingually expanded fossettes, relatively short protocones, and mesial displacement of
97
landmark 11 (around the area where the pli caballin is located); the opposite is observed
for positive CV 1 scores. The second Canonical Axis (CV 2) clearly separates the small
specimens from northeastern Mexico and the specimens from Bluefish Caves from the
rest of the groups. Negative CV 2 scores reflect a mesial extension of the anterior margin
of the protocone and a more prominent mesostyle (landmarks 3 and 4 are more separated
from each other); the opposite is seen for positive CV 2 scores. The third Canonical Axis
(CV 3) does not clearly separate any of the groups, but arranges the intermediate size
groups from south to north: specimens from northeastern Mexico show negative scores,
whereas specimens from Wyoming have positive scores (Figure 2.35). Examination of
the transformation grid for the CV 3 axis, shows that negative scores correspond to a
displacement away from the center of the tooth of the pli paraconule (landmark 17), pli
postfossette (landmark 14), and landmark 11; the opposite is observed for positive CV 3
scores.
The pair-wise permutation tests identified significant differences in the Procrustes
distance for all but eight comparisons (Table 2.10). Two of these comparisons concern
the large size group from northeastern Mexico, which is not significantly different from
the large size groups of the American Southwest and Alberta. Likewise, these last two
groups are not statistically different from each other. The medium size group from
Natural Trap Cave is not significantly different from the medium size group of the
American Southwest. The four remaining pair-wise permutation tests that are nonsignificant include the large size group from Natural Trap Cave, which has a sample size
of only two specimens and, thus, the reliability of these results is questionable.
98
first five Canonical Variates resulting from CVA of 24 landmark coordinates of the
occlusal enamel pattern of the upper premolars (P3/P4).
Eigenvalues
% Variance
Cumulative %
1
10.9984
43.64
43.64
2
6.0334
23.94
67.58
3
3.5944
14.26
81.84
4
1.8776
7.45
89.29
5
1.3469
5.34
94.64
99
Figure 2.34. Plot of the first two Canonical Variates resulting from CVA of 24 landmark
coordinates of the occlusal enamel pattern of the upper premolars (P3/P4). Shown on the
margins of the graph is the change in tooth shape along each corresponding axis. The
groups included in the analysis are: 1) large specimens from Cedral, Mexico (Cl); 2)
medium specimens from Cedral (Cm) as well as all teeth from San Josecito Cave (J),
Mexico; 3) small specimens from Cedral, Mexico (Cs); 4) large specimens from different
localities of the American Southwest (identified by a lower case “l” beside the specimen
abbreviation; refer to Figure 2.1 for abbreviations); 5) medium specimens from different
localities of the American Southwest (identified by a lower case “m” beside the specimen
abbreviation; refer to Figure 2.1 for abbreviations); 6) medium specimens from Natural
Trap Cave, Wyoming (N); 7) large specimens from Natural Trap Cave, Wyoming (Nl); 8)
large specimens from the Edmonton area gravel pits (E) and Wally’s Beach (W), Alberta;
and 9) all of the specimens digitized from Bluefish Caves, Yukon (B). A lower case “a”
beside the specimen abbreviation indicates a tooth that yielded aDNA (these include
EQ38 and EQ45 from Bluefish Caves). An asterisk (*) beside the specimen abbreviation
denotes a tooth associated (i.e., it belongs to the same individual) with a specimen from
which aDNA was obtained (including teeth associated with EQ3 from Dry Cave, New
Mexico, EQ9 from Natural Trap Cave, EQ43 from Wally’s Beach, and EQ44 as well as
EQ47 from Bluefish Caves).
100
10
-10
-10
10
101
landmark coordinates of the occlusal enamel pattern of the upper premolars (P3/P4).
Shown on the margins of the graph is the change in tooth shape along each corresponding
axis. The groups included in the analysis are: 1) large specimens from Cedral, Mexico
(Cl); 2) medium specimens from Cedral (Cm) as well as all teeth from San Josecito Cave
(J), Mexico; 3) small specimens from Cedral, Mexico (Cs); 4) large specimens from
different localities of the American Southwest (identified by a lower case “l” beside the
specimen abbreviation; refer to Figure 2.1 for abbreviations); 5) medium specimens from
different localities of the American Southwest (identified by a lower case “m” beside the
specimen abbreviation; refer to Figure 2.1 for abbreviations); 6) medium specimens from
Natural Trap Cave, Wyoming (N); 7) large specimens from Natural Trap Cave, Wyoming
(Nl); 8) large specimens from the Edmonton area gravel pits (E) and Wally’s Beach (W),
Alberta; and 9) all of the specimens digitized from Bluefish Caves, Yukon (B). A lower
case “a” beside the specimen abbreviation indicates a tooth that yielded aDNA (these
include EQ38 and EQ45 from Bluefish Caves). An asterisk (*) beside the specimen
abbreviation denotes a tooth associated (i.e., it belongs to the same individual) with a
specimen from which aDNA was obtained (including teeth associated with EQ3 from
Dry Cave, New Mexico, EQ9 from Natural Trap Cave, EQ43 from Wally’s Beach, and
EQ44 as well as EQ47 from Bluefish Caves).
102
10
-10
-10
10
103
Table 2.9. Procrustes distances among groups for the upper premolars (P3/P4).
Abbreviations: Cl = large specimens from Cedral, Mexico. Cm/J = medium specimens
from Cedral and specimens from San Josecito Cave, Mexico; Cs = small specimens from
Cedral, Mexico; SWl = large specimens from the American Southwest; SWm = medium
specimens from the American Southwest; Nl = large specimens from Natural Trap Cave,
Wyoming; N = medium specimens from Natural Trap Cave, Wyoming; E/W = large
specimens from the Edmonton area and Wally’s Beach, Alberta; B = specimens from
Bluefish Caves, Yukon.
Cl
B
Cm/J
Cs
SWl
SWm
Nl
B
0.0606
Cm/J
0.0847
0.0649
Cs
0.1354
0.1099
0.0683
SWl
0.0358
0.0614
0.0870
0.1351
SWm
0.0618
0.0543
0.0412
0.0871
0.0657
Nl
0.0634
0.0657
0.0758
0.1095
0.0745
0.0590
N
0.0856
0.0698
0.0400
0.0672
0.0864
0.0370
0.0696
E/W
0.0327
0.0455
0.0746
0.1247
0.0324
0.0538
0.0670
N
0.0780
104
distances among groups of the upper premolars (P3/P4). Abbreviations: Cl = large
specimens from Cedral, Mexico. Cm/J = medium specimens from Cedral and specimens
from San Josecito Cave, Mexico; Cs = small specimens from Cedral, Mexico; SWl =
large specimens from the American Southwest; SWm = medium specimens from the
American Southwest; Nl = large specimens from Natural Trap Cave, Wyoming; N =
medium specimens from Natural Trap Cave, Wyoming; E/W = large specimens from the
Edmonton area and Wally’s Beach, Alberta; B = specimens from Bluefish Caves, Yukon.
Cl
B
Cm/J
Cs
SWl
SWm
Nl
B
<.0001
Cm/J
<.0001
<.0001
Cs
<.0001
<.0001
<.0001
SWl
0.3251
<.0001
<.0001
<.0001
SWm
0.0031
<.0001
0.0153
0.0007
0.001
Nl
0.2502
0.0250
0.0244
0.0263
0.028
0.4479
N
<.0001
<.0001
<.0001
<.0001
<.0001
0.0514
0.0618
E/W
0.1672
<.0001
<.0001
<.0001
0.2875
0.0007
0.0801
N
<.0001
105
2.3.3
Geometric morphometrics of the enamel pattern of lower premolars
The lower premolars show a marginally significant relationship between shape (as
defined by the Procrustes coordinates) and log centroid size (p = 0.0437). The regression
on centroid size accounts for 2.257 % of the total shape variation. As for the case of the
upper premolars, the residuals were calculated and used in further statistical analyses.
The first three Canonical Variates (CV 1 to CV 3) account for 71.93 % of the
relative between-group variation (Table 2.11). The groups generally plot along CV 1
from small to large (Figure 2.36), reflecting the same overall pattern observed in the
CVA of the upper premolars and the PCA of the linear measurements. Examination of the
transformation grids reveals that the CV 1 axis corresponds to a morphological gradient
which goes from a caballine double knot, with a deep, U-shaped linguaflexid on the right
side of the plot (i.e., CV 1 values greater than 0) to a hemione-like double knot with a
shallow and more open, U-shaped linguaflexid on the left side of the plot (i.e., CV 1
values less than 0). Moreover, positive CV 1 scores also reflect a tooth morphology in
which the metaconid is “constricted” (i.e., the bucco-distal margin of the metaconid is
displaced towards the linguaflexid) and the metastylid is “open” (i.e., the bucco-mesial
margin of the metastylid is displaced away from the linguaflexid); the opposite pattern is
observed for specimens with negative CV 1 scores. The small and large groups from
northeastern Mexico, the small specimens from the American Southwest, and the
specimens from Bluefish Caves all have positive CV 2 scores and are clearly separated
from the rest of the groups along this axis. The transformation grids show that positive
CV 2 scores correspond to a relatively rounded metastylid, whereas specimens with
negative CV 2 scores reflect a triangular metastylid. The specimens from Bluefish Caves,
106
the large and medium size specimens from Natural Trap Cave and the small groups from
northeastern Mexico and the American Southwest all have negative CV 3 scores and plot
separately from the remaining groups in the dataset (Figure 2.37). Negative CV 3 scores
correspond to a bucco-lingually compressed metastylid, whereas positive scores reflect a
bucco-lingually expanded metastylid.
In contrast to the upper premolars, there were fewer pair-wise comparisons in
which the Procrustes distance between groups was statistically different (Table 2.13).
This is partially due to the inclusion of groups with small sample sizes, namely the small
groups from northeastern Mexico and the American Southwest, the large size group from
Natural Trap Cave, and the medium size group from Alberta. Of the remaining groups in
the dataset, the most relevant differences are: 1) the Bluefish Caves group is significantly
different from all other groups; 2) the medium size group from northeastern Mexico
differs from the medium size group of Natural Trap Cave as well as the large size groups
from northeastern Mexico, the American Southwest, and Alberta; 3) the medium size
group from the American Southwest is statistically different from the large size groups of
Alberta and the American Southwest; and 4) the medium size group from Natural Trap
Cave differs from the large size group of Alberta.
107
first five Canonical Variates resulting from CVA of 50 semilandmark coordinates of the
double knot (metaconid-metastylid-entoconid complex) of the lower premolars (p3/p4).
Eigenvalues
% Variance
Cumulative %
1
30.9264
32.85
32.85
2
21.6312
22.98
55.83
3
15.1508
16.10
71.93
4
8.3076
8.83
80.75
5
5.6457
6.00
86.75
108
Figure 2.36. Plot of the first two Canonical Variates resulting from CVA of 50
semilandmark coordinates of the double knot (metaconid-metastylid-entoconid complex)
of the lower premolars (p3/p4). Shown on the margins of the graph is the change in shape
along each corresponding axis. The groups included in the analysis are: 1) large
specimens from Cedral, Mexico (Cl); 2) medium specimens from Cedral (Cm) as well as
all teeth from San Josecito Cave (J), Mexico; 3) small specimens from Cedral, Mexico
(Cs); 4) large specimens from different localities of the American Southwest (identified
by a lower case “l” beside the specimen abbreviation; refer to Figure 2.1 for
abbreviations); 5) medium specimens from different localities of the American Southwest
(identified by a lower case “m” beside the specimen abbreviation; refer to Figure 2.1 for
abbreviations); 6) small specimens from Villa Ahumada (Vs) and Highway 45 (Gs),
Chihuahua, Mexico; 7) medium specimens from Natural Trap Cave, Wyoming (N); 8)
large specimens from Natural Trap Cave, Wyoming (Nl); 9) large specimens from the
Edmonton area gravel pits (E) and Wally’s Beach (W), Alberta; 10) medium specimens
from the Edmonton area gravel pits (Em), Alberta; and 11) all of the specimens digitized
from Bluefish Caves, Yukon (B). A lower case “a” beside the specimen abbreviation
indicates a tooth that yielded aDNA (these include EQ1 from Dry Cave, New Mexico,
EQ4 from the Edmonton area gravel pits, EQ13 as well as EQ22 from Natural Trap Cave,
EQ43 from Wally’s Beach, and EQ39, EQ48, and EQ50 from Bluefish Caves). An
asterisk (*) beside the specimen abbreviation denotes a tooth associated (i.e., it belongs to
the same individual) with a specimen from which aDNA was obtained (including teeth
associated with EQ42, EQ51, and EQ53 from Bluefish Caves).
109
15
-15
-15
15
110
semilandmark coordinates of the double knot (metaconid-metastylid-entoconid complex)
of the lower premolars (p3/p4). Shown on the margins of the graph is the change in shape
along each corresponding axis. The groups included in the analysis are: 1) large
specimens from Cedral, Mexico (Cl); 2) medium specimens from Cedral (Cm) as well as
all teeth from San Josecito Cave (J), Mexico; 3) small specimens from Cedral, Mexico
(Cs); 4) large specimens from different localities of the American Southwest (identified
by a lower case “l” beside the specimen abbreviation; refer to Figure 2.1 for
abbreviations); 5) medium specimens from different localities of the American Southwest
(identified by a lower case “m” beside the specimen abbreviation; refer to Figure 2.1 for
abbreviations); 6) small specimens from Villa Ahumada (Vs) and Highway 45 (Gs),
Chihuahua, Mexico; 7) medium specimens from Natural Trap Cave, Wyoming (N); 8)
large specimens from Natural Trap Cave, Wyoming (Nl); 9) large specimens from the
Edmonton area gravel pits (E) and Wally’s Beach (W), Alberta; 10) medium specimens
from the Edmonton area gravel pits (Em), Alberta; and 11) all of the specimens digitized
from Bluefish Caves, Yukon (B). A lower case “a” beside the specimen abbreviation
indicates a tooth that yielded aDNA (these include EQ1 from Dry Cave, New Mexico,
EQ4 from the Edmonton area, EQ13 as well as EQ22 from Natural Trap Cave, EQ43
from Wally’s Beach, and EQ39, EQ48, and EQ50 from Bluefish Caves). An asterisk (*)
beside the specimen abbreviation denotes a tooth associated (i.e., it belongs to the same
individual) with a specimen from which aDNA was obtained (including teeth associated
with EQ42, EQ51, and EQ53 from Bluefish Caves).
111
15
-15
-15
15
112
Table 2.12. Procrustes distances among groups for the lower premolars (p3/p4). Abbreviations: Cl = large specimens from Cedral,
Mexico. Cm/J = medium specimens from Cedral and specimens from San Josecito Cave, Mexico; Cs = small specimens from Cedral,
Mexico; SWl = large specimens from the American Southwest; SWm = medium specimens from the American Southwest; SWs =
small specimens from the American Southwest (Villa Ahumada and Highway 45, Chihuahua); Nl = large specimens from Natural
Trap Cave, Wyoming; N = medium specimens from Natural Trap Cave, Wyoming; E/W = large specimens from the Edmonton area
gravel pits and Wally’s Beach, Alberta; Em = medium specimens from the Edmonton area gravel pits, Alberta; B = specimens from
Bluefish Caves, Yukon.
Cl
Em
B
Cm/J
Cs
Em
B
Cm/J
Cs
SWl
SWm
SWs
Nl
0.0894
0.0865 0.1224
0.1056 0.0762 0.1575
0.1383 0.1224 0.2062 0.0688
SWl
0.0369 0.0699 0.0849 0.0980 0.1389
SWm
0.0838 0.0519 0.1302 0.0387 0.0892 0.0722
SWs
0.1093 0.0963 0.1771 0.0728 0.0515 0.1089 0.0739
Nl
0.1392 0.1072 0.1510 0.0898 0.1452 0.1236 0.0872 0.1494
N
0.0698 0.0444 0.1111 0.0596 0.1069 0.0620 0.0321 0.0828 0.0977
E/W
N
0.0511 0.0722 0.1008 0.1134 0.1443 0.0378 0.0857 0.1071 0.1483 0.0726
113
Table 2.13. P-values from permutation tests (10,000 permutation rounds) for Procrustes distances among groups of the lower
premolars (p3/p4). Abbreviations: Cl = large specimens from Cedral, Mexico. Cm/J = medium specimens from Cedral and specimens
from San Josecito Cave, Mexico; Cs = small specimens from Cedral, Mexico; SWl = large specimens from the American Southwest;
SWm = medium specimens from the American Southwest; SWs = small specimens from the American Southwest (Villa Ahumada
and Highway 45, Chihuahua); Nl = large specimens from Natural Trap Cave, Wyoming; N = medium specimens from Natural Trap
Cave, Wyoming; E/W = large specimens from the Edmonton area gravel pits and Wally’s Beach, Alberta; Em = medium specimens
from the Edmonton area gravel pits, Alberta; B = specimens from Bluefish Caves, Yukon. Statistically significant p-values are shown
in bold.
Cl
Em
B
Cm/J
Cs
Em
B
Cm/J
Cs
SWl
SWm
SWs
Nl
0.5058
0.0406 0.1796
0.0022 0.3584 <.0001
0.0784 0.4690 0.0010 0.2060
SWl
0.5379 0.4552 0.0068 0.0003 0.0141
SWm
0.0630 0.8363 0.0001 0.2552 0.1435 0.0223
SWs
0.2377 0.6013 0.0047 0.2328 0.9087 0.0705 0.3682
Nl
0.6303 1.0000 0.1799 0.4938 0.3942 0.2581 0.7017 0.7455
N
0.0973 0.8424 0.0017 0.0315 0.0855 0.0571 0.5407 0.2564 0.6039
E/W
N
0.2837 0.4330 0.0009 <.0001 0.0143 0.3376 0.0062 0.0659 0.1217 0.0339
114
2.3.4
Mitochondrial aDNA
I was able to extract and amplify mitochondrial aDNA from 22 of 50 late Pleistocene
specimens I sampled (Table A 5 of the Appendix). For two of these specimens, EQ3 and
EQ4, I only obtained a short fragment (117 bp) of the HVR I and, except for a
preliminary assessment which will be discussed below, these specimens were excluded
from the phylogenetic analyses because of the large amount of missing data. For the
remaining 20 specimens I obtained the complete target sequence for 15 specimens. The
aDNA extraction and amplification success rate varied among the sites, following a
primarily north to south trend, with the highest success rate for the Bluefish Caves
specimens (Table 2.14).
The Bayesian phylogenetic analysis using a 584 bp fragment of the HVR I
yields a polytomy consisting of caballine and stilt-legged clades (identified as clades 1
and 2, respectively in Figure 2.38) and the early middle Pleistocene specimen from
Thistle Creek, Yukon Territory, sequenced by Orlando et al. (2013). The analysis also
recovers 16 of the 18 extant horse haplogroups identified by Achilli et al. (2012). The two
horse haplogroups that are not recovered in the analysis are haplogroups O and F. The
Pleistocene sequences here studied separate into caballine and stilt-legged clades. All of
the sequences from Bluefish Caves and Wally’s Beach fall in the caballine clade, whereas
the sequences from Natural Trap Cave and the one obtained from San Josecito Cave
cluster in the stilt-legged clade. Two sequences from Dry Cave fall in the stilt-legged
clade, with a third sequence from this site clustering in the caballine clade. Within the
caballine group, there is a well-supported clade (identified as clade 3 in Figure 2.38) that
includes the modern horse haplogroups as well as a clade (clade 4 in Figure 2.38)
115
comprised by the sequences from Bluefish Caves, a sequence from the Yukon Territory,
and a sequence from the Taymyr Peninsula, Siberia. Clade 3 also includes Pleistocene
horses from Germany, Siberia, Alberta, and Argentina. The Wally’s Beach horses as well
as the caballine specimen from Dry Cave and a late Pleistocene specimen from Alaska
fall outside of Clade 3, forming a stem group to the extant caballine clade. There is little
structure in the stilt-legged clade and most of the sequences group together forming a
polytomy identified as Clade 5 in Figure 2.38. Within this clade two specimens from
Natural Trap Cave here studied and a specimen from the Yukon Territory cluster together
as Clade 6.
The same overall pattern identified in the analysis of the 584 bp fragment of the
HVR I is obtained in the phylogenetic analysis using a 348 bp fragment of the same
region. Both caballine and stilt-legged clades (clades 1 and 2 in Figure 2.39) are
recovered with comparable support to the analysis described above, with the middle
Pleistocene Thistle Creek specimen not assigned to any of these clades. However, in this
analysis only 14 of the extant horse haplogroups identified by Achilli et al. (2012) are
obtained. Haplogroups C, F, N, and O are not recovered in the analysis. The late
Pleistocene specimens here studied fall into the same groups mentioned above. The
sequences from Bluefish Caves and Wally’s Beach, as well as one of the sequences from
Dry Cave cluster in the caballine clade, whereas the sequences from Natural Trap Cave,
two from Dry Cave and the one obtained from San Josecito Cave group in the stilt-legged
clade. As for the analysis of the 584 bp fragment, within the caballine group there is a
clade (identified as clade 3 in Figure 2.39) that includes all of the extant horse
haplogroups as well as several late Pleistocene and historic equid sequences. Within this
116
clade, the sequences from Bluefish Caves form a separate group along with other
specimens from Yukon, Alaska, and Siberia (clade 4 in Figure 2.39). Also included in
clade 3 are sequences of late Pleistocene specimens from Germany, northeastern Siberia,
China, Alberta, and Argentina. Caballine sequences that fall outside of clade 3
correspond mostly to North American late Pleistocene specimens (except JW17 which is
from the Ural Mts., Central Asia), including the Wally’s Beach specimens, the caballine
sequence from Dry Cave, as well as specimens from Alaska, Yukon, Alberta, and Natural
Trap Cave. One of the sequences from Wally’s Beach groups with sequences from
Natural Trap Cave, Yukon, and Alaska (clade 5 in Figure 2.39), whereas the other
specimen from Wally’s Beach clusters with other sequences from Alberta (clade 6 in
Figure 2.39). As for the analysis of the 584 bp fragment of the HVR I, there is little
structure in the stilt-legged clade and most of the specimens form a polytomy (clade 7 in
Figure 2.39).
A phylogenetic analysis of the 117 bp fragment of the HVR I represented in the
sequences obtained for specimens EQ3 and EQ4 yielded little resolution, but the few
clades identified are congruent with those reported in the two analyses described above
(Figure 2.40). This analysis revealed that the sequence of EQ3 is most similar to the
sequence of a stilt-legged equid from Quartz Creek, Yukon (clade 1 in Figure 2.40), and
the sequence of EQ4 is most similar to the sequence of EQ16 (clade 2 in Figure 2.40).
These results suggest that both specimens are likely members of the stilt-legged group.
117
Table 2.14. Ancient DNA extraction and amplification success rate by locality. *
indicates localities with specimens for which only a short fragment (117 bp) of the HVR I
was obtained and are not considered as successful amplifications.
Locality
No. successful extractions
and amplifications
Success rate (%)
Bluefish Caves, Yukon
10/10
100
Pit 48, Edmonton, Alberta
0/2*
0
Wally’s Beach, Alberta
2/2
100
4/6
66.7
Blackwater Draw, New Mexico
0/3
0
Dry Cave, New Mexico
3/9*
33.3
Dark Canyon Cave, New Mexico
0/3
0
Other sites, New Mexico
0/3
0
San Josecito Cave, Mexico
1/2
50.0
Cedral, Mexico
0/9
0
Loltún, Mexico
0/1
0
118
Figure 2.38. Consensus tree of Bayesian (Markov chain Monte Carlo) phylogenetic analysis displaying relationships between
mitochondrial control region (HVR 1) haplotypes of extinct and extant equids, rooted with domestic donkey (Equus africanus asinus
(L., 1758)) and Somali Wild Ass (Equus africanus somaliensis (Noack, 1884)) as the outgroup. The tree was constructed using 583 bp
fragments of the HVR I. Posterior probabilities of the major nodes are listed for each of the branches. Identified by letters are the
modern horse haplogroups defined by Achilli et al. (2012) that were recovered in the analysis.
119
120
121
2.4
2.4.1
Discussion
Interpretation and synthesis of morphometric and molecular analyses
The results of the morphometric analysis using the linear measurements indicate that each
geographic region has anywhere between one and three tooth size groups. Tooth size in
many mammals, including equids, is positively correlated with body mass (Fortelius,
1990; Janis, 1990). Moreover, extant equid species and monospecific quarry samples of
fossil equid species do not show sexual dimorphism in the cheek tooth dimensions
investigated here (MacFadden, 1992). This evidence suggests that the different tooth size
categories indicate the presence of equid populations that differed in body mass. Body
mass is one of the morphological characters that tends to differ in sympatric,
taxonomically close species (Brown and Wilson, 1956). Therefore, given the temporal
overlap of the samples within each geographic region, it is reasonable to hypothesize that
these different size groups correspond to different equid species.
The geometric morphometric analyses of the third and fourth upper and lower
premolars show that the equid groups identified in the linear morphometric analysis
within each geographic region not only differ in size, but also show differences in the
upper P3/P4 and lower p3/p4 occlusal enamel pattern when standardizing for tooth size.
Moreover, the geometric morphometric analyses provide insights about morphological
variation across geographic regions. Taking into consideration the results of the linear
morphometric analyses and the results for both geometric morphometric analyses, four
morphological groups are identified across the Western Interior of North America. These
groups correspond to: 1) the small size group from Cedral, Mexico, and the American
122
Southwest (comprised of a small sample of teeth from northern Chihuahua); 2) a group
consisting of the medium size specimens from northeastern Mexico (Cedral and San
Josecito Cave), the American Southwest, Natural Trap Cave, and Alberta (comprised of a
small sample of teeth from the Edmonton area gravel pits); 3) a group consisting of the
large specimens from Cedral, the American Southwest, Natural Trap Cave (comprised by
a relatively small sample of specimens), and Alberta; and 4) the equid specimens from
Bluefish Caves, Yukon, which overlap the lower size range of the large specimens from
Cedral, the American Southwest, Natural Trap Cave, and Alberta, but have a statistically
different occlusal enamel pattern for both upper P3/P4 and lower p3/p4.
The identification of four morphological groups of Equus for the late Pleistocene
of the Western Interior of North America differs from the latest morphological revisions
of the genus. Winans (1989) identifies the presence of three equid species groups that
were widely distributed throughout North America during late Pleistocene: Equus
alaskae (Hay), 1913b (small and stout-legged species group), E. francisci Hay, 1915
(small and stilt-legged species group), and E. laurentius Hay, 1913a (large and stoutlegged species group). In contrast, Azzaroli (1998) recognizes nine species of equids that
were present in the continent during this time interval, six of which he mentions have
been found in localities from the Western Interior of North America. These are E.
fraternus Leidy, 1860 and E. conversidens Owen, 1869 (short legged equids which
Azzaroli [1998] considers were related to South American species of Equus), E. excelsus
Leidy, 1858 (a large and stout legged equid with a heavy skull and mandible), E.
niobrarensis Hay, 1913a (a large equid with more slender limbs than E. excelsus as well
as a more slender skull and mandible), E. mexicanus (Hibbard) 1955 (a large equid which
123
according to Azzaroli [1998] shares some skull features with species of Equus from
South America), and E. francisci Hay, 1915 (a stilt-legged equid).
The analysis of mitochondrial aDNA for the most part agrees with the results of
the morphological study (Table 2.15). Mitochondrial aDNA was successfully extracted,
amplified, and sequenced from specimens belonging to each of the four groups identified
by the morphological analyses, except for the small size group from Cedral, Mexico, and
the American Southwest. The analysis of aDNA recovers the two main clades identified
previously by Weinstock et al. (2005) and which they refer to as the New World “stiltlegged” (NWSL) and caballine clades. It is interesting to note that all of the specimens
assigned to the medium size group from which aDNA was recovered fall within the
NWSL clade. This was unexpected as the medium size specimens from Dry Cave, New
Mexico (specimens identified as E. conversidens by Harris and Porter [1980], but
identified as E. alaskae by Winans [1989]), and the specimens from San Josecito Cave
(Stock, 1950, 1953; Winans, 1989; Azzaroli, 1998, Eisenmann, 2013a), northeastern
Mexico, are not associated with slender metapodials. These results indicate a certain
degree of plasticity in the metapodial proportions of this group. Examination of the PCA
graphs of Winans, (1989, Figures 14.6C and 14.6D) lends support to this idea and hints at
the presence of a geographical cline in which the degree of metapodial slenderness
increases from San Josecito Cave to Natural Trap Cave, with the specimens from Dry
Cave occupying an intermediate position. This graph also shows that the specimens from
Natural Trap Cave do not attain the degree of slenderness presented by other North
American Pleistocene equid samples (such as those from Channing, Texas), which other
researchers consider as true stilt-legged equids (Eisenmann et al., 2008; Baskin et al.,
124
2013). The implication of these results is that genetic data for true North American stiltlegged equids (such as E. francisci [Lundelius and Stevens, 1970] and E. semiplicatus
[Eisenmann et al., 2008]) is presently lacking. A geographical cline was also revealed in
the occlusal enamel pattern of the upper P3/P4 by the geometric morphometric analysis.
The third Canonical Axis (CV 3) arranged the intermediate size specimens from south to
north: specimens from northeastern Mexico have negative scores, whereas specimens
from Wyoming have positive scores, with specimens from the American Southwest
occupying an intermediate position (Figure 2.35).
The specimens referred to the large size group from Alberta and Dry Cave as well
as the specimens from Bluefish Caves from which aDNA was obtained have sequences
that identify them as belonging to the caballine clade. Within this clade there is a group
(clade 3 in Figures 2.38 and 2.39) which includes the haplogroups of extant horses as
defined by Achilli et al. (2012). The Bluefish Caves specimens along with previously
sequenced specimens from Alaska, Yukon, and Siberia cluster in clade 3 forming a
distinct, apparently extinct haplogroup from those identified by Achilli et al. (2012). The
specimens of the large size group from Alberta and Dry Cave as well as previously
published sequences from Alaska, Yukon, Alberta, and Wyoming cluster outside of clade
3, forming a stem group to the extant caballines.
Despite repeated attempts, aDNA was not recovered from specimens of the small
equid group from Cedral, Mexico. Given its distinctive morphology, I hypothesize that
this equid represents a separate lineage. It may prove to be more closely related to the
medium size equid, as it does not possess a caballine tooth morphology. In both
geometric morphometric analyses the first Canonical Variate (CV 1) separates caballine
125
equids, which show positive scores, from non-caballine equids, which show negative
scores (Figures 2.34 and 2.36). The small specimens from Cedral as well as the small
specimens from the American Southwest, have the most negative scores in the plot.
Taking into account the morphological and the molecular analyses, I conclude
that there were three equid species present during the late Pleistocene of the Western
Interior of North America: one caballine (i.e., Equus ferus Boddaert, 1785) and two noncaballine species. Due to differences in size, tooth morphology, and geographic
distribution between the caballine group from Bluefish Caves and the rest of the caballine
specimens (i.e., Alberta, Wyoming, the American Southwest, and Cedral, Mexico), I
consider it might be convenient to divide them into two subspecies, pending further study
of the E. ferus species complex.
2.4.2
Taxonomic nomenclature of late Pleistocene equids from the Western Interior
of North America
Equid taxonomy is highly confused and clarifying it is beyond the scope of this research.
This requires careful evaluation of every single holotype. Previous researchers (e.g.,
Winans, 1985, 1989; Eisenmann, 2013a) have lamented that several holotypes consist of
isolated teeth or partial tooth rows and have questioned the diagnostic value of these
elements, regarding the names based on them as nomina dubia. The methodology applied
here presents the opportunity to evaluate many of these holotypes, potentially helping to
clarify equid taxonomy.
As a result of the existing problems in equid taxonomy, it is important to mention
that the names I use for the species identified in this study must be, for the time being,
regarded as tentative. The caballine equid species appears to be conspecific with E. ferus
126
and this is the name I propose should be assigned to this material. However, based on
differences in size, tooth morphology, and geographic distribution, I suggest using the
subspecific designation Equus ferus lambei for the specimens from Bluefish Caves and
Equus ferus scotti for the large caballine specimens from the remaining geographic
regions (i.e., Alberta, Wyoming, the American Southwest, and Cedral, Mexico). Equus
lambei Hay, 1917 is the name that has been applied in the literature for the equid material
from Bluefish Caves (e.g., Burke and Cinq-Mars, 1996, 1998) and I propose retaining it
here as a subspecific name. Winans (1989) suggested that E. lambei might be a junior
synonym of E. alaskae (Hay), 1913b, along with the specimens from San Josecito cave
referred as E. conversidens leoni by Stock (1950, 1953). The synonymy with E. alaskae
may prove to be correct, but the material from San Josecito Cave is clearly distinct based
on the morphological and molecular analyses reported here. Azzaroli (1995, 1998)
considered E. lambei as a valid species, but thought it was probably a subspecies of E.
niobrarensis Hay, 1913a.
The assignment of the subspecific name of the large caballine equid is more
problematic, given the greater variety of names that have been proposed for large
(presumably stout-legged) North American equids including: Equus excelsus Leidy,
1858; E. complicatus Leidy, 1858; Equus pacificus Leidy, 1868; Equus scotti Gidley,
1900; E. niobrarensis Hay, 1913a; E. occidentalis sensu Merriam, 1913; E. mexicanus
Hibbard, 1955. Of these equids, the holotype of E. excelsus, which is middle Pleistocene
in age, has certain morphological features that indicate it is not a caballine equid
(Eisenmann, 2006). The same is true for E. occidentalis sensu Merriam, 1913, which
based on the morphology of the upper P3/P4 premolars (Barrón-Ortiz and Theodor, 2011)
127
as well as the lack of infundibulae on the lower incisors and other cranial characters
(Azzaroli, 1995; 1998), appears to represent a different equid species from the ones
present in the Western Interior of North America, indicating the existence of at least four
late Pleistocene species of Equus in North America. Out of the remaining species names
E. scotti seems to be the most appropriate for the subspecific designation of the large
form of Equus ferus, until evaluation of the holotypes based on isolated cheek teeth (e.g.,
E. complicatus and Equus pacificus) is undertaken.
The medium size equid species, whose mitochondrial aDNA corresponds to the
NWSL clade of Weinstock et al. (2005), is referred to Equus conversidens Owen, 1869.
This name has been widely used in the literature of North American late Pleistocene
equids, although not without some confusion (see Scott, 1996, for different
morphological concepts of this species). The morphological and molecular datasets for
this species included several specimens studied by previous authors and which were
identified by them as E. conversidens, including material from San Josecito Cave (e.g,
Stock 1950, 1953; Azzaroli, 1995; 1998; Scott 1996), specimens from Dry Cave (Harris
and Porter, 1980; Harris, 2015), U-bar Cave (Harris, 1987), Scharbauer Ranch (Quinn,
1957), and Blackwater Draw (Lundelius, 1972). Alberdi et al. (2014) also report the
presence of E. conversidens from Cedral, Mexico; however, many of the specimens that
Alberdi et al. (2014) identify as the small equid from Cedral I identify here as E.
conversidens. The specimens from Wally’s Beach were identified as E. conversidens by
McNeil (2009); however this assignment is not supported by the morphological and
molecular analyses of the specimens from this site included in my study. The results
128
show that the specimens from Wally’s Beach are caballine equids and are members of E.
ferus scotti.
The proposal put forward by different authors (e.g., Dalquest, 1978; Harris and
Porter, 1980; Azzaroli, 1998) regarding the close phylogenetic affinity of E. conversidens
to South American equids of the subgenus Amerhippus (sometimes regarded as a distinct
genus [e.g., Eisenmann, 2013a]), based primarily on specimens from San Josecito Cave,
is not supported by the molecular analysis. The specimens of Equus (Amerhippus)
neogeus cluster well within the caballine clade (Figures 2.38 and 2.39) as it was
originally reported by Orlando et al. (2008).
Fossil material of Equus conversidens was recognized in four of the five
geographic regions studied. It is well represented in northeastern Mexico (including
Cedral and San Josecito Cave), the American Southwest (i.e., Algerita Blossom Cave,
Blackwater Draw, Dark Canyon Cave, Dry Cave, Lubbock Lake, Quitaque Creek, Salt
Creek, Scharbauer Ranch, and U-Bar Cave), and Natural Trap Cave, Wyoming. This
species is much less common in Alberta, where it was identified based on at least four
specimens from the Edmonton area gravel pits, but not from Wally’s Beach, and it was
not found in the material examined from Bluefish Caves, Yukon. The presence of this
species in the Edmonton area gravel pits is further supported by the association of some
of the specimens studied (right and left p2 as well as left p3) as part of a partial dentary
(P98.5.480) in which all of the incisors lack an infundibulum (a funnel-like cup of enamel
filled with cementum). Partial mandibles and mandibular symphyses with lower incisors
from San Josecito Cave (e.g., LACM 18404, 18383, 18802, 120758, 18644) and those
identified as E. conversidens from Dry Cave (UTEP 22-955, 26-1064) by Harris and
129
Porter (1980) and Harris (2015) lack an infundibulum in all of the incisors. In contrast,
mandibles and partial mandibles with associated lower incisors assigned to E. ferus
lambei from Bluefish Caves (e.g., CMH MgVo-2 B3-3-23, MgVo-2 C3(E)-3-19, MgVo2 H6-3-7, MgVo-3 85-95, MgVo-3 85-76, MgVo-3 85-64, MgVo-3 M-9-83) and those
assigned to E. ferus scotti (including specimens from Wally’s Beach [RAM DhPg-8
876.1, DhPg-8 863, DhPg-8 3437.2], the Edmonton area gravel pits [RAM P97.11.2A],
Dry Cave [UTEP 22-1657], Salt Creek [UTEP 34-5], and Scharbauer Ranch [TMM 9981]) have an infundibulum on the first and second lower incisors and this feature is more
variable on the third lower incisors. This pattern is certainly consistent with the results
obtained for the morphological and molecular analyses of the cheek teeth; nevertheless
the sample size represented by these specimens is not adequate to fully document the
frequency of this morphological trait in each species or subspecies and further study is
required. Eisenmann (1979) has noted that the frequency of infundibula in the lower
incisors of modern equid species can show important intraspecific variation. Moreover, as
with other morphological characters of the enamel pattern of equid teeth, the morphology
of the infundibulum changes as the tooth wears down until it completely disappears;
therefore, the assessment of this character has to take into consideration the stage of tooth
wear.
The taxonomic assignment of the small equid from Cedral, northeastern Mexico,
and the few specimens from northern Chihuahua, Mexico, here grouped with the
American Southwest samples, is not completely clear. Alberdi et al. (2014) considered
that the small equid from Cedral represents a new species, which they named Equus
cedralensis, but the morphology of the teeth from Cedral as well as the tooth dimensions
130
are comparable to those of E. tau Owen, 1869. The maxillary figured and described by
Owen (1869) (designated the lectotype of E. tau by Mooser and Dalquest [1975]) has the
third premolar damaged, but the fourth premolar shows many of the traits identified in the
geometric morphometric analysis as present in the small species from Cedral: mesostyle
and parastyle not prominent, shallow parastyle-mesostyle valley (the mesostyle-metastyle
valley is not preserved in Owen’s [1869] specimen), and the region of the occlusal
enamel corresponding to landmark 11 displaced mesially (CV1 transformation grid in
Figure 2.34). Other morphological traits commonly present in the small equid from
Cedral and shared with the cheek teeth figured by Owen (1869) are a straight (flat)
lingual border of the protocone and the absence of a pli caballin. All of the features
mentioned above are also present in the holotype of E. francisci figured by Lundelius and
Stevens (1970) and Eisenmann et al. (2008). The holotype of E. tau appears to have been
lost (Mooser and Dalquest, 1975), nevertheless, different researchers have assigned
material from a variety of localities from Mexico and the United States to this species
(e.g., Mooser and Dalquest, 1975; Dalquest, 1979; Melgarejo-Damian and MontellanoBallesteros, 2008), some of which may or may not correspond to the species described by
Owen (1869). The most common morphological concept of E. tau in the literature is that
of a small-sized equid with slender metapodials (e.g., Dalquest, 1979) and, as a result,
some researchers have synonymised E. francisci with E. tau (e.g., Dalquest, 1979). It is
not clear, however, whether E. tau possessed slender metapodials as the material
described by Owen (1869) was not associated with metapodials or any other postcranial
elements. According to Alberdi et al. (2014), the small equid from Cedral does not
possess slender metapodials. Until the exact taxonomic status of E. tau and other small
131
North American equids (e.g., E. littoralis Hay, 1913a; E. achates Hay and Cooke, 1930)
is clarified I prefer to refer to the small species from Cedral and Chihuahua, Mexico, as
E. cedralensis.
132
Table 2.15. Summary of the results of the morphometric analyses of the cheek teeth and the Bayesian phylogenetic analyses of
mitochondrial aDNA. Four taxa are identified based on tooth size, the morphology of the occlusal enamel pattern of the third and forth
upper premolars (P3/P4), the morphology of the metaconid, linguaflexid, and metastylid of the third and fourth lower premolars
(p3/p4), and aDNA of the mitochondrial control region (mt aDNA), hypervariable region I. The last column presents the tentative
taxonomic identification of each taxon. NWSL = New World stilt-legged clade of Weinstock et al. (2005). Ancient DNA extraction
for specimens of E. cedralensis failed.
Size
Upper P3/P4
Shallow parastyle-mesostyle and mesostylemetastyle valleys, fossettes bucco-lingually
Small
expanded, landmark 11 displaced mesially,
anterior margin of protocone does not
extend mesially
Relatively shallow parastyle-mesostyle and
mesostyle-metastyle valleys, fossettes
sometimes bucco-lingually expanded,
Medium
landmark 11 in some specimens displaced
mesially, anterior margin of protocone
extends mesially
Deep parastyle-mesostyle and mesostylemetastyle valleys, fossettes bucco-lingually
Large
compressed, landmark 11 displaced distally,
anterior margin of protocone extends
mesially
Deep parastyle-mesostyle and mesostylemetastyle valleys, fossettes bucco-lingually
Mediumcompressed, landmark 11 displaced distally,
Large
anterior margin of protocone does not
extend mesially
Lower p3/p4
mt aDNA
Taxonomic id.
Generally shallow and V- or broad Ushaped linguaflexid, open metaconid,
and relatively rounded metastylid
--
E. cedralensis
Generally shallow and V- or broad Ushaped linguaflexid, open metaconid,
and triangular metastylid
NWSL
E. conversidens
Generally deep and U-shaped
linguaflexid, constricted metaconid, and
bucco-lingually expanded metastylid
Caballine
E. ferus scotti
Generally deep and U-shaped
linguaflexid, constricted metaconid, and
bucco-lingually compressed metastylid
Caballine
E. ferus lambei
133
2.5
Conclusions
Four equid taxa are identified from the late Pleistocene of the Western Interior of North
America, based on morphological and molecular analyses of the cheek teeth: Equus
cedralensis, E. conversidens, E. ferus scotti, and E. ferus lambei. Equus cedralensis is a
small-sized equid which appears to have been restricted during the late Pleistocene to the
southern latitudes of the Western Interior of North America, as it was only identified
from Cedral, Mexico, and the American Southwest (sites located in northern Chihuahua,
Mexico). The ancient DNA of this species is currently unknown.
Equus conversidens is a medium-sized equid which was previously identified
based on mitochondrial aDNA as the New World stilt-legged clade (Weinstock et al.,
2005). The results of the present study suggest that this species exhibited a north-south
cline in the degree of metapodial slenderness and that genetic data for true North
American stilt-legged equids (such as E. francisci [Lundelius and Stevens, 1970] and E.
semiplicatus [Eisenmann et al., 2008]) are presently lacking. A north-south geographical
cline was also revealed in the occlusal enamel pattern of the upper P3/P4 by the
geometric morphometric analysis. E. conversidens was widely distributed in North
America and in this study it was identified from northeastern Mexico (Cedral and San
Josecito Cave), the American Southwest (e.g., Blackwater Draw, Dark Canyon Cave, Dry
Cave, Quitaque Creek, Salt Creek, Scharbauer Ranch, and U-Bar Cave), Natural Trap
Cave, and Alberta (a small sample of teeth from the Edmonton area gravel pits).
Equus ferus scotti is a large-sized caballine equid that in the phylogenetic analysis
of aDNA forms a stem group to the extant caballine clade. This equid was found in North
134
America south of the continental ice sheets during the late Pleistocene. It was identified
from Cedral, Mexico, the American Southwest (e.g., Blackwater Draw, Dry Cave, Isleta
Cave No. 2, Salt Creek, Scharbauer Ranch, and U-Bar Cave), Natural Trap Cave (where
it is represented by relatively few specimens) and Alberta (including the Edmonton area
gravel pits and Wally’s Beach site).
Equus ferus lambei is a caballine equid with a size range intermediate to that of E.
conversidens and Equus ferus scotti. It was identified in this study from Bluefish Caves,
Yukon Territory, and other studies report it from other parts of Beringia. Genetically, the
specimens from Bluefish Caves are placed within the clade that includes all of the extant
horse mitochondrial haplogroups; however, these specimens, along with previously
sequenced specimens from Alaska, Yukon, and Siberia, cluster together forming a
distinct, apparently extinct haplogroup.
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Perissodactyls. Clarendon Press, Oxford.
Woodburne, M. O. 2003. Craniodental analysis of Merychippus insignis and
Cormohipparion goorisi (Mammalia, Equidae), Barstovian, North America. Bulletin
American Museum of Natural History. 279:397–468.
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extraction from ancient bones using silica-based spin columns. American Journal of
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Morphometrics for Biologists: A Primer. Elsevier Academic Press, San Diego.
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CHAPTER 3. DENTAL MICROWEAR AND MESOWEAR IN LATE
PLEISTOCENE EQUIDS AND BISON: TESTING PREDICTIONS OF
NUTRITIONAL EXTINCTION MODELS
3.1
Introduction
The late Pleistocene extinction is the second largest extinction event in North America in
the past 55 million years (Alroy, 1999), and it is particularly notable because of the role it
had in shaping current biodiversity patterns (Koch and Barnosky, 2006; Hofreiter and
Stewart, 2009). Mammals were among the most adversely affected groups and it is
estimated that over 30 genera disappeared from the continent (Grayson, 1991, 2007;
Koch and Barnosky, 2006; Faith and Surovell, 2009; Stuart, 2015). The causes of the
extinction have been extensively debated and several extinction models have been
proposed. Some models identify climate change as the primary causal factor (e.g., Kiltie,
1984; King and Saunders, 1984; Graham and Lundelius, 1984; Guthrie, 1984; Barnosky,
1986; Ficcarelli et al., 2003; Forster, 2004; Scott, 2010), others point to overhunting and
alteration of natural habitats by early human populations (Martin, 1967, 1984; Mosimann
and Martin, 1975; Diamond, 1989), and yet others invoke catastrophic events, such as a
bolide impact (Firestone et al., 2007) or a hyperdisease (MacPhee and Marx, 1997).
Currently there is weak support for the catastrophic extinction models (e.g., Lyons
et al., 2004; Koch and Barnosky, 2006; Surovell et al., 2009; Holliday et al., 2014;
Meltzer et al., 2014) and much of the debate regarding the late Pleistocene extinctions has
focused on the relative importance of climate change versus human impacts, particularly
hunting. Some of the climate change extinction models point to nutritional stress as the
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primary factor responsible for the extinctions (e.g., Graham and Lundelius, 1984;
Guthrie, 1984). The recent development of different methodologies for the reconstruction
of mammalian paleodiets (e.g., dental wear and stable isotopes) promises to shed new
light on this matter by allowing the formulation and testing of novel hypotheses about
patterns of feeding ecology expected under different extinction models. Ultimately, finer
reconstructions of paleodiets for Pleistocene mammals will result in a better
understanding of community feeding ecology during the time leading up to the
extinctions. Efforts on this front have already commenced (e.g., Koch et al., 1998; Hoppe
and Koch, 2006; Sánchez et al., 2006; Fox-Dobbs et al., 2008; Rivals et al., 2008; Rivals
et al., 2010; Faith, 2011). These types of studies will open up the way to evaluating the
relative contribution of climate-induced vegetation changes during the late Pleistocene to
the disappearance of a wide variety of mammalian species.
In this chapter I employ methodologies based on dental wear (i.e., mesowear and
low magnification dental microwear) to reconstruct the diets of horses and bison to test
two nutritionally-based extinction models relating to climate-induced vegetation changes
during the terminal Pleistocene: the coevolutionary disequilibrium (Graham and
Lundelius, 1984) and mosaic-nutrient extinction models (Guthrie, 1984). Horses and
bison are excellent herbivore mammals to study because they were an important
component of Pleistocene land-mammal communities (particularly throughout the
Western Interior of North America) and their fossilized remains are abundant
(FAUNMAP, 1994). Moreover, some studies suggest that both types of ungulate may
have interacted ecologically as competitors for food resources (e.g., Feranec et al., 2009).
I focused on the study of the cheek teeth of these ungulates because teeth are the most
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commonly found fossil elements, are taxonomically informative, and record a wealth of
information about the biology of an organism, including diet and overall health status
during the period of tooth formation.
3.1.1
The coevolutionary disequilibrium extinction model
Graham and Lundelius (1984) developed the coevolutionary disequilibrium extinction
model, working under the assumption that late Pleistocene communities were highly
coevolved systems, similar to those currently found on the African savannas. The African
grazing succession is an example of a coevolved system in which grazing by one
mammalian herbivore species stimulates the growth of other plant species or plant parts
that in turn form the food resource of another herbivore species. In this ecosystem,
coevolved foraging sequences partition the environment through well-defined niche
differentiation, allowing the coexistence of many large herbivores. There is evidence that
plant and animal species responded individualistically to the climate events at the end of
the Pleistocene (Graham et al., 1996; Stewart, 2009). This individualistic response restructured the vegetation, causing a disruption of coevolutionary interactions between
plants and animals, resulting in coevolutionary disequilibrium. This would have created
nutritional stress and/or detoxification problems for some herbivores which had to adapt
to new plant associations. For most species, especially large herbivorous mammals, a
coevolutionary disequilibrium would reduce niche differentiation and consequently
increase competition among herbivores. Competition would have driven species with
reduced fitness to extinction. Species better adapted to the new community patterns
would have thrived and established a new interaction sphere.
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Graham and Lundelius (1984) presented four predictive hypotheses to test the
coevolutionary disequilibrium extinction model, which pointed to specific extinction and
survival patterns. These include correlation between the timing of community changes
and the timing of the extinctions, association of surviving remnants or ecomorphs of the
extinct fauna with analogous floral groups to those of the late Pleistocene, and divergence
and habitat partitioning of surviving large herbivores as a consequence of competition.
Additional hypotheses and predictions for this extinction model that can be derived based
on the reconstruction of ungulate paleodiets are presented below. These are the
hypotheses tested in this study and they are framed specifically for the bison and equid
species I investigated, but can be extended to include other ungulate species:
H10: Sympatric species of horse and bison inhabiting North America prior to the
rapid climatic changes at the end of the Pleistocene (referred here as the
postglacial), did not differ significantly in their diets suggesting that they did not
partition the available food resources.
H1A: Sympatric species of these ungulates prior to the postglacial differed
significantly in their diets, indicating that they partitioned the available food
resources just as modern large herbivorous ungulates of the African savannas do
today.
H1 Prediction: If the sympatric species of horse and bison partitioned food resources
prior to the rapid climatic changes of the postglacial (i.e., during the preglacial and fullglacial time intervals), then the signals of the dietary proxies (mesowear and low
magnification microwear) should be statistically different for the different taxa.
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H20: Sympatric species of horse and bison did not differ significantly in their diets
during the postglacial, suggesting that they were not partitioning the available
food resources and were potentially competing for them.
H2A: Sympatric species of these ungulates from this time interval differed
significantly in their diets, indicating that they were partitioning the available food
resources.
H2 Prediction: If sympatric species of horse and bison were not partitioning the available
food resources during the postglacial potentially due to coevolutionary disequilibrium
brought about by a change in the composition of vegetational communities, then the
signal of each dietary proxy (i.e., dental microwear and mesowear) should not be
significantly different for the different taxa.
3.1.2
The mosaic-nutrient extinction model
Guthrie (1984) draws from several lines of evidence, including the fossil record and
interactions between living ungulates and plants, to propose an ecological model of
megafaunal extinctions. He argues that the mosaic vegetation pattern present throughout
the Pleistocene allowed ungulates, especially large caecalid ungulates (e.g., horse and
mammoth), to obtain the right mix of nutrients needed for survival. These ungulates often
need to eat a variety of plants besides their staple forage (e.g., grass for grazers) to obtain
a well-balanced diet. Ruminants (e.g., bison and deer) also need to supplement their diets,
but Guthrie (1984) cites evidence that they are also able to synthesize nutrients in the
rumen through the help of microbial activity. In addition, ungulates are adapted to
overcome some plant defenses but not others. Large caecalid grazers like horse and
mammoth, are able to deal with grass phytoliths and a high concentration of fibre, but are
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not as efficient, as is the case for ruminants, at detoxifying allelochemics which are
commonly found in forbs and other browse. Guthrie (1984) reasons that as long as a
diversity of plant species existed, nutrient supplements could be acquired by large
caecalids by diluting a variety of different toxins, many of which could be detoxified in
reduced quantities.
Guthrie’s (1984) extinction model proposes that climatic changes in seasonal
regimes (i.e., increased seasonality and less intra-annual variability) during the
Pleistocene-Holocene transition decreased local plant diversity, increased zonation of
plant communities, and caused a shift in net anti-herbivore defenses. This change affected
the growing season for ungulates by shortening it and decreasing the net annual quality
and quantity of food resources available. Decreased local faunal diversity, body size,
geographic distribution, and often extinction occurred as a result of the restriction in
available food resources. Some hypotheses that can be formulated and tested for this
model are:
H10: Bison and horse species did not suffer a decrease in the variety of plant
species consumed during the postglacial relative to preglacial and full-glacial
periods.
H1A: These ungulates underwent a significant decrease in the variety of plant
species consumed during the postglacial, potentially due to a reduction in local
plant diversity.
H1 Prediction: If the species of horse and bison experienced a significant decrease in the
variety of plant species in their diets during the postglacial, then the statistical dispersion
(measured by the variance) of the variables of each dietary proxy (i.e., low magnification
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microwear variables and mesowear score) should be significantly smaller for this time
interval than for the preglacial and full-glacial periods.
3.1.3
Nutritional stress
Both coevolutinary disequilibrium and mosaic-nutrient extinction models point to
nutritional stress on herbivorous mammals as the primary factor responsible for the late
Pleistocene extinctions (Graham and Lundelius, 1984; Guthrie, 1984). This would trigger
a “bottom-up” ecosystem collapse starting with the herbivores and filtering upwards to
the apex carnivores. For these extinction models to be considered feasible, not only do
the predictions here formulated have to be met, but also increased nutritional stress of
herbivore mammals during the terminal Pleistocene must be demonstrated. Recent
advances regarding the inference of physiological stress from dental remains, allows the
opportunity to test this hypothesis. This topic is addressed in Chapter 4.
3.2
Limitations and Assumptions
The primary assumption that is made in this study is that consumption of different plant
species and plant parts is recorded in the dental wear of herbivore teeth. A large number
of studies of dental wear at different scales and using different techniques (e.g., low
magnification microwear, texture microwear analysis, conventional mesowear, mesowear
using the mesowear ruler), have consistently shown that dental wear varies significantly
across broad dietary groups such as grazers, browsers, mixed feeders, frugivores, and
generalists (e.g., Solounias et al., 1988; Fortelius and Solounias, 2000; Solounias and
Semprebon, 2002; Merceron et al., 2005; Ungar et al., 2007). However, in order to test
both extinction models, finer dietary differences within these broad trophic groups have
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to be detected. For example, the coevolutionary disequilibrium extinction model uses the
grazing succession of the African savannas as an example of a highly coevolved system
(Graham and Lundelius, 1984). This particular system consists of several grazers, such as
the plains zebra (Equus quagga), wildebeest (Connocaethes taurinus), hartebeest
(Alcelaphus buselaphus) and topi (Damaliscus lunatus). Field studies have shown that in
some areas these grazers partition dietary resources by feeding on different plant parts
and grasses at different growth stages (e.g., Gwynne and Bell, 1968; Bell, 1971; Murray
and Brown, 1993).
Few studies have been conducted to test whether finer dietary differences within
the broad dietary groups can be detected based on dental wear. One of these studies was
undertaken by Fortelius and Solounias (2000), when they introduced the mesowear
method. These authors report that mesowear is able to recover the grazing succession
with the plains zebra showing the most abrasive mesowear signal, followed by the topi,
wildebeest, and the Grant’s gazelle which is a seasonal mixed feeder (Fortelius and
Solounias, 2000). Scott (2012), investigating dental microwear texture analysis of extant
African bovids, identified significant differences in microwear among species within
some dietary categories (e.g., obligate grazers, variable grazers, browsers, and browsersgrazer intermediates) and related them to subtle differences in diet. In another study,
Barrón-Ortiz et al. (2014) investigated the mesowear and low magnification dental
microwear of three sympatric equid species from the late Pleistocene of Cedral,
northeastern Mexico. Significant differences in the microwear pattern of all three species
were detected, whereas mesowear was only significantly different in one of the species.
The results of the mesowear analysis are consistent with stable isotope data for these
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equids (Pérez-Crespo et al., 2009) in that the species that has a significantly different
mesowear signature is identified as a C3/C4 mixed feeder, whereas the other two species
show a high proportion of C4 grasses in their diet (Barrón-Ortiz et al., 2014). More
importantly, the analysis of dental microwear identified significant differences between
the two C4 grazing equids (Barrón-Ortiz et al., 2014), suggesting that it is possible to
detect finer dietary differences within the grazing trophic group using feature-based low
magnification dental microwear.
The three studies mentioned above suggest that finer differences within broad
dietary groups can be obtained through the analysis of dental wear. However, the nature
of the differences in dental wear identified in these studies and what they actually
indicate about the feeding ecology of the ungulates investigated is less clear. That is
because, despite extensive research, there is still no consensus about the primary agent
responsible for the formation of dental wear features. Phytoliths, lignin and cellulose, as
well as exogenous grit, have each been proposed as the primary factor producing dental
wear (e.g., Walker et al., 1978; Ungar et al., 1995; Sanson et al., 2007; Merceron et al.,
2007; Lucas et al., 2013; Schulz et al., 2013; Tütken et al., 2013). If phytoliths are the
primary agent causing dental wear, then plants or plant parts differing in their
concentration and type of phytoliths would produce different dental wear patterns.
Alternatively, if exogenous grit is responsible for producing dental wear, then differences
in dental wear would reflect feeding in different microhabitats (i.e., dusty versus less
dusty), or it could also reflect feeding on plant species or plant parts that differentially
accumulate dust on their surface. It is also possible that both exogenous grit and the
physical properties of the vegetation contribute, or might even interact, to produce dental
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wear. Resolution of this important issue is beyond the scope of this study, and I must
limit myself to working under the assumption that feeding on different plant species and
plant parts is recorded to some extent in the dental wear of herbivore teeth.
An additional assumption that I make in this study relates to the different
digestive physiologies of equids and bison. Equids are hindgut fermenters which have
high chewing efficiency and rapid passage times, that is they consume large amounts of
plant material that passes rapidly through the digestive system and which gets fermented
by microbial activity in the caecum (Janis, 1976; Clauss et al., 2009). Equids further have
molarized premolars which greatly assist in the mechanical breakdown of plant material
(Janis, 1988). Bison are ruminant foregut fermenters and have a four-chambered stomach
in which microbial fermentation of plant material occurs in the rumen, the first chamber
of the stomach (Janis, 1976). To complement the fermentation process, ruminants
periodically regurgitate the food located in the rumen and rechew it (Janis, 1976). The
second (reticulum) and third (omasum) chambers act as filters and the fourth chamber
(abomasum) is the true stomach (Janis, 1976). The digestive system of ruminants
achieves a high degree of particle size reduction, greater than that observed for hindgut
fermenters and non-ruminant foregut fermenters (Fritz et al., 2009).
There are few studies that have investigated whether differences in digestive
physiology systematically bias the dental wear patterns produced. Campbell et al. (2013)
conducted a preliminary study in which they examined low magnification microwear
(specifically average counts of scratches and pits) on occlusal enamel bands located in the
lingual side, center, and buccal side of upper molars of 18 extant and extinct
perissodactyls, including six equid species, and four extant ruminant species, including
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bison. These authors found that discriminant function analyses correctly classified extant
perissodactyls according to diet when microwear data from the labial edge of the tooth
was used, whereas the opposite pattern was observed in the four ruminants studied
(Campbell et al., 2013). Further studies are needed to corroborate the preliminary
conclusions drawn by Campbell et al. (2013). The vast majority of the photographs I
obtained are from enamel bands located in the central portion of the tooth. If the pattern
reported by Campbell et al. (2013) is confirmed by other studies and for a larger number
of ungulate taxa, then using the central portion of the tooth may not be the most optimal
area for inferring the diet of either equid or bison samples, but it may well be more
appropriate for comparing these two ungulate groups than using only the lingual or labial
sides. This is the second important assumption that I make in this study: differences in
digestive physiology of the equid and bison species here investigated do not significantly
bias dental wear patterns. If this assumption is severely violated, then I would expect to
see statistically significant differences in the dental wear of all the sympatric equid and
bison samples studied, which, as will be seen in the results section, is not the case.
3.3
This study focused on the equids and bison from the Western Interior of North America
of late Pleistocene (Wisconsinan glacial stage). The specimens that I studied come from
three geographic regions which comprise the following localities: Bluefish Caves,
Yukon; gravel pits around the Edmonton area and Wally’s Beach, Alberta; Dark Canyon
Cave, the Dry Cave localities, and Blackwater Draw Loc. 1, located in eastern New
Mexico, as well as Scharbauer Ranch and Lubbock Lake sites, from western Texas
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(Figure 3.1). The data I collected were arranged into preglacial, full-glacial, and
postglacial time intervals. The time incorporated by these time intervals varied slightly
for each geographic region. The material from Bluefish Caves, which consisted of only
one equid species (Equus ferus lambei; Chapter 2), could only be divided into two time
intervals: preglacial/full-glacial (~31 ky – 14 ky RCBP) and postglacial (~14 ky – 10 ky
RCBP). Specimens were assigned to one of these two time intervals based on published
work (Cinq-Mars, 1979; Morlan, 1989), documents on file at the Canadian Museum of
History (CMH Archives A2002-9 [Jacques Cinq-Mars’ documents]: box 11, f.7), and the
spatial and stratigraphic provenance of equid specimens (retrieved from specimen
catalogs and maps in the CMH Archives; A2002-9: box 2, f.1, f.2, f.4; box 3, f.1, f.3 –
f.9, f.13; box 8, f.4, f.5) relative to bones that have been subjected to radiocarbon dating
(Canadian Archaeological Radiocarbon Database [CARD 2.0], accessed March 2015).
These divisions correspond to a change in the vegetation of the region from tundra during
the preglacial/full-glacial to dwarf birch during the postglacial (Cinq-Mars, 1979; Ritchie
et al., 1982). Different publications mention the occurrence of bison remains at Bluefish
Caves (Cinq-Mars, 1979; Cinq-Mars, 1990), but I did not locate any bison cheek teeth in
the collection of the Canadian Museum of History. Thus, I only studied equid specimens
from this site.
The material from Alberta was divided into preglacial (>60 ky – 21 ky RCBP) and
postglacial time intervals (~13 ky – 10 ky RCBP), based on published radiocarbon dates
(Waters et al., 2015) and the association of specimens with localities that have only
yielded dates of preglacial or postglacial age (Burns, 1996; Jass et al., 2011). Fossil
material from the full-glacial is not represented in Alberta because most of the province
159
was covered by the Laurentide and Cordilleran ice sheets at that time (Young et al., 1994,
1999; Burns, 1996; Jass et al., 2011). The specimens from Alberta studied in this chapter
consisted of only one equid species (Equus ferus scotti; although a second less common
species, Equus conversidens, was recognized from the Edmonton area gravel pits
[Chapter 2]), as well as material referrable to Bison sp.
The fossil material from the American Southwest (specifically eastern New
Mexico and western Texas) can be divided into preglacial (~25 ky – 20 ky RCBP), fullglacial (~20 ky – 15 ky RCBP), and postglacial (~15 ky – 10 ky RCBP) ages, based on
different publications (Harris, 1987, 1989, 2015; Tebedge, 1988; Haynes, 1995; Holliday
and Meltzer, 1996). I was able to obtain data for only one equid species (Equus
conversidens) during the preglacial, whereas for the full-glacial I was able to collect data
for the two common equid species that inhabited this region during the late Pleistocene
(Equus ferus scotti and Equus conversidens; Chapter 2). Although bison (Bison antiquus)
was present in the American Southwest throughout the late Pleistocene (McDonald,
1981), I was only able to obtain mesowear and microwear data for postglacial specimens.
I also collected data for postglacial specimens of Equus ferus scotti and Equus
conversidens.
The samples for study consisted of cheek teeth housed at the following
institutions: Archaeology Collection (Bluefish Caves; MgVo-1, 2, and 3) of the Canadian
Museum of History (CMH); Quaternary Paleontology (P) and Archaeology collections
(Wally’s Beach site; DhPg-8) of the Royal Alberta Museum (RAM); Vertebrate
Paleobiology Collection, Laboratory for Environmental Biology, University of Texas at
160
El Paso (UTEP); and the Vertebrate Paleontology Collection of the Vertebrate
Paleontology Laboratory, University of Texas at Austin (TMM).
Figure 3.1. Geographic location of the fossil sites considered in this study.
3.3.1
Analysis of dental wear
Dietary reconstructions for herbivorous mammals obtained by the study of dental wear
are based on the physical interaction between the foodstuff and/or exogenous grit
comminuted and the herbivore’s teeth. The processes shaping dental wear are attrition
(tooth-on-tooth wear) and abrasion (tooth-on-food wear) (Fortelius and Solounias, 2000).
Grazers tend to suffer more abrasive wear, whereas browsers are primarily attrition-
161
dominated (Fortelius and Solounias, 2000; Solounias and Semprebon, 2002). Dental wear
of ungulates can be separated into mesowear and microwear, which provide insights into
dietary preferences at different scales. Mesowear is studied on the cusps of the cheek
teeth (Fortelius and Solounias, 2000; Franz-Odendaal and Kaiser, 2003; Kaiser and
Solounias, 2003; Louys et al., 2011) and reflects long-term average wear; attrition is
suggested to promote high and sharp cusps, whereas abrasion results in lower and more
blunted cusps (Fortelius and Solounias, 2000; Rivals and Athanassiou, 2008). Microwear
refers to microscopic features observed on the enamel band of the occlusal surface of the
teeth, generated during mastication by the food and/or exogenous grit ingested (Walker et
al., 1978; Teaford and Oyen, 1989; Solounias and Semprebon, 2002). Thus, mesowear
provides information about diet representing a relatively long period of an individual’s
lifetime, whereas microwear records the diet of an individual within the last weeks, days,
or perhaps hours prior to death (Teaford and Oyen, 1989; Fortelius and Solounias, 2000;
Solounias and Semprebon, 2002).
I used the extended mesowear method (Franz-Odendaal and Kaiser, 2003; Kaiser
and Solounias, 2003) and low magnification microwear method (Solounias and
Semprebon, 2002; following the modifications by Fraser et al. [2009]), to test the
hypotheses outlined for the coevolutionary disequilibrium and mosaic nutrient extinction
models and to infer the paleodiets of horses and bison from each geographic region
studied. A total of 226 specimens, consisting mostly of isolated teeth, were analyzed
(Tables A 7 and A 8 of the Appendix). Statistical tests were conducted using PAST 2.17
(Hammer et al., 2001), MATLAB 7.8 (MathWorks, 2009), and STATISTICA v. 9
162
(StatSoft®, 2009) software packages. The significance level for all tests was set to a pvalue of 0.05.
3.3.1.1 Low magnification microwear
Several methodologies exist for the study of dental microwear of which low
magnification microwear (e.g., Solounias and Semprebon, 2002; Semprebon et al., 2004;
Merceron et al., 2004, 2005; Nelson et al., 2005; Gomes Rodrigues et al., 2009) and
microwear texture analysis (e.g., Ungar et al., 2003, 2010; Scott et al., 2005, 2006;
Merceron et al., 2010) are currently the most widely applied. In this study, I examined
dental microwear at a low magnification (35 X) using high-resolution clear epoxy casts. I
counted microwear features on high dynamic range images (HDR; Figure3.2) prepared
following the methodology in Fraser et al. (2009), using an Olympus E-M10 digital
camera and a Nikon SMZ1500 stereomicroscope; the digital resolution of the images
obtained is 0.6 pixels/µm. Cleaning, molding, and casting of the teeth studied were done
according to Solounias and Semprebon (2002). Only teeth in middle stages of wear were
used. In addition, to minimize systematic biases during data collection, I randomized the
order of the specimens during photography and the order of the HDR images was also
randomized prior to data collection to ensure observer blindness (Mihlbachler et al.,
2012).
The majority of the specimens studied consisted of isolated upper (M1, M2, and
M3) and lower (m1, m2, and m3) molars. In the case of associated teeth (i.e., teeth that
belong to the same individual), I studied the second molar and if this tooth was damaged
or absent I selected one of the other molars at random. I preferentially studied microwear
163
features on the lingual enamel band of the paracone and/or metacone for the upper molars
and the buccal enamel band of the preflexid and/or postflexid for the lower molars. For
specimens in which these enamel bands were damaged, I collected microwear data from
the lingual enamel band of the fossettes, for the upper molars, and the protoconid or
hypoconid enamel band for the lower molars. The microwear variables scored per tooth
specimen are partially based on those presented by Solounias and Semprebon (2002) and
include the average number of scratches and pits of two counting areas on the enamel
band, each 0.4 X 0.4 mm. Pits are microwear features that are circular to sub-circular in
outline, whereas scratches are elongated features typically with a length to width ratio of
at least 4:1. I also recorded scratch texture for each counting area by noting whether the
scratches present consisted of fine scratches (scratches that appear the narrowest), coarse
scratches (scratches that appear wider), or mixed scratches (a combination of both fine
and coarse scratches). I subsequently assigned a score of 0 if it consisted of fine
scratches, 1 if it consisted of fine and coarse scratches, and 2 if it consisted of coarse
scratches (e.g., Rivals et al., 2007; Rivals and Athanassiou, 2008). The average scratch
texture score of the two counting areas was then calculated for each specimen. I also
obtained the average number of cross scratches (scratches oriented at an oblique angle
with respect to the majority of scratches), average number of large pits (which are at least
twice the diameter of small pits), as well as the average number of exceptionally wide
scratches (at least twice the width of coarse scratches) for the two counting areas. Finally,
I recorded the presence of gouges (large, irregular microwear scars) on the visible enamel
band of the photograph, providing a score of 1 if the feature was present or 0 if it was
164
absent. The data collected following this approach are shown in Table A 7 of the
Appendix.
In order to test the hypotheses developed for the coevolutionary disequilibrium
extinction model, I conducted non-parametric multivariate analyses of variance tests (NPMANOVA), in which significance is estimated by permutation, using 100,000 replicates
and the Mahalanobis distance measure. Bonferroni corrected pairwise comparisons were
used to identify which species are significantly different from each other. These analyses
were preformed using PAST 2.17 (Hammer et al., 2001) on the data in Table A 7 of the
Appendix.
To test the hypotheses outlined for the mosaic-nutrient extinction model I
calculated the quotient resulting from the division of the variance of a specific microwear
variable at time interval 1 by the variance of that same variable at time interval 2.
Significance of the variance quotient was assessed by bootstrap analysis conducted using
MATLAB 7.8 (MathWorks, 2009), employing 100,000 replicates. For this analysis I
examined the counted microwear variables found in Table A 7 of the Appendix: average
number of scratches, average number of pits, average number of cross scratches, average
number of large pits, and average number of wide scratches.
As a final component of the analysis of dental microwear, I conducted dietary
reconstructions for each species by geographic region and time interval. This was done
by comparing the microwear data I collected with the dataset reported by Solounias and
Semprebon (2002) for modern ungulate species. Recent studies have found high interobserver error in the scoring of microwear features using low magnification procedures
(e.g., Mihlbachler et al., 2012). This means that until I am able to examine some of the
165
specimens studied by Solounias and Semprebon (2002), it is difficult to assess whether
these authors and I are scoring microwear features in a similar manner, especially
because I scored microwear features on HDR images, whereas these authors quantified
microwear features without the aid of any type of photographs. As a result, the dietary
reconstructions here presented should be regarded as tentative. Nevertheless, these issues
do not interfere with the primary objective of the study, which is to test the
coevolutionary disequilibrium and mosaic-nutrient extinction models. Accurately
reconstructing the diet of each sample is not required to test the hypotheses developed for
these two extinction models.
It was necessary to adjust the microwear data I collected to make it comparable to
the dataset of Solounias and Semprebon (2002). These authors did not quantify the
average number of cross scratches and large pits, but rather noted the presence of more
than four cross scratches and more than four large pits in each counting area and
calculated the percentage of individuals presenting these variables for each species.
Solounias and Semprebon (2002) also noted the presence of gouges, fine scratches,
coarse scratches, and mixed scratches and calculated the percentage of individuals
presenting these variables per species. The dataset of Solounias and Semprebon (2002),
therefore, consisted of the following variables: average number of scratches, average
number of pits, percentage of individuals per species with more than four cross scratches
per field, percentage of individuals with more than four large pits per field, percentage of
individuals per species with fine, coarse, and mixed scratches, and percentage of
individuals per species with gouges present. Because the percentage of fine, coarse, and
mixed scratches adds up to 100 percent, in the analysis I conducted I used only the first
166
two variables. All of the percentages were normalized for statistical analyses using the
arcsine transformation.
I compared the adjusted microwear data I collected (Table 3.4) with the extant
ungulate dataset gathered by Solounias and Semprebon (2002). I first conducted a
discriminant function analysis (DFA) on the Solounias and Semprebon (2002) dataset,
assuming equal prior classification probabilities for all dietary groups. Subsequntly, I
used the classification functions generated by the DFA to classify the horse and bison
samples I studied into one of the dietary categories identified by Solounias and
Semprebon (2002): browsers, fruit browsers, grazers, meal-by-meal mixed feeders, and
seasonal mixed feeders.
167
Figure 3.2. High dynamic range image of the postfossette lingual enamel band (upper
M2) of an equid tooth showing one of the 0.4 X 0.4 mm counting areas. This specimen
shows relatively large numbers of scratches, with several pits and few cross scratches.
3.3.1.2 Extended mesowear method
The mesowear method was proposed by Fortelius and Solounias (2000) for
reconstructing ungulate diets based on the analysis of the buccal (ectoloph) cusps of the
M2 teeth. The variables considered include the development of the cusps (high or low)
and the shape of the sharpest cusp (whether anterior or posterior) which can be scored as
sharp, round, or blunt (Fortelius and Solounias, 2000). The method was subsequently
extended in equids by Kaiser and Solounias (2003) to include the P4, M1, M2, and M3
upper tooth positions. Franz-Odendaal and Kaiser (2003) reported that the mesowear
168
method can be extended to the M3 tooth position in the ruminant species they
investigated.
I collected mesowear data for teeth in middle stages of wear (i.e., heavily worn as
well as very little worn teeth were not included in the analysis) following the extended
mesowear methods mentioned above. Most of the specimens studied consisted of isolated
teeth. In the case of horses, I recorded mesowear data from P4, M1, M2, and M3 teeth.
For bison, I obtained mesowear data from M2 and M3 teeth; however, in order to
increase sample size in some cases I obtained mesowear data from M1 teeth. In some
instances there were associated teeth (belonging to the same individual). In those cases, I
preferentially recorded mesowear data from the M2. If the M2 was damaged or absent, I
randomly selected one of the other tooth positions. Sometimes I encountered specimens
in which the right and left M2 were present in a good state of preservation. In that case I
selected one of the two teeth at random. I recorded the mesowear data by direct
observation of the specimens and the frequency of the different variables was obtained
for each sample. Subsequently, I calculated the mesowear score (Kaiser, 2011), which
combines cusp relief and shape into a single value: 0 (high and sharp cusps), 1 (high and
round cusps), 2 (low and sharp cusps), 3 (low and round cusps), and 4 (low and blunt
cusps) (Figure 3.3).
I used the mesowear score to test the hypotheses developed for the coevolutionary
disequilibrium and mosaic-nutrient extinction models. In the former case, I conducted
Kruskal-Wallis tests to assess whether the mesowear score significantly differs among
sympatric bison and horse species. To test the hypotheses outlined for the mosaic-nutrient
extinction model, I obtained the variance of the mesowear score for each equid and bison
169
sample, and then calculated the quotient resulting from the division of the variance of the
mesowear score at time interval 1 by the variance at time interval 2. Significance of the
variance quotient was assessed by bootstrap analysis conducted using MATLAB 7.8
(MathWorks, 2009) on 100,000 replicates.
In order to reconstruct the diet of the different samples, I performed a DFA using
the dataset of extant ungulates published by Fortelius and Solounias (2000), with the
exclusion of the minute abraded brachydont species and species with a sample size lower
than ten specimens. The variables percent high, percent sharp, and percent blunt cusps
were employed in the DFA analysis. These variables were normalized using the arcsine
transformation prior to performing the analysis. I followed the conservative dietary
classification in Fortelius and Solounias (2000). The DFA was performed assuming equal
prior classification probabilities for all groups. The classification functions derived from
the DFA were subsequently used to classify the equid and bison samples into one of three
extant ungulate dietary categories: browsers, mixed feeders, and grazers.
Figure 3.3. Buccal view of the apices of three equid upper cheek teeth showing the
different cusp morphologies studied in the mesowear method. A) Upper M2 showing
high relief as well as round (anterior) and sharp (posterior) cusps; mesowear score = 0. B)
Upper M1 displaying low relief and round cusps; mesowear score = 3. C) Upper M2 with
low relief and blunt cusps; mesowear score = 4. The anterior side of the tooth is on the
right in A and B, whereas it is on the left in C. Scale bar = 5 mm. (Modified from BarrónOrtiz et al., 2014).
170
3.4
3.4.1
Results
Microwear
Analysis of the low magnification microwear data (Table A 7 of the Appendix) indicates
statistically significant differences in some of the samples studied for evaluating the
hypotheses of the coevolutionary disequilibrium extinction model. The NP-MANOVA
test (Table 3.2) reveals that the microwear pattern of Equus conversidens from the
American Southwest is marginally statistically different from the microwear pattern of E.
ferus scotti for the full-glacial time interval (F = 1.713, p = 0.0496). In contrast, the
microwear pattern of these two equid species, as well as that of Bison antiquus, is not
significantly different for the postglacial (NP-MANOVA test, F = 0.8747, p = 0.6263). In
the case of the specimens from Alberta, the comparison of the horse and bison samples
for the preglacial time interval is marginally not significant (NP-MANOVA test, F =
1.556, p = 0.07901). A lack of statistical difference is also found for the horse and bison
samples from the postglacial time interval of Alberta (NP-MANOVA test, F = 0.9605, p
= 0.5284).
The variance of the five counted microwear variables of each species sample did
not significantly decrease during the postglacial relative to full-glacial and preglacial time
intervals (Table 3.3). Only two pairwise-comparisons are statistically significant and four
other comparison show the opposite trend in which the variance significantly increased
during the postglacial (Table 3.3).
The DFA (Table 3.5) of the Solounias and Semprebon (2002) dataset correctly
classified 75 % of extant species by diet; 90.0 % for browsers, 100 % for fruit browsers,
77.8 % for grazers, 75.0 % for meal-by-meal mixed feeders, and 41.7 % for seasonal
171
mixed feeders. The discriminant functions generated (Table 3.6) classify all of the horse
and bison samples I studied (Table 3.4) as seasonal mixed feeders, except for the
American Southwest samples of Equus conversidens from the preglacial and full-glacial
time intervals, which were classified as grazers (Table 3.7).
172
Table 3.1. Summary statistics of microwear variables of late Pleistocene equid and bison samples studied. n = number of specimens; s
= average number of scratches; p = average number of pits; cs = average number of cross scratches; g = average gouge score, ranging
from 0 (none present) to 1 (all enamel bands observed had at least 1 gouge present); lp = average number of large pits; ws = average
number of wide scratches; ts = average texture score.
Locality and species
Time interval
n
s
p
cs
lp
g
ws
ts
Bluefish Caves
Preglacial/Full-glacial
13
22.46
16.77
2.54
1.12
0.12
0.73
0.65
Equus ferus lambei
Postglacial
12
25.63
16.21
4.00
1.17
0.46
0.50
0.67
Alberta
Preglacial
7
25.07
16.07
2.36
1.79
0.79
1.00
0.86
Equus ferus scotti
Postglacial
7
23.64
25.29
3.00
1.07
0.64
1.29
0.86
Alberta
Preglacial
9
23.39
18.67
3.28
1.22
0.61
1.67
1.00
Bison sp.
Postglacial
9
24.78
18.89
3.11
0.78
0.61
1.06
0.83
Preglacial
15
28.67
16.00
3.20
0.77
0.50
0.70
0.93
Full-glacial
6
27.50
17.42
3.33
0.83
0.33
1.42
1.00
Postglacial
13
23.58
21.12
1.69
2.15
0.85
2.00
1.08
American Southwest
Full-glacial
12
25.46
16.75
2.63
1.33
0.63
0.71
0.88
Equus ferus scotti
Postglacial
10
23.10
22.65
2.50
1.75
0.90
1.25
1.00
Postglacial
9
25.11
22.50
3.17
1.78
1.00
1.50
0.94
American Southwest
Equus conversidens
American Southwest
Bison antiquus
173
Table 3.2. Results of NP-MANOVA tests (10,000 replications and using the Mahalanobis
distance measure) used to evaluate the hypotheses of the coevolutionary disequilibrium
extinction model using the variables in Table A 7 of the Appendix. n = sample size; F =
F-statistic; p = p-value. Statistically significant p-values are shown in bold.
Locality
Species
Equus ferus scotti
Alberta
Bison sp.
Equus ferus scotti
Bison sp.
Equus conversidens
American
Southwest
Equus ferus scotti
Time interval
Preglacial
Postglacial
Full-glacial
Equus conversidens
Equus ferus scotti
Bison antiquus
n
7
9
7
9
6
12
F
p
1.556
0.0790
0.9605
0.5284
1.713
0.0496
0.8747
0.6263
13
Postglacial
10
9
174
Table 3.3. Results of bootstrap statistical analyses conducted to test the hypotheses of the mosaic-nutrient extinction model using four
counted microwear variables: s = average number of scratches; p = average number of pits; cs = average number of cross scratches; lp
= average number of large pits; ws = average number of wide scratches; VarQ = variance quotient (variance at time interval 1 divided
by variance at time interval 2); p = p-value based on bootstrap analysis using 10,000 replicates. Statistically significant p-values are
indicated in bold. * identifies comparisons in which the variance at time interval 2 is greater than at time interval 1.
s
Time interval
comparisons
Bluefish Caves
Equus ferus lambei
Postglacial
Alberta
Preglacial
Equus ferus scotti
Postglacial
Alberta
Preglacial
Bison sp.
Postglacial
Preglacial
Full-glacial
American Southwest
Full-glacial
Equus conversidens
Postglacial
Preglacial
Postglacial
American Southwest
Full-glacial
Equus ferus scotti
Postglacial
p
cs
lp
ws
VarQ
P
VarQ
P
VarQ
p
VarQ
P
VarQ
p
1.24
0.37
1.03
0.48
0.97
0.52
1.85
0.28
0.52
0.81
0.54
0.80
0.65
0.70
2.94
0.13
3.54
0.04
1.35
0.27
0.22
0.98*
0.71
0.72
0.64
0.78
0.32
0.77
1.09
0.44
1.44
0.32
1.32
0.40
1.77
0.25
0.82
0.63
0.18
0.99*
0.61
0.69
0.54
0.82
0.76
0.55
0.61
0.70
0.79
0.67
0.88
0.61
0.71
0.77
1.35
0.30
0.51
0.82
0.14
1.00*
3.30
0.04
0.31
0.97*
1.43
0.28
0.42
0.96*
0.49
0.89
175
Table 3.4. Summary statistics of microwear variables of late Pleistocene equid and bison samples studied following the methodology
of Solounias and Sembrebon (2002). n = number of specimens, S = average number of scratches, P = average number of pits, CS =
percentage of specimens with cross scratches, LP = percentage of specimens with large pits, G = percentage of specimens with
gouges, F = percentage of specimens with fine scratches, C = percentage of specimens with coarse scratches, M = percentage of
specimens with mixed scratches.
Time interval
n
S
P
CS
LP
G
F
C
M
Bluefish Caves
13
22.46
16.77
8.33
8.33
15.38
33.33
0.00
66.67
Equus ferus lambei
Postglacial
12
25.63
16.21
40.00
0.00
50.00
35.00
0.00
65.00
Alberta
Preglacial
7
25.07
16.07
0.00
0.00
85.71
12.50
0.00
87.50
Equus ferus scotti
Postglacial
7
23.64
25.29
23.08
0.00
71.43
15.38
0.00
84.62
Alberta
Preglacial
9
23.39
18.67
30.77
0.00
66.67
0.00
0.00
100
Bison sp.
Postglacial
9
24.78
18.89
42.86
7.14
66.67
28.57
7.14
64.29
Preglacial
15
28.67
16.00
28.00
0.00
60.00
8.00
0.00
92.00
Full-glacial
6
27.50
17.42
10.00
0.00
33.33
0.00
0.00
100
Postglacial
13
23.58
21.12
5.26
10.53
84.62
0.00
5.26
94.74
American Southwest
Full-glacial
12
25.46
16.75
12.50
0.00
66.67
12.5
0.00
87.50
Equus ferus scotti
Postglacial
10
23.10
22.65
0.00
0.00
90.00
0.00
0.00
100
Postglacial
9
25.11
22.50
8.33
0.00
100
8.33
0.00
91.67
American Southwest
Equus conversidens
American Southwest
Bison antiquus
176
Table 3.5. Results of discriminant function analysis (DFA) of the Solounias and
Semprebon (2002) microwear dataset of extant ungulate species. The variables used in
the analysis were: average number of scratches, average number of pits, percentage of
individuals per species with more than four cross scratches per field, percentage of
individuals with more than four large pits per field, percentage of individuals per species
with fine and coarse scratches, and percentage of individuals per species with gouges
present. All of the percentages were normalized for statistical analyses using the arcsine
transformation.
Wilks’ Lambda
F
p
0.0884
4.1262
<0.000
microwear data of extant ungulate species published by Solounias and Semprebon
(2002), assuming equal prior classification probabilities for all dietary groups (p = 0.20).
Dietary groups: B = browsers, FB = fruit browsers, G = grazers, M = meal-by-meal
mixed feeders, SM = seasonal mixed feeders. Variables: S = average number of
scratches, P = average number of pits, CS = percentage of specimens with cross
scratches, LP = percentage of specimens with large pits, G = percentage of specimens
with gouges, F = percentage of specimens with fine scratches, C = percentage of
specimens with coarse scratches. All of the variables corresponding to percentages were
normalized for the analysis using the arcsine transformation.
Variable
B
FB
G
M
SM
S
0.8645
1.3141
1.6702
1.8856
1.3010
P
0.1409
0.0183
-0.0890
-0.0696
0.0311
CS
5.5524
11.5739
8.5471
10.0587
7.3397
LP
10.6330
22.1427
15.8302
16.7477
12.4398
G
0.1991
-2.7278
1.7066
3.8458
2.1182
F
18.8598
14.0748
14.2915
16.3990
17.6292
C
5.9276
5.5792
4.0572
1.6630
5.4380
Constant -24.1526 -39.0501 -37.1549 -47.4356 -30.3572
177
Table 3.7. Classification posterior probabilities of the samples studied based on a discriminant function analysis of the microwear data
of extant ungulates published by Solounias and Semprebon (2002), assuming equal prior classification probabilities for all dietary
groups (p = 0.20). B = browsers, FB = fruit browsers, G = grazers, M = meal-by-meal mixed feeders, SM = seasonal mixed feeders.
Time interval
B
FB
G
M
SM
Bluefish Caves
0.0444
0.0001
0.1861
0.0197
0.7497
Equus ferus lambei
Postglacial
0.0034
0.0000
0.2420
0.1630
0.5916
Alberta
Preglacial
0.0059
0.0000
0.2215
0.0620
0.7106
Equus ferus scotti
Postglacial
0.0218
0.0000
0.0890
0.0350
0.8542
Alberta
Preglacial
0.0039
0.0000
0.4456
0.0637
0.4868
Bison sp.
Postglacial
0.0029
0.0000
0.2683
0.1382
0.5906
Preglacial
0.0002
0.0000
0.5170
0.3294
0.1534
Full-glacial
0.0006
0.0000
0.7368
0.0805
0.1821
Postglacial
0.0036
0.0000
0.4651
0.0519
0.4794
American Southwest
Full-glacial
0.0035
0.0000
0.3212
0.1050
0.5703
Equus ferus scotti
Postglacial
0.0178
0.0000
0.1750
0.0196
0.7876
Postglacial
0.0029
0.0000
0.1541
0.1522
0.6908
American Southwest
Equus conversidens
American Southwest
Bison antiquus
178
3.4.2
Mesowear
The mean mesowear score was used to evaluate the hypotheses of the coevolutionary
disequilibrium and mosaic nutrient extinction models. Overall, the mean mesowear score
of each sample analyzed (Table 3.8) plots on the abrasion end of the mesowear spectrum
(Figure 3.4). The mesowear score of E. conversidens from the American Southwest is not
statistically different from the mesowear score of E. ferus scotti for the full-glacial time
interval (Kruskall-Wallis test, H = 1.00, p = 0.2834), although it should be pointed out
that the sample size of E. conversidens consists of only two specimens (Table 3.9). The
mesowear score for these two equid species, along with the specimens of Bison antiquus,
for the postglacial of the American Southwest are also not significantly different
(Kruskall-Wallis test, H = 1.309, p = 0.4851). The Kruskall-Wallis test reveals that the
mesowear score for the preglacial samples of horse and bison from Alberta are
significantly different (H = 5.442, p = 0.01341), but this is not the case for the postglacial
samples of these ungulates (H = 1.771, p = 0.1582).
The variance of the mesowear score of each species sample did not significantly
decrease during the postglacial relative to full-glacial and preglacial time intervals (Table
3.10). None of the pairwise-comparisons are statistically significant and in one
comparison (preglacial versus postglacial samples of E. conversidens from the American
Southwest) the opposite trend was observed (Table 3.10).
The DFA (Table 3.11) conducted on a subset of the extant ungulate dataset of
Fortelius and Solounias (2000) correctly classified 75.6 % of the species by diet; 77.8 %
for browsers, 76.0 % for mixed feeders, and 72.7 % for grazers. The discriminant
functions generated (Table 3.12) classify the horse and bison samples studied within the
179
dietary group comprised by extant grazers, such as the plains zebra (Equus quagga) and
the plains bison (Bison bison bison), with posterior probabilities greater than 0.74 (Table
3.13).
180
Table 3.8. Summary statistics of the mesowear variables of late Pleistocene equid and bison samples studied. n = number of
specimens, MS = mesowear score, h = percentage of specimens with high occlusal relief, l = percentage of specimens with low
occlusal relief, s = percentage of specimens with sharp cusps, r = percentage of specimens with round cusps, b = percentage of
specimens with blunt cusps.
Time interval
n
MS
h
l
s
r
b
Bluefish Caves
8
2.63
12.50
87.50
25.00
62.50
12.50
Equus ferus lambei
Postglacial
5
3.00
0.00
100
20.00
60.00
20.00
Alberta
Preglacial
21
3.05
14.29
85.71
4.76
57.14
38.10
Equus ferus scotti
Postglacial
7
2.86
0.00
100
28.57
57.14
14.29
Alberta
Preglacial
6
1.67
66.67
33.33
0.00
100.00
0.00
Bison sp.
Postglacial
7
1.86
57.14
42.86
14.29
71.43
14.29
Preglacial
8
3.38
0.00
100
0.00
62.50
37.50
Full-glacial
2
3.50
0.00
100
0.00
50.00
50.00
Postglacial
14
2.71
14.29
85.71
21.43
57.14
21.43
American Southwest
Full-glacial
6
2.33
33.33
66.67
16.67
66.67
16.67
Equus ferus scotti
Postglacial
10
2.50
20.00
80.00
30.00
50.00
20.00
Postglacial
8
1.88
50.00
50.00
25.00
62.50
12.50
American Southwest
Equus conversidens
American Southwest
Bison antiquus
181
Table 3.9. Results of Kruskall-Wallis tests used to evaluate the hypotheses of the
coevolutionarty disequilibrium extinction model using the mesowear score MS. n =
sample size; H = H-statistic; p = p-value. Statistically significant p-values are shown in
bold.
Locality
Species
Equus ferus scotti
Alberta
Bison sp.
Equus ferus scotti
Bison sp.
Equus conversidens
American
Southwest
Equus ferus scotti
Time interval
Preglacial
Postglacial
Full-glacial
Equus conversidens
Equus ferus scotti
Bison antiquus
n
21
6
8
7
2
6
H
p
5.442
0.0134
1.771
0.1582
1.000
0.2834
1.309
0.4851
14
Postglacial
10
8
182
Table 3.10. Results of bootstrap statistical analyses conducted to test the hypotheses of
the mosaic-nutrient extinction model using the mesowear score (MS). Var = variance of
each sample; VarQ = variance quotient (variance at time interval 1 divided by variance at
time interval 2); p = p-value based on bootstrap analysis using 10,000 replicates.
Statistically significant p-values are indicated in bold. * identifies comparisons in which
the variance at time interval 2 is greater than at time interval 1.
MS
Time interval
comparisons
Var
Bluefish Caves
1.4107
Equus ferus lambei
Postglacial
0.5000
Alberta
Preglacial
1.0476
Equus ferus scotti
Postglacial
0.4107
Alberta
Preglacial
1.0667
Bison sp.
Postglacial
2.1429
Preglacial
0.2679
Full-glacial
0.5000
American Southwest
Full-glacial
0.5000
Equus conversidens
Postglacial
0.9890
Preglacial
0.2679
Postglacial
0.9890
American Southwest
Full-glacial
2.2667
Equus ferus scotti
Postglacial
2.0556
VarQ
p
2.8214
0.3106
2.5507
0.1719
0.4978
0.8653
0.5357
0.6971
0.5056
0.5388
0.2708
0.9546*
1.1027
0.4488
183
Table 3.11. Results of discriminant function analysis (DFA) of the dataset of extant
ungulates published by Fortelius and Solounias (2000), with the exclusion of the minute
abraded brachydont species and species with a sample size lower than ten specimens. The
variables percent high, percent sharp, and percent blunt cusps were normalized using the
arcsine transformation and these values were used in the analysis.
Wilks’ Lambda
F
p
0.2822
11.7645
<0.000
mesowear data of extant ungulate species published by Fortelius and Solounias (2000),
with the exclusion of the minute abraded brachydont species and species with a sample
size lower than ten specimens. The analysis was conducted assuming equal prior
classification probabilities for all dietary groups (p = 0.33). Dietary groups: B = browsers,
G = grazers, M = mixed feeders. Variables: h = percentage of specimens with high
occlusal relief, s = percentage of specimens with sharp cusps, b = percentage of
specimens with blunt cusps. All of the variables were normalized for the analysis using
the arcsine transformation.
Variable
B
G
M
h
27.0565
20.0305
25.7976
s
19.7424
7.5856
12.8349
b
34.4630
35.2358
33.5449
Constant
-32.1042
-16.6522
-24.4111
184
Table 3.13. Classification posterior probabilities of the equid and bison samples studied
based on a discriminant function analysis of the mesowear data of extant ungulate species
published by Fortelius and Solounias (2000), with the exclusion of the minute abraded
brachydont species and species with a sample size lower than ten specimens. The analysis
was conducted assuming equal prior classification probabilities for all dietary groups (p =
0.33). B = browsers, G = grazers, M = mixed feeders.
Time interval
B
G
M
Bluefish Caves
0.0011
0.9707
0.0282
Equus ferus lambei
Postglacial
0.0000
0.9977
0.0022
Alberta
Preglacial
0.0000
0.9959
0.0041
Equus ferus scotti
Postglacial
0.0001
0.9963
0.0036
Alberta
Preglacial
0.0001
0.9045
0.0954
Bison sp.
Postglacial
0.0053
0.8037
0.1910
Preglacial
0.0000
0.9999
0.0001
Full-glacial
0.0000
0.9999
0.0001
Postglacial
0.0007
0.9777
0.0216
American Southwest
Full-glacial
0.0017
0.9362
0.0621
Equus ferus scotti
Postglacial
0.0038
0.9405
0.0557
Postglacial
0.0157
0.7370
0.2473
American Southwest
Equus conversidens
American Southwest
Bison antiquus
185
Figure 3.4. Average mesowear score for the late Pleistocene bison and equid samples
studied and extant ungulate species reported in Kaiser et al. (2013). Each data point is the
average for a species sample. Abbreviations: LB = leaf browsers, MF = mixed feeders, G
= grazers, Pre-LGM = preglacial, LGM = full-glacial, Post-LGM = postglacial, ElB =
Equus ferus lambei (Bluefish Caves, Yukon), EsA = Equus ferus scotti (Alberta), BpA =
Bison sp. (Alberta), EcS = Equus conversidens (American Southwest), EsS = Equus ferus
scotti (American Southwest), BpA = Bison antiquus (American Southwest). Leaf
browsers: Alces alces (AA), Ammodorcas clarkei (AC), Antilocapra americana (AM),
Capreolus capreolus (OL), Dicerorhinus sumatrensis (DS), Diceros bicornis (DB),
Giraffa camelopardalis (GC), Litocranius walleri (LW), Odocoileus hemionus (OH),
Odocoileus virginianus (OV), Okapia johnstoni (OJ), Tragelaphus strepsiceros (TS),
Tragelaphus euryceros (TE). Mixed feeders: Aepyceros melampus (Am), Antidorcas
marsupialis (Ma), Axis axis (Aa), Axis porcinus (Ap), Boselaphus tragocamelus (Tr),
Budorcas taxicolor (Bt), Camelus dromedarius (Cd), Capra ibex (Ci), Capricornis
sumatraensis (Cs), Cervus canadensis (Cc), Lama guanicoe (Lg), Nanger granti (Ng),
Ourebia ourebi (Oo), Ovibos moschatus (Om), Ovis canadensis (Oc), Redunca
fulvorufula (Rf), Rucervus duvaucelii (Rd), Rusa unicolor (Ru), Saiga tatarica (St),
Syncerus caffer (Sc), Taurotragus oryx (To), Tetracerus quadricornis (Tq), Tragelaphus
angasii (Ta), Tragelaphus imberbis (Ti), Tragelaphus scriptus (Ts), Vicugna vicugna
(Vv). Grazers: Alcelaphus buselaphus (ab), Bison bison (bb), Ceratotherium simum (cs),
Connochaetes taurinus (ct), Damaliscus lunatus (dl), Equus grevyi (eg), Equus quagga
(eq), Hippotragus equinus (he), Hippotragus niger (hn), Kobus ellipsiprymnus (ke).
186
187
3.5
Discussion
The coevolutionary disequilibrium (Graham and Lundelius, 1984) and mosaic-nutrient
(Guthrie, 1984) extinction models are two climate-based models that have been proposed
to explain the late Pleistocene megafaunal extinction. The coevolutionary disequilibrium
model emphasizes competition for food resources among species as a result of changing
vegetational assemblages (Graham and Lundelius, 1984), whereas the mosaic-nutrient
model proposes that a change from a mosaic vegetation pattern to a more zonal, low
diversity pattern decreased the dietary supplements available to herbivores (Guthrie,
1984). Although these models present different scenarios that lead to nutritional stress
and extinction of some herbivore species, they are not mutually exclusive. In theory both
could have operated, resulting in a scenario in which herbivores are faced with a
decreased diversity of plants in their diets and a disruption of coevolved foraging
sequences, increasing competition among species. This latter scenario, however, is not
supported by the dental wear analyses. The results of the analyses of dental wear are
overall consistent with the two predictions established for the coevolutionary
disequilibrium model, but not with the prediction established for the mosaic-nutrient
model.
Working under the assumption that feeding on different vegetation would be
reflected in the dental wear pattern (see Limitations and Assumptions section in the
Introduction section of this chapter), a population of herbivores feeding on a restricted
number of plant species during the terminal Pleistocene, as suggested in the mosaicnutrient model, would produce a dental wear sample in which the statistical dispersion of
the microwear and mesowear variables is small, relative to populations feeding on a
188
greater diversity of plant species during preglacial and full-glacial times. As in seen in
Tables 3.3 and 3.10, analyses of the dental wear data do not support this prediction. The
variance of the microwear variables and the mesowear score are, for the most part, not
significantly smaller during the postglacial. Out of 36 pairwise-comparisons involving the
postglacial, only two were statistically significant and five other comparisons showed the
opposite trend, with a significantly greater variance during the postglacial (Tables 3.3 and
3.10). There are a number of potential explanations that can be advanced to account for
the lack of a statistically significant decrease in dental wear variance during the
postglacial: 1) local plant diversity did not actually decrease during the postglacial as it is
assumed by the mosaic-nutrient model; 2) local plant diversity decreased at this time, but
ungulates were able to extend their home ranges or migrate to obtain the right mix of
nutrients; 3) local plant diversity decreased during the postglacial, but the resulting
change in diet is not recorded in the dental wear.
Testing the hypothesis that local plant diversity decreased during the terminal
Pleistocene has been difficult, because many of the commonly used proxies, such as
fossil pollen, present certain limitations that make it difficult to reconstruct species-level
vegetation changes. Although pollen records are highly informative, they tend to be
biased towards groups that produce large quantities of pollen such as many graminoids
(grasses, sedges, and rushes) and Artemisia, whereas many insect-pollinated plants are
not adequately represented in these records (Anderson et al., 2003). Even when
accounting for these potential biases, it is difficult to identify certain pollen types down to
species level, which results in an underestimation of actual plant diversity (Lamb and
Edwards, 1988). The study of plant macrofossils provides more detailed records of local
189
vegetation (e.g., Kienast et al., 2005; Zazula et al., 2006); however, the conditions for the
preservation of such remains are far less common and, as a result, plant macrofossil
assemblages are relatively rare. In addition, these studies still suffer from some
taxonomical limitations and usually cannot provide quantitative estimates of abundance.
The recent development and improvement of ancient DNA techniques has
presented researchers with an alternative approach to reconstructing past vegetation
changes, through the study of DNA preserved in sediment samples. This approach has
been used to study changes in Arctic vegetation over the past 50,000 years (Willerslev et
al., 2014). In contrast to pollen data, which indicate high plant diversity during the LGM,
Willerslev et al. (2014) found that plant diversity was lowest during the LGM (25 – 15 ky
cal BP [calibrated radiocarbon years before the present]) relative to the Pre-LGM (50 –
25 ky cal BP) and Post-LGM (15 – 0 ky cal BP) intervals they studied. Moreover, plant
assemblages became more similar to each other during the LGM (Willerslev et al., 2014).
These results are not consistent with the assumptions of the mosaic-nutrient model, which
state that local plant diversity was high in the Pleistocene, but environmental changes
during the terminal Pleistocene drastically decreased diversity and increased zonation of
plant communities (Guthrie, 1984). The study of ancient DNA from sediment samples,
however, presents its own challenges and limitations, such as the potential mixing of
DNA across stratigraphic layers. It is therefore important to corroborate the results
reported by Willerslev et al. (2014) using independent lines of evidence.
Determining whether the reduction in plant diversity during the LGM identified
by Willerslev et al. (2014) is reflected in the dental wear of Equus ferus lambei from
Bluefish Caves, northern Yukon, cannot be made at this time because uncertainties in the
190
stratigraphic provenance of the specimens only allowed separation of specimens into
postglacial (~14 ky – 10 ky RCBP) and preglacial/full-glacial (~31 ky – 14 ky RCBP)
time intervals. Nevertheless, the lack of a statistically significant decrease in dental wear
variance during the postglacial is more consistent with the pattern reported by Willerslev
et al. (2014), than with the prediction established for the mosaic-nutrient model.
In addition to spatial and temporal plant diversity, Willerslev et al. (2014)
examined the relative abundance of different plant growth forms. These researchers
determined that, although a mosaic of plant communities was present in the Arctic, plant
assemblages during the Pre-LGM and LGM were dominated by forbs. Moreover, by
studying aDNA from gut and dung samples of large ungulates (e.g., mammoth, horse,
and bison), it was found that these herbivores had diets particularly rich in forbs
(Willerslev et al., 2014). These results are also not consistent with the mosaic-nutrient
model, which portrays large caecalid ungulates, such as horse and mammoth, as primarily
feeding on grass and supplementing their diets by consuming a variety of other plant
types (Guthrie, 1984).
In contrast to the mosaic-nutrient extinction model, the results of the analysis of
dental wear are overall consistent with the two predictions established for the
coevolutionary disequilibrium extinction model. The first prediction states that prior to
the severe climatic changes that occurred during the terminal Pleistocene, sympatric
species of ungulate herbivores partitioned available food resources (Graham and
Lundelius, 1984). In this case dietary niche partitioning would be reflected by a
statistically significant difference in dental microwear and mesowear score. This
prediction is generally supported for the ungulates studied from the American Southwest
191
and Alberta. The dental microwear of Equus conversidens and E. ferus scotti from the
American Southwest during the full-glacial is significantly different. Statistically
significant differences were also detected for the mesowear score of E. ferus scotti and
Bison sp. from preglacial deposits of Alberta. The analysis of the mesowear score of the
equid samples from the American Southwest is considered inconclusive because of the
small sample size of E. conversidens, which consisted of only two specimens. Similarly,
the dental microwear of E. ferus scotti and Bison sp. from Alberta is marginally not
significantly different, also likely due to the small sample size for these species.
Although the results of the microwear and mesowear analyses support the
hypothesis of dietary resource partitioning in sympatric bison and equid species from the
American Southwest and Alberta, the analysis of dental wear provides little insight into
the mechanism by which this division of resources might have taken place. Extant
ungulates partition dietary resources in a variety of ways: feeding on different plant
species, feeding on different plant parts and growth stages of the same species, feeding at
different heights, and feeding in distinct microhabitats (e.g., Bell, 1971; Jarman and
Sinclair, 1979; McNaughton and Georgiadis, 1986; du Toit, 1990; Spencer 1995; Stewart
et al., 2002). Which of these alternatives for partitioning food resources was employed by
the bison and equid species studied cannot be determined from the microwear data alone.
Additional lines of evidence, such as ecomorphological studies, are needed to establish
hypotheses by which these ungulates might have partitioned dietary resources.
The second prediction outlined for the coevolutionary disequilibrium extinction
model states that sympatric species of horse and bison were competing for available food
resources during the terminal Pleistocene, due to coevolutionary disequilibrium brought
192
about by a change in the composition of vegetational communities. Under this scenario
dental microwear and mesowear should not be significantly different for the different
taxa. This is the pattern that is observed for the postglacial ungulate species from the
American Southwest (i.e., E. conversidens, E. ferus scotti, and Bison antiquus). The same
was found for the horse and bison samples of E. ferus scotti and Bison sp. from
postglacial deposits of Alberta. The results of the microwear and mesowear analyses of
the postglacial ungulate species from the American Southwest and Alberta are, therefore,
consistent with the second prediction of the coevolutionary disequilibrium extinction
model.
The results of a number of dental wear (Rivals et al., 2008; Rivals et al., 2010)
and stable isotope (Koch et al., 1998; Hoppe and Koch, 2006; Fox-Dobbs et al., 2008)
studies also support the assumption of dietary resource partitioning postulated for the
coevolutionary disequilibrium extinction model. In other cases, however, dietary niche
overlap is the emerging pattern (e.g., Feranec, 2004; Prado et al., 2005; Hoppe and Koch,
2006; Fox-Dobbs et al., 2008; Pérez-Crespo et al., 2012). Nevertheless, it is important to
point out that all of the studies cited above, and also the study presented here, examined
only one or two dietary proxies, which shed light on only a small portion of the feeding
ecology of the Pleistocene megafauna. Dietary niche partitioning may occur along any of
countless multidimensional axes (Hutchinson, 1957). Therefore, identification of statistically
significant differences among species using one dietary proxy would provide support for
dietary niche partitioning, but the opposite is not true. Inability to detect significant
differences among species using one dietary proxy does not necessarily indicate they were
competing for food resources, because the species could be segregating along another
dimensional axis not considered in the study. This is an important point that is often missed
193
in paleoecological studies. A multi-proxy approach to reconstructing feeding ecology is
required to better elucidate community feeding structure during the Pleistocene at
different temporal and spatial scales. In that vein, the present study would benefit from
the incorporation of additional paleoecological proxies such as stable isotope analysis.
With these considerations in mind, it can only be concluded that the analyses of
mesowear and dental microwear do not reject the hypothesis of competition for food
resources during the postglacial in the bison and equid species investigated. It is
interesting to note that this pattern was recovered for both Alberta and the American
Southwest, even though these two regions experienced different ecosystem dynamics
during the terminal Pleistocene. Preglacial ecosystems in Alberta were completely
eliminated during the full-glacial by the advance and coalescence of the Laurentide and
Cordilleran ice sheets (Young et al., 1994, 1999; Burns, 1996). Radiocarbon dating of
mammal specimens indicates that most of Alberta remained covered by the Laurentide
ice sheet for approximately 9,000 radiocarbon years (Burns, 1996). As the ice sheets
receded new ecosystems with new community associations were established. In contrast
to Alberta the American Southwest did not become covered by ice sheets; nevertheless,
important environmental changes occurred in this region during the postglacial.
Paleontological and palynological evidence indicate that the American Southwest
experienced significant changes in temperature, precipitation, and humidity (Connin et
al., 1998). Both regions experienced different, but nonetheless major ecological
disturbances during the terminal Pleistocene.
One emerging pattern common to Alberta, the American Southwest and other
regions of North America is the increased abundance of bison relative to other large
herbivorous mammals, such as equids and mammoth, during the latest Pleistocene.
194
Although both bison and equids returned to Alberta as the Laurentide and Cordilleran ice
sheets receded, the evidence at hand indicates that bison was now the dominant ungulate
species, in contrast to preglacial ecosystems in which equids were the dominant ungulates
(Jass et al., 2011). A similar increase in the relative abundance of bison has been reported
for the midcontinent of North America (McDonald, 1981), Alaska and the Yukon
Territory (Guthrie, 2006), the southern Great Plains (Wyckoff and Dalquest, 1997), and
the Pacific Coast (Scott et al., 2010).
The great abundance and geographic distribution of bison during the latest
Pleistocene, especially in western North America, has led Scott (2010) to propose an
ecological extinction model for the late Pleistocene megafaunal extinctions, in which
bison played a pivotal role. Scott (2010) notes that one major difference of the
Pleistocene-Holocene transition with respect to previous glacial-interglacial transitions
was the proliferation of Bison antiquus, a large, aggressive, herd-dwelling ruminant. Scott
(2010) argues that B. antiquus and other late Pleistocene megafauna, such as mammoths
and equids, were competing for available resources. Shifts in resource abundance and
distribution due to changing climatic factors associated with the end of the Wisconsinan
glaciation would have increased competition for those resources. Scott (2010) further
states that responses of large herbivorous mammals to earlier climatic shifts (e.g.,
selection of different forage, reduction of body size, or migration to a different area)
would have been altered by the widespread abundance and population density of bison.
Even communities where bison were rare or absent could also be impacted, as large
mammals displaced by bison in other regions moved in, increasing the competition
among herbivores (Scott, 2010).
195
Scott (2010) cites isotope data for Rancho La Brea, California, and Florida that
apparently support the argument that bison competed for resources with other late
Pleistocene megafauna. Bison and equids from Rancho La Brea seemed to have relied
heavily on C3 plants (Coltrain et al., 2004; Feranec et al., 2009), with bison periodically
incorporating C4 plants in its diet, suggesting that these ungulates were seasonally
competing for similar food resources (Feranec et al., 2009). Similar results have been
reported for Florida, in which mammoths, bison, and equids apparently had similar diets,
although these diets varied geographically across the state (Feranec, 2004). Nevertheless,
the fact that these herbivorous mammals fed on plants with similar isotope compositions
does not necessarily imply that they were competing for food resources. For instance,
African grazing ungulates feed mostly on C4 grasses and their mean δ13C values largely
overlap (e.g., Cerling et al., 2003), yet many of these grazing herbivores partition
available grass resources by feeding on different structural components and/or grasses at
different growth stages (e.g., Gwynne and Bell, 1968; Bell, 1971; Murray and Brown,
1993). As emphasized by McNaughton and Georgiadis (1986), grass is not a
homogeneous resource and nutritional quality varies among its major structural
components (leaf, sheath, and stem) as well as seasonally.
Based on the results obtained from the present study, the pattern of competition
among bison and other late Pleistocene ungulates postulated by Scott (2010) is supported
for the equid and bison samples from the postglacial of Alberta and the American
Southwest, but not for the preglacial of Alberta. This pattern is more consistent with the
coevolutionary disequilibrium extinction model (Graham and Lundelius, 1984), than with
the model proposed by Scott (2010); however, additional studies are needed to further
196
evaluate these two extinction models. Nevertheless, Scott (2010) raises an important
point that has been overlooked by many researchers investigating the late Pleistocene
extinctions. An often raised objection against climate-based extinction models is that the
Pleistocene-Holocene transition was not more severe in magnitude or duration than
previous glacial-interglacial transitions and, because Pleistocene faunas survived earlier
glacial-interglacial transitions without major extinction events, then climate change must
not have been the primary factor responsible for the late Pleistocene extinctions (Koch
and Barnosky, 2006). Scott (2010), using North American bison as an example,
emphasizes that this point of view ignores the fact that the Pleistocene megafauna was
not a static, cohesive entity. Large mammal communities were dynamic in nature and this
must be considered when assessing the causes of the late Pleistocene extinctions.
3.5.1
Diets of late Pleistocene equids and bison
The horse and bison samples studied show mesowear signatures indicative of an abrasive
diet and are, therefore, classified by the DFA within the dietary group comprised by the
extant grazing ungulates in the dataset of Fortelius and Solounias (2000). All of the bison
samples have mean mesowear scores which are smaller than those of the equid samples
for each corresponding geographic region and time interval studied; however, this
difference is only statistically significant for the preglacial horse and bison samples from
Alberta. Comparable, highly abrasive diets have been reported for horse and bison
samples from a variety of sites throughout North America, including the American
Southwest (Rivals and Semprebon, 2012) and eastern Beringia (Rivals et al., 2010). Both
Equus sp. and Bison antiquus from Blackwater Draw, New Mexico, studied by Rivals
and Semprebon (2012), showed a mesowear score indicative of an abrasive diet similar to
197
that of extant grazing ungulates, with Equus sp. showing a higher mean mesowear score
(i.e., more abrasive diet) than Bison antiquus (Rivals and Semprebon, 2012). The same
pattern was observed for E. lambei and B. priscus from the late Pleistocene of Alaska, in
which both species plot on the abrasive end of the mesowear spectrum, with B. priscus
showing a smaller average mesowear score than E. lambei (Rivals et al., 2010).
In contrast to the analysis of mesowear, DFA of the dental microwear classified
the samples of horse and bison studied with extant seasonal mixed feeders, except for the
American Southwest samples of E. conversidens from the preglacial and full-glacial time
bins, which were classified as grazers. Extant members of these two lineages are typically
regarded as grazers (Nowak, 1999), and, therefore, identification of bison samples and
most of equid samples as seasonal mixed feeders would initially seem surprising.
However, dental wear studies and stable isotope analyses have found significant dietary
plasticity in fossil members of these two ungulate lineages. Rivals et al. (2007) reported a
wide dietary spectrum for North American Pleistocene and early Holocene bison, which
ranged from pure grazing to mixed feeding. Akersten et al. (1988) report that Bison
antiquus from Rancho La Brea, California, incorporated a small proportion of grasses in
its diet based on plant remains extracted from the teeth of seven individuals.
Extinct species of Equus also presented a considerable degree of dietary
flexibility. Mesowear analysis indicates that E. capensis from the Pleistocene of South
Africa was a mixed-feeder, possibly adapted to eating the unique fynbos vegetation that
can still be found in the south-western part of the country (Kaiser and Franz-Odendaal,
2004). The Pleistocene equid species from the pampean region of Argentina were
ingesting a pure C3 or an isotopically mixed diet (Sanchez et al., 2006). Similar results
198
have been reported for equids from Rancho La Brea, California (Coltrain et al., 2004),
and Florida (Koch et al., 1998). Furthermore, plant remains recovered from a juvenile
horse from Rancho La Brea consisted of more than 50 % dicotyledons, indicative of a
browsing strategy (Akersten et al. 1988).
Although classification of the bison samples and most of the equid samples as
seasonal mixed feeders is consistent with the studies highlighted above, these results
should be, for the moment, considered tentative. As was discussed in the methods section,
it is unclear how accurate these dietary reconstructions are, in light of the high
interobserver error reported for low magnification microwear analyses (see Mihlbachler
et al., 2012, for additional discussion on this issue).
3.6
Conclusions
The study of dental wear of equid and bison samples from the American Southwest,
Alberta, and northern Yukon, support the hypotheses formulated for the coevolutionary
disequilibrium extinction model (Graham and Lundelius, 1984), but not for the mosaicnutrient model (Guthrie, 1984). Sympatric species of equids and bison had significantly
different dental wear patterns (and therefore presumably different diets) during the
preglacial and full-glacial intervals, but not during the postglacial. These results indicate
that environmental changes during the terminal Pleistocene disrupted large herbivore
communities, possibly resulting in increased competition for food resources. Whether
these community changes were severe enough to increase physiological stress for some
ungulate species is a question investigated in the next chapter. Nonetheless, the results of
199
the present study add to the evidence indicating that ecosystems were in a heightened
state of flux at the time humans entered the Americas.
3.7
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CHAPTER 4. ENAMEL HYPOPLASIA IN LATE PLEISTOCENE EQUIDS AND
BISON: INSIGHTS INTO EARLY SYSTEMIC STRESS OF TWO
HERBIVOROUS MAMMALS
4.1
Introduction
In reconstructing the paleobiology of extinct mammals, probably the most important
anatomical elements are the teeth. Teeth are not only archives of paleoecological,
paleoclimatic and, in the case of Quaternary mammals, paleogenetic information, but
they also record episodes of tooth developmental disruption correlated with systemic
stress experienced by the individual while the teeth were being formed. Periods of
disruption in tooth development during enamel matrix formation are recorded in the teeth
in the form of tooth defects known as enamel hypoplasia (Goodman and Rose, 1990;
Moggi-Cecchi and Crovella, 1991; Hillson, 1996, 2005; Kierdorf and Kierdorf, 1997;
Guatelli-Steinberg, 2000, 2003; Witzel et al., 2008). These tooth defects have been
extensively used in anthropological and archaeological studies to infer the health of past
primate populations, especially humans (Goodman and Rose, 1990; Moggi-Cecchi and
Crovella, 1991; Skinner and Goodman, 1992; Hillson, 1996, 2005; Guatelli-Steinberg,
2000, 2003; Skinner and Hopwood, 2004; King et al., 2005; Schwartz et al., 2006; Witzel
et al., 2008). In the context of the late Pleistocene extinctions, the study of enamel
hypoplasia provides the opportunity to test whether herbivorous mammals were
potentially experiencing increased levels of systemic stress during the terminal
Pleistocene as predicted by different climate-based extinction models. The two climatebased extinction models investigated in my dissertation, coevolutionary disequilibrium
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(Graham and Lundelius, 1984) and mosaic-nutrient (Guthrie, 1984) extinction models,
draw upon the individualistic response of plant species to climate change to present a
plausible scenario in which nutritional stress is considered one of the primary causes for
the late Pleistocene extinctions.
Teeth are excellent elements for inferring episodes of early systemic stress
because they are well represented in the fossil record, they can be identified to species,
and enamel is not remodeled after maturation (Hillson, 2005). Therefore, enamel retains a
permanent record of dental growth disruptions that occurred during tooth development
(Hillson, 2005). Moreover, teeth provide the opportunity for estimating chronology and
duration of potential stress episodes (Dobney and Ervynck, 2000; Franz-Odendaal et al.,
2004). In this study, I examined the prevalence of enamel hypoplasia in the cheek teeth of
North American late Pleistocene equids and bison as a proxy for the incidence of early
systemic stress in these ungulates. The hypotheses tested are:
H0: No significant difference in the frequency of enamel hypoplasia and number
of hypoplastic events per affected tooth for bison and horse samples after the fullglacial.
HA: These ungulates, in particular horses, show a significant increase in the
frequency of enamel hypoplasia and number of hypoplastic events per affected
tooth during the terminal Pleistocene (postglacial), potentially caused by an
increase in systemic stress (specifically nutritional stress) due to new vegetational
associations.
Prediction: The coevolutionary disequilibrium and mosaic-nutrient extinction models
both predict an increase in systemic stress (specifically nutritional stress), particularly for
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the species that became extinct. Systemic stress encountered by an individual while the
dentition was being formed can be inferred by examining for enamel hypoplasia. If
horses experienced an important increase in systemic stress during the postglacial, the
frequency of enamel hypoplasia, as well as the number of hypoplastic events per affected
tooth, for this time interval should be significantly greater than that for earlier time
periods (full-glacial and preglacial).
4.1.1
Tooth development and enamel hypoplasia
Tooth development starts at the cusps and progresses down to the roots (Hoppe et al.,
2004; Hillson, 2005). During the development of a tooth, enamel is deposited by
ameloblasts in a circadian manner (Dean et al., 2001; Hillson, 2005). Enamel is secreted
by ameloblasts between the outer surface of the tooth and the enamel-dentine junction in
a process called apposition (Ramirez-Rozzi and Bermudez de Castro, 2004). Apposition
determines the thickness of the enamel. The deposition of enamel progresses down the
tooth as new ameloblasts differentiate over the whole crown height; this process
determines the elongation (extension) of the tooth (Ramirez-Rozzi and Bermudez de
Castro, 2004). Throughout these two processes (apposition and extension) several
microscopic features within the enamel are formed (Figure 4.1; Moggi-Cecchi, 2001;
Tafforeau et al., 2007). The smallest of all are cross-striations, which correspond to the
daily enamel deposition by ameloblasts and they proceed from the enamel-dentine
junction to the outer surface of the tooth. As cross striations are being formed by
ameloblasts, a second cycle affects the deposition of enamel by these cells which causes
the production of distinct lines that are called Retzius’ striae. In anatomically modern
humans, Retzius’ striae have a modal periodicity of nine days that is, nine cross-striations
218
are found between two Retzius’ striae (Ramirez-Rozzi and Bermudez de Castro, 2004;
Guatelli-Steinberg et al., 2005). Thus, Retzius’ striae formation proceeds at a constant
rate which is consistent within a single tooth and in all teeth belonging to the same
individual (Guatelli-Steinberg et al., 2005). The number and inclination of Retzius’ striae
are a direct reflection of the extension rate. In the cuspal enamel, Retzius’ striae are
placed one above the other like a series of domes. On the sides of the tooth (i.e.,
imbricational enamel) Retzius’ striae crop-out as perikymata. After the enamel matrix has
been secreted, mineralization of the enamel begins (Hillson, 2005).
Enamel hypoplasia is a developmental defect that is caused by a physical
disruption of the amelobasts that secrete enamel (Goodman and Rose, 1990). This defect
most commonly occurs as a result of systemic stress and causes a thinning of the enamel.
The Federation Dentaire Internationale (FDI) established an international index for the
study of enamel hypoplasia, which recognizes different categories of this defect: single
pits, areas missing enamel, non-linear grooves, non-linear multiple pits, horizontal linear
grooves, and horizontal linear pits (Federation Dentaire Internationale, 1982) (Figure
4.2). Non-linear pits and areas missing enamel are thought to result from localized
physical trauma, usually associated with a thinning of the bone covering the developing
tooth commonly caused by poor maternal diet (deficiencies in calcium, vitamin A or
vitamin D) and premature births (Skinner and Hung, 1986). Small horizontal linear pits
and horizontal linear grooves are known as linear enamel hypoplasia. Linear defects have
been associated with different systemic stressors (e.g., weaning, parturition, nutritional
stress, and illness) at the time of tooth formation (Franz-Odendaal, 2004; Franz-Odendaal
et al., 2004). Some researchers consider that the width and depth of linear enamel
219
hypoplasia correspond, respectively, to the duration of the stress episode and its severity
(Goodman et al., 1980; Suckling, 1989).
Disruption of the mineralization phase of tooth enamel formation causes a
developmental defect known as enamel hypomineralization (Suckling and Purdell-Lewis,
1982), which results in a discolouration of the enamel (Neiburger, 1990). As a result,
hypomineralization is hard to distinguish from diagenesis and it is therefore usually not
investigated in archaeological and fossil teeth (Franz-Odendaal et al., 2004; Hillson,
2005).
Enamel hypoplasia has been extensively studied in primates, including humans, to
infer the occurrence of episodes of early systemic stress (e.g., Goodman and Rose, 1990;
Moggi-Cecchi and Crovella, 1991; Hillson, 1996, 2005; Guatelli-Steinberg, 2000, 2003;
Skinner and Hopwood, 2004; King et al., 2005; Schwartz et al., 2006; Witzel et al.,
2008). In contrast, relatively few studies have been conducted on archaeological and
paleontological non-primate mammals, including Neogene rhinoceroses (Mead, 1999;
Roohi et al., 2015), domestic pigs and wild boar (Dobney and Ervynck, 2000; Dobney et
al., 2004; Witzel et al., 2006), late Pleistocene and Holocene bison (Niven, 2002; Niven
et al., 2004; Byerly, 2007), Pliocene giraffids (Franz-Odendaal et al., 2004), cattle
(Kierdorf et al., 2006), Pleistocene equids (Timperley and Lundelius, 2008), domestic
sheep and goats (Kierdorf et al., 2012; Upex et al., 2014), and the Pleistocene notungulate
Toxodon (Braunn et al., 2014).
220
Figure 4.1. A) Diagram of a human molar cross section showing perikymata, striae of
Retzius, and cross-striations. B) Microphotograph of imbricational enamel. The striae of
Retzius are indicated by white arrows; cross-striations are also evident (Figure adapted
from Moggi-Cecchi, 2001).
221
A
B
C
D
Figure 4.2. Different types of enamel hypoplasia: A) area missing enamel exposing the
dentine underneath (CMH MgVo-2 (E3)-H-3; left P4); B) non-linear multiple pits (RAM
P02.8.45); C) two sets of small horizontal linear pits (UTEP 22-64; left M2); C)
horizontal linear grooves (RAM P94.1.341). Scale bar = 5 mm.
4.2
Limitations and Assumptions
Testing of the coevolutionary disequilibrium (Graham and Lundelius, 1984) and mosaicnutrient (Guthrie, 1984) extinction models requires assessment of nutritional stress in
Pleistocene herbivore mammals. Although several studies indicate that enamel
hypoplasia can be associated with nutritional stress (e.g., Goodman and Rose, 1990;
Hillson, 1996; Larsen, 1997; Zhou and Corruccini, 1998; Dobney and Ervynck, 2000;
222
Hillson, 2005; Guatelli-Steinberg and Benderlioglu, 2006), this tooth defect has a
multifactorial etiology and a variety of other stressors, in addition to malnutrition, have
been associated with enamel hypoplasia. Systemic and infectious diseases, severe fevers,
premature births, parturition, weaning, parasite infestation, and intoxication with fluoride
are some of the stressors that have been linked to the development of enamel hypoplasia
in mammals (Shearer et al., 1978; Shupe and Olson, 1983; Skinner and Hung, 1986;
Suckling et al., 1986; Suckling et al., 1988; Miles and Grigson, 1990; Kierdorf et al.,
1993; Hillson, 1996, 2005; Larsen, 1997; Dobney and Ervynck, 2000; Kierdorf et al.,
2000; Kierdorf et al., 2004). Inferring which stressor potentially caused enamel
hypoplasia in a given individual cannot be accomplished without additional lines of
evidence, such as knowledge of the diet and life history of the species under study (e.g.,
Dobney and Ervynck, 2000; Franz-Odendaal et al., 2004; Niven et al., 2004). Therefore,
the presence of enamel hypoplasia is more commonly treated as an indicator of overall
health during tooth development.
Despite the inability to unequivocally identify nutritional stress in the equid and
bison samples here studied without additional lines of evidence, the identification of
increased enamel hypoplasia during the terminal Pleistocene in these ungulates in
addition to the results presented in Chapter 3 would be consistent with the nutritional
extinction models advanced to explain the late Pleistocene extinctions.
4.3
The samples for study consisted of late Pleistocene equid and bison cheek teeth from
Bluefish Caves, Yukon; the Edmonton area gravel pits and Wally’s Beach site, Alberta;
223
and several sites in the American Southwest including Dark Canyon Cave, Dry Cave, and
Blackwater Draw, New Mexico, as well as Sharbauer Ranch and Lubbock Lake sites,
Texas (Figure 4.3). All of the specimens I studied are deposited in the following
institutions, with corresponding specimen acronyms indicated in parentheses:
Archaeology Collection (Bluefish Caves; MgVo-1, 2, and 3) of the Canadian Museum of
History (CMH); Quaternary Paleontology (P) and Archaeology collections (Wally’s
Beach site; DhPg-8) of the Royal Alberta Museum (RAM); Vertebrate Paleobiology
Collection, Laboratory for Environmental Biology, University of Texas at El Paso
(UTEP); and the Vertebrate Paleontology collection of the Vertebrate Paleontology
Laboratory, University of Texas at Austin (TMM).
The data I collected were arranged into preglacial, full-glacial, and postglacial
time intervals, as was done for the dental wear analyses conducted in Chapter 3. The time
encompassed by these intervals varied slightly for each geographic region. The material
from Bluefish Caves, which consisted of only one equid species (Equus ferus lambei;
Chapter 2), could only be divided into two time intervals: preglacial/full-glacial (~31 ky –
14 ky RCBP) and postglacial (~14 ky – 10 ky RCBP). Specimens were assigned to one of
these two time intervals based on published work (Cinq-Mars, 1979; Morlan, 1989),
documents on file at the Canadian Museum of History (CMH Archives A2002-9 [Jacques
Cinq-Mars’ documents]: box 11, f.7), and the spatial and stratigraphic provenance of
equid specimens (retrieved from specimen catalogs and maps in the CMH Archives;
A2002-9: box 2, f.1, f.2, f.4; box 3, f.1, f.3 – f.9, f.13; box 8, f.4, f.5) relative to bones
that have been subjected to radiocarbon dating (Canadian Archaeological Radiocarbon
Database [CARD 2.0], accessed March 2015). These divisions correspond to a change in
224
the vegetation of the region from tundra during the preglacial/full-glacial to dwarf birch
during the postglacial (Cinq-Mars, 1979; Ritchie et al., 1982). Different publications
mention the occurrence of bison remains at Bluefish Caves (Cinq-Mars, 1979; CinqMars, 1990), but I did not locate any bison cheek teeth in the collection of the Canadian
Museum of History. Thus, I only studied equid specimens from this site.
The material from Alberta was divided into preglacial (>60 ky – 21 ky RCBP)
and postglacial time intervals (~13 ky – 10 ky RCBP), based on published radiocarbon
dates (Waters et al., 2015) and the association of specimens with localities that have only
yielded dates of preglacial or postglacial age (Burns, 1996; Jass et al., 2011). Fossil
material from the full-glacial is not represented in Alberta because most of the province
was covered by the Laurentide and Cordilleran ice sheets at that time (Young et al., 1994,
1999; Burns, 1996; Jass et al., 2011). The specimens from Alberta studied in this chapter
consisted of only one equid species (Equus ferus scotti; although a second less common
species, Equus conversidens, was recognized from the Edmonton area gravel pits
[Chapter 2]), and material referrable to Bison sp.
The fossil material from the American Southwest (specifically eastern New
Mexico and western Texas) can be divided into preglacial (~25 ky – 20 ky RCBP), fullglacial (~20 ky – 15 ky RCBP), and postglacial (~15 ky – 10 ky RCBP) ages, based on
different publications (Harris, 1987, 1989, 2015; Tebedge, 1988; Haynes, 1995; Holliday
and Meltzer, 1996). I was able to obtain data for only one equid species (Equus
conversidens) during the preglacial, whereas for the full-glacial I was able to collect data
for the two common equid species that inhabited this region during the late Pleistocene
(Equus ferus scotti and Equus conversidens; Chapter 2). Although bison (Bison antiquus)
225
was present in the American Southwest throughout the late Pleistocene (McDonald,
1981), I was only able to obtain mesowear and microwear data for postglacial specimens.
I also collected data for postglacial specimens of Equus ferus scotti and Equus
conversidens.
Most of the specimens I studied consisted of isolated teeth. The initial objective of
my study was to focus on a single tooth position; however, this resulted in very small
sample sizes. I therefore included in the analysis as many complete teeth as I could
reliably identify to species. Identification of the specimens to species was done using the
methodologies presented in Chapter 2 for the equid teeth and published sources for the
bison teeth (Lundelius, 1972; Jass et al., 2011; Harris, 2015). In the case of equids, I
examined premolars (P2 – P4; p2 – p4) and molars (M1 – M3; m1 – m3). For bison I
only studied molars (M1 – M3; m1 – m3), but not premolars, because the latter teeth are
much smaller. This difference in size could potentially bias the preservation of premolars
in the fossil record relative to molars and it could also affect their representation in
research collections as a result of collecting biases. Moreover, the difference in size
between premolars and molars might indicate that these two tooth groups have a different
dental developmental geometry, a factor that is known to affect the identification of
enamel hypoplasia when using macroscopic methods (Hillson and Bond, 1997; Hillson,
2014).
In some cases there were associated teeth belonging to the same individual. When
this occurred in equid specimens I examined either the P4 or M3 for enamel hypoplasia in
addition to the M1 (p4 or m3 in addition to m1 in the case of lower teeth). This is because
the timing of tooth crown formation for the P4/p4 and M3/m3 teeth minimally overlaps
226
with the timing of crown formation for the M1/m1 (Figure 4.4; Hoppe et al., 2004). Thus,
hypoplastic deffects not occurring on the apical portion of the tooth crown (immediately
below the area of the cusps) of the P4/p4 or M3/m3 can be identified as separate stress
events from those present in the M1/m1. The timing of crown formation for all other
tooth positions overlaps to a greater extent (Figure 4.4; Hoppe et al., 2004) and a
thorough assessment of the location of hypoplastic deffects is needed to determine
whether deffects present in different tooth positions actually correspond to distinct stress
episodes. In the case of associated bison teeth belonging to the same individual, I
examined enamel hypoplasia in each molar position: M1, M2, and M3 (m1, m2, and m3
in the case of lower teeth). This is because the timing of tooth crown formation for each
of these tooth positions minimally overlaps (Figure 4.5; Gadbury et al., 2000; Niven et
al., 2004). Therefore, hypoplastic deffects not occurring on the apical portion of the tooth
crown (immediately below the area of the cusps) especially of M2/m2 and M3/m3 can be
considered as distinct stress episodes.
Evidence of enamel hypoplasia naturally becomes eliminated as the tooth wears
down, because of this I originally examined unworn or little worn teeth. Nevertheless,
restricting the assessment of enamel hypoplasia to unworn or little worn teeth resulted in
small sample sizes. Therefore, it was necessary to study every reasonably complete tooth
that could be assessed for enamel hypoplasia. I do not expect that this introduced
systematic variation into the data, because this approach was undertaken for all of the
fossil assemblages studied; however, it must have to some extent reduced the frequency
of incidences of enamel hypoplasia across all samples. Fortunately, emerging evidence
indicates that the cheek teeth of hypsodont ungulates present non-linear crown extension
227
rates and the lower portion of the tooth takes up most of the total crown formation period.
For example, Upex et al. (2014) mention that the lower 25 % of caprine cheek teeth
encompasses approximately 50 % of the total crown formation time. Exact data on the
extension rate of equid and bison cheek teeth are currently lacking, but my personal
observation of perikymata on the teeth of these ungulates suggests a similar crown
extension pattern to that reported by Upex et al. (2014). Therefore, loss of the upper
portion of a hypsodont cheek tooth due to dental wear represents a very small portion of
the total crown formation time. Upex et al. (2014) further note that enamel hypoplasia
occurs almost exclusively on the lower (cervical) portion of the tooth crown of caprine
cheek teeth, regardless of the state of dental wear, and suggest that this might be due to
variation in crown extension rates. As a result, these authors conclude that as long as
younger age categories are represented in each sample studied, the use of teeth in more
advanced stages of wear will not significantly bias recording of enamel hypoplasia to the
lower portion of the crown (Upex et al., 2014).
One important complication of the study of enamel hypoplasia of several
hypsodont ungulate molars, including those of equids and bison, is the presence of
cementum covering the tooth crown, which helps to anchor the tooth into the maxillary or
dentary while the roots develop and the tooth erupts into the mouth (Kierdorf et al., 2006;
Upex et al., 2014). Cementum covering the tooth crown develops after the enamel has
been secreted and mineralized and it gets laid down periodically in response to
continuous tooth eruption (Kierdorf et al., 2006; Upex et al., 2014). As a result,
cementum can obscure evidence of enamel hypoplasia (Kierdorf et al., 2006). In order to
circumvent this problem, Upex et al. (2014) suggest removing the cementum using a
228
tungsten drill bit. This was a procedure I could not attempt on the specimens I studied
because of conservation concerns. Another alternative would be to CT-scan the
specimens and digitally remove the coronal cementum in order to inspect the enamel; this
procedure was undertaken for a limited number of specimens (see below) because it is
not cost nor time effective. Nevertheless, cementum did not pose a serious problem to the
examination and study of enamel hypoplasia, because for a large portion of the specimens
I studied the cementum weathered and degraded, exposing the enamel underneath.
Cementum is softer and contains a larger percentage of organic matter than enamel
(Hillson, 2005). Therefore, cementum is degraded more easily than enamel. When
examining the specimens, I qualitatively scored the extent to which cementum covers the
tooth crown using a scoring system that ranges from 0 to 5: 0 indicating that the tooth
crown is not covered by cementum, 1 denoting that 1 to 25 % of the tooth crown is
covered by cementum, 2 indicating that 26 to 50 % of the tooth crown is covered by
cementum, 3 denoting that 51 to 75 % of the tooth crown is covered by cementum, 4
indicating that 76 to 95 % of the tooth crown is covered by cementum, but that the
cementum present consists of a thin layer, and 5 denoting that the entire tooth crown is
covered by a thick layer of cementum. I did not use specimens with a score of 5, even if
they showed evidence of hypoplasia beneath the cementum. Some equid teeth from
Bluefish Caves had one side of the tooth crown (the buccal side in lower teeth and the
lingual side in upper teeth) completely covered by cementum, but not the remaining
sides. I decided to score the exposed sides for enamel hypoplasia and include these
specimens in the analysis, because otherwise the sample size for this locality would have
been extremely limited.
229
All of the specimens, except three equid dentaries from Wally’s Beach, were
examined directly without the aid of magnification. I used oblique lighting to facilitate
the identification of enamel hypoplasia. The vast majority of the equid cheek teeth from
Wally’s Beach are encased in dentaries or maxillaries, preventing the direct assessment of
these specimens for enamel hypoplasia. Therefore, three dentaries from this site were CTscanned to allow examination of the cheek teeth. The specimens were CT-scanned by Dr.
Andrew Nelson, Department of Anthropology, University of Western Ontario, using a
Nikon XT H 225 ST MicroCT Scanner with the following settings: 190 kVp, 85
microamps, 500 msec exposure time, averaged 2 frames/projection, and voxel size of 70
µm. The software Inspect-X v. 4.3 was used for scan capture, CT-Pro 3D v. 4.3 for
volume reconstruction, and VG Studio Max v.2.2 for visualization and export to dicom. I
created 3-D surface models of the CT-scanned specimens using the computer software
AMIRA 5.3.3. I adjusted the threshold to digitally remove the dentary and the cementum
from the cheek teeth in order to be able to detect the presence of enamel hypoplasia on
the surface of the tooth crown (Figure 4.6A). I then prepared digital histological sections
using the “ObliqueSlice” module in AMIRA 5.3.3. to verify that the tooth defects
identified on the external surface of the tooth crown correspond to enamel hypoplasia
(Figure 4.6B). All of the tooth defects identified in the 3-D surface models showed
thinning of the imbricational enamel (Figure 4.6B), which is characteristic of enamel
hypoplasia (Goodman and Rose, 1990). These observations support the contention that
similar tooth defects identified in the specimens that were assessed via direct observation
correspond to enamel hypoplasia. Other minor fluctuations in enamel thickness were
sometimes observed in the digital histological sections as well as on the crown surface of
230
the 3-D surface models and the specimens assessed via direct observation; in the latter
two cases, these appear as shallow and faint grooves. Goodman and Rose (1990) indicate
that very small, shallow grooves may not be true hypoplastic defects. For this reason and
because of the subjectivity in assessing whether grooves are deep or shallow, some
studies suggest that only clearly defined, deep grooves be classified as enamel hypoplasia
(e.g., Goodman and Rose, 1990; Franz-Odendaal et al., 2004). This was the protocol that
I followed. However, contrary to Goodman and Rose (1990), some researchers have
indicated that groove defects present a continuum of sizes from the microscopic (the
smallest consisting of an increase in spacing between just two adjacent perikyma
grooves) to those observed with the naked eye, and that macroscopically visible defects
do not necessarily represent a more substantial growth disruption (Hillson and Bond,
1997; Hillson, 2014). If this is indeed the case, then the results presented here may
actually underestimate the true frequency of enamel hypoplasia in all of the samples
studied.
I investigated two variables for the specimens observed directly and those that
were CT-scanned: 1) presence/absence of enamel hypoplasia and 2) number of
hypoplastic events present per affected tooth (Table A 9 of the Appendix). Any form of
enamel hypoplasia was included in the analysis, because separation of the tooth defects
into the categories established by the Federation Dentaire Internationale for the study of
enamel hypoplasia (Federation Dentaire Internationale, 1982) resulted in very small
sample sizes. With this information, I calculated the percentage of individuals presenting
enamel hypoplasia in the different study samples, to determine the frequency of this tooth
defect. As it was described above, when dealing with associated specimens belonging to
231
the same individual, I examined either the P4 or M3 for enamel hypoplasia in addition to
the M1 in equid specimens (p4 or m3, and m1 for lower teeth), and the M1, M2, and M3
in bison specimens (m1, m2, and m3 for lower teeth). I also calculated the mean number
of hypoplastic events per affected tooth, per study sample. Hypoplastic defects occurring
at comparable heights on the same tooth crown were presumed to result from the same
stress event and were, therefore, counted as a single hypoplastic event. When dealing
with associated specimens, I added the number of hypoplastic events in each tooth
considered (P4 or M3, and M1 in equids [p4 or m3, and m1 for lower teeth], and M1,
M2, and M3 in bison [m1, m2, and m3 for lower teeth]) and divided this value by the
number of teeth scored to determine the mean number of hypoplastic events per tooth.
For each geographic region and species, I conducted one-tailed Z-tests of
proportions to determine whether the frequency of enamel hypoplasia increased during
the postglacial relative to the previous time interval(s). Similarly, I conducted one-tailed
bootstrap t-tests, to determine whether the number of hypoplastic events per affected
tooth increased during the postglacial, potentially indicating that stress events became
more recurrent during this time interval as compared to full-glacial and preglacial
intervals. I performed these tests for bison and equid samples separately, because
currently it is not known whether both ungulate groups are equally sensitive to the
development of enamel hypoplasia. Furthermore, the tooth crown of bison teeth develops
faster than that of equids. For example, crown formation of the m3 takes on average 16
months in plains bison (Figure 4.5; Niven et al., 2004), whereas it takes 34 months in
domestic horse (Figure 4.6; Hoppe et al., 2004). Thus, equid teeth can potentially record
more stress events than bison teeth, especially if these occurred periodically with a
232
periodicity of up to two and a half years in the longer developing teeth such as the P4/p4,
M2/m2, and M3/m3 (Figure 4.6). All statistical tests were conducted using the software
package MATLAB 7.8 (MathWorks, 2009). The significance level for all tests was set to
a p-value of 0.05.
Figure 4.3. Geographic location of the fossil sites considered in this study.
233
60
Age (months)
50
40
30
20
10
0
p2
p3
p4
m1
m2
m3
modern horses (Equus ferus caballus), based on data reported by Hoppe et al. (2004).
35
30
Age (months)
25
20
15
10
5
0
-5
p2
p3
p4
m1
m2
m3
modern bison (Bison bison), based on data reported by Niven et al. (2004).
234
A
B
c
c
b
a
b
a
Figure 4.6. Example of CT-scan data that was used to determine the presence of enamel
hypoplasia in three equid mandibles from Wally’s Beach, Alberta. A) 3-D digital surface
model of lower m1 (RAM DhPg-8 864) showing four hypoplastic events (horizontal
linear grooves) indicated by the arrows. B) Radial digital section through the anterior
portion of the same tooth showing the three hypoplastic events found on the protoconid
column, labeled as a, b, and c.
235
4.4
Results
Enamel hypoplasia was observed in all equid and bison samples studied. The frequency
of this tooth defect showed a larger range of variation in equids than in bison. The
incidence of enamel hypoplasia in the equid samples ranged from 31.25 % in the
preglacial sample of Equus conversidens from the American Southwest to 64.29 % in the
postglacial sample of E. ferus scotti from Alberta (Figure 4.7; Table 4.1). In contrast, the
incidence of enamel hypoplasia in the bison samples ranged from 25.71 % in the
preglacial sample of Bison sp. from Alberta to 29.41 % in the postglacial samples of
Bison sp. from Alberta and Bison antiquus from the American Southwest (Figure 4.7;
Table 4.1).
The frequency of enamel hypoplasia in equids is greater for the postglacial than
the preglacial in two out of the three species samples in which this comparison was made
(Table 4.2). The sample of E. conversidens from the American Southwest shows an
incidence of enamel hypoplasia of 31.25 % for the preglacial and 51.61 % for the
postglacial and this difference is statistically significant (Z-test of proportions, Z = 1.8099, p = 0.0352). Similarly, the frequency of enamel hypoplasia of E. ferus scotti from
Alberta is 43.05 % for the preglacial and 64.29 % for the postglacial and this difference
approaches statistical significance (Z-test of proportions, Z = -1.5286, p = 0.0632). The
incidence of enamel hypoplasia for the postglacial sample of E. ferus lambei from
Bluefish Caves is not significantly greater than the incidence calculated for the
preglacial/full-glacial interval (53.85 % vs. 52.94 %; Z = -0.0492, p = 0.4804). Also not
significant is the comparison of preglacial (25.71 %) and postglacial (29.41 %) Bison sp.
samples from Alberta (Z-test of proportions, Z = -0.3437, p = 0.3655) as well as the full-
236
glacial (41.67 %) and postglacial (54.55 %) samples of E. ferus scotti from the American
Southwest (Z-test of proportions, Z = -0.8092, p = 0.2092).
The average number of hypoplastic events per affected tooth increased during the
postglacial in all of the equid pairwise comparisons except one (Figure 4.8; Table 4.3).
The largest increase was observed in Equus ferus lambei from Bluefish Caves, in which
the average number of hypoplastic events per affected tooth increased from 1.33 in the
preglacial/full-glacial interval to 3.43 in the postglacial (bootstrap t-test, t = 4.4512, p =
0.0007). The average number of hypoplastic events also increased in the equid samples
from the American Southwest, where it went from 1.23 in the preglacial to 1.78 in the
postglacial for E. conversidens (bootstrap t-test, t = 1.9395, p = 0.0316) and 1.60 in the
full-glacial to 2.30 in the postglacial for E. ferus scotti (although in this case the increase
in hypoplastic events only approaches statistical significance; bootstrap t-test, t = 1.4383,
p = 0.0595). Contrary to these trends, the average number of hypoplastic events per
affected tooth significantly decreased during the postglacial in E. ferus scotti from
Alberta (2.16 events in the preglacial versus 1.37 in the postglacial; bootstrap t-test, t = 1.9339, p = 1 - 0.9762 = 0.0238), whereas in Bison sp. from the same geographic region
the average number of events appears to remain constant in the preglacial (1.31) as in the
postglacial (1.30) (bootstrap t-test, t = -0.0298, p = 0.5207).
237
Table 4.1. Summary statistics of enamel hypoplasia data for the equid and bison samples
studied. n = total number of specimens examined, H = number of specimens with enamel
hypoplasia, PH = percentage of specimens with enamel hypoplasia, ME = mean number
of hypoplastic events per affected specimen.
Time interval
N
H
PH (%)
ME
Bluefish Caves
17
9
52.94
1.33
Equus ferus lambei
Postglacial
13
7
53.85
3.43
Alberta
Preglacial
151
65
43.05
2.16
Equus ferus scotti
Postglacial
14
9
64.29
1.37
Alberta
Preglacial
35
9
25.71
1.31
Bison sp.
Postglacial
34
10
29.41
1.30
Preglacial
48
15
31.25
1.23
Full-glacial
5
3
60.00
1.33
Postglacial
31
16
51.61
1.78
American Southwest
Full-glacial
12
5
41.67
1.60
Equus ferus scotti
Postglacial
55
30
54.55
2.30
Postglacial
17
5
29.41
0.80
American Southwest
Equus conversidens
American Southwest
Bison antiquus
238
Percentage of specimens
70
60
50
40
30
20
10
Bf El
AB Es
AB Bp
SW Ec
SW Es
Post-LGM
Post-LGM
LGM
Post-LGM
Pre-LGM
Post-LGM
Pre-LGM
Post-LGM
Pre-LGM
Pre-LGM/LGM
Post-LGM
0
SW Ba
Figure 4.7. Incidence of enamel hypoplasia in the equid and bison samples studied. Bf El
= Equus ferus lambei, Bluefish Caves; AB Es = E. ferus scotti, Aberta; AB Bp = Bison
sp., Alberta; SW Ec = E. conversidens, American Southwest; SW Es = E. ferus scotti,
American Southwest; SW Ba = B. antiquus, American Southwest. Time interval
abbreviations: Pre-LGM = preglacial, LGM = full-glacial, Post-LGM = postglacial.
239
Table 4.2. Results of one-tailed Z-tests of proportions used to determine whether the
incidence of enamel hypoplasia significantly increased during the postglacial relative to
the previous time interval(s). n = total number of specimens examined; PH = percentage
of specimens with enamel hypoplasia; Z = Z-statistic; p = p-value. Statistically significant
p-values are shown in bold. Equus conversidens from the American Southwest for the
full-glacial interval was excluded from the analysis because of its small sample size.
Time interval
comparisons
n
PH (%)
Bluefish Caves
17
52.94
Equus ferus lambei
Postglacial
13
53.85
Alberta
Preglacial
151
43.05
Equus ferus scotti
Postglacial
14
64.29
Alberta
Preglacial
35
25.71
Bison sp.
Postglacial
34
29.41
American Southwest
Preglacial
48
31.25
Equus conversidens
Postglacial
31
51.61
American Southwest
Full-glacial
12
41.67
Equus ferus scotti
Postglacial
55
54.55
Z
p
-0.0492
0.4804
-1.5286
0.0632
-0.3437
0.3655
-1.8099
0.0352
-0.8092
0.2092
240
Mean hypopastic events
4
3.5
3
2.5
2
1.5
1
0.5
Bf El
AB Es
AB Bp
SW Ec
SW Es
Post-LGM
Post-LGM
LGM
Post-LGM
Pre-LGM
Post-LGM
Pre-LGM
Post-LGM
Pre-LGM
Pre-LGM/LGM
Post-LGM
0
SW Ba
Figure 4.8. Mean number of hypoplastic events per affected specimen in the equid and
bison samples studied. Bf El = Equus ferus lambei, Bluefish Caves; AB Es = E. ferus
scotti, Aberta; AB Bp = Bison sp., Alberta; SW Ec = E. conversidens, American
Southwest; SW Es = E. ferus scotti, American Southwest; SW Ba = B. antiquus,
American Southwest. Time interval abbreviations: Pre-LGM = preglacial, LGM = fullglacial, Post-LGM = postglacial.
241
Table 4.3. Results of one-tailed bootstrap t-tests to determine whether the number of
stress events per affected specimen increased during the postglacial relative to the
previous time interval(s). nH = total number of specimens with enamel hypoplasia; ME =
mean number of hypoplastic events per affected specimen; t = t-statistic; p = p-value.
Statistically significant p-values are shown in bold. * identifies comparisons in which the
mean number of hypoplastic events per affected specimen significantly decreased during
the postglacial (i.e., showing the opposite trend than the one being tested). Equus
conversidens from the American Southwest for the full-glacial interval was excluded
from the analysis because of its small sample size.
Time interval
comparisons
nH
ME
Bluefish Caves
9
1.33
Equus ferus lambei
Postglacial
7
3.43
Alberta
Preglacial
65
2.16
Equus ferus scotti
Postglacial
9
1.37
Alberta
Preglacial
9
1.31
Bison sp.
Postglacial
10
1.30
American Southwest
Preglacial
15
1.23
Equus conversidens
Postglacial
16
1.78
American Southwest
Full-glacial
5
1.60
Equus ferus scotti
Postglacial
30
2.30
t
p
4.4512
0.0007
-1.9339
0.9762*
-0.0298
0.5207
1.9395
0.0316
1.4383
0.0595
242
4.5
Discussion
North America and other regions around the world experienced significant climatic
changes during the late Pleistocene (Alley, 2000; Guilderson et al., 2001; Hodell et al.,
2010). This has led many researchers to propose that climate change played an important
role in the late Pleistocene megafaunal extinctions (e.g., Kiltie, 1984; King and Saunders,
1984; Graham and Lundelius, 1984; Guthrie, 1984; Barnosky, 1986; Ficcarelli et al.,
2003; Forster, 2004; Scott, 2010). Different climate-based extinction models propose that
populations of large mammals, especially the species that became extinct, were exposed
to increased levels of systemic physiological stress, such as nutritional stress, resulting
from climatic and environmental changes (Graham and Lundelius, 1984; Guthrie, 1984).
The results of the analysis of enamel hypoplasia of late Pleistocene equids and bison from
the Western Interior of North America indicate that disruptions in tooth development,
particularly in the equid taxa studied, increased during the postglacial relative to earlier
time intervals. Working under the assumption that enamel hypoplasia primarily reflects
episodes of systemic stress (Goodman and Rose, 1990), these results support the
hypothesis that equids experienced increased levels of systemic physiological stress
during the postglacial. In all of the equid samples studied, the frequency of enamel
hypoplasia and/or recurrence of hypoplastic events increased during this time interval
(Tables 4.2 and 4.3). Nevertheless, as discussed below, these changes were not spatially
or temporally uniform.
The specimens of Equus ferus lambei from Bluefish Caves, northern Yukon,
show that although the frequency of enamel hypoplasia did not significantly change from
the preglacial/full-glacial to the postglacial (both time intervals show hypoplasia
243
frequencies of ~53 %), the number of hypoplastic events per affected tooth significantly
increased during the postglacial from 1.33 to 3.43. These results indicate that E. ferus
lambei in eastern Beringia, which apparently was already exposed to relatively high
levels of stystemic stress during the preglacial/full-glacial with more than 50 % of the
specimens showing some kind of enamel hypoplasia, experienced more recurrent severe
stress events during the postglacial. Considering that the average horse cheek tooth takes
approximately 26 months to form (Hoppe et al., 2004), some of the postglacial specimens
of E. ferus lambei were experiencing more than one severe stress event in a single year.
In Alberta, postglacial specimens of E. ferus scotti show a greater incidence of
enamel hypoplasia, with 64.29 % of specimens displaying a hypoplastic defect as
compared to the preglacial sample in which the incidence is 43.05 %. Contrary to the
increase in the incidence of hypoplasia, the number of hypoplastic events per affected
tooth is significantly smaller in the postglacial (1.37) than in the preglacial (2.16). These
results might indicate that stress events encountered by E. ferus scotti were less recurrent
during the postglacial, but when they did occur they were more severe affecting a greater
proportion of individuals. In contrast to these results, the postglacial sample of Bison sp.
from Alberta does not show a significantly greater frequency of enamel hypoplasia nor a
greater number of hypoplastic events per affected tooth than preglacial specimens. This
suggests that, contrary to E. ferus scotti, Bison sp. did not endure significantly greater
levels of systemic stress during the postglacial relative to what members of this ungulate
group encountered during preglacial times.
The two equid species studied from the American Southwest, E. conversidens and
E. ferus scotti, show an increase in the average number of hypoplastic events per affected
244
tooth during the postglacial. In the case of E. conversidens the number of hypoplastic
events significantly increased from 1.23 in the preglacial to 1.78 in the postglacial,
whereas in E. ferus scotti it increased from 1.60 in the full-glacial to 2.30 in the
postglacial. The frequency of enamel hypoplasia also increased during the postglacial in
both equid species, but it was only statistically significant in E. conversidens, which
shows an increase from 31.25 % in the preglacial to 51.61 % in the postglacial. These
results suggest that episodes causing systemic stress might have increased in severity and
also probably became more recurrent. The postglacial sample of Bison antiquus shows
comparable levels of hypoplasia as the preglacial and postglacial Bison sp. samples from
Alberta, with a hypoplasia frequency of 29.41 %.
The implication of the results described above for the late Pleistocene extinction
debate requires a determination of whether the frequency and number of hypoplastic
defects, especially for postglacial equid samples, are sufficiently high to suggest a
dramatic increase in the morbidity of these ungulates. Unfortunately, at the time of
writing, data on enamel hypoplasia in extant wild equid populations are lacking and they
are scarce for wild bison populations. Byerly (2009), in a macroscopic study of dental
pathologies in Bison from terminal Pleistocene and Holocene archaeological assemblages
in the Northwestern and Central Great Plains, examined a collection of modern bison
specimens from Montana (collected in 1886) and Yellowstone (donated to the
Smithsonian Institution between 1909 and 1919). The frequency of enamel hypoplasia in
the individuals with the cemento-enamel junction visible is 22.2 % for the sample from
Montana and 25.0 % for Yellowstone, although the sample size for the latter is very small
with only four minimum number of individuals [MNI] versus 27 MNI for the sample
245
from Montana (Byerly, 2009). These frequencies are relatively lower than those obtained
for the postglacial bison samples from Alberta and the American Southwest. The
frequency of enamel hypoplasia in the archaeological assemblages studied by Byerly
(2009), for samples greater than 10 MNI, ranges from 7.7 % in the Horner I assemblage,
Wyoming (~9,500 yr RCBP [radiocarbon years before the present]), to 36.8 % in the
Frasca site, Colorado (~8,900 yr RCBP). Comparable values were reported by Niven et
al. (2004) for Buffalo Creek, Wyoming (~2,500 yr RCBP), and Kaplan-Hoover, Colorado
(~2,700 yr RCBP), in which 32.3 % and 14.1 %, respectively, of the molars examined
show enamel hypoplasia. In this context, the level of hypoplasia in the postglacial bison
samples from Alberta and the American Southwest is within the upper range reported for
Holocene samples. Nevertheless, a lack of knowledge on the level of hypoplasia found in
healthy and stable populations versus populations subjected to severe systemic stress
prevents a determination of whether postglacial bison were experiencing detrimental
levels of stress. This is a topic that merits further investigation.
To my knowledge, only one previous study has examined enamel hypoplasia in
North American late Pleistocene equids. Timperley and Lundelius (2008) reported the
results of a preliminary survey in which they macroscopically analyzed enamel
hypoplasia in the upper and lower cheek tooth dentition of equid specimens from three
terminal Pleistocene localities (Blackwater Draw, Cueva Quebrada, and Gault) and three
older Rancholabrean sites (Curry Gravel Pit, Norman Valley Pit, and Trinity River
Terraces) in Texas and New Mexico. Except for Cueva Quebrada, where two species
(Equus scotti and E. francisci) were previously identified by Lundelius (1984), these
researchers studied enamel hypoplasia at the generic level (Timperley and Lundelius,
246
2008). In contrast to the results reported here, the equid specimens from the terminal
Pleistocene localities do not show a greater frequency of enamel hypoplasia than the
older Rancholabrean sites: Blackwater Draw 40 %; Equus scotti and E. francisci from
Cueva Quebrada 16 % and 13 %, respectively, Gault 19 %, Curry Gravel Pit 56 %,
Norman Valley Pit 26 %, and Trinity River Terraces 25 % (Timperley and Lundelius,
2008). Moreover, the hypoplasia frequencies for the terminal Pleistocene samples of
Cueva Quebrada and Gault are significantly lower than the ones obtained for the terminal
Pleistocene (postglacial) samples from Bluefish Caves, Alberta, and the American
Southwest. The discrepancy of these results could reflect actual differences in the
frequency of enamel hypoplasia among the sites studied or they could potentially be due
to differences in the data collection protocol. It is reasonable to expect that
geographically widespread taxa, such as Equus, would encounter certain regions with
relatively more optimal conditions for growth and reproduction than others. The area in
the vicinity of Cueva Quebrada and Gault sites, Texas, could potentially have harbored
such favorable habitats. Alternatively, the low frequencies of enamel hypoplasia reported
for these two sites could be due to bias introduced during data collection. It is not clear
how specimens with cementum preserved on the tooth crown were recorded by
Timperley and Lundelius (2008). Cementum develops after the enamel has been secreted
and mineralized in response to continuous tooth eruption and can, therefore, obscure
evidence of enamel hypoplasia (Kierdorf et al., 2006; Upex et al., 2014). A further
complication of comparing the results published by Timperley and Lundelius (2008) with
the ones reported here is the potential inter-observer difference in the scoring of enamel
hypoplasia. The macroscopic recording of hypoplasia using the naked eye or a low
247
magnification hand lens introduces difficulties in the comparison between studies
(Hillson, 2005). Under this approach, it is up to the individual observer to determine the
lower limit for recording the smallest hypoplastic defects, so there can be little
comparability between studies (Hillson and Bond, 1997; Hillson, 2005).
In all of the geographic regions and time intervals studied, but especially in the
postglacial equid material from Bluefish Caves and the American Southwest, it was
common to find specimens showing more than one hypoplastic defect in the same tooth.
Some studies suggest it is possible to determine the duration and timing of hypoplastic
events macroscopically with the use of point calipers, by measuring the width of the tooth
defect as well as its height from the cemento-enamel junction (e.g., Niven et al., 2004;
Byerly, 2007). However, these methods have been shown to be inaccurate because of the
way that teeth grow: tooth development is non-linear and, therefore, perikymata are more
closely packed together towards the cervix of the tooth crown (Hillson and Bond, 1997;
Hillson, 2014). A microscopic assessment is a better alternative for determining the exact
timing and duration of hypoplastic events, particularly for horizontal groove defects
(Hillson, 2014). The use of careful microscopy to study the number and spacing of
perikymata on the surface (or on thin sections) of individual teeth, will allow the
determination of whether recurrent stress events observed in the postglacial equid
specimens from Bluefish Caves and the American Southwest were periodic or episodic in
nature. Guthrie (1984) suggested that size diminution in many late Pleistocene ungulate
mammals, including Beringian equids (Guthrie, 2003), was the direct result of increased
seasonality among other environmental changes, which significantly reduced the growing
season. Enamel hypoplasia has been associated with seasonal stress events in a number of
248
species, including orangutans (Skinner and Hopwood, 2004), chimpanzees (Skinner and
Pruetz, 2012), and domestic sheep (Upex and Dobney, 2012). It therefore offers an
opportunity for studying seasonal environmental changes during the late Pleistocene.
4.6
Conclusions
The analysis of enamel hypoplasia of late Pleistocene equids and bison from the Western
Interior of North America indicate that systemic stress, particularly in the equid taxa
studied, significantly increased during the postglacial. In all of the equid samples the
frequency of enamel hypoplasia and/or number of hypoplastic events per affected tooth
increased during this time interval, although these changes were not spatially or
temporally uniform. The extent to which the increase in systemic stress was detrimental
to equid populations remains to be further investigated, but it is suggestive that
environmental changes might have played an important role in the extinction of equids
and perhaps other Pleistocene megafauna. At the very least it is possible that postglacial
equid populations were at a critical state and were “pushed over the edge” by increased
hunting pressures from an expanding human population. Archaeological evidence from
the Wally’s Beach site in southern Alberta clearly shows that humans successfully hunted
these ungulates (Kooyman et al., 2001; Kooyman et al., 2006; Waters et al., 2015).
4.7
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Young, R. R., J. A. Burns, D. G. Smith, L. D. Arnold and R. B. Rains. 1994. A single,
late Wisconsin, Laurentide glaciation, Edmonton area and southwestern Alberta.
Geology. 22:683–686.
Zhou, L. and R. S.Corruccini. 1998. Enamel hypoplasias related to famine stress in living
Chinese. American Journal of Human Biology. 10:723–733.
261
CHAPTER 5. CONCLUSIONS
At the end of the Pleistocene epoch, approximately 50,000 – 11,000 cal BP, many species
around the world became extinct or were extirpated at a continental scale in a geological
instant (Koch and Barnosky, 2006). Climatic changes seemed to have played a significant
role in the late Pleistocene extinctions on some continents, such as Europe (Stuart, 2015).
In the case of North America, however, the relative contribution of climate change versus
human impacts has been extensively debated (e.g., Grayson, 1991; Barnosky et al., 2004;
Koch and Barnosky, 2006; Scott, 2010) and this continues to be a contentious subject.
This dissertation focused on testing two nutritional extinction models based on climateinduced vegetation changes that have previously been proposed to explain the late
Pleistocene megafaunal extinctions: coevolutionary disequilibrium (Graham and
Lundelius, 1984) and mosaic-nutrient (Guthrie, 1984) extinction models. These models
were tested through the study of dental wear (microwear and mesowear) and enamel
hypoplasia of equid and bison specimens from the Western Interior of North America. In
order to undertake this task it was first necessary to determine the number of equid
species that inhabited this region of the continent during the late Pleistocene.
Molecular and morphometric analyses of the cheek tooth dentition indicate that
four equid taxa were present in the Western Interior of North America during the late
Pleistocene (Chapter 2). Two non-caballine species and two caballine subspecies were
identified, which, pending further study of North American Pleistocene Equus, are
referred as: Equus cedralensis, E. conversidens, E. ferus scotti, and E. ferus lambei.
Notably the separation into caballine and non-caballine equids was observed in the
Bayesian phylogenetic analysis of mitochondrial ancient DNA as well as in the geometric
262
morphometric analyses of the upper and lower cheek teeth. In addition, these analyses
demonstrate that E. conversidens corresponds to the New World Stilt-Legged clade
identified in previous molecular studies (Weinstock et al., 2005; Vilstrup et al., 2013),
suggesting that genetic data for true North American stilt-legged equids is presently
lacking. Also lacking is genetic data for the small-sized equid identified as E. cedralensis.
Future genetic studies should, therefore, try to target extracting and sequencing ancient
DNA from these two equid lineages.
The results of this study also provide insights into the spatial and temporal
distribution of equid taxa, revealing a latitudinal diversity gradient across the Western
Interior of North America during the last ~30,000 years of the Pleistocene. Three equid
species are identified in the fossil material from northeastern Mexico and the American
Southwest (Equus cedralensis, E. conversidens, and E. ferus scotti), but with some
regional variation as Equus cedralensis is found in low numbers in the American
Southwest and only E. conversidens was identified at San Josecito Cave, northeastern
Mexico. Two species are recognized in Wyoming and Alberta (E. conversidens and E.
ferus scotti), but there is also regional and temporal variation in the distribution of these
taxa. Equus ferus scotti is found in low abundance at Natural Trap Cave, Wyoming,
whereas the opposite trend is observed in Alberta where E. conversidens is represented
by a small number of specimens. In addition, E. conversidens in Alberta appears to have
been restricted to the preglacial, as it was not identified in any of the postglacial samples
analyzed, suggesting that this equid did not return to the province after the Laurentide and
Cordilleran ice sheets started to recede, approximately 13,000 RCBP (Young et al., 1994;
Burns, 1996). A single equid species is identified at Bluefish Caves, northern Yukon (E.
263
ferus lambei). The temporal range of the fossil deposits at Bluefish Caves extends from
~ 30,000 to the early Holocene and, thus, identification of a single equid species at this
locality is consistent with the conclusions of Guthrie (2003; 2006) and Weinstock et al.
(2005) who indicate that only one equid species (a caballine equid) was present in Alaska
and the Yukon after ~ 30,000 years ago. The patterns described here highlight the
dynamic nature of the spatial and temporal distribution of late Pleistocene North
American equids. Further molecular and morphometric analyses of equid specimens from
other localities within and outside of the Western Interior of North America will allow for
a better understanding of the biogeography and extinction of late Pleistocene equids.
After identifying the equid species present during the late Pleistocene in the
Western Interior of North America, Chapter 3 focused on the study of dental wear
(microwear and mesowear) of bison and equid species to test predictions formulated for
the coevolutionary disequilibrium (Graham and Lundelius, 1984) and mosaic-nutrient
(Guthrie, 1984) extinction models. Testing of these models is of particular importance
because they try to take into account the complex interactions between environmental
changes and their effects on biological communities. This means that their explanatory
mechanisms are not limited to exceptional circumstances present during the late
Pleistocene (e.g., an extraterrestrial impact [Firestone et al., 2007]) and can in theory
operate under current conditions of rapid climatic change.
The fossil record demonstrates that species and populations within species
respond individualistically to climatic changes and not as part of communities (e.g.,
Graham et al. 1996, Stewart, 2009). Based on the individualistic response of plant species
to climate change, the coevolutionary disequilibrium and mosaic-nutrient models present
264
alternative, although not mutually exclusive, scenarios where nutritional stress is
considered one of the primary causes of the extinction of different herbivore mammals,
including equids. The coevolutionary disequilibrium model emphasizes disruption of
coevolved foraging sequences as a result of changing vegetational assemblages, resulting
in competition for food resources among sympatric herbivore species (Graham and
Lundelius, 1984). Conversely, the mosaic-nutrient model proposes that a change from a
mosaic vegetation pattern to a more zonal, low diversity pattern decreased the dietary
supplements available to herbivores (Guthrie, 1984).
The study of dental microwear and mesowear of bison and equid species from
three geographic regions of the Western Interior of North America (the American
Southwest [eastern New Mexico and western Texas], Alberta [Wally’s Beach Site and the
Edmonton area gravel pits], and eastern Beringia [Bluefish Caves, Yukon Territory])
yielded results which are generally consistent with the predictions formulated for the
coevolutionary disequilibrium model, but not for the mosaic-nutrient model. Sympatric
species of Bison and Equus show statistically different dental wear patterns during the
preglacial and full-glacial, indicating that these ungulates were partitioning available
dietary resources during these time intervals. In contrast, the dental wear of postglacial
sympatric species of these ungulates is not significantly different, suggesting that they
were not partitioning available food resources and were potentially competing for them as
predicted under the coevolutionary disequilibrium model (Graham and Lundelius, 1984).
On the other hand, the decrease in dietary supplements during the terminal Pleistocene
especially required by certain ungulate species, such as equids and mammoths, as
proposed in the mosaic-nutrient model (Guthrie, 1984), is not supported by the analyses
265
of dental wear. The statistical dispersion of the microwear and mesowear variables did
not significantly decrease during the postglacial in either equid or bison samples, as
would be expected under a more homogenous diet. Nevertheless, the validity of these
conclusions rests on the assumption that dental wear is able to record subtle differences in
diet. Although some studies hint at the possibility that this might indeed be the case (e.g.,
Fortelius and Solounias, 2000; Scott, 2012; Barrón-Ortiz et al., 2014), further
investigations into the dietary resolution of dental wear are very much needed, not only
for testing of nutritional extinction models but also to allow for finer reconstructions of
ungulate feeding ecology. It is also important to undertake similar studies as the one
presented here employing a larger representation of ungulate species. The assessment of
bison and equid species reported admittedly provides a limited glimpse into the dynamics
of North American late Pleistocene ungulate communities. Furthermore, dental wear
studies should be complemented with other independent dietary proxies such as stable
isotope analyses and the study of dental calculus.
Identifying that equid and bison species were potentially competing for food
resources during the terminal Pleistocene does not in itself indicate that this resulted in
increased nutritional stress for these ungulates. This topic was indirectly evaluated in
Chapter 4 through the study of enamel hypoplasia in bison and equid specimens from the
same localities as the ones investigated for the study of dental wear. Enamel hypoplasia
results from a disruption in tooth development during enamel matrix formation, usually
as a result of systemic stress (e.g., Goodman and Rose, 1990; Hillson, 1996; Kierdorf and
Kierdorf, 1997; Guatelli-Steinberg, 2000, 2003; Witzel et al., 2008). Nutritional
deficiencies, systemic and infectious diseases, severe fevers, and a number of other
266
stressors have been associated with enamel hypoplasia in humans as well as other animals
(Goodman and Rose, 1990; Hillson, 1996; Zhou and Corruccini, 1998; Dobney and
Ervynck, 2000; Kierdorf et al., 2004). Although the multifactorial etiology of enamel
hypoplasia makes it virtually impossible to determine whether a specific hypoplastic
defect is due to nutritional stress without additional independent data, the significant
increase in enamel hypoplasia observed in postglacial samples, particularly in equids, is
consistent with both extinction models investigated as well as other climate-based
extinction models that have been proposed to explain the late Pleistocene megafaunal
extinctions (e.g., Kiltie, 1984; King and Saunders, 1984; Barnosky, 1986; Scott, 2010).
One limitation of the present study is that a lack of information on the levels of
enamel hypoplasia in modern stable populations versus populations subjected to severe
systemic stress prevents determining whether postglacial equids and, perhaps, bison were
experiencing detrimental levels of stress. This is a topic that merits further investigation.
Another area for further research is establishing the exact timing and duration of
horizontal groove defects through a microscopic assessment (Hillson and Bond, 1997;
Hillson, 2014). The use of careful microscopy to study the number and spacing of
perikymata on individual teeth, will allow the determination of whether recurrent stress
events observed in the postglacial equid specimens from Bluefish Caves and the
American Southwest were periodic or episodic in nature. Enamel hypoplasia has been
associated with seasonal stress events in a number of species including orangutans
(Skinner and Hopwood, 2004), chimpanzees (Skinner and Pruetz, 2012), and domestic
sheep (Upex and Dobney, 2012). It therefore offers the opportunity to study seasonal
environmental changes during the late Pleistocene.
267
Collectively, the different studies presented in this dissertation contribute
significantly to the increasing body of knowledge about the biotic and abiotic events that
occurred during the terminal Pleistocene. These studies have become an important area of
research as a result of the interest in global climate change and its potential impact on
biodiversity and society. Understanding of the Pleistocene-Holocene transition is critical
to predicting how modern organisms might react to major climatic changes.
5.1
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Barrón-Ortiz, C. R., J. M. Theodor and J. Arroyo-Cabrales. 2014. Dietary resource
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Firestone R. B., A. West, J. P. Kennett, et al. 2007. Evidence for an extraterrestrial impact
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273
Appendix
Table A 1. Measurement data of late Pleistocene equid samples studied. AP = anteroposterior length, TR = transversal width. INAH =
Instituto Nacional de Antropología e Historia, LACM = Los Angeles County Museum of Natural History.
Specimen
Inst.
Locality
Tooth position
AP
TR
2745
INAH
Cedral
Upper
P2l
37.07
25.87
2763
INAH
Cedral
Upper
P2l
39.12
25.61
2575
INAH
Cedral
Upper
P2l
37.04
26.23
4596
INAH
Cedral
Upper
P2l
37.88
27.59
4526
INAH
Cedral
Upper
P2l
38.17
29.53
2769
INAH
Cedral
Upper
P2r
38.54
26.63
3838
INAH
Cedral
Upper
P2 average
39.29
27.86
2737
INAH
Cedral
Upper
P2l
38.43
25.85
2589/2585 INAH
Cedral
Upper
P2 average
37.10
25.90
2581
INAH
Cedral
Upper
P2l
37.63
26.71
2679
INAH
Cedral
Upper
P2r
36.51
26.49
2761
INAH
Cedral
Upper
P2r
38.70
25.50
3836
INAH
Cedral
Upper
P2r
30.62
21.30
4595
INAH
Cedral
Upper
P2l
28.95
20.62
2754
INAH
Cedral
Upper
P2r
32.20
21.51
4540
INAH
Cedral
Upper
P2l
31.71
21.71
4544
INAH
Cedral
Upper
P2r
31.00
19.91
3867
INAH
Cedral
Upper
P2r
30.18
21.26
4547
INAH
Cedral
Upper
P2 average
31.10
21.57
2746
INAH
Cedral
Upper
P2l
29.05
20.67
4587
INAH
Cedral
Upper
P2r
24.51
20.83
3830
INAH
Cedral
Upper
P2r
25.04
18.33
3829
INAH
Cedral
Upper
P2l
25.60
18.16
2747
INAH
Cedral
Upper
P2r
24.10
18.68
192/116867 LACM San Josecito Cave
Upper
P2l
30.44
21.24
Upper
P2r
32.02
23.30
Upper
P2l
32.78
24.19
274
Table A 1, continued. Measurement data of late Pleistocene equid samples studied. AP = anteroposterior length, TR = transversal
width. LACM = Los Angeles County Museum of Natural History, TMM = Vertebrate Paleontology Laboratory, University of Texas
at Austin, UTEP = University of Texas at El Paso (* indicates Dry Cave localities), KU = University of Kansas.
Specimen
192/116874
192/18660
192/18660
192/uncat.
192/18660
192/156481
937-504
998-uncat.
998-26
998-24
5689-162-21
22-1609
46-139
22-1617
22-1619
25-537
27358
36836
61159
42970
44396
32877
39426
36140
48438
34023
39422
Inst.
LACM
LACM
LACM
LACM
LACM
LACM
TMM
TMM
TMM
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Blackwater Draw
Scharbauer Ranch
Scharbauer Ranch
Scharbauer Ranch
U-Bar Cave
Animal Fair*
Isleta Cave No. 2
Animal Fair*
Animal Fair*
Camel Room*
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Upper
P2l
Upper
P2r
Upper
P2l
Upper
P2r
Upper
P2l
Upper
P2l
Upper
P2r
Upper
P2l
Upper
P2l
Upper
P2r
Upper
P2r
Upper
P2 average
Upper
P2l
Upper
P2l
Upper
P2l
Upper
P2 average
Upper
P2l
Upper
P2l
Upper
P2r
Upper
P2 average
Upper
P2r
Upper
P2r
Upper
P2r
Upper
P2l
Upper
P2r
Upper
P2r
Upper
P2l
AP
32.87
31.53
31.37
31.12
29.44
33.86
34.13
39.06
38.38
38.36
30.60
30.08
35.77
36.12
32.72
30.44
32.96
31.01
32.41
31.70
30.55
31.66
34.31
33.98
32.54
33.57
30.54
TR
23.73
22.92
21.42
23.34
21.56
25.21
23.41
27.93
25.73
24.98
23.00
22.63
24.15
26.46
22.00
21.90
23.07
22.30
22.55
20.77
21.76
22.35
23.87
24.56
23.17
25.09
22.77
275
width. KU = University of Kansas, RAM = Royal Alberta Museum, CMH = Canadian Museum of History.
Specimen
46645
35189
53793
33790
35288
27319
39666
41181
41179
33220
40630
32880
31439
57157
35848
46644
71.1 (Horse D)
860.1 (Horse 3)
P02.6.2
P98.5.84
3437.1 (Horse 2)
H7(E)-14-10/
H7(E)-15-1
H8(S)-10-1
G7(E1/2)-11-10
M7-2-29
T.P.1-E-47
J8-1-116
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
RAM
RAM
RAM
RAM
RAM
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Wally's Beach
Wally's Beach
CloverBar Pit
Pit 48
Wally's Beach
Tooth position
Upper
P2 average
Upper
P2l
Upper
P2r
Upper
P2l
Upper
P2r
Upper
P2r
Upper
P2l
Upper
P2l
Upper
P2r
Upper
P2l
Upper
P2l
Upper
P2r
Upper
P2r
Upper
P2r
Upper
P2r
Upper
P2r
Upper
P2 average
Upper
P2 average
Upper
P2r
Upper
P2r
Upper
P2 average
AP
31.82
30.71
31.22
30.19
31.73
31.24
33.38
33.70
33.82
31.25
31.26
31.70
35.52
32.19
31.27
31.42
35.44
36.09
35.00
37.09
33.05
TR
21.88
22.64
22.22
22.13
22.08
22.23
23.69
24.23
24.11
22.74
23.35
21.29
23.50
23.19
22.94
21.25
22.72
23.33
22.59
26.25
23.02
CMH
MgVo-1
Upper
P2 average
38.83
23.20
CMH
CMH
CMH
CMH
CMH
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
Upper
Upper
Upper
Upper
Upper
P2l
P2l
P2r
P2l
P2l
37.36
35.40
35.84
37.52
36.04
23.73
23.67
22.27
23.54
23.38
276
width. CMH = Canadian Museum of History, INAH = Instituto Nacional de Antropología e Historia.
Specimen
N-3-15
Inst.
CMH
Locality
MgVo-3
Tooth position
Upper
P2r
AP
36.09
TR
23.69
B3-3-18/
C3(E)-2-41
CMH
MgVo-2
Upper
P2 average
33.16
23.43
I7-3-33
CMH
MgVo-1
Upper
P2l
36.95
24.15
T.P.1-F-36/
T.P.1-F-37
CMH
MgVo-3
Upper
P2 average
36.97
24.46
I7-1-12
I7-1-16
N-10-3
K6-1-5
J7-1-64
(D3)_6.6
F7-C-20
T.P.1-E-46
H7(W)-3-37
(D3)6.8
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-2
MgVo-1
MgVo-3
MgVo-1
MgVo-2
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
P2r
P2l
P2r
P2r
P2l
P2r
P2r
P2l
P2l
P2l
36.93
33.02
35.68
34.61
34.01
35.36
35.40
37.55
36.13
34.22
25.68
23.24
24.12
24.40
23.94
23.35
23.10
24.67
23.52
22.19
H5-3-23/
H5-3-22
CMH
MgVo-2
Upper
P2 average
36.68
25.01
J8-1-115
J8-1-159
3839
2599
2677
2784
2604
2662
2606
2603
2584
CMH
CMH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
MgVo-1
MgVo-1
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
P2r
P2l
P3/P4r
P4l
P4r
P3l
P4r
P3l
P3r
P4l
P4l
35.82
35.66
27.63
26.49
29.62
31.04
29.02
28.37
29.08
29.14
28.47
23.46
23.30
28.84
27.18
30.30
31.29
29.24
29.75
29.30
31.04
30.59
277
width. INAH = Instituto Nacional de Antropología e Historia.
Specimen
4522
2604
3838
2603
3833
2595
3859
3847
2563
2607
2573/2574
2608
2651
2572
4554
4540
2638
3850
4536
4543
4589
4547
2564
2652
4545
3832
2593
2779
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Upper
P3r
Upper
P4l
Upper
P3 average
Upper
P3l
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P3l
Upper
P4r
Upper
P3 average
Upper
P4r
Upper
P3l
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P3r
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P4 average
Upper
P4l
Upper
P3?/P4l
Upper
P4r
Upper
P4r
Upper
P4r
Upper
P3r
AP
29.77
27.80
31.03
30.75
26.72
30.19
28.55
28.32
28.68
29.05
28.91
30.24
23.86
21.77
23.40
22.66
20.92
23.33
22.44
22.96
26.00
22.36
23.88
22.29
19.98
24.91
20.98
23.60
TR
30.15
30.20
30.44
29.24
28.80
29.76
29.72
31.04
28.23
30.26
29.12
29.59
23.10
22.60
22.79
23.94
22.22
23.07
22.62
22.03
25.00
22.75
25.07
23.97
22.85
24.69
22.83
23.44
278
width. INAH = Instituto Nacional de Antropología e Historia, LACM = Los Angeles County Museum of Natural History.
Specimen
2668
4587
3854
3836
2773
3863
3830
3864
3841
4553
3829
4548
3868
2653
2783
3844
4528
3861
2576
3840
192/18674
192/uncat.
192/18111
192/116867
192/18105
192/18673
192/18657
192/156496
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Tooth position
Upper
P4r
Upper
P3r
Upper
P4l
Upper
P4r
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P4l
Upper
P3l
Upper
P4l
Upper
P4l
Upper
P3r
Upper
P4r
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3r
Upper
P4r
Upper
P4l
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P4l
Upper
P3r
Upper
P3l
Upper
P4r
Upper
P3r
AP
19.38
20.03
18.80
18.84
17.88
19.34
19.26
18.06
20.14
17.54
18.41
19.45
19.69
29.66
28.70
28.23
30.74
19.95
29.64
20.15
25.19
24.58
23.59
22.88
25.36
23.39
24.10
22.56
TR
23.68
22.22
22.45
21.45
19.35
19.83
20.07
18.94
21.06
19.36
20.11
19.70
20.60
28.09
28.65
28.91
27.30
20.48
29.64
20.80
25.03
25.63
25.41
24.77
24.60
25.48
25.51
23.61
279
at Austin, UTEP = University of Texas at El Paso (* indicates Dry Cave localities).
Specimen
192/156487
192/156484
192/156483
192/156497
192/156486
192/uncat.
41228-236
41228-360
41228-240
41228-1051
892-457
937-253
937-504
937-923
937-678
998-7
998-24
998-25
998-25
41228-302
937-986
22-981
34-46
119-14
34-8
22-1609
112-2
Inst.
LACM
LACM
LACM
LACM
LACM
LACM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Lubbock Lake
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Scharbauer Ranch
Scharbauer Ranch
Scharbauer Ranch
Scharbauer Ranch
Dark Canyon Cave
Blackwater Draw
Charlies Parlor*
Salt Creek
Algerita Blossom Cave
Salt Creek
Animal Fair*
Nash Draw
Tooth position
Upper
P3/P4r
Upper
P4r
Upper
P3/P4l
Upper
P4r
Upper
P4l
Upper
P3l
Upper
P4l
Upper
P4r
Upper
P3r
Upper
P3r
Upper
P4l
Upper
P4l
Upper
P3/P4r
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P4r
Upper
P3/P4r
Upper
P3/P4r
Upper
P4l
Upper
P4/M1r
Upper
P4l
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P4l
Upper
P4r
AP
22.46
25.58
25.17
23.48
22.09
24.68
23.94
22.73
24.93
23.68
22.90
29.29
24.55
25.91
30.07
25.18
30.47
28.37
30.67
23.47
23.18
28.80
31.05
26.88
21.43
23.93
30.34
TR
24.02
25.97
25.54
25.38
22.69
23.98
26.57
26.36
23.59
23.79
22.69
29.12
27.56
25.95
30.83
24.94
31.09
29.72
27.62
24.06
23.40
30.49
30.20
26.69
23.29
25.87
31.19
280
width. UTEP = University of Texas at El Paso (* indicates Dry Cave localities), KU = University of Kansas.
Specimen
46-139
22-1608
25-537
5689-117-6
5689-67-6
39268
27215
38555
48366
48719
45751
46778
39232
36548
42970
41178
32316
32785
34020
35769
46645
41524
32789
36687
43306
36456
38844
38519
Inst.
UTEP
UTEP
UTEP
UTEP
UTEP
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Isleta Cave No. 2
Animal Fair*
Camel Room*
U-Bar Cave
U-Bar Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Upper
P3l
Upper
P4 average
Upper
P4 average
Upper
M1/P4r
Upper
P3l
Upper
P3/P4l
Upper
P3r
Upper
P3r
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P4r
Upper
P3r
Upper
P3 average
Upper
P3l
Upper
P3/P4r
Upper
P3r
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P4r
AP
27.72
28.08
22.83
23.86
28.46
24.12
25.86
23.37
23.03
26.13
25.22
24.56
24.83
25.11
24.37
25.61
24.08
25.27
22.60
21.56
25.69
24.37
23.36
25.75
25.65
27.09
25.11
23.80
TR
26.12
29.44
24.81
24.29
28.86
26.28
24.74
24.43
25.12
24.37
24.78
25.01
23.99
25.40
23.48
23.64
24.04
23.51
25.64
24.29
23.28
24.33
23.80
24.74
24.90
27.15
24.58
25.97
281
width. KU = University of Kansas.
Specimen
38193
53793
45557
53793
32986
44390
44079
27214
43665
44132
39493
41960
41984
39722
31485
35870
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
34083/34084 KU
41045
KU
35542
KU
41180
KU
39803
KU
33219
KU
53793
KU
38688
KU
35596
KU
36748
KU
27902
KU
35085
KU
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Upper
P3l
Upper
P3l
Upper
P4 average
Upper
P3r
Upper
P4l
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3/P4l
Upper
P4 average
Upper
P3r
Upper
P4l
Upper
P3r
Upper
P4l
Upper
P3/P4r
Upper
P4l
Upper
P3/P4r
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P3l
Upper
P4r
Upper
P4l
Upper
P4l
Upper
P3l
AP
24.80
28.32
24.04
24.88
25.09
24.12
24.75
24.80
24.68
24.52
26.53
27.43
26.52
25.53
22.42
23.81
24.48
25.07
23.29
23.84
25.78
25.66
26.29
24.34
23.19
22.86
23.68
25.98
TR
24.53
26.59
25.23
24.90
27.26
23.71
23.56
24.37
24.60
24.85
25.47
25.92
28.52
24.22
24.62
24.58
26.25
26.11
25.49
26.05
23.78
24.71
28.14
25.22
25.69
23.59
25.66
26.06
282
width. KU = University of Kansas, RAM = Royal Alberta Museum.
Specimen
36438
36614
57157
38192
33536
50630
38190
32581
32704
36830
39685
39556
58354
45357
45356
P02.10.4
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
RAM
71.1 (horse D) RAM
P94.1.557
RAM
P98.5.462
RAM
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Pit 48
Wally's Beach
Pit 48
Pit 48
Tooth position
Upper
P3r
Upper
P3l
Upper
P4r
Upper
P4l
Upper
P4l
Upper
P4r
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3 average
Upper
P3r
Upper
P4r
Upper
P3/P4l
Upper
P3/P4l
Upper
P4r
Upper
P4 average
Upper
P3r
Upper
P3?l
AP
27.31
27.01
24.05
25.33
24.63
23.86
22.59
24.65
26.60
24.82
24.30
25.15
26.14
25.45
23.95
26.65
25.68
25.79
28.96
TR
25.40
25.86
25.97
27.47
24.10
25.85
24.70
23.92
25.50
23.74
24.61
24.63
27.62
24.13
24.60
25.94
27.50
25.23
27.74
3437.1
RAM
Wally's Beach
Upper
P4 average
26.16
26.53
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
P3/P4r
P3l
P4r
P4l
P4l
P3l
P3l
P3r
30.18
28.26
30.50
28.26
28.94
29.82
30.32
30.81
30.10
27.49
31.16
28.20
29.05
28.49
30.55
30.51
(Horse 2)
P94.1.866
P02.10.125
P89.13.610
P98.5.234
P94.1.259
P94.1.747
P89.13.617
P94.1.242
283
width. RAM = Royal Alberta Museum, CMH = Canadian Museum of History.
Specimen
P95.2.42
P94.8.161
P95.2.1
P94.1.583
P89.13.397
P94.1.150
P94.1.470
P89.13.400
P98.5.52
860.1 (Horse 3)
P94.1.498
P98.5.21/P98.5.20
P99.3.6
K6-2-23
K7-1-6
D6-D-4
K8-1-15
K7-5-22
K8-1-8
L7-7-3
H8(N)-8-6
G7(E1/2)-11-13
H7(W)-3-36
H7(E)-14-20
J7-4-31/J8-1-166
85-89
I7-1-48
T.P.1-5.36?/T.P.1-F-29
Inst.
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
Locality
Apex Evergreen
Riverview Pit
Apex Evergreen
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Wally's Beach
Pit 48
Pit 48
Pit 48
MgVo-1
MgVo-1
MgVo-2
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-3
Tooth position
Upper
P3r
Upper
P4l
Upper
P4r
Upper
P3l
Upper
P4/P3l
Upper
P3/P4l
Upper
P3l
Upper
P4l
Upper
P4r
Upper
P3average
Upper
P4r
Upper
P3average
Upper
(P4l
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P4l
Upper
P4average
Upper
P3l
Upper
P3l
Upper
P3average
AP
29.13
28.35
29.22
27.96
27.21
28.48
29.36
27.28
26.37
26.29
28.08
30.60
27.88
27.72
27.99
28.27
28.11
26.71
28.85
26.53
26.05
27.73
26.88
26.85
25.44
28.06
27.01
29.29
TR
27.96
29.11
29.78
27.91
27.25
26.16
28.86
27.61
29.12
25.00
28.66
29.45
27.47
26.62
27.07
27.41
26.83
27.12
27.68
27.24
26.00
25.57
28.75
27.77
26.31
27.18
26.53
27.95
284
width. CMH = Canadian Museum of History.
Specimen
B4(S)-12-8
Misc-52
85-41
E7-19-1
J7-1-72
I7-2-2
85-Misc-1
85-Misc:1.5
K6-1-"X"
C6(W)-13.1
H7(E)-21-2
L8(N)-7-24
S-3-11
C-8.5
C-9.11
M7-2-21
K7-1-16
G6-4-4
S-3-104
EE0946-1_T3-21-79
85-Misc-130
S-3-79
(D3)_6.7
I7-1-21
J8-5-3
H6-3-26
H5-3-23/H5-3-24
H7(E)-14-9
Inst.
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
Locality
MgVo-2
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-2
MgVo-1
MgVo-2
MgVo-1
MgVo-1
MgVo-3
MgVo-3
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-3
MgVo-3
MgVo-2
MgVo-1
MgVo-1
MgVo-2
MgVo-2
MgVo-1
Tooth position
Upper
P3l
Upper
P4r
Upper
P4r
Upper
P3r
Upper
P4l
Upper
P3l
Upper
P4r
Upper
P4r
Upper
P3r
Upper
P4l
Upper
P4l
Upper
P3r
Upper
P4l
Upper
P3l
Upper
P4r
Upper
P3l
Upper
P3l
Upper
P3l
Upper
P4r
Upper
P4r
Upper
P4l
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P3average
Upper
P3/P4l
AP
27.09
25.74
27.38
26.05
27.61
26.64
27.53
25.99
27.61
26.06
25.71
28.88
26.92
28.33
26.58
25.72
27.61
27.53
26.45
28.09
25.91
28.16
27.08
27.92
27.53
28.90
29.59
25.39
TR
26.19
26.89
25.85
25.93
27.61
25.90
28.94
25.88
26.40
26.20
26.48
26.38
26.95
26.77
26.58
24.99
27.22
26.84
27.05
28.21
26.24
27.09
25.74
26.47
26.06
26.53
27.87
27.33
285
Specimen
M7-2-22
(K6) 3.7
2667
2775
2619
3873
2319
2646
2536
2606
2771
3845
2610
2770
2637
2537
2778
2782
2577
2573/2574
3831
2617
2676
3867
2781
3846
4539
4590
Inst.
CMH
CMH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
MgVo-1
MgVo-2
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Upper
P3/P4r
Upper
P3r
Upper
M2l
Upper
M1r
Upper
M1r
Upper
M1r
Upper
M1r
Upper
M2r
Upper
M1r
Upper
M2r
Upper
M1r
Upper
M1l
Upper
M1/M2r
Upper
M2l
Upper
M2r
Upper
M2l
Upper
M2l
Upper
M2r
Upper
M2l
Upper
M2 average
Upper
M1r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M1r
Upper
M2r
Upper
M1r
Upper
M2l
AP
25.39
28.25
18.56
22.81
26.35
28.87
26.09
23.73
25.75
27.58
23.98
24.02
24.56
23.96
25.48
25.78
25.80
26.52
25.63
25.45
25.11
26.34
22.54
21.73
20.17
21.38
20.28
18.82
TR
26.40
25.65
20.42
24.48
27.83
30.32
28.18
24.34
27.08
27.91
27.06
27.55
26.03
26.41
26.23
26.02
26.59
27.63
26.40
27.13
27.95
28.93
23.90
24.76
22.75
22.18
22.48
20.65
286
Specimen
4540
4541
3853
2385
2652
2086
4537
2594
2780
2308
4545
4542
4594
2779
2648
2609
4547
2785
3843
3836
3871
4587
3870
2796
3828
3843
3858
3842
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Upper
M1l
Upper
M1?l
Upper
M1r
Upper
M2r
Upper
M1 average
Upper
M1l
Upper
M2r
Upper
M2l
Upper
M1l
Upper
M1
Upper
M2r
Upper
M2l
Upper
M2l
Upper
M2r
Upper
M2l
Upper
M2r
Upper
M2 average
Upper
M1r
Upper
M1l
Upper
M2l
Upper
M2l
Upper
M1r
Upper
M1r
Upper
M1r
Upper
M2r
Upper
M2r
Upper
M1l
Upper
M1l
AP
19.82
20.91
19.05
20.81
19.97
20.66
19.97
23.25
20.10
24.12
19.78
20.06
21.80
20.42
20.37
20.14
20.52
20.73
18.09
18.28
17.43
19.00
17.90
17.19
17.66
17.40
17.24
17.20
TR
22.61
20.62
20.93
21.63
21.14
21.97
20.55
22.96
22.96
23.07
20.71
20.42
22.75
22.53
21.88
21.25
20.63
21.31
19.46
18.10
18.57
20.62
18.44
18.57
19.10
18.84
18.96
19.77
287
Specimen
3829
3830
2622
4534
4555
2655
4597
2316
2595
2538
3866
2542
2530
2743
4530
4551
4530
192/uncat.
192/uncat.
192/18658
192/116867
18187/unc.
192/uncat.
192/uncat.
192/17969
192/17969
192/18662
192/18658
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Tooth position
Upper
M1l
Upper
M2r
Upper
M2l
Upper
M2l
Upper
M2r
Upper
M1r
Upper
M2 r
Upper
M2l
Upper
M2l
Upper
M1r
Upper
M1l
Upper
M2r
Upper
M2l
Upper
M2r
Upper
M2l
Upper
M2 average
Upper
M1/M2l
Upper
M1r
Upper
M1l
Upper
M1r
Upper
M1l
Upper
M1 average
Upper
M2l
Upper
M1l
Upper
M1r
Upper
M2l
Upper
M1l
Upper
M2r
AP
17.88
17.37
17.59
16.84
17.51
17.30
17.45
17.62
26.9
20.37
24.58
16.22
19.71
27.58
21.80
23.17
21.74
20.53
22.22
20.73
20.55
20.80
22.50
20.73
20.44
21.39
21.78
21.12
TR
18.95
18.38
19.25
18.53
19.49
19.16
18.63
18.58
28.52
21.70
28.29
17.02
20.31
29.77
22.74
25.87
22.62
22.31
23.30
24.46
22.87
23.92
22.49
21.80
21.91
22.46
24.01
21.92
288
width. LACM = Los Angeles County Museum of Natural History, TMM = Vert. Paleo. Laboratory, University of Texas at Austin.
Specimen
192/uncat.
192/uncat.
192/18657
192/156482
192/uncat.
192/uncat.
192/18658
192/18658
192/18662
192/uncat.
192/18664
192/uncat.
192/uncat.
192/uncat.
192/uncat.
Inst.
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
18657/18658 LACM
192/18658 LACM
192/18664 LACM
192/uncat.
LACM
192/uncat.
LACM
192/uncat.
LACM
937-195
TMM
41228-308 TMM
41228-261 TMM
937-207
TMM
998-8
TMM
937-194
TMM
937-203
TMM
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Blackwater Draw
Dark Canyon Cave
Dark Canyon Cave
Blackwater Draw
Scharbauer Ranch
Blackwater Draw
Blackwater Draw
Tooth position
Upper
M2r
Upper
M1l
Upper
M1l
Upper
M2r
Upper
M2l
Upper
M1/M2l
Upper
M1l
Upper
M1r
Upper
M1l
Upper
M1r
Upper
M2r
Upper
M2l
Upper
M2r
Upper
M2l
Upper
M2r
Upper
M1/M2 average
Upper
M1/M2l
Upper
M1/M2r
Upper
M1/M2l
Upper
M2r
Upper
M1/M2r
Upper
M2r
Upper
M1l
Upper
M1-M2l
Upper
M2r
Upper
M2l
Upper
M1l
Upper
M2r
AP
23.44
21.66
21.47
19.76
20.95
21.08
19.53
21.68
21.54
21.00
21.41
21.60
21.92
22.03
20.72
21.97
21.96
21.34
21.77
21.77
22.31
23.13
20.72
22.11
24.57
22.32
21.38
21.72
TR
24.28
23.95
23.08
20.17
25.38
23.35
22.28
23.46
22.96
23.72
22.53
22.15
23.55
22.14
21.26
23.87
23.64
22.09
23.26
21.72
23.18
23.22
22.58
24.10
24.65
22.54
22.18
22.34
289
width. TMM = Vertebrate Paleontology Laboratory, University of Texas at Austin, UTEP = University of Texas at El Paso (*
indicates Dry Cave localities).
Specimen
937-191
937-968
937-322
937-738
937-738
937-173
937-172
41228-59
4-827
34-26
75-29
120-218
22-1609
22-961
103-2
54-827
25-537
46-139
22-1608
22-64
54-1212
119-51
22-985
5689-54-2
112-3
175-1
937-799
Inst.
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
TMM
Locality
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Bison Chamber*
Salt Creek
Dark Canyon Cave
Big Manhole Cave
Animal Fair*
Charlies Parlor*
Imperial
TTII*
Camel Room*
Isleta Cave No. 2
Animal Fair*
Animal Fair*
TTII*
Charlies Parlor*
U-Bar Cave
Nash Draw
Fresnal Canyon
Blackwater Draw
Tooth position
Upper
M1r
Upper
M1r
Upper
M1r
Upper
M1l
Upper
M2r
Upper
M2l
Upper
M1l
Upper
M2-M1l
Upper
M1r
Upper
M2r
Upper
M2r
Upper
M1/M2r
Upper
M1 average
Upper
M1r
Upper
M1l
Upper
M1l
Upper
M1 average
Upper
M2l
Upper
M2 average
Upper
M1l
Upper
M2average
Upper
M2l
Upper
M1 average
Upper
M1r
Upper
M2r
Upper
M1l
Upper
M2l
AP
24.00
26.06
22.39
26.72
25.39
25.32
25.82
25.03
21.46
23.89
22.84
21.84
21.79
21.15
25.80
22.65
22.56
24.41
26.36
26.64
22.56
19.85
24.02
23.21
27.10
27.02
28.18
TR
26.00
27.72
22.19
28.25
26.75
25.87
26.34
25.32
23.36
24.41
23.39
21.03
24.80
23.12
25.89
23.26
23.60
24.05
25.81
27.40
23.45
21.90
25.37
23.86
27.76
27.77
26.47
290
Specimen
33538
39542
38845
50631
33886
40729
40707
40853
42950
32319
31942
35953
38637
39598
33795
31497
46645
38119
39099
35373
32636
34132
32988
39905
53793
44169
41984
44399
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Upper
M2l
Upper
M2r
Upper
M1r
Upper
M2r
Upper
M1r
Upper
M1l
Upper
M1r
Upper
M1r
Upper
M1l
Upper
M2l
Upper
M1r
Upper
M1r
Upper
M2r
Upper
M1l
Upper
M1l
Upper
M1l
Upper
M1l
Upper
M1r
Upper
M1l
Upper
M1l
Upper
M2l
Upper
M1l
Upper
M2r
Upper
M2r
Upper
M1r
Upper
M1l
Upper
M1/M2 average
Upper
M1r
AP
20.86
22.85
22.66
22.90
22.33
20.67
21.71
20.86
21.39
20.99
21.23
21.93
21.55
21.24
22.11
24.41
22.84
21.13
21.62
21.70
24.67
22.23
23.89
21.98
21.47
22.61
23.76
20.85
TR
22.81
24.84
23.39
23.99
24.17
22.46
22.00
22.72
22.81
22.57
22.77
23.74
23.41
23.33
23.48
26.21
23.34
22.62
23.46
23.40
25.84
24.03
25.65
22.94
23.78
23.61
25.66
22.52
291
Specimen
40632
38143
35047
35574
44390
44079
43338
33791
36796
43666
41961
42949
39803
38687
27900
39630
34022
44079
36689
31577
57157
32051
39803
39554
45355
34019
35086
33884
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Upper
M1r
Upper
M2l
Upper
M1/M2r
Upper
M2r
Upper
M1l
Upper
M1r
Upper
M1r
Upper
M2r
Upper
M2r
Upper
M2l
Upper
M2l
Upper
M2r
Upper
M1r
Upper
M1l
Upper
M2l
Upper
M1/M2r
Upper
M2r
Upper
M2r
Upper
M2l
Upper
M1r
Upper
M1r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M1/M2l
Upper
M1r
Upper
M2l
Upper
M2r
AP
21.98
21.97
22.53
22.07
21.80
21.62
22.28
22.99
25.13
21.76
24.60
22.04
23.39
21.72
22.39
22.23
21.63
21.32
25.07
22.24
21.49
21.31
23.34
21.70
21.56
22.16
23.13
22.86
TR
23.65
22.79
24.98
23.09
23.49
23.51
24.14
24.35
26.55
22.99
24.66
23.57
23.70
23.91
23.40
24.04
23.58
23.15
25.31
24.21
23.42
22.41
23.55
23.02
23.22
24.40
23.72
25.10
292
Specimen
34275
Inst.
KU
58354/56806 KU
44397
KU
33730
KU
42970
KU
34024
KU
32950
KU
31442
KU
38690
KU
32580
KU
32787
KU
38858
KU
39685
KU
53690
KU
39555
KU
38674
KU
P94.8.84
RAM
P94.8.14
RAM
P94.1.378
RAM
P05.10.56
RAM
P94.1.556
RAM
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Riverview Pit
Riverview Pit
Pit 48
Pit 48
Pit 48
Tooth position
Upper
M2l
Upper
M1average
Upper
M2l
Upper
M2r
Upper
M1l
Upper
M1r
Upper
M2l
Upper
M1r
Upper
M1l
Upper
M1r
Upper
M1r
Upper
M1r
Upper
M1 average
Upper
M1r
Upper
M2r
Upper
M1/M2l
Upper
M1r
Upper
M2l
Upper
M1l
Upper
M2r
Upper
M1r
AP
22.84
24.53
20.77
24.52
22.35
20.85
23.72
21.28
22.34
22.45
23.98
21.02
22.53
21.70
21.30
24.48
23.89
27.54
26.37
25.65
28.50
TR
23.81
26.59
22.31
25.63
23.71
24.02
24.31
24.73
23.82
24.40
24.43
23.68
24.15
25.04
22.94
25.23
25.81
28.81
27.96
26.00
28.57
3437.1
RAM
Wally's Beach
Upper
M2 average
23.45
23.39
RAM
RAM
RAM
RAM
RAM
RAM
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Upper
Upper
Upper
Upper
Upper
Upper
M2r
M1l
M2r
M1r
M2l
M1l
24.83
24.18
26.10
26.08
26.44
23.77
25.90
26.19
25.70
28.11
25.55
23.88
(Horse 2)
P94.1.497
P89.13.60
P94.1.390
P94.1.468
P04.3.40
P94.1.613
293
width. RAM = Royal Alberta Museum.
Specimen
P89.13.613
P89.13.267
P89.13.269
P89.13.616
P91.11.8
P98.5.191
P90.6.38
P94.1.765
P95.2.24
P95.6.89
P89.13.618
P95.6.41
P95.2.54
P94.1.248
P94.1.342
P94.1.478
P02.8.1
P94.1.388
P94.8.38
P94.1.141
P94.1.884
Inst.
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
860.1 (Horse 3) RAM
71.1 (horse D) RAM
P94.1.854
RAM
P98.5.52
RAM
2990.1
RAM
P89.13.223 RAM
P04.3.40
RAM
Locality
Pit 48
Pit 48
Pit 48
Pit 48
Pit 46
Pit 48
Apex Evergreen Pit
Pit 48
Apex Evergreen Pit
Pit 48
Pit 48
Pit 48
Apex Evergreen Pit
Pit 48
Pit 48
Pit 48
TBG Pit 4
Pit 48
Riverview Pit
Pit 48
Pit 48
Wally's Beach
Wally's Beach
Pit 48
Pit 48
Wally's Beach
Pit 48
Pit 48
Tooth position
Upper
M1l
Upper
M2l
Upper
M1r_
Upper
M2r
Upper
M1l
Upper
M1r
Upper
M1r
Upper
M2l
Upper
M1l
Upper
M2l
Upper
M2r
Upper
M2l
Upper
M2l
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M2r
Upper
M1 average
Upper
M1 average
Upper
M1l
Upper
M1r
Upper
M1l
Upper
M1r
Upper
M1/M2l
AP
24.94
25.60
25.38
27.40
25.98
28.30
24.54
26.04
25.34
24.67
25.57
25.04
24.93
26.38
23.64
25.46
26.72
25.62
26.12
25.87
26.13
23.14
22.70
25.37
21.79
25.19
24.97
26.10
TR
26.19
27.45
24.57
25.07
28.21
30.62
24.66
25.82
26.44
25.41
25.41
25.56
25.36
26.84
23.80
25.92
27.07
26.42
25.59
23.83
27.35
25.68
26.24
27.81
23.74
27.65
25.84
25.53
294
Specimen
P89.13.398
H7(E)-15-6
E6.4.38
L7-7-2
85-Misc-140
I7-3-35
H7(W)-3-25
Misc-52
Inst.
RAM
CMH
CMH
CMH
CMH
CMH
CMH
CMH
J8-1-170/J8-1-73 CMH
G7(E1/2)-17-5
CMH
85-41
CMH
G7(E1/2)-12-2
CMH
Misc-52
CMH
E7-20-8
CMH
I7-1-40
CMH
N-3-16
CMH
M-9-90/M-9-94 CMH
C5(S)-6.2/B3-3-20 CMH
85-Misc-135
CMH
T.P.1-F-67
CMH
85-Misc-5
CMH
85-Misc-31
CMH
L7-5-2
CMH
J7-1-36
CMH
K6-1-25
CMH
S-3-79
CMH
L8(N)-8-2
CMH
H6-6-14
CMH
Locality
Pit 48
MgVo-1
MgVo-2
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-3
MgVo-2
MgVo-3
MgVo-3
MgVo-3
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-2
Tooth position
Upper
M2l
Upper
M2l
Upper
M1r
Upper
M1r
Upper
M1l
Upper
M2r
Upper
M2r
Upper
M1r
Upper
M2 average
Upper
M2r
Upper
M1r
Upper
M1l
Upper
M2r
Upper
M1r
Upper
M2l
Upper
M1r
Upper
M2 average
Upper
M2 average
Upper
M2l
Upper
M1l
Upper
M2r
Upper
M1r
Upper
M2l
Upper
M2r
Upper
M2r
Upper
M1r
Upper
M1r
Upper
M1r
AP
25.01
23.95
24.57
23.53
25.08
23.48
23.87
22.89
23.01
24.69
23.60
23.61
23.47
23.17
23.33
24.48
24.96
24.21
24.83
25.60
24.82
23.13
24.29
25.11
25.40
22.81
23.62
24.55
TR
24.58
25.09
27.00
24.50
27.19
25.99
24.02
24.62
24.69
24.79
26.08
24.78
24.55
25.07
25.11
26.47
25.00
25.09
24.75
27.75
25.02
24.84
24.09
25.56
24.20
25.46
25.52
25.48
295
Specimen
I7-1-19
J8-1-67
J8-1-77/J8-1-117
J8-1-29
EE0946-1_T3-21-81
I7-3-26
H5-3-27/H5-2-16
J6-4.4
85-120
S-3-10
C-9.16
S-3-8
M7-2-18
J7-7.19
2613
2612
2758
4592
2749
4523
3838
2536
2591
3865
2583
2652
2623
4540
Inst.
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-2
MgVo-2
MgVo-3
MgVo-3
MgVo-3
MgVo-3
MgVo-1
MgVo-2
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Upper
M2l
Upper
M2l
Upper
M2 average
Upper
M2l
Upper
M2r
Upper
M2r
Upper
M1 average
Upper
M1l
Upper
M2l
Upper
M1l
Upper
M1l
Upper
M2l
Upper
M1r
Upper
M2l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3 average
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3 average
Upper
M3r
Upper
M3r
AP
25.08
24.52
23.77
24.30
24.30
23.96
25.17
24.37
25.40
24.25
24.45
25.36
22.20
24.91
28.65
30.80
29.60
33.44
29.82
29.24
29.95
28.91
25.37
29.29
21.82
21.39
21.35
26.02
TR
25.75
24.63
26.45
25.01
25.24
24.94
26.95
26.07
26.91
26.14
24.38
25.21
24.44
25.42
23.70
21.32
23.53
25.01
23.32
23.25
25.66
22.81
19.96
26.67
18.09
17.41
18.79
19.73
296
width. INAH = Instituto Nacional de Antropología e Historia, LACM = Los Angeles County Museum of Natural History, TMM =
Vertebrate Paleontology Laboratory, University of Texas at Austin.
Specimen
4538
4545
3893
4587
3855
3849
2795
2776
3860
2595
2752
4547
2563
2573/2574
192/18188
192/uncat.
192/uncat.
192/uncat.
192/uncat.
192/uncat.
192/18659
192/uncat.
192/17969
41228-402
41228-1026
892-458
41228-1030
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
TMM
TMM
TMM
TMM
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Dark Canyon Cave
Dark Canyon Cave
Lubbock Lake
Dark Canyon Cave
Tooth position
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3r
Upper
M3 average
Upper
M3r
Upper
M3 average
Upper
M3l
Upper
M3 average
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3r
AP
26.45
21.18
21.63
19.61
18.45
17.28
16.47
20.13
20.51
31.63
31.89
21.04
21.42
30.69
22.58
24.78
23.35
24.39
24.89
22.80
22.67
23.33
22.67
27.81
24.09
23.20
22.31
TR
19.57
18.00
17.35
16.47
15.20
15.90
15.58
19.00
18.55
26.28
25.85
18.45
18.40
23.57
20.97
19.54
20.44
18.93
19.29
18.68
21.09
19.24
20.28
23.16
20.58
19.01
19.66
297
indicates Dry Cave localities), KU = University of Kansas.
Specimen
41228-391
22-981
120-84
22-1609
22-65
46-139
22-1608
22-64
39537
40631
38856
33794
36454
39685
33885
33864
32768
35816
32989
36690
32362
36549
44397
45557
44400
35542
35459
Inst.
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Dark Canyon Cave
Charlies Parlor*
Big Manhole Cave
Animal Fair*
Animal Fair*
Isleta Cave No. 2
Animal Fair*
Animal Fair*
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3 average
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3r
AP
26.44
32.73
23.57
22.84
30.78
26.99
28.29
27.86
26.06
23.01
24.71
23.75
25.47
23.81
23.13
22.63
23.26
22.80
24.91
22.27
23.26
24.23
21.89
23.04
21.97
22.77
23.07
TR
21.08
24.00
20.57
20.57
22.97
22.17
24.41
24.10
21.65
20.80
21.51
20.64
22.37
22.62
21.48
20.36
20.21
19.60
21.87
21.23
20.30
19.10
20.40
20.93
20.40
20.55
20.15
298
Specimen
35954
46645
41961
34131
44390
41984
43313
39510
27899
38744
36688
39631
35373
35048
39421
57157
71.1 (Horse D)
P89.13.614
P93.8.47
3437.1
(Horse 2)
P94.8.52
P95.1.94
P94.1.843
P89.13.270
P94.1.518
P02.6.1
860.1 (Horse 3)
H7(E)-16-9
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
RAM
RAM
RAM
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Wally's Beach
Pit 48
Pit 45
Tooth position
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3l
Upper
M3 average
Upper
M3l
Upper
M3r
AP
25.55
23.55
25.44
22.46
22.31
25.96
22.42
24.12
25.43
24.21
28.75
24.81
23.48
24.10
25.27
25.39
30.56
30.83
31.46
TR
23.45
21.07
20.98
21.40
20.31
21.62
20.49
22.12
21.30
20.16
24.39
21.18
20.29
22.02
21.50
20.58
22.18
22.83
26.02
RAM
Wally's Beach
Upper
M3 average
26.43
21.16
RAM
RAM
RAM
RAM
RAM
RAM
RAM
CMH
Riverview Pit
CloverBar Pit
Pit 48
Pit 48
Pit 48
CloverBar Pit
Wally's Beach
MgVo-1
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
M3r
M3r
M3r
M3r
M3l
M3r
M3 average
M3l
28.78
25.77
33.16
30.49
29.14
29.29
26.94
27.37
22.96
22.30
22.74
26.37
22.69
23.83
22.98
23.07
299
Specimen
M7-1-1
L8(N)-7-4
G7(E1/2)-11-11
I7-1-5
I8(S)-12-7
I7-1-56
J8-1-138
E6-4-55
G7(E1/2)-11-12
Misc-52
85-Misc-6
K6-1-4
C6(W)-12.1
.5-3-9
H7(E)-20-5
L7-2-1
85-Misc-132
EE0946-1_T3-21-78
K7-5-20
3913
2597
3893
4567
4558
4578
4606
4585
3911
Inst.
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-2
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-2
MgVo-3
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-1
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3l
Upper
M3r
Upper
M3r
Upper
M3l
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2r
AP
26.95
26.64
24.66
26.15
25.47
24.92
23.70
27.29
25.04
25.36
26.58
27.22
27.28
26.44
24.57
25.71
26.22
26.83
25.06
26.15
31.56
22.75
21.75
22.06
32.69
31.21
35.55
23.37
TR
22.87
22.58
22.59
22.17
22.74
21.69
22.96
23.21
23.29
23.15
22.67
23.79
22.87
23.23
22.19
21.14
22.19
22.85
21.37
14.93
15.12
11.90
11.15
11.34
17.07
19.37
17.37
13.63
300
Specimen
2598
2546
2587
2721
2727
2738
2681
2570
2314
4557
4584
2671
4600
2569
2666
4577
2566
2618
4566
2633
3874
2549
3878
3883
4573
4611
4556
388(1?)
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2 average
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2r
AP
32.93
24.15
33.20
25.23
32.77
36.59
25.98
28.88
32.49
28.55
34.23
32.17
24.43
35.06
36.91
24.96
35.59
31.58
33.18
30.47
28.86
30.48
29.25
27.46
31.13
29.31
25.15
23.46
TR
16.64
12.33
18.90
13.12
16.49
18.06
13.03
14.07
18.04
14.66
16.22
16.42
13.03
15.57
16.90
12.72
17.69
16.54
17.26
16.82
16.51
16.72
16.21
14.42
16.87
15.29
11.34
13.82
301
Specimen
120841/120843
192/18197
192/18197
192/18198
192/18198
192/18198
192/120844
41228-uncat.
8106
41228-345
937-123
937-952
937-192
41228-229
41228-244
22-956
22-1528
22-669
34-5
22-960
25-537
33866
38859
39067
34205
36586
40730
Inst.
LACM
LACM
LACM
LACM
LACM
LACM
LACM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
KU
KU
KU
KU
KU
KU
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Dark Canyon Cave
Quitaque Creek
Dark Canyon Cave
Blackwater Draw
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Dark Canyon Cave
Animal Fair*
Charlies Parlor*
Animal Fair*
Salt Creek
Charlies Parlor*
Camel Room*
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Lower
p2 average
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2 average
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2l
AP
28.41
28.25
27.67
28.24
27.40
30.52
27.54
27.15
24.63
30.62
27.18
33.45
34.68
30.72
25.60
26.12
28.55
28.15
33.47
29.50
28.45
25.84
27.27
28.27
27.17
28.56
26.39
TR
14.57
14.48
13.89
13.71
13.85
13.20
14.54
14.08
12.38
11.55
13.83
17.59
16.65
13.38
10.89
13.20
15.99
12.80
15.50
14.28
12.73
12.69
13.79
13.25
13.08
15.83
14.16
302
Specimen
39592
40852
39344
40554
32878/32838
48439
31489
31488
39835
36626
27878
41528
35051
39942
38600
38745
42969
31547
36891
861.1 (Horse 3)
P02.8.67
P99.3.162
3437.2 (Horse 2)
P96.2.45
P89.13.399
P02.8.48
P94.1.559
P98.5.480
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Wally's Beach
TBG Pit 4
Pit 48
Wally's Beach
Pit 48
Pit 48
TBG Pit 4
Pit 48
Pit 48
Tooth position
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2r
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2 average
Lower
p2r
Lower
p2l
Lower
p2 average
Lower
p2l
Lower
p2r
Lower
p2r
Lower
p2l
Lower
p2 average
AP
25.96
29.02
26.31
29.69
29.66
27.90
26.26
26.20
27.44
28.61
27.88
29.44
27.86
26.67
29.11
30.73
28.42
30.94
25.84
32.02
33.90
32.75
28.75
33.20
34.07
29.12
31.11
27.26
TR
12.85
14.70
12.92
14.09
14.24
13.22
13.46
13.14
12.13
13.68
13.61
14.82
14.56
13.01
13.02
13.89
13.60
14.35
13.72
15.85
15.09
15.16
15.96
14.90
16.10
13.57
15.37
11.77
303
Specimen
M-9-132
SE-24
J7-6.23
K7-5-23
Inst.
CMH
CMH
CMH
CMH
Locality
MgVo-3
MgVo-1
MgVo-2
MgVo-1
Tooth position
Lower
p2l
Lower
p2l
Lower
p2r
Lower
p2l
AP
32.16
28.28
31.19
29.62
TR
15.28
14.66
13.62
15.04
85-Misc-138/ 85-Misc143
CMH
MgVo-3
Lower
p2 average
32.80
15.68
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
INAH
INAH
INAH
INAH
INAH
INAH
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-2
MgVo-1
MgVo-3
MgVo-1
MgVo-2
MgVo-2
MgVo-2
MgVo-3
MgVo-1
MgVo-1
MgVo-3
MgVo-2
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
p2r
p2l
p2r
p2l
p2l
p2r
p2 average
p2l
p2 average
p2 average
p2 average
p2r
p2l
p2r
p2 average
p2l
p4?r
p4l
p4/p3l
p3r
p4r
p3r
33.33
32.89
33.22
32.70
30.67
31.26
33.81
30.75
30.79
29.06
31.13
32.30
31.11
31.01
30.02
31.31
27.58
27.20
30.53
28.58
31.28
29.97
16.03
15.19
14.80
14.31
14.71
14.30
15.85
14.44
13.97
14.78
14.61
14.60
14.06
14.30
14.47
13.43
15.55
14.69
16.83
19.40
19.39
15.55
K8-1-2
85-Misc-141
J7-1-44
J7-1-9
Misc-1
EE0946-1_T3-21-82
85-89/85-95
D6(NE)-8-15
H6-3-8/H6-3-7?
C3(E)-2-37/C3(E)-3-18
B3-3-23/C3(E)-3-2
85-90
I7-3-12
I7-3-27
85-76
J7-7.20
2697
2698
3430
2554
4601
2592
304
Specimen
s/N3
2684
2567
2645
2641
2315
2689
2556
3920
2625
4582
2663
2586
2669
2322
4583
2687
4609
2658
2633
4568
2614
2688
Uncat.
3887
2591
2718
2649
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Lower
p3l
Lower
p3/p4r
Lower
p3l
Lower
p3r
Lower
p3l
Lower
p4r
Lower
p4l
Lower
p3r
Lower
p3l
Lower
p3/p4l
Lower
p3/p4r
Lower
p3l
Lower
p4r
Lower
p3/p4r
Lower
p3l
Lower
p4l
Lower
p3r
Lower
p3/p4l
Lower
p4l
Lower
p3r
Lower
p4r
Lower
p4l
Lower
p4l
Lower
p4l
Lower
p4l
Lower
p3l
Lower
p4r
Lower
p3r
AP
29.15
29.32
28.22
31.17
31.33
28.92
30.78
29.55
28.57
30.26
30.43
31.32
27.01
30.59
31.73
29.37
30.91
30.29
30.56
30.25
27.50
29.28
30.55
27.55
24.76
29.56
24.22
25.70
TR
16.55
18.55
17.00
19.53
19.56
18.44
20.49
17.60
18.16
17.09
16.91
20.37
17.78
17.29
17.53
16.85
17.61
18.20
20.23
17.24
17.56
18.28
19.80
16.45
14.70
17.36
15.00
16.57
305
Specimen
2312
3900
3891
2720
2707
4559
2635
2708
4575
3920
3874
2706
3927
3892
2709
4562
2553
4577
2716
3874
2670
3878
3933
192/18199
192/18393
192/18394
8535/8543
192/18199
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
LACM
LACM
LACM
LACM
LACM
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Tooth position
Lower
p3l
Lower
p3r
Lower
p3/p4l
Lower
p4r
Lower
p3l
Lower
p4?l
Lower
p3/p4l
Lower
p3r
Lower
p3r
Lower
p4l
Lower
p3l
Lower
p3l
Lower
p3l
Lower
p3r
Lower
p3r
Lower
p3r
Lower
p4r
Lower
p3 average
Lower
p4l
Lower
p4l
Lower
p4r
Lower
p4 average
Lower
p4?l
Lower
p4l
Lower
p4l
Lower
p4r
Lower
p3 average
Lower
p3l
AP
23.50
22.27
25.13
22.14
22.80
21.53
22.11
22.90
22.76
28.35
30.18
20.92
21.87
19.78
22.87
22.47
24.99
24.05
22.94
30.39
28.93
27.66
26.87
23.38
25.30
24.06
24.33
23.81
TR
15.17
12.99
16.02
14.45
13.35
13.84
13.04
13.88
12.78
17.00
19.34
10.68
15.24
11.09
12.79
13.18
14.67
13.42
13.46
19.26
16.95
17.19
15.40
17.01
16.14
16.69
15.55
15.37
306
Specimen
192/18199
192/18199
192/18199
192/18199
192/156490
192/156493
192/156491
192/156494
192/156489
192/156495
192/18199
192/18393
192/18199
192/18199
192/156492
937-949
937-122
937-972
998-9
937-965
937-945
41228-3821
41228-1031
937-48
937-973
937-940
937-725
41228-386
Inst.
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Blackwater Draw
Blackwater Draw
Blackwater Draw
Scharbauer Ranch
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Dark Canyon Cave
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Tooth position
Lower
p4r
Lower
p3l
Lower
p4l
Lower
p4r
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p4l
Lower
p4l
Lower
p4r
Lower
p4l
Lower
p4l
Lower
p3/p4r
Lower
p4r
Lower
p4l
Lower
p3l
Lower
p4l
Lower
p3/p4r
Lower
p3r
Lower
p3/p4l
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p3/p4r
Lower
p4l
Lower
p4l
Lower
p4r
Lower
p3r
AP
24.20
25.62
22.68
23.65
24.05
23.84
22.57
23.67
22.79
23.17
23.35
25.06
25.58
24.47
22.27
28.69
25.94
26.31
23.09
28.48
29.37
26.63
23.32
25.61
25.18
29.18
27.95
26.74
TR
16.81
16.09
14.70
15.26
14.42
14.10
14.16
14.21
14.05
14.14
15.18
15.05
14.53
15.50
13.78
15.82
14.22
16.48
15.84
15.63
17.63
15.57
15.35
15.29
15.25
17.72
16.52
14.66
307
Specimen
937-250
937-933
937-244
41228-389
937-169
998-1/998-2
41228-381
189-5
189-4
22-1528
203-1
75-31/75-29
23-65
22-61
22-669
22-1615
22-956
22-1538
937-955
937-954
937-251
34344
40838
50629
33867
31434
36543
Inst.
TMM
TMM
TMM
TMM
TMM
TMM
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
TMM
TMM
TMM
KU
KU
KU
KU
KU
KU
Locality
Blackwater Draw
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Blackwater Draw
Scharbauer Ranch
Dark Canyon Cave
Villa Ahumada
Villa Ahumada
Charlies Parlor*
Highway 45, Chi.
Dark Canyon Cave
Stalag 17*
Animal Fair*
Animal Fair*
Charlies Parlor*
Animal Fair*
Charlies Parlor*
Blackwater Draw
Blackwater Draw
Blackwater Draw
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Lower
p3l
Lower
p3/p4l
Lower
p4l
Lower
p4r
Lower
p4r
Lower
p4 average
Lower
p3r
Lower
p3/p4r
Lower
p3/p4r
Lower
p3 average
Lower
p3l
Lower
p3r
Lower
p3r
Lower
p3l
Lower
p4r
Lower
p4/p3r
Lower
p3 average
Lower
p4r
Lower
p4-m1l
Lower
p4/m1r
Lower
p4/m1l
Lower
p3/p4l
Lower
p4l
Lower
p4r
Lower
p3/p4l
Lower
p3/p4l
Lower
p3r
AP
28.66
27.94
28.82
24.85
28.38
28.38
24.22
20.52
19.33
28.56
20.45
25.08
25.17
30.67
23.75
28.06
24.18
28.45
28.30
27.18
27.80
24.89
22.71
24.93
23.54
23.58
23.66
TR
15.93
15.53
16.54
14.83
17.79
14.93
14.22
12.86
12.20
16.01
11.79
15.29
15.49
16.43
14.26
14.74
13.54
15.79
16.61
16.97
15.96
14.74
15.04
14.36
14.35
14.43
14.28
308
Specimen
39067
40733
39904
38572
36159
44424
40866
32767
27907
39098
40638
27879
33881
36626
40835
36625
41983
36433
27390
44394
41044
44395
33945
36158
36619
39944
40855
36624
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Lower
p3 average
Lower
p4l
Lower
p3/p4r
Lower
p3r
Lower
p3r
Lower
p3l
Lower
p3r
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p3/p4r
Lower
p4r
Lower
p3l
Lower
p3r
Lower
p3/p4r
Lower
p4l
Lower
p3l
Lower
p3/p4l
Lower
p4l
Lower
p4r
Lower
p4r
Lower
p4l
Lower
p4l
Lower
p4r
Lower
p3r
Lower
p3l
Lower
p4r
Lower
p3/p4r
AP
24.64
22.02
24.38
23.43
23.35
24.01
26.40
24.24
24.02
23.65
25.61
23.01
25.15
24.98
23.89
23.15
24.81
25.35
25.45
23.13
24.63
23.34
24.45
23.65
23.87
23.57
25.66
24.54
TR
13.91
13.90
14.99
13.97
13.84
14.91
16.05
13.79
14.87
14.02
15.66
13.85
15.30
15.71
13.79
13.00
15.41
15.04
15.57
14.25
14.96
13.85
15.39
13.96
14.82
14.02
16.51
15.61
309
Specimen
33729
41528
41710
36620
32587
27253
39809
38689
35114
35082
41492
27216
69.1
P94.1.386
P99.3.162
P89.13.7
P91.11.2
P94.1.716
P94.1.585
P02.2.4
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Wally's Beach
Pit 48
Pit 48
Pit 48
Pit 46
Pit 48
Pit 48
Apex Evergreen
Tooth position
Lower
p4l
Lower
p3l
Lower
p3/p4l
Lower
p4l
Lower
p4l
Lower
p3l
Lower
p4l
Lower
p4l
Lower
p3/p4l
Lower
p4l
Lower
p3/p4l
Lower
p4r
Lower
p3l
Lower
p4r
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p3/p4l
Lower
p3r
Lower
p3/p4l
AP
24.59
28.07
24.99
23.05
25.15
26.26
24.40
23.05
24.21
25.23
27.34
24.72
26.24
28.10
27.08
27.27
29.11
27.81
29.80
27.41
TR
15.82
16.64
14.76
13.05
15.49
15.11
16.21
14.14
14.59
15.69
15.87
15.21
15.08
16.47
16.50
15.91
14.46
16.78
14.97
16.48
3437.2
RAM
Wally's Beach
Lower
p3 average
26.21
15.59
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
TBG Pit 4
Lower
Lower
Lower
Lower
Lower
Lower
Lower
p3/p4l
p3/4l
p3l
p3l
p3/p4r
p4l
p4r
27.09
28.34
24.36
31.60
30.16
31.44
27.40
15.94
14.36
13.83
15.68
16.06
15.43
15.26
(Horse 2)
P94.1.670
P98.5.484
P94.1.499
P94.1.486
P89.13.50
P94.1.632
P02.8.48
310
Specimen
P98.5.480
861.1 (Horse 3)
P94.1.341
P94.5.5
S-3-98
85-90
I6-E-5
S-3-94
K8-2-2
J7-8.19
L8(N)-4-7
L8(N)-7-28
J7-C-16
L8(N)-8-1
L8(N)-7-2
J8-1-147
85-64
L8(N)-7-27
K8-2-2
K6-1-14
85-Misc-133
85-32
L8(N)-7-15
EE0946-1 T3-21-85
H6-3-8/H6-3-7?
D6(NE)-8-14
85-Misc-32
Inst.
RAM
RAM
RAM
RAM
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
Locality
Pit 48
Wally's Beach
Pit 48
Pit 45
MgVo-3
MgVo-3
MgVo-2
MgVo-3
MgVo-1
MgVo-2
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-3
MgVo-1
MgVo-1
MgVo-2
MgVo-1
MgVo-3
Tooth position
Lower
p3l
Lower
p4 average
Lower
m1/p4l
Lower
p4/m1r
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p4r
Lower
p3l
Lower
p4l
Lower
p3r
Lower
p3l
Lower
p3l
Lower
p4r
Lower
p3l
Lower
p3l
Lower
p3r
Lower
p4l
Lower
p4r
Lower
p4r
Lower
p3r
Lower
p4l
Lower
p4l
Lower
p3r
Lower
p3 average
Lower
p3l
Lower
p3r
AP
24.26
26.53
29.66
29.02
26.29
28.79
26.59
26.78
27.05
24.64
28.00
27.87
27.74
26.65
27.01
27.78
28.20
26.40
27.66
27.51
28.29
25.95
26.86
27.51
27.66
27.35
29.38
TR
14.44
15.79
15.90
16.51
15.95
15.50
16.43
17.87
17.28
15.18
16.17
15.80
16.07
16.05
16.21
16.11
15.49
15.88
16.68
16.93
17.12
16.59
17.44
14.82
15.12
15.16
15.92
311
Specimen
Inst.
Locality
C3(E)-2-37/C3(E)3-18
CMH
MgVo-2
Lower
CMH
CMH
CMH
CMH
CMH
CMH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
MgVo-3
MgVo-1
MgVo-3
MgVo-2
MgVo-1
MgVo-3
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
85-90
I7-3-10
85-89/85-95
B3-3-23/C3(E)-3-2
I7-3-25
85-76
4561
255?
4581
2590
2567
2692
2562
3874
s/N4
4579
4580
3880
2605
2644
4561
4561
4612
4560
4570
2313
Tooth position
AP
TR
p3 average
26.64
15.21
p4r
p3l
p4 average
p4 average
p4r
p4 average
m2r
m1/m2l
m2l
m2l
m1l
m2r
m2l
m2l
m2r
m2r
m2r
m1r
m2 average
m2r
m1r
m2
m1/m2l
m1/m2l
m2r
m1l
27.58
27.21
27.84
26.02
26.47
27.43
25.87
26.31
27.23
27.65
26.75
25.70
26.21
25.14
25.82
24.75
25.37
26.04
25.06
27.72
28.01
29.16
26.86
24.72
29.25
26.23
16.17
15.91
16.55
16.48
16.20
16.47
18.60
18.09
16.42
17.81
16.74
16.19
15.17
15.60
17.94
16.72
15.70
17.08
14.61
15.32
19.25
17.88
18.12
15.78
15.61
15.61
312
Specimen
3916
2611
2729
2693
3928
2592
2656
2567
2730
2317
3894
2567
2566?
2739
3932
2642
4604
2596
2734
2596
3875
2578
2661
2590
4605
2614
2616
2614/2552
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Lower
m1l
Lower
m2r
Lower
m2r
Lower
m1r
Lower
m2l
Lower
m1r
Lower
m2r
Lower
m1/m2l
Lower
m2l
Lower
m2r
Lower
m2r
Lower
m2l
Lower
m2l
Lower
m1/m2l
Lower
m1l
Lower
m2l
Lower
m1r
Lower
m2r
Lower
m2r
Lower
m1r
Lower
m1?l
Lower
m2l
Lower
m2l
Lower
m1/m2r
Lower
m2l
Lower
m2l
Lower
m2r
Lower
m2 average
AP
27.15
27.82
28.87
25.27
28.89
24.17
25.21
23.98
26.55
25.41
26.19
24.61
25.79
26.88
24.84
25.87
27.10
25.23
26.12
24.91
26.06
25.45
27.69
26.82
25.21
25.44
26.25
25.67
TR
19.22
15.55
19.65
16.32
18.70
17.76
15.87
17.41
16.06
17.62
17.62
14.90
15.64
17.98
16.59
15.75
16.41
16.56
15.43
15.45
18.87
15.76
15.94
16.03
15.32
16.38
16.20
15.80
313
Specimen
4565
2735
2633
2322
2548
3912
4586
2626
2629
2627
2726
265?
3906
3925
2665
2559
2723
3887
4608
5887
2561
2547
4563
3908
4614
2545
2632
2704
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Tooth position
Lower
m2r
Lower
m2r
Lower
m2r
Lower
m1l
Lower
m1/m2l
Lower
m2r
Lower
m2l
Lower
m1r
Lower
m2r
Lower
m2l
Lower
m2r
Lower
m1r
Lower
m1r
Lower
m2l
Lower
m2l
Lower
m2r
Lower
m2l
Lower
m1l
Lower
m1r
Lower
m2l
Lower
m1l
Lower
m2l
Lower
m2r
Lower
m1l
Lower
m2r
Lower
m2r
Lower
m2r
Lower
m2l
AP
27.94
27.00
25.68
26.49
19.92
20.76
24.92
20.26
20.77
23.04
23.91
23.71
21.65
20.78
19.35
23.79
23.57
22.55
21.99
22.63
21.38
21.29
20.73
18.50
18.95
17.44
17.64
18.18
TR
18.21
15.88
15.74
16.47
12.73
12.32
17.21
14.30
12.78
15.99
14.87
16.09
13.40
11.79
13.30
13.41
13.03
13.67
13.67
13.33
11.57
12.10
11.93
12.34
11.28
10.98
10.46
11.30
314
Specimen
3898
2710
2711
3888
2712
2673
4602
4577
2310
3931
2731
2739
2732
3220
3912
3913
3878
3934
2605
2628
3903
192/18199
192/18199
192/18393
192/18199
192/18393
192/18199
192/18199
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
LACM
LACM
LACM
LACM
LACM
LACM
LACM
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Tooth position
Lower
m1l
Lower
m1r
Lower
m2r
Lower
m1l
Lower
m2/m1r
Lower
m2l
Lower
m2r
Lower
m1 average
Lower
m2r
Lower
m2r
Lower
m2l
Lower
m1/m2l
Lower
m1l
Lower
m1l
Lower
m2r
Lower
m2r
Lower
m2 average
Lower
m1/m2l
Lower
m1/p4l
Lower
m1/p4r
Lower
m1/p4r
Lower
m1r
Lower
m1/m2r
Lower
m1/m2l
Lower
m2l
Lower
m1l
Lower
m1r
Lower
m2r
AP
18.09
19.90
20.34
19.03
17.99
19.80
21.03
20.64
20.29
26.18
28.64
26.73
27.02
28.62
20.36
21.16
25.73
26.34
20.36
21.94
17.61
21.51
21.51
23.96
22.28
22.19
23.62
24.48
TR
11.78
12.38
11.86
11.90
11.27
11.77
12.79
12.55
11.49
17.98
14.60
18.03
17.93
17.63
12.13
12.51
15.26
16.75(
16.25
14.53
12.15
13.80
14.71
13.91
14.87
14.00
14.84
13.96
315
Specimen
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18199
192/18191
192/18199
192/18199
192/18199
192/18195
192/18195
192/18199
192/18194
192/18199
192/18199
192/18199
192/18199
192/18194
192/18194
Inst.
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
LACM
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
San Josecito Cave
Tooth position
Lower
m2l
Lower
m1/m2l
Lower
m2r
Lower
m2l
Lower
m2l
Lower
m1r
Lower
m1/m2l
Lower
m1/m2l
Lower
m1/m2l
Lower
m2r
Lower
m2l
Lower
m2r
Lower
m1/m2r
Lower
m2l
Lower
m2l
Lower
m2r
Lower
m2r
Lower
m2r
Lower
m1l
Lower
m2l
Lower
m1l
Lower
m1r
Lower
m1l
Lower
m1l
Lower
m1l
Lower
m1l
Lower
m1/m2r
Lower
m1/m2r
AP
20.57
21.50
22.40
22.04
22.91
21.61
21.55
23.59
21.24
21.26
21.85
22.30
22.81
20.04
21.90
22.04
21.45
19.74
22.57
20.96
22.02
22.47
21.48
21.96
22.69
22.75
21.23
21.59
TR
13.58
13.26
14.93
14.54
14.25
13.73
12.98
15.39
12.94
13.26
13.98
13.81
14.24
11.69
13.34
13.26
12.61
11.74
12.60
12.48
14.00
13.20
12.60
13.91
15.09
14.18
12.41
13.19
316
width. TMM = Vertebrate Paleontology Laboratory, University of Texas at Austin.
Specimen
192/18199
192/18190
937-678
937-930
937-121
937-702
937-859
998-10
937-944
41228-3849
937-225
937-938
41228-3888
41228-3841
41228-361
937-964
41228-233
937-204
41228-159
937-252
937-760
41228-234
937-966
41228-158
41228-394
41228-232
937-39
937-971
Inst.
LACM
LACM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
Locality
San Josecito Cave
San Josecito Cave
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Scharbauer Ranch
Blackwater Draw
Dark Canyon Cave
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Blackwater Draw
Dark Canyon Cave
Blackwater Draw
Dark Canyon Cave
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Blackwater Draw
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Blackwater Draw
Blackwater Draw
Tooth position
Lower
m1/m2r
Lower
m1/m2l
Lower
m1/m2r
Lower
m2r
Lower
m1r
Lower
m1-m2r
Lower
m1l
Lower
m2r
Lower
m2l
Lower
m1-m2r
Lower
m2r
Lower
m2l
Lower
m1l
Lower
m2r
Lower
m2l
Lower
m2l
Lower
m2l
Lower
m2l
Lower
m1r
Lower
m1l
Lower
m2r
Lower
m2l
Lower
m2r
Lower
m1-m2r
Lower
m2l
Lower
m2l
Lower
m2l
Lower
m2r
AP
23.00
22.58
24.94
23.91
23.65
25.61
25.66
21.77
24.27
22.58
24.81
23.27
23.28
24.26
21.62
25.66
23.45
23.94
22.86
27.59
27.18
23.05
25.27
23.65
22.71
23.17
27.22
26.06
TR
13.97
12.86
16.78
14.33
13.17
15.82
15.22
13.34
14.10
13.16
16.11
15.37
13.29
13.50
12.33
14.79
13.65
14.64
14.73
14.04
15.64
13.68
14.31
13.77
13.40
13.40
16.96
14.71
317
Specimen
937-781
937-119
41228-1025
937-848
937-969
3234
937-953
41228-1038
41228-289
937-906
22-1528
22-956
22-1664
158-1
22-1607
5689-1-225
22-648
23-78
119-15
119-51
23-77
34-9
22-61
25-537
22-1616
31-44
937-931
Inst.
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
TMM
Locality
Blackwater Draw
Blackwater Draw
Dark Canyon Cave
Blackwater Draw
Blackwater Draw
Quitaque Creek
Blackwater Draw
Dark Canyon Cave
Dark Canyon Cave
Blackwater Draw
Charlies Parlor*
Animal Fair*
Hampton Court*
El Barreal
Animal Fair*
U-Bar Cave
Animal Fair*
Stalag 17*
Stalag 17*
Salt Creek
Animal Fair*
Camel Room*
Charlies Parlor*
Early Man Corridor*
Blackwater Draw
Tooth position
Lower
m1l
Lower
m2r
Lower
m1l
Lower
m1r
Lower
m1r
Lower
m1-m2r
Lower
m1-m2r
Lower
m2r
Lower
m1-m2?l
Lower
m2r
Lower
m2 average
Lower
m1 average
Lower
m1/m2l
Lower
m2r
Lower
m1r
Lower
m1l
Lower
m1/m2l
Lower
m2r
Lower
m2r
Lower
m2l
Lower
m1l
Lower
m2r
Lower
m1l
Lower
m2 average
Lower
m1r
Lower
m1/m2r
Lower
m2l
AP
26.44
25.58
26.22
25.46
25.64
27.62
26.12
23.73
23.56
21.46
26.14
21.76
21.32
21.74
25.70
24.61
25.71
23.30
25.01
22.97
23.56
21.73
26.62
21.68
25.61
23.57
27.81
TR
16.78
16.26
15.07
16.83
15.71
16.90
14.99
14.07
13.43
12.94
15.76
14.25
12.11
13.35
15.13
18.25
14.72
13.49
14.97
13.40
12.43
13.97
14.86
12.44
15.11
13.94
16.35
318
Specimen
937-937
34-11
54-1312
33938
50629
31445
53690
35914
54625
40731
36492
39067
35767
34206
36491
27908
35080
35084
33793
41182
35910
36679
36622
39097/39096
36831
40629
35050
40904
Inst.
TMM
UTEP
UTEP
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Blackwater Draw
Salt Creek
TTII*
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Lower
m1l
Lower
m1r
Lower
m1l
Lower
m2l
Lower
m1r
Lower
m1/m2l
Lower
m2r
Lower
m2l
Lower
m1r
Lower
m1l
Lower
m1/m2l
Lower
m1r
Lower
m2r
Lower
m2l
Lower
m2l
Lower
m1r
Lower
m2r
Lower
m2l
Lower
m1/m2r
Lower
m1l
Lower
m2r
Lower
m2l
Lower
m2l
Lower
m1 average
Lower
m1/m2r
Lower
m1/m2l
Lower
m2l
Lower
m1r
AP
25.65
23.98
25.67
21.27
21.60
20.94
22.65
21.49
22.80
20.29
21.90
22.70
20.50
23.12
22.13
22.86
22.26
22.19
22.55
22.21
23.12
22.96
21.98
22.07
22.00
23.09
22.43
24.01
TR
15.35
16.46
15.41
13.40
14.16
13.61
13.43
11.77
12.33
13.55
14.45
14.28
11.86
14.16
12.63
12.92
12.71
12.28
13.64
13.86
13.00
14.43
12.50
13.85
13.67
13.20
14.48
14.40
319
Specimen
35083
32367
36797
44395
44394
34127
39945
39122
36626
39972
31566
38796
53793
27217
33792
41548
41043
36802
39810
34124
39946
38797
39490
41528
34129
38118
42989
34138
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Lower
m2r
Lower
m1/m2r
Lower
m2l
Lower
m2l
Lower
m2r
Lower
m1r
Lower
m2l
Lower
m2l
Lower
m1r
Lower
m2r
Lower
m1/m2r
Lower
m2r
Lower
m1/m2r
Lower
m1r
Lower
m1r
Lower
m1r
Lower
m2l
Lower
m2l
Lower
m1/m2l
Lower
m2r
Lower
m1l
Lower
m2r
Lower
m1/m2l
Lower
m2l
Lower
m1/m2l
Lower
m2l
Lower
m2l
Lower
m1r
AP
22.33
22.50
26.11
20.31
20.71
21.07
21.63
22.59
21.98
23.24
23.64
22.64
22.41
23.26
21.75
21.68
21.44
26.10
21.76
21.51
21.85
22.16
22.97
24.90
23.75
22.55
24.90
21.45
TR
13.39
14.49
16.26
12.32
11.92
13.59
13.11
12.43
13.22
14.26
12.44
13.64
12.82
14.71
12.91
12.86
13.33
15.16
12.59
12.47
12.59
12.92
12.68
13.64
13.61
12.76
13.99
12.62
320
Specimen
39971
40575
36558
P95.1.70
P96.2.21
3437.2 (Horse 2)
P94.1.113
P89.13.395
P94.1.347
P94.1.307
P94.1.212
P94.1.519
P94.1.686
P05.10.46
P94.1.372
P89.13.619
P90.6.37
P94.1.344
P02.8.48
P90.6.49
P94.4.7
P94.1.124
861.1 (Horse 3)
P94.1.970
P94.1.614
E7-15-5
K8-1-29
EE0946-1 T3-17-15
Inst.
KU
KU
KU
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
CMH
CMH
CMH
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
CloverBar Pit
Pit 48
Wally's Beach
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Apex Evergreen
Pit 48
TBG Pit 4
Apex Evergreen
Pit 46
Pit 48
Wally's Beach
Pit 48
Pit 48
MgVo-1
MgVo-1
MgVo-1
Tooth position
Lower
m2r
Lower
m1/m2r
Lower
m2l
Lower
m1/m2l
Lower
m2l
Lower
m1 average
Lower
m1l
Lower
m1l
Lower
m1r
Lower
m1l
Lower
m2?r
Lower
m2l
Lower
m1/m2r
Lower
m2l
Lower
m2r
Lower
m1/m2r
Lower
m1l
Lower
m2r
Lower
m1r
Lower
m2l
Lower
m1r
Lower
m2r
Lower
m1 average
Lower
m1/p4r
Lower
m1/p4l
Lower
m1l
Lower
m1l
Lower
m1r
AP
25.66
22.49
23.21
24.30
27.30
23.42
27.68
24.33
26.07
27.76
25.60
27.29
25.44
25.89
26.71
27.34
26.33
27.44
24.63
26.86
27.48
28.34
23.53
26.55
28.98
24.04
23.23
23.71
TR
13.65
12.15
13.55
13.11
14.41
15.12
14.48
14.68
17.48
15.95
14.62
14.67
14.62
15.74
16.20
15.28
14.48
15.71
14.89
14.57
14.57
15.44
15.08
14.68
15.95
14.88
16.45
17.15
321
Specimen
J8-1-169
85-90
L8(N)-5-2
L8(N)-7-5
L8(N)-7-3
L8(N)-9-10
J8-1-149
M7-2-27
K6-1-17
L8(N)-11-10
85-64
M7-2-34
J7-1-11
85-Misc-3/85-95
85-90
L8(N)-7-9
EE0946-1 T3-21-86
H6-3-8/H6-3-7
H8(N)-8-4
B3-3-16/C3(E)-3-2
85-70
I7-3-22
85-76
C3(E)-2-37/ C3(E)-3-2)
I7-3-19
3878
3907
4561
Inst.
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
INAH
INAH
INAH
Locality
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-1
MgVo-3
MgVo-3
MgVo-1
MgVo-1
MgVo-2
MgVo-1
MgVo-2
MgVo-3
MgVo-1
MgVo-3
MgVo-2
MgVo-1
Cedral
Cedral
Cedral
Tooth position
Lower
m2r
Lower
m1 average
Lower
m1r
Lower
m2l
Lower
m2r
Lower
m1l
Lower
m1l
Lower
m1r_
Lower
m1r
Lower
m2l
Lower
m2r
Lower
m2l
Lower
m2l
Lower
m2 average
Lower
m1r
Lower
m1r
Lower
m2r
Lower
m2 average
Lower
m2r
Lower
m2 average
Lower
m2r
Lower
m1r
Lower
m1/m2l
Lower
m2 average
Lower
m2l
Lower
m3 average
Lower
m3r
Lower
m3r
AP
25.05
24.53
24.28
24.57
24.95
24.78
22.84
25.35
24.63
25.29
24.34
25.92
25.11
25.58
25.15
25.68
24.23
25.49
27.02
24.37
25.36
23.14
25.52
25.22
24.48
34.35
37.63
37.98
TR
16.16
16.31
16.30
15.00
14.73
15.41
14.21
15.38
17.16
14.41
14.28
15.48
15.80
14.98
15.49
15.48
14.65
13.80
14.14
14.90
15.14
14.49
14.86
14.49
14.35
13.28
15.40
16.04
322
Specimen
2703
2620
2313
4580
3927
2551
3915
2639
2592
2640
3889
3926
Uncat.
4572
2725
3897
Uncat.
3905
2719
4571
4564
2722
2664
2633
3874
4577
192/18195
Inst.
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
INAH
LACM
Locality
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
San Josecito Cave
Tooth position
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3 average
Lower
m3l
AP
21.18
36.89
35.24
35.33
37.02
35.55
27.25
25.03
32.26
32.88
23.61
36.94
32.24
25.22
24.99
22.23
25.36
25.89
24.80
37.72
25.23
26.87
31.85
33.11
32.99
25.55
29.89
TR
9.90
13.61
14.68
13.63
15.51
14.92
11.35
11.15
12.99
12.87
9.86
11.93
13.37
10.47
10.51
9.97
10.97
11.21
10.29
14.33
10.64
11.37
14.04
14.54
13.97
10.84
12.66
323
Specimen
192/18198
192/18198
192/18194
937-906
937-246
8106
937-125
937-970
937-223
937-692
892-299
937-702
937-977
22-1645
33948
34271
35052
36823
35768
40706
36489
39067
35081
41220
44266
34172
41042
Inst.
LACM
LACM
LACM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
UTEP
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
Locality
San Josecito Cave
San Josecito Cave
San Josecito Cave
Blackwater Draw
Blackwater Draw
Quitaque Creek
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Lubbock Lake
Blackwater Draw
Blackwater Draw
Animal Fair*
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Tooth position
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3l
AP
26.49
28.42
26.61
27.49
34.84
29.29
36.11
32.77
34.38
31.43
33.67
29.93
37.35
32.50
29.01
28.77
27.37
27.29
27.40
27.48
29.63
27.16
26.80
28.40
27.08
26.13
28.98
TR
10.61
13.49
11.95
12.07
12.94
11.37
13.89
13.40
12.74
10.86
13.44
10.90
17.01
13.67
12.91
12.88
10.65
10.37
10.56
10.33
11.01
11.41
11.27
11.57
9.92
11.19
11.56
324
Specimen
36680
45358
44395
38658
46723
36800
36621
36626
41491
31501
53793
34126
36490
38805
38117
38189
42989
27909
42070
Inst.
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
KU
3437.2 (Horse 2) RAM
P89.15.1
RAM
P94.1.348
RAM
P05.10.26
RAM
861.1 (Horse 3) RAM
S-3-89
CMH
H6-5-24
CMH
85-90
CMH
K8-1-11
CMH
Locality
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Wally's Beach
Riverview Pit
Pit 48
Pit 48
Wally's Beach
MgVo-3
MgVo-2
MgVo-3
MgVo-1
Tooth position
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3 average
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3 average
Lower
m3l
Lower
m3r
Lower
m3 average
Lower
m3l
AP
30.11
27.73
28.27
27.84
28.01
34.85
26.06
26.50
31.24
30.94
28.72
28.58
28.81
27.77
31.55
31.35
29.40
29.94
28.07
30.48
37.61
36.88
34.02
31.08
32.96
31.05
36.30
32.72
TR
12.80
10.35
11.14
11.15
10.55
14.17
10.37
11.46
12.69
12.40
11.30
12.54
11.68
11.66
10.77
11.18
12.57
11.11
?
13.55
13.92
15.12
12.76
13.77
14.02
13.54
13.53
13.66
325
width. CMH = Canadian Museum of History.
Specimen
J8-1-153
L8(N)-12-2
85-25
85-64
K6-1-16
L8(N)-7-29
85-Misc-28
J7-1-16
85-Misc-134
85-95
I7-3-36
B3-3-23/C3(E)-3-2
85-90
85-70
C3(E)-3-2
Inst.
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
Locality
MgVo-1
MgVo-1
MgVo-3
MgVo-3
MgVo-1
MgVo-1
MgVo-3
MgVo-1
MgVo-3
MgVo-3
MgVo-1
MgVo-2
MgVo-3
MgVo-3
MgVo-2
Tooth position
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3l
Lower
m3l
Lower
m3l
Lower
m3r
Lower
m3r
Lower
m3r
Lower
m3 average
Lower
m3r
Lower
m3 average
Lower
m3 average
AP
29.78
32.28
32.80
32.68
32.46
33.05
32.96
31.42
33.68
35.47
33.10
33.65
32.17
33.60
31.67
TR
11.72
13.25
13.90
13.73
13.30
13.14
13.28
13.11
13.17
13.67
11.02
13.94
13.36
13.13
12.97
326
Table A 2. Late Pleistocene equid specimens (lower teeth) included in the geometric morphometric analysis. Loc. ab. = Abbreviation
of locality names used in Chapter 2 figures (l = large, m = medium, s = small specimens; teeth that yielded aDNA are identified by “a”
and those associated with specimens from which aDNA was obtained are indicated with “*”).
Specimen
36625
2614
192/156491
4562
41228-393
P98.5.484
P91.11.2
C3(E)-2-37
192/156494
937-961
3437.1 (Horse 2)
937-169
35082
27216
C3(E)-3-2
22-669
36626
2687
192/uncat.
192/156492
4575
22-1528
41228-389
69.1
192/uncat.
J8-1-147
192/156495
Inst.
KU
INAH
LACM
INAH
TMM
RAM
RAM
CMH
LACM
TMM
RAM
TMM
KU
KU
CMH
UTEP
KU
INAH
LACM
LACM
INAH
UTEP
TMM
RAM
LACM
CMH
LACM
Locality
Natural Trap Cave
Cedral
San Josecito Cave
Cedral
Dark Canyon Cave
Pit 48
Pit 46
MgVo-2
San Josecito Cave
Blackwater Draw
Wally's Beach
Blackwater Draw
Natural Trap Cave
Natural Trap Cave
MgVo-2
Animal Fair (Dry Cave)
Natural Trap Cave
Cedral
San Josecito Cave
San Josecito Cave
Cedral
Charlies Parlor (Dry Cave)
Dark Canyon Cave
Wally's Beach
San Josecito Cave
MgVo-1
San Josecito Cave
Loc. ab.
N
Cl
J
Cm
Km
E
E
B
J
Ll
Wa
Ll
N
N
B*
Dm
N
Cl
J
J
Cm
Dl
Km
W
J
Ba
J
Tooth position
Lower
p4l
Lower
p4l
Lower
p4r
Lower
p3r
Lower p3/p4l
Lower p3/p4l
Lower
p4r
Lower
Lower
p4l
Lower p3/p4l
Lower
p3l
Lower
p4r
Lower
p4l
Lower
p4r
Lower p3l/p4
Lower
p4r
Lower
p3r
Lower
p3r
Lower
p4l
Lower
p4l
Lower
p3r
Lower
p4r
Lower
p4r
Lower
p4r
Lower
p4l
Lower
p3l
Lower
p4r
327
Table A 2, continued. Late Pleistocene equid specimens (lower teeth) included in the geometric morphometric analysis. Loc. ab. =
Abbreviation of locality names used in Chapter 2 figures (l = large, m = medium, s = small specimens; teeth that yielded aDNA are
identified by “a” and those associated with specimens from which aDNA was obtained are indicated with “*”).
Specimen
2592
22-1538
P94.1.386
40835
2688
192/156493
8106
4577
41228-386
J7-C-16
861.1 (Horse 3)
J7-8.19
L8(N)-4-7
937-244
34344
54-1312
35114
33729
36624
937-949
H6-3-8
22-1615
2591
41710
2707
36543
S-3-98
Inst.
INAH
UTEP
RAM
KU
INAH
LACM
TMM
INAH
TMM
CMH
RAM
CMH
CMH
TMM
KU
UTEP
KU
KU
KU
TMM
CMH
UTEP
INAH
KU
INAH
KU
CMH
Locality
Cedral
Pit 48
Natural Trap Cave
Cedral
San Josecito Cave
Quitaque Creek
Cedral
Dark Canyon Cave
MgVo-1
Wally's Beach
MgVo-2
MgVo-1
Blackwater Draw
Natural Trap Cave
TTII (Dry Cave)
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
Blackwater Draw
MgVo-2
Cedral
Natural Trap Cave
Cedral
Natural Trap Cave
MgVo-3
Loc. ab.
Cl
Dl
E
N
Cl
J
Qm
Cm
Km
B
W
B*
Ba
Ll
N
Dl
N
N
N
Ll
B
Dl
Cl
N
Cm
Na
B
Tooth position
Lower
p3r
Lower
p4r
Lower
p4r
Lower p3/p4r
Lower
p4l
Lower
p3r
Lower
p4r
Lower p3/p4
Lower
p3r
Lower
p3l
Lower
p4l
Lower
p3l
Lower
p3r
Lower
p4l
Lower p3/p4l
Lower
p4l
Lower p3/p4l
Lower
p4l
Lower p3/p4r
Lower
p3l
Lower p3l/p4
Lower p4/p3r
Lower
p3l
Lower p3/p4l
Lower
p3l
Lower
p3r
Lower
p3l
328
Specimen
P94.1.499
L8(N)-7-15
937-250
937-973
23-65
85-90
2698_
31434
2708
192/uncat.
I6-E-5
P94.1.585
192/uncat.
192/uncat.
998-9
S-3-94
937-251
25-537
2554
2709
K8-2-3
4601
85-95
J8-1-145
192/uncat.
P94.1.632
937-725
Inst.
RAM
CMH
TMM
TMM
UTEP
CMH
INAH
KU
INAH
LACM
CMH
RAM
LACM
LACM
TMM
CMH
TMM
UTEP
INAH
INAH
CMH
INAH
CMH
CMH
LACM
RAM
TMM
Locality
Pit 48
MgVo-1
Blackwater Draw
Blackwater Draw
Stalag 17 (Dry Cave)
MgVo-3
Cedral
Natural Trap Cave
Cedral
San Josecito Cave
MgVo-2
Pit 48
San Josecito Cave
San Josecito Cave
Scharbauer Ranch
MgVo-3
Blackwater Draw
Camel Room (Dry Cave)
Cedral
Cedral
MgVo-1
Cedral
MgVo-3
MgVo-1
San Josecito Cave
Pit 48
Blackwater Draw
Loc. ab.
Ema
B
Ll
Lm
Dma
B*
Cl
N
Cm
J
Ba
E
J
J
Rm
B
Ll
Dm
Cl
Cs
B
Cl
B
B
J
E
Ll
Tooth position
Lower
p3l
Lower
p4l
Lower
p3l
Lower
Lower
p3r
Lower
p4r
Lower
p4l
Lower p3/p4l
Lower
p3r
Lower
p3l
Lower
p4r
Lower
p3r
Lower
p3l
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p4l
Lower
p3r
Lower
p3r
Lower
p3r
Lower
p4l
Lower
p4r
Lower p3r/p4
Lower
p4l
Lower
p3l
Lower
p4l
Lower
p4r
329
Specimen
75-31
937-954
2706
41228-3821.2
192/156488
937-933
32587
50629
54348
192/uncat.
P89.13.50
33867
L8(N)-7-2
203-1
189-4
3929
192/uncat.
3892
P89.13.7
P99.3.162
85-64
937-965
192/156489
937-940
2633
41592_
P89.13.620
Inst.
UTEP
TMM
INAH
TMM
LACM
TMM
KU
KU
KU
LACM
RAM
KU
CMH
UTEP
UTEP
INAH
LACM
INAH
RAM
RAM
CMH
TMM
LACM
TMM
INAH
KU
RAM
Locality
Dark Canyon Cave
Blackwater Draw
Cedral
Dark Canyon Cave
San Josecito Cave
Blackwater Draw
Natural Trap Cave
Natural Trap Cave
Natural Trap Cave
San Josecito Cave
Pit 48
Natural Trap Cave
MgVo-1
Highway 45, Chihuahua
Villa Ahumada
Cedral
San Josecito Cave
Cedral
Pit 48
Pit 48
MgVo-3
Blackwater Draw
San Josecito Cave
Blackwater Draw
Cedral
Natural Trap Cave
Pit 48
Loc. ab.
Km
Ll
Cs
Km
J
Ll
N
N
N
J
E
Na
B
Gs
Vs
Cs
J
Cs
E
E
B
Ll
J
Ll
Cl
N
E
Tooth position
Lower
p3r
Lower
p4r
Lower
p3l
Lower
p3r
Lower
p3l
Lower
p3/p4l
Lower
p4l
Lower
p4r
Lower
p4r
Lower
p4r
Lower
p3/p4r
Lower
p3/p4l
Lower
p3l
Lower
p3l
Lower
p3/p4r
Lower
p4r
Lower
p4r
Lower
p3r
Lower
p3r
Lower
p3l
Lower
p3r
Lower
p3/p4l
Lower
p4l
Lower
p4l
Lower
p3r
Lower
p3l
Lower
p4r
330
Specimen
189-5
41983
4559
27390
36158
192/156490
P98.5.480
937-972
937-945
937-122
P97.11.2A
D6(NE)-8-14
P94.1.486
2649_
2628
2312
2684
2645_
3909
4569
Inst.
UTEP
KU
INAH
KU
KU
LACM
RAM
TMM
TMM
TMM
RAM
CMH
RAM
INAH
INAH
INAH
INAH
INAH
INAH
INAH
Locality
Villa Ahumada
Natural Trap Cave
Cedral
Natural Trap Cave
Natural Trap Cave
San Josecito Cave
Pit 48
Blackwater Draw
Blackwater Draw
Blackwater Draw
Riverview Pit
MgVo-1
Pit 48
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Cedral
Loc. ab.
Vs
N
Cm
Nl
N
J
Em
Lm
Ll
Lm
E
B
E
Cm
Cm
Cm
Cl
Cl
Cl
Cl
Tooth position
Lower
p3/p4r
Lower
p3l
Lower
p4?l
Lower
p4l
Lower
p4r
Lower
p3l
Lower
p3l
Lower
p3/p4r
Lower
p3l
Lower
p4l
Lower
p3r
Lower
p3l
Lower
p3l
Lower
p3r
Lower
p4r
Lower
p3l
Lower
p3/p4r
Lower
p3r
Lower
p3r
Lower
p4r
331
Table A 3. Late Pleistocene equid specimens (upper teeth) included in the geometric morphometric analysis. Loc. ab. = Abbreviation
of locality names used in Chapter 2 figures (l = large, m = medium, s = small specimens; teeth that yielded aDNA are identified by “a”
and those associated with specimens from which aDNA was obtained are indicated with “*”).
Specimen
2584
41228-1051
H5-3-24
192/uncat.
P94.1.498
34-8
I7-1-21
192/uncat.
K8-1-8
2608
937-253
2606
38192
52450
192/uncat.
L7-7-3
P02.10.125
36548
192/uncat.
E7-19-1
3838
62586
192/156497
41228-360
4587
46-139
192/uncat.
Inst.
INAH
TMM
CMH
LACM
RAM
UTEP
CMH
LACM
CMH
INAH
TMM
INAH
KU
KU
LACM
CMH
RAM
KU
LACM
CMH
INAH
KU
LACM
TMM
INAH
UTEP
LACM
Locality
Cedral
Dark Canyon Cave
MgVo-2
San Josecito Cave
Pit 48
Salt Creek
MgVo-1
San Josecito Cave
MgVo-1
Cedral
Blackwater Draw
Cedral
Natural Trap Cave
Natural Trap Cave
San Josecito Cave
MgVo-1
Pit 48
Natural Trap Cave
San Josecito Cave
MgVo-1
Cedral
Natural Trap Cave
San Josecito Cave
Dark Canyon Cave
Cedral
Isleta Cave No. 2
San Josecito Cave
Loc. ab.
Cl
Km
B
J
E
Sm
B
J
B
Cl
Ll
Cl
N
N
J
B
E
N
J
B
Cl
N
J
Km
Cs
Il
J
Tooth position
Upper
P4l
Upper
P3r
Upper
P3r
Upper
P3r
Upper
P4r
Upper
P4l
Upper
P3r
Upper
P3/P4r
Upper
P3l
Upper
P4r
Upper
P4l
Upper
P3r
Upper
P4l
Upper
P4r
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3r
Upper
P4r
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P3r
332
Table A 3, continued. Late Pleistocene equid specimens (upper teeth) included in the geometric morphometric analysis. Loc. ab. =
Specimen
112-2
32315
192/uncat.
2604
192/uncat.
85-120
27214
32789
P89.13.397
36614
P98.5.21
36456
3850
2572
192/156496
I7-1-48
36748
3836
G7(E1/2)-14-3
119-14
K8-1-15
3847
41984
2662
937-504.1
46645
H7(E)-21-2
Inst.
UTEP
KU
LACM
INAH
LACM
CMH
KU
KU
RAM
KU
RAM
KU
INAH
INAH
LACM
CMH
KU
INAH
CMH
UTEP
CMH
INAH
KU
INAH
TMM
KU
CMH
Locality
Nash Draw
Natural Trap Cave
San Josecito Cave
Cedral
San Josecito Cave
MgVo-3
Natural Trap Cave
Natural Trap Cave
Pit 48
Natural Trap Cave
Pit 48
Natural Trap Cave
Cedral
Cedral
San Josecito Cave
MgVo-1
Natural Trap Cave
Cedral
MgVo-1
MgVo-1
Cedral
Natural Trap Cave
Cedral
Blackwater Draw
Natural Trap Cave
MgVo-1
Loc. ab.
Hl
N
J
Cl
J
B
N
N
E
N
E
Nl
Cm
Cm
J
B
N
Cm
B*
Am
B
Cl
Nl
Cl
Lm
N
B
Tooth position
Upper
P4r
Upper
p4l
Upper
P4r
Upper
P4l
Upper
P4r
Upper
P4l
Upper
P3r
Upper
P3/P4r
Upper
P4/P3l
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P4l
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P4l
333
Specimen
2607
192/uncat.
P94.1.282
H7(E)-14-20
85-Misc-1.5
32985
3842
K7-5-22
P83.4.2
38688
P94.1.557
P94.4.6
3836
39232
RAM Horse 2
34020
P89.13.400
35769
48366
G6-4-4
81897
4554
2593
H8(N)-8-6
P94.1.470
3840
39803
Inst.
INAH
LACM
RAM
CMH
CMH
KU
INAH
CMH
RAM
KU
RAM
RAM
INAH
KU
RAM
KU
RAM
KU
KU
CMH
KU
INAH
INAH
CMH
RAM
INAH
KU
Locality
Cedral
San Josecito Cave
Pit 48
MgVo-1
MgVo-2
Natural Trap Cave
Cedral
MgVo-1
Villenueve
Natural Trap Cave
Pit 48
Pit 46
Cedral
Natural Trap Cave
Wally's Beach
Natural Trap Cave
Pit 48
Natural Trap Cave
Natural Trap Cave
MgVo-1
Natural Trap Cave
Cedral
Cedral
MgVo-1
Pit 48
Cedral
Natural Trap Cave
Loc. ab.
Cl
J
E
B
B
N
Cs
B
E
N
E
E
Cs
N
W*
N
E
N
N
B
N
Cm
Cm
B
E
Cs
N
Tooth position
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P4l
Upper
P4r
Upper
P3r
Upper
P3/P4
Upper
P3l
Upper
P3/P4l
Upper
P3l
Upper
P3r
Upper
P4l
Upper
P4l
Upper
P3r
Upper
P3r
Upper
P4r
Upper
P4l
Upper
P3r
Upper
P4r
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P4r
Upper
P4r
Upper
P3l
Upper
P4l
Upper
P3r
334
Specimen
998-25
42970
3862
33219
2638
(D3)-6-7
T.P.1-5
P89.13.610
38555
937-253
48342
J8-1-166
192/156487
860.1 (Horse 3)
2595
54-1212
4548
192/156483
44396
3863
81894
862 (Horse A)
937-678
3854
34084
2652
85-89
Inst.
TMM
KU
INAH
INAH
INAH
CMH
CMH
RAM
KU
TMM
KU
CMH
LACM
RAM
INAH
UTEP
INAH
LACM
KU
INAH
KU
RAM
TMM
INAH
KU
INAH
CMH
Locality
Scharbauer Ranch
Natural Trap Cave
Cedral
Cedral
Cedral
MgVo-2
MgVo-3
Pit 48
Natural Trap Cave
Blackwater Draw
Natural Trap Cave
MgVo-1
San Josecito Cave
Wally's Beach
Cedral
TTII (Dry Cave)
Cedral
San Josecito Cave
Natural Trap Cave
Cedral
Natural Trap Cave
Wally's Beach
Blackwater Draw
Cedral
Natural Trap Cave
Cedral
MgVo-3
Loc. ab.
Rl
N*
Cs
N
Cm
B
B
E
N
Ll
N
B
J
W
Cl
Dm
Cs
J
N
Cs
N
W
Ll
Cs
N
Cm
Ba
Tooth position
Upper
P3/P4r
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P3l
Upper
P3r
Upper
P4r
Upper
P3r
Upper
P4l
Upper
P4l
Upper
P4l
Upper
P3/P4r
Upper
P4r
Upper
P3r
Upper
P3r
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P4/P3r
Upper
P4r
Upper
P3r
Upper
P4l
Upper
P4l
Upper P3?/P4l
Upper
P3l
335
Specimen
22-1608
T3-21-79
27215
48719
P94.1.242
H7(W)-3-36
192/uncat.
35085
D6-D-4
B4(S)-12-8
4547
937-923
192/uncat.
41178
K6-2-23
K7-1-6
22-1609
P98.5.234
192/156484
45751
2576
P99.3.6
P94.1.259
3868
4540
85-41
27902
Inst.
UTEP
CMH
KU
KU
RAM
CMH
LACM
KU
CMH
CMH
INAH
TMM
LACM
KU
CMH
CMH
UTEP
RAM
LACM
KU
INAH
RAM
RAM
INAH
INAH
CMH
KU
Locality
MgVo-1
Natural Trap Cave
Natural Trap Cave
Pit 48
MgVo-1
San Josecito Cave
Natural Trap Cave
MgVo-2
MgVo-2
Cedral
Blackwater Draw
San Josecito Cave
Natural Trap Cave
MgVo-1
MgVo-1
Pit 48
San Josecito Cave
Natural Trap Cave
Cedral
Pit 48
Pit 48
Cedral
Cedral
MgVo-3
Natural Trap Cave
Loc. ab.
Dl
B*
N
N
E
Ba
J
N
B
B
Cm
Lm
J
N
B
B
Dm*
E
J
N
Cl
E
E
Cs
Cm
B
N
Tooth position
Upper
P3l
Upper
P4r
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P3r
Upper
P3l
Upper
P4l
Upper
P4r
Upper
P3l
Upper
P3l
Upper
P3l
Upper
P3l
Upper
P3l
Upper
P4l
Upper
P4r
Upper
P3r
Upper
P4r
Upper
P4?l
Upper P3/P4l
Upper
P4r
Upper
P3l
Upper
P3r
Upper
P4l
336
Specimen
32785
J7-1-12
25-537
36438
C6(W)-13-1
38612
46778
2651
192/156486
Inst.
KU
CMH
UTEP
KU
CMH
KU
KU
INAH
LACM
Locality
Natural Trap Cave
MgVo-1
Camel Room (Dry Cave)
Natural Trap Cave
MgVo-2
Natural Trap Cave
Natural Trap Cave
Cedral
San Josecito Cave
Loc. ab.
N
B
Dm
N
B
N
N
Cm
J
Tooth position
Upper
P3r
Upper
P3l
Upper
P3r
Upper
P3r
Upper
P4l
Upper
P3r
Upper
P3l
Upper
P3l
Upper
P4l
337
Table A 4. Primers used to amplify a 621 bp fragment of the HVR I, mitochondrial control region. Position numbers are given
according to the location of the first nucleotide of the primer over the complete mtDNA sequence of Equus ferus caballus (GenBank
accession number NC_001640).
Primer Name
EQL1-15425F
EQH1-15596R
EQ-15496F
EQ-15628R
EQ-15575F
EQ-15708R
EQ-15668_2F
EQ-15852R
EQ-15782F
EQ-15945R
EQ-15889_2F
EQ-16018R
EQ-15948F
EQ-16085R
EQ-15799R
Sequence
ACCATCAACACCCAAAGC
TTAATGCACGAYGTACATAGG
ACCCTCATGTRCYATGTCAGTA
TGTACATGCTTATTATTCATGGG
GCCTATGTACRTCGTGCATT
TGTTGRCTGGAAATGATTTG
TCGTGCATACCCCATYCAAG
GAACCAGATGCCAGGTATAGTTTC
TCCCAATCCTCGCTCCG
TGTGAGCATGGGCTGATTAGTC
CTTTCCCCTTAAATAAGACATCTCG
CTTTGACGGCCATAGCTGAGT
TAACTGTGRTTTCATGCATTTGG
GGTTGCTGATGCGGAGTAATAA
CCGGAGCGAGGATTGGG
Description
Horse, mtDNA HVR1, Forward primer
Horse, mtDNA HVR1, Reverse primer
338
Table A 5. Equid specimens that were sampled for ancient DNA. * indicates succesful aDNA extractions; (p) = partially failed.
Sample no.
EQ1*
EQ2*
EQ3(p)/EQ18
EQ4(p)
EQ5
EQ6/EQ40*
Specimen
UTEP 23-65
UTEP 22-648
UTEP 22-1609
RAM P94.1.499
RAM P94.1.486
Locality
Pit 48, Alberta
Pit 48, Alberta
Element
Lower p3r
Lower m1l
Upper P4l
Lower p3l
Lower p3l
U of C Historic Horse,
Calgary, Alberta
Rib
EQ7
EQ8
EQ9*
EQ10
EQ11
EQ12
EQ13*
EQ14
EQ15
EQ16*
EQ17
EQ19
EQ20
EQ21
EQ22*
EQ23
EQ24
EQ25
EQ26
EQ27
EQ28
INAH DP 2315
UTEP 22-1539
KU 42970
INAH DP L-12, VII, 152
INAH DP 4586
UTEP 22-65
KU 33867
UTEP 75-29
INAH DP 2676
UTEP 4-827
UTEP 46-139
INAH DP 4587
UTEP 22-1615/22-1616?
TMM 41228-250
KU 36543
UTEP 5689-67-6
INAH DP 2592
INAH DP 2704
UTEP 22-1538
KU 32785
INAH DP 3843
Cedral, Mexico
Natural Trap Cave, WY
Loltun, Mexico
Cedral, Mexico
Dark Canyon Cave, NM
Cedral, Mexico
Isleta Cave No. 2, NM
Cedral, Mexico
U-Bar Cave, New Mexico
Cedral, Mexico
Cedral, Mexico
Cedral, Mexico
Lower p4r
Lower p3/p4
Upper P2l
Lower p3/p4
Lower m2l
Upper M3l
Lower p3/p4l
Upper M2r
Upper M2r
Upper M1r
Upper P3l
Lower m3r
Lower p4?r
Lower m1r
Lower p3r
Upper P3
Lower m1r
Lower m2l
Lower p4r
Upper P3r
Upper M1l
EQ29/EQ29-2*
(repeat)
RAM DhPg-8 2993.1
Wally's Beach, Alberta
Upper DP4
(repeat)
Age (yr RCBP)
339
Table A 5, continued. Equid specimens that were sampled for ancient DNA. Succesful aDNA extractions are indicated in bold.
Sample no.
EQ30*
EQ31
EQ32
EQ33
EQ34
EQ35
EQ36
EQ37
EQ38*
EQ39/EQ39-2*
(repeat)
EQ41*
EQ42*
EQ43 (p2)* /
EQ43-2 (p3)*
EQ44*
EQ45*
EQ46
EQ47*
EQ48*
EQ49
EQ50/EQ50-2*
Specimen
LACM 192/156481
UTEP 120-41
INAH DP 3863
KU 35118
INAH DP 3889
LACM 192/156482
UTEP 22-1664
TMM 41228-3821
CMH MgVo-1 H7(W)-3-36
Provenance
Big Manhole Cave, NM
Cedral, Mexico
Cedral, Mexico
Bluefish Cave 1, Yukon
Element
Upper P2l
Lower p3l
Upper P3l
Lower p3/p4l
Lower m3r
Upper M1
Lower m1/m2l
Lower p3r
Upper P3r
CMH MgVo-1 J8-1-147
Lower p3l
KU 42070
CMH MgVo-2 J7-8-19
RAM DhPg-8 3437.1/2 (Horse
2)
CMH MgVo-1 G7(E1/2)-11-13
CMH MgVo-3 85-89
TMM 937-253
CMH MgVo-1 T3-21-86
CMH MgVo-2 I6-E-5
TMM 937-48
Lower m3r
Lower p4l
Wally's Beach, Alberta
Lower p2 and p3
Blackwater Draw, NM
Blackwater Draw, NM
Upper P3l
Upper P3l
Upper P4l
Lower m2r
Lower p4r
Lower p3/p4r
Lower p3r
CMH MgVo-1 L8(N)-4-7
EQ51*
CMH MgVo-2 B3-3-16
EQ52*
TMM 937-947
EQ53/EQ53-2*
CMH MgVo-3 85-90 p3
(repeat)
(repeat)
Blackwater Draw, NM
Lower m2r
Lower m1r
Lower p3r
Age (yr RCBP)
340
Table A 6. Equid sequences used in the Bayesian phylogenetic analysis. Hap. = Haplogroup.
Specimen
1 ChP01
4 Arb05
10 WeP01
11 Mrm14
17 AkT11
19 Irn09
22 NoF01
24 ILH01
25 Mrm05
26 Prz01
27 Prz02
32 Gia02
37 Arb06
38 Mrm06
41 CsP04
42 Trk01
43 Mrm15
44 Irn02
45_Bel01
48 APH01
55_And01
61_CsP05
62 Cly01
66 Sad01
67 Exm01
70 Irn12
Species/Breed
Equus ferus caballus
Chincoteague Pony
E. f. caballus Arabian
E. f. caballus Westphalian
E. f. caballus Maremmano
E. f. caballus Akhal-Teke
E. f. caballus Unspecified Iranian Breed
E. f. caballus Norwegian Fjord
E. f. caballus Icelandic Horse
E. f. przewalskii
E. f. przewalskii
Provenance
Hap.
North America
Middle East
Europe Centre
Europe South
Asia Centre
Middle East
Europe North
Europe North
Europe South
Asia Centre
Asia Centre
Sardinia; Europe
E. f. caballus Giara Horse
South
Middle East
Europe South
E. f. caballus Caspian Pony
Middle East
E. f. caballus Trakhener
Europe North
Europe South
E. f. caballus Unspecified Iranian Breed Middle East
E. f. caballus Belgian Draft
Europe Centre
E. f. caballus American Paint Horse North America
E. f. caballus Andalusian
Europe South
E. f. caballus Caspian Pony
Middle East
E. f. caballus Clydesdale
Europe North
E. ferus caballus Saddlebred
North America
E. f. caballus Exmoor Pony
Europe North
E. f. caballus
Middle East
Unspecified Iranian Breed
Element
GenBank #
Age (yr RCBP)
A
JN398377
Recent
A
B
B
C
C
D
D
E
F
F
JN398380
JN398386
JN398387
JN398393
JN398395
JN398398
JN398400
JN398401
JN398402
JN398403
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
G
JN398407
Recent
G
H
I
I
J
J
K
L
L
M
M
N
N
JN398412
JN398413
JN398416
JN398417
JN398418
JN398419
JN398420
JN398421
JN398430
JN398436
JN398439
JN398441
JN398442
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
Recent
O
JN398445
Recent
341
Table A 6, continued. Equid sequences used in the Bayesian phylogenetic analysis. Hap. = Haplogroup.
Specimen
71 Irn03
73 Arb01
75 AkT01
77 AkT04
82 Mrm09
83 Irn04
NC_001788
X97337
AP012271
AP012269
HQ439484
AF072994
X79547
JW328
MS272
NC_001640.1
TC21c
YG148.2
CGG10022
PET09
SMNS
Vog IV-6671
SMNS 8010
Ek 253/557
EK 253/556
EK 994/217
Species/Breed
E. f. caballus
E. f. caballus
Equus asinus
Equus asinus
Equus asinus somalicus
E. f. przewalskii
E. f. przewalskii
E. f. przewalskii
E. f. caballus
Equus sp. (NWSL)
Equus sp. (NWSL)
E. f. caballus
Provenance
Hap.
Middle East
Equus sp.
Thistle Creek, Yukon
Equus sp.
Equus sp. (JW177)
Equus sp. (JW175)
Equus sp. (JW266)
Equus sp. (JW196)
Equus sp. (JW202)
Equus sp. (JW16)
Equus sp. (JW17)
Yukon
Petersfels, Germany
Hohlefels, Germany
Vogelherd IV, Germany
Bockstein, Germany
Ignatievskaya, Ural Mts.
Ignatievskaya, Ural Mts.
Sur’ya 5, Ural Mts.
Bol. Lyakhovsky Island, NE Siberia
IEM 202-279 Equus sp. (JW25)
Element
GenBank #
Age (yr RCBP)
P
JN398446
Recent
Middle East
Asia Centre
Asia Centre
Europe South
P
Q
Q
R
JN398448
JN398450
JN398452
JN398456
Recent
Recent
Recent
Recent
Middle East
R
JN398457
Recent
NC_001788
X97337
AP012271
AP012269
HQ439484
AF072994
X79547
JX312726
JX312727
Recent
Recent
Recent
Recent
Recent
Recent
Recent
NC_001640.1
Recent
Astragalus
Astragalus
Radius/Ulna
Metatarsal
Calcaneus
Phalange II
Phalange I
DQ007558
DQ007556
DQ007591
DQ007590
DQ007572
DQ007571
JN570954
12,545±50
12,550±60
13,845±50
47,100±1000
Pelvis
DQ007573
2,220±50*
Europe North?
Asia Centre
Asia Centre
Asia Centre
Mineral Hill Cave, Nevada
Upper Quartz Creek, Yukon
2,218±34
342
Table A 6, continued. Equid sequences used in the Bayesian phylogenetic analysis.
Specimen
IEM 202-128
IEM 202-847
IEM202-244
Species
Equus sp. (JW27)
Equus sp. (JW28)
Equus sp. (JW29)
PIN 3659-6
Equus sp. (JW188)
PIN 3659-1
Equus sp. (JW189)
IEM203-42
Equus sp. (JW190)
IEM 205-6
Equus sp. (JW191)
PIN 3658-121
IEM 207-30
PIN 169-43
PIN 3751-151
Equus sp. (JW194)
Equus sp. (JW195)
Equus sp. (JW209)
Equus sp. (JW207)
PIN 3100-421
Equus sp. (JW210)
IEM 200-483
Equus sp. (JW203)
UA-97-061221
AA26819
CMN MgVo3-85-60
CMN 49368
YG110.111
YG150.82
P94.1.415
P89.21.1
KU42625
Provenance
Bol. Lyakhovsky Island, N-E Siberia
Ulakhan-Sullar, Adycha R., Yana
Basin, N-E Siberia
Ulakhan-Sullar, Adycha R., Yana
Basin, N-E Siberia
Lena R. Delta, N-E Siberia
Bykovsky Peninsula, Lena Delta, N-E
Siberia
Alyoshkina, Kolyma R., N-E Siberia
Lena R. Delta, N-E Siberia
Kolyma R. lower course, N-E Siberia
Yana R. Lower course, N-E Siberia
Chukochya R., Kolyma Lowland, N-E
Siberia
Bykovsky Peninsula, Lena Delta, N-E
Siberia
Element
Humerus
Femur
Pelvis
GenBank #
DQ007605
DQ007574
DQ007575
Age (yr RCBP)
20,100±170*
28,800±1100*
34800±1000*
Metatarsal
DQ007553
53,100±1700
Metatarsal
DQ007576
Humerus
DQ007577
Tibia
DQ007578
Humerus
Ulna
Metacarpal
Metatarsal
DQ007579
DQ007580
DQ007581
DQ007582
Metatarsal
DQ007583
Scapula
DQ007552
27,500±400*
Equus sp. (JW69)
Castle River, Alaska
Radius
DQ007584
15,090
Equus sp. (JW184)
Ester Creek, Alaska
Metacarpal
DQ007554
12,510±130
Equus sp. (JW78)
Bluefish Cave, Yukon
Metatarsal
DQ007585
Equus sp. (JW98)
Equus sp. (JW128)
Equus sp. (JW129)
Equus sp. (JW71)
Equus sp. (JW174)
Equus sp. (JW157)
Old Crow Loc. 22, Yukon
Irish Gulch, Yukon
Edmonton Pit 48, Alberta
Grand Prairie, Alberta
Metacarpal
Metacarpal
Metatarsal
Metatarsal
Femur
Metatarsal
DQ007557
DQ007586
DQ007587
DQ007559
DQ007594
DQ007588
31220±180
43,900±180
11,200±90
343
Specimen
KU51467
HS23
YT03/280
YT03/286
YT03/279
Species
(JW160)
Equus sp. (NWSL)
(JW161)
Equus sp. (NWSL)
(JW277)
Equus sp. (NWSL)
(JW125)
Equus sp. (NWSL)
(JW126)
Equus sp. (JW163)
Equus sp. (JW119)
Equus sp. (JW123)
Equus sp. (JW120)
P97.12.9
Equus sp. (JW172)
P98.6.8
Equus sp. (JW170)
P96.2.33
Equus sp. (JW218)
P96.9.18
Equus sp. (JW222)
P88.19.3
Equus sp. (JW219)
P95.1.12
Equus sp. (JW220)
P94.2.1
Equus sp. (JW221)
P95.2.29
Equus sp. (JW216)
Equus (Amerhippus)
neogeus (CH423)
KU62158
LACM
109/150807
YG130.3
YG109.7
Provenance
Element
Humerus
GenBank #
DQ007589
Age (yr RCBP)
Metatarsal
DQ007569
Gypsum Cave, Nevada
Femur
DQ007570
13,070±55
Quartz Creek, Yukon
Phalange I
DQ007567
46,600±1000
Quartz Creek, Yukon
Metatarsal
DQ007568
>47,000
Tonghe Bridge, Harbin, China
Cloverbar sand and gravel,
Edmonton, AB
Edmonton, AB
Pit 48, Edmonton, AB
Twin Bridges Gravel Pit 80,
Edmonton, AB
Apex Evergreen Pit, Edmonton, AB
Edmonton, AB
Twin Bridges Gravel Pit 80,
Edmonton, AB
Apex Evergreen Pit, Edmonton, AB
Metatarsal
Radius
Radius
Skull
DQ007604
DQ007601
DQ007603
DQ007602
Metacarpal
DQ007593
Metatarsal
DQ007592
Metacarpal
DQ007597
Scapula
DQ007600
Metatarsal
DQ007595
Metatarsal
DQ007598
Metacarpal
DQ007599
Metatarsal
DQ007596
Inti Huasi, SL province, Argentina
M1/M2
EU030680
344
Specimen
MLP 44 XII
29 23
AF326676
AF326677
AF326678
AF326679
AF326665
AF326668
AF326669
AF326670
AF326671
AF326672
AF326673
AF326674
AF326675
Species
Equus (Amerhippus)
neogeus (CH425)
E. f. caballus Anc 1
E. f. caballus EC8A
E. f. caballus Pleist1
Provenance
Arroyo Tapalque´ (Olavarrıá), BA
province, Argentina
Domestic
Domestic
Alaska
Alaska
Alaska
Alaska
Alaska
Alaska
Alaska
Alaska
Element
GenBank #
p3
EU030682
AF326676
AF326677
AF326678
AF326679
AF326665
AF326668
AF326669
AF326670
AF326671
AF326672
AF326673
AF326674
AF326675
Age (yr RCBP)
200-500 AD
Recent
Viking Period
200-500 AD
12,000 – 28,000
12,000 – 28,000
12,000 – 28,000
12,000 – 28,000
12,000 – 28,000
12,000 – 28,000
12,000 – 28,000
12,000 – 28,000
345
Equus ferus lambei
Bluefish Caves
Table A 7. Microwear data of late Pleistocene equid and bison samples studied. S = average number of scratches; P = average number
of pits; CS = average number of cross scratches; LP = average number of large pits; WS = average number of wide scratches; G =
gouges: 0 = none observed, 0.5 = at least one gouge present in one out of two enamel bands observed; 1 = at least one gouge present in
the enamel bands observed; TS = average texture score. CMH = Canadian Museum of History.
Species
Specimen
Institution Locality
Tooth position Time interval
S
P
CS LP WS G
TS
D5-F-31
CMH
MgVo-2
Upper M3r Pre-/Full-glacial
21 16.5
2
0 0.5
0 0.5
H7(E)-20-5
CMH
MgVo-1
Upper M3l Pre-/Full-glacial
25.5 12.5
3
0 1.5
0
1
D6(NE)-8-13
CMH
MgVo-1
Lower m2l Pre-/Full-glacial
25
10
1
0
1
0
1
C3(E)-3-2
CMH
MgVo-2
19.5
15
2 1.5
2
0
1
H6-5-24
CMH
MgVo-2
Lower m3r Pre-/Full-glacial
24
23 2.5 0.5
0
0
0
T.P.1-F-67
CMH
MgVo-3
17.5 22.5
1
2
1
0
1
H7(W)-3-25
CMH
MgVo-1
Upper M2r Pre-/Full-glacial
19.5
16
1 0.5 0.5 0.5
1
Pre-/Full-glacial
E7-20-8
CMH
MgVo-1
Upper M1r
19 14.5 2.5
1
1
0
1
C5(S)-6.2
CMH
MgVo-2
16.5
27 0.5
3
0
0
0
Pre-/Full-glacial
H6-5-21
CMH
MgVo-2
Upper M2r
24
17
4
0
1
0
1
C3(E)-3-2
CMH
MgVo-2
23.5
18
4
6
0
1
0
F6-E-7
CMH
MgVo-2
24
11
1
0
0
0
0
T3-21-86
CMH
MgVo-1
33
15 8.5
0
1
0
1
L8(N)-7-3
CMH
MgVo-1
Lower m2r Postglacial
22 10.5 2.5
2 2.5
0
1
L8(N)-7-4
CMH
MgVo-1
Upper M3l Postglacial
25 11.5 4.5
0
0 0.5 0.5
L8(N)-8-2
CMH
MgVo-1
Upper M1r Postglacial
27
15
1
0
1
0 0.5
T3-17-15
CMH
MgVo-1
25.5
22 3.5
4
0
0 0.5
L8(N)-5-2
CMH
MgVo-1
18
14
3
1
0
0
1
L8(N)-11-10
CMH
MgVo-1
Lower m2l Postglacial
30
11
5
0
0
1
0
M7-2-34
CMH
MgVo-1
29 14.5 5.5
1
0
1
1
L8(N)-7-5
CMH
MgVo-1
25.5 17.5
2 2.5
2
1
1
L7-7-2
CMH
MgVo-1
Upper M1r Postglacial
28
24
6
2
0
0
1
L7-5-2
CMH
MgVo-1
Upper M2l Postglacial
22.5
22
7
0
0
0
0
M7-2-27
CMH
MgVo-1
23 20.5
1 1.5 0.5
1 0.5
L8(N)-7-9
CMH
MgVo-1
32
12
7
0
0
1
1
346
Equus ferus scotti
Alberta
Bison sp.
Alberta
Table A 7, continued. Microwear data of late Pleistocene equid and bison samples studied. S = average number of scratches; P =
average number of pits; CS = average number of cross scratches; LP = average number of large pits; WS = average number of wide
scratches; G = gouges: 0 = none observed, 0.5 = at least one gouge present in one out of two enamel bands observed; 1 = at least one
gouge present in the enamel bands observed; TS = average texture score. RAM = Royal Alberta Museum.
Species Specimen
Inst.
Locality
Tooth position
Time interval S
P
CS LP WS G TS
P92.8.10
RAM
TBG Pit 1042
Upper
M1l
Preglacial
23 16.5
2
1 3.5
0
1
P96.2.32
RAM
Pit 48
Lower
m2l
Preglacial
24.5 16.5 4.5
1
1 0.5
1
P94.1.201
RAM
Pit 48
Lower
m2l
Preglacial
26.5
14 3.5 1.5
2
0
1
P68.2.690
RAM
M2l
Preglacial
20
18
3
0
0
1
1
Apex Evergreen Pit Upper
P95.6.73
RAM
Pit 48
Lower
m2r
Preglacial
23.5
16 4.5 1.5 1.5
0
1
P68.2.667
RAM
m2l
Preglacial
21
21
0
1
1
1
1
Apex Evergreen Pit Lower
P68.2.666
RAM
m2r
Preglacial
23
24
7
2
3
1
1
Apex Evergreen Pit Lower
P04.3.62
RAM
Pit 48
Lower
m3r
Preglacial
24
19
3
0
1
1
1
P90.4.1
RAM
TBG Pit 4
Upper
M2l
Postglacial
22
19
0
5
3
1
2
P02.8.27
RAM
TBG Pit 4
Lower
m2?r Postglacial
25
26
2
0
2
0
1
P02.8.15
RAM
TBG Pit 4
Lower
m3l
Postglacial
23.5 22.5
6
0
0
0 0.5
P02.8.8
RAM
TBG Pit 4
Lower
m3r
Postglacial
20
20
1
0
0
1
0
P02.8.49
RAM
TBG Pit 4
Lower
m2l
Postglacial
31 15.5 5.5
0 0.5
0 0.5
P02.8.39
RAM
TBG Pit 4
Upper
M3r
Postglacial
30.5
18 6.5
0 0.5 0.5
1
P02.8.18
RAM
TBG Pit 4
Lower
m1?r Postglacial
19.5
21 0.5 0.5 0.5
1 0.5
P02.8.13
RAM
TBG Pit 4
Upper
M2l
Postglacial
23.5
14 2.5 1.5
1
1
1
P02.8.26
RAM
TBG Pit 4
Lower
m2r
Postglacial
28
14
4
0
2
1
1
P94.1.124
RAM
Pit 48
Lower
m2r
Preglacial
25.5 18.5 0.5 1.5
2 0.5
1
P02.10.4
RAM
Pit 48
Upper
M1r
Preglacial
25
17
2
3
1
1
1
P94.8.84
RAM
Riverview Pit
Upper
M1r
Preglacial
21
14
2
0
0
1
0
P05.10.46
RAM
Pit 48
Lower
m2l
Preglacial
23
12
2
4
2
1
1
P94.1.854
RAM
Pit 48
Upper
M1l
Preglacial
27
13
3
1
2
0
1
P94.1.113
RAM
Pit 48
Lower
m1l
Preglacial
26
14
4
0
0
1
1
P94.8.38
RAM
Riverview Pit
Upper
M2r
Preglacial
28
24
3
3
0
1
1
864 (Horse A) RAM
Wally's Beach
Lower
m3l
Postglacial
21
26 2.5 2.5 2.5 0.5
1
347
Equus conversidens
American Southwest
Bison antiquus
American Southwest
Equus ferus
scotti
Alberta
gouge present in the enamel bands observed; TS = average texture score. RAM = Royal Alberta Museum, TMM = Vertebrate
Paleontology Laboratory, University of Texas at Austin, UTEP = University of Texas at El Paso. * indicates Dry Cave localities.
Species Specimen
Inst.
Locality
Tooth position
Time interval S
P
CS LP WS G TS
861.1 (Horse 3) RAM Wally's Beach
Lower m2l
Postglacial
25.5 27.5
3 1.5 1.5
1
1
P97.11.2B
RAM Riverview Pit
Lower m2l
Postglacial
29 25.5
4
1 1.5
0
1
Upper M2r
Postglacial
21
26
2
0
2
0
1
865.1 (Horse B) RAM Wally's Beach
Upper M2r
Postglacial
20
34
3 0.5 0.5
1 0.5
74.1 (Horse C)
RAM Wally's Beach
Lower m1r/m1l Postglacial
25.5 18.5
3 0.5
1
1 0.5
69.1 (Horse D)
RAM Wally's Beach
Lower m1r
Postglacial
23.5 19.5 3.5 1.5
0
1
1
27
21
4
4
2
1
1
937-492
TMM Blackwater Draw Lower m3l
Postglacial
26
23
4
1
2
1
1
937-667
TMM Blackwater Draw Lower m2r
Postglacial
22
20
2
4
2
1
1
4-18
UTEP Bison Chamber* Upper M2l
Postglacial
27 20.5 1.5 0.5
1
1
1
892-bed #1
TMM Lubbock Lake
Upper M1r
Postglacial
25
23
1
1
2
1
1
937-907
TMM Blackwater Draw Upper M2/M3r Postglacial
26 19.5 2.5 1.5 2.5
1
1
937-uncat.
TMM Blackwater Draw Upper M3l
Postglacial
21
24
3
0
1
1
1
937-886
TMM Blackwater Draw Upper M1/M2l? Postglacial
26
29
8
0
1
1
1
937-uncat.
TMM Blackwater Draw Upper M2r
Postglacial
26 22.5 2.5
4
0
1 0.5
54-1252
UTEP TTII*
Upper M2l
Postglacial
41228-3849
TMM Dark Canyon Cave Lower m1/m2r
Preglacial
30.5 23.5
4
2
0
1
1
41228-232
TMM Dark Canyon Cave Lower m2l
Preglacial
29.5 14.5 2.5
0
0
0
1
41228-361
Preglacial
28
20 2.5
0
0 0.5
0
41228-158
TMM Dark Canyon Cave Lower m1/m2r
Preglacial
33
14
5
0
1
0
1
41228-371
TMM Dark Canyon Cave Upper M2r
Preglacial
31.5 16.5
5
0
1 0.5
1
Dark
Canyon
Cave
41228-261
TMM
Upper M1/M2l Preglacial
27
14 3.5
0 0.5
0
1
41228-394
Preglacial
29
23
2
4
1
1
1
Dark
Canyon
Cave
41228-uncat.
TMM
Lower m2r
Preglacial
23
15 0.5
1 1.5 0.5
1
41228-235
TMM Dark Canyon Cave Lower m2?r
Preglacial
32
13
4
1
0
0
1
41228-233
Preglacial
24 17.5 4.5
1
1
1
1
348
Equus conversidens
American Southwest
gouge present in the enamel bands observed; TS = average texture score. TMM = Vertebrate Paleontology Laboratory, University of
Texas at Austin, UTEP = University of Texas at El Paso. * indicates Dry Cave localities.
Species Specimen
Inst.
Locality
Tooth position
Time interval S
P
CS LP
WS G TS
41228-308
TMM Dark Canyon Cave
Upper M1l
Preglacial
27.5
11 3.5
0.5
1 1
1
41228-234
Lower m2l
Preglacial
31.5 15.5 2.5
1.5
0.5 0
1
Upper M3r
Preglacial
32
14
3
0
1 1
1
41228-1030
41228-159
Lower m1r
Preglacial
23.5 16.5 4.5
0.5
1 1
1
Dark
Canyon
Cave
TMM
Upper M3r
Preglacial
28
12
1
0
1 0
1
41228-1026
22-669
UTEP Animal Fair*
Lower p4r
29
19
5
0
0 1
1
Full-glacial
22-1664
UTEP Hampton Court*
Lower m1/m2l Full-glacial
26.5
23
2
3
2.5 0
1
22-955
UTEP Charlies Parlor*
Lower m2l
25.5
17
3
0.5
1 0
1
Full-glacial
22-956
UTEP Animal Fair*
Lower m2r
31.5 15.5
3
0
1.5 0
1
Full-glacial
22-961
Upper M1r
24
14
4
0
3 0
1
Full-glacial
22-1609
UTEP Animal Fair*
Upper M1r
28.5
16
3
1.5
0.5 1
1
Full-glacial
937-930
Postglacial
20 25.5
1
5.5
0.5 1
1
23-78
UTEP Stalag 17*
Lower m2r
Postglacial
18.5
25 1.5
2
0.5 0
1
937-203
Postglacial
20
17
0
1
4 1
2
23-77
UTEP Stalag 17*
Lower m1l
Postglacial
29
19
1
1
2 1
1
31-47
UTEP Early Man Corridor* Upper M2l
Postglacial
24 23.5 2.5
4.5
2.5 1
1
937-906
Postglacial
23
27
0
4
2 1
1
937-322
Postglacial
22
25
2
1
4 1
1
998-8
TMM Scharbauer Ranch Upper M2l
Postglacial
25
13
2
2
1 1
1
54-827
UTEP TTII*
Upper M1l
Postglacial
26
19
1
2
3 1
1
54-1212
UTEP TTII*
Upper M2r
Postglacial
30.5
21 2.5
0.5
0.5 1
1
4-827
UTEP Bison Chamber*
Upper M1r
Postglacial
22
16
2
1
1 0
1
937-702
Postglacial
22.5 18.5 4.5
2
3.5 1
1
23-64
UTEP Stalag 17*
Lower m2r
Postglacial
24
25
2
1.5
1.5 1
1
349
Equus ferus scotti
American Southwest
scratches; G = average gouge score: 0 = none observed, 0.5 = at least one gouge present in one out of two enamel bands observed; 1 =
at least one gouge present in the enamel bands observed; TS = average texture score. TMM = Vertebrate Paleontology Laboratory,
University of Texas at Austin, UTEP = University of Texas at El Paso. * indicates Dry Cave localities.
Species Specimen Inst.
Locality
Tooth position
Time
interval
S
P
CS LP WS G
TS
Full-glacial
22-1616
Lower
m1r
31.5
14
3
0
0
0 0.5
Full-glacial
22-981
Upper
M2l
21.5 17.5 1.5
2
1
1
1
Full-glacial
22-65
UTEP Animal Fair*
Upper
M3l
25.5
16
2 2.5
0
1
1
Full-glacial
22-1607
UTEP Animal Fair*
Lower
m1r
24.5
19
3 1.5
1.5 0.5
1
Full-glacial
22-1608
UTEP Animal Fair*
Upper
M2r
31.5 16.5
5
2
2.5
1
1
22-1645
UTEP Animal Fair*
Lower
m3l
35 14.5
4 1.5
0
0 0.5
Full-glacial
22-1528
Lower
m2l
21 18.5
2 1.5
1.5
1
1
Full-glacial
22-61
UTEP Animal Fair*
Lower
m1l
20.5
15 2.5
3
0
0
1
Full-glacial
22-648
UTEP Animal Fair*
Lower
m1/m2l Full-glacial
27.5
14
3 0.5
0.5
1
1
22-1611
Upper
M2l
26.5 16.5 1.5
0
0.5
0 0.5
Full-glacial
22-985
Upper
M1r
19
19
0 0.5
0.5
1
1
Full-glacial
Full-glacial
22-64
UTEP Animal Fair*
Upper
M2l
21.5 20.5
4
1
0.5
1
1
937-971
TMM Blackwater Draw
Lower
m2r
Postglacial
22.5
21 2.5
0
1
1
1
937-678
TMM Blackwater Draw
Lower
m1/m2r Postglacial
25
20
4
0
0
1
1
Blackwater
Draw
937-252
TMM
Lower
m1l
Postglacial
25
26
1
2
0
1
1
54-1312
UTEP TTII*
Lower
m1l
Postglacial
20 28.5 3.5 3.5
1
1
1
Blackwater
Draw
937-760
TMM
Lower
m2r
Postglacial
29
20
1
2
2.5
1
1
937-738
TMM Blackwater Draw
Upper
M2r
Postglacial
19.5 19.5 1.5
3
2.5
1
1
937-247
TMM Blackwater Draw
Upper
M3l
Postglacial
21
23
2
4
1
1
1
937-956
TMM Blackwater Draw
Lower
m1/m2r Postglacial
24 28.5 2.5
2
1.5
1
1
937-947
TMM Blackwater Draw
Lower
m1r
Postglacial
23
17
3
0
0
0
1
998-1
TMM Scharbauer Ranch Lower
m1r
Postglacial
22
23
4
1
3
1
1
350
Bison sp.
Alberta
Equus ferus lambei
Bluefish Caves
Table A 8. Mesowear data of late Pleistocene equid and bison samples studied. CR = cusp relief; P = paracone; M = metacone; MS =
mesowear score; l = low cusps; h = high cusps; r = round cusps; s = sharp cusps; b = blunt cusps. CMH = Canadian Museum of
History, RAM = Royal Alberta Museum.
Species Specimen
Inst.
Locality
Tooth
Time interval
position
CR P
M
MS
H7(W)-3-25 CMH
MgVo-1
M2r
Pre-/Full-glacial
l
r
r
3
H7(E)-20-5
CMH
MgVo-1
M3l
Pre-/Full-glacial
l
b
r
3
T3-21-81
CMH
MgVo-1
M2r
Pre-/Full-glacial
h
s
s
0
E7-20-8
CMH
MgVo-1
M1r
Pre-/Full-glacial
l
b
b
4
D5-F-31
CMH
MgVo-2
M3r
Pre-/Full-glacial
l
r
r
3
C5(S)-6.2
CMH
MgVo-2
M2l
Pre-/Full-glacial
l
s
2
T.P.1-F-67
CMH
MgVo-3
M1l
Pre-/Full-glacial
l
r
r
3
T.P.1-F-35
CMH
MgVo-3
M2r
Pre-/Full-glacial
l
r
r
3
M7-1-1
CMH
MgVo-1
M3r
Postglacial
l
r
3
L8(N)-8-2
CMH
MgVo-1
M1r
Postglacial
l
r
r
3
L8(N)-7-4
CMH
MgVo-1
M3l
Postglacial
l
s
r
2
L7-5-2
CMH
MgVo-1
M2l
Postglacial
l
r
b
3
I8(S)-12-7
CMH
MgVo-1
M3l
Postglacial
l
b
4
P94.1.643
RAM
Pit 48
M3l
Preglacial
h
r
1
P95.6.2
RAM
Pit 48
M1l
Preglacial
l
r
r
3
P95.6.1
RAM
Pit 48
M3l
Preglacial
h/
r
r
1
P96.2.20
RAM
Pit 48
M3r
Preglacial
h
r
1
P98.5.400
RAM
Pit 48
M1l
Preglacial
h
r
r
1
P68.2.690
RAM
Apex Evergreen Pit M2l
Preglacial
l
b
r
3
P02.8.12
RAM
TBG Pit 4
M2r
Postglacial
h
r
r
1
P02.8.13
RAM
TBG Pit 4
M2l
Postglacial
l
r
r
3
P02.8.4
RAM
TBG Pit 4
M3r
Postglacial
h
r
1
P02.8.40
RAM
TBG Pit 4
M1l?
Postglacial
l
b
4
P02.8.9
RAM
TBG Pit 4
M2l
Postglacial
h
r
s
0
P02.8.24
RAM
TBG Pit 4
M1r
Postglacial
l
r
r
3
P90.4.1
RAM
TBG Pit 4
M2l
Postglacial
h
r
r
1
351
Equus ferus scotti
Alberta
Table A 8, continued. Mesowear data of late Pleistocene equid and bison samples studied. CR = cusp relief; P = paracone; M =
metacone; MS = mesowear score; l = low cusps; h = high cusps; r = round cusps; s = sharp cusps; b = blunt cusps. RAM = Royal
Alberta Museum.
Species
Specimen
Inst. Locality
Tooth
Time interval
position
CR P M MS
P89.13.396
RAM Pit 48
P4l
Preglacial
l
r
3
P98.5.234
RAM Pit 48
P4l
Preglacial
l
b
4
P02.10.4
RAM Pit 48
M2r
Preglacial
l
2
s
P94.1.843
RAM Pit 48
M3r
Preglacial
l
r r
3
P98.5.52
RAM Pit 48
M1r
Preglacial
l b
4
P04.3.40
RAM Pit 48
M1/M2l
Preglacial
h r r
1
P89.13.400
RAM Pit 48
P4l
Preglacial
l
r r
3
P94.1.259
RAM Pit 48
P4l
Preglacial
l
b
4
P94.1.141
RAM Pit 48
M2r
Preglacial
h r r
1
P94.1.479
RAM Pit 48
M1/M2?l Preglacial
l
r
3
P94.1.613
RAM Pit 48
M1l
Preglacial
l
r b
3
P94.1.150
RAM Pit 48
P4l
Preglacial
l
r
3
P94.8.161
RAM Riverview Pit
P4l
Preglacial
l
r
3
P90.6.38
RAM Apex Evergreen Pit M1r
Preglacial
l
r
3
P95.2.24
RAM Apex Evergreen Pit M1l
Preglacial
l b b
4
P91.11.1
RAM Pit 46
M1r
Preglacial
h
r
1
P91.11.8
RAM Pit 46
M1l
Preglacial
l b
4
P93.8.47
RAM Pit 45
M3r
Preglacial
l b
4
P94.8.52
RAM Riverview Pit
M3r
Preglacial
l
r
3
P94.8.38
RAM Riverview Pit
M2r
Preglacial
l b
4
P94.4.6
RAM Pit 46
P4l
Preglacial
l b b
4
862 (Horse A) RAM Wally's Beach
M2r
Postglacial
l
r r
3
821 RAM Wally's Beach
M1r
Postglacial
l
s r
2
M2r
Postglacial
l b b
4
352
Equus conversidens
American Southwest
Bison antiquus
American
Southwest
E. ferus
scotti
Alberta
Table A 8, continued. Mesowear data of late Pleistocene equid and bison samples studied. CR = cusp relief; P = paracone; M =
metacone; MS = mesowear score; l = low cusps; h = high cusps; r = round cusps; s = sharp cusps; b = blunt cusps. RAM = Royal
Alberta Museum, TMM = Vertebrate Paleontology Laboratory, University of Texas at Austin, UTEP = University of Texas at El Paso.
* indicates Dry Cave localities.
Species
Specimen
Int.
Locality
Tooth
Time interval
position
CR P M MS
M2l
Postglacial
l
r
b
3
71.1 (Horse D) RAM Wally's Beach
3437.1
Postglacial
RAM Wally's Beach
M2l
(Horse 2)
l
r
r
3
865.1
RAM Wally's Beach
M2r
Postglacial
l
s
r
2
P98.8.85
RAM Gertzen Pit
M1r
Postglacial
l
r
r
3
54-1252
UTEP TT II*
M2l
Postglacial
h
r
r
1
937-uncat.
TMM Blackwater Draw
M2r
Postglacial
h
s
s
0
937-886
TMM Blackwater Draw
M3?l
Postglacial
l
b
4
937-907
TMM Blackwater Draw
M2/M3l
Postglacial
l
r
3
937-708
TMM Blackwater Draw
M3l
Postglacial
l
r
3
937-580
TMM Blackwater Draw
M2l
Postglacial
l
r
3
937-uncat.
TMM Blackwater Draw
M3l
Postglacial
h
r
s
0
892-bed #1
TMM Lubbock Lake
M2r
Postglacial
h
r
1
41228-302
TMM Dark Canyon Cave P4l
Preglacial
l
r
3
41228-1026 TMM Dark Canyon Cave M3r
Preglacial
l
r
r
3
41228-1041 TMM Dark Canyon Cave M3l
Preglacial
l
b
4
41228-360
TMM Dark Canyon Cave P4r
Preglacial
l
b b
4
41228-60
TMM Dark Canyon Cave M1/P4l
Preglacial
l
r
3
41228-402
TMM Dark Canyon Cave M3l
Preglacial
l
b
4
41228-391
TMM Dark Canyon Cave M3r
Preglacial
l
r
r
3
75-29
UTEP Dark Canyon Cave M2r
Preglacial
l
r/s
3
22-1609
UTEP Animal Fair*
M2l
Full-glacial
l
b
b
4
22-961
M1r
Full-glacial
l/h r
b
3
353
Table A 9. Hypoplasia data of late Pleistocene equid and bison samples studied. Number and location of hypoplastic defects: b =
buccal, l = lingual, a = anterior, p = posterior. CMH = Canadian Museum of History. Associated teeth indicated by a sequential
number under tooth position.
Species Specimen
Inst.
Locality Tooth position Time interval
Hypoplastic defects
Cementum score
H7(W)-3-25
CMH MgVo-1 Upper M2r Pre-/Full-glacial
1l
3
T3-21-79
CMH MgVo-1 Upper P4r-1 Pre-/Full-glacial
2b
3
T3-21-80
CMH MgVo-1 Upper M1r-1 Pre-/Full-glacial
0
3
4b,
1l
(same event as lower
E7-19-2
CMH MgVo-1 Upper P4r-2 Pre-/Full-glacial
3b, 4l
Equus ferus lambei
Bluefish Caves
b)
E7-20-8
H7(E)-20-5
G6-4-4
D5-F-31
C3(E)-3-2
C5(S)-6.2
H6-6-14
H6-3-26
T.P.I-F.44
T.P.1-F-67
T.P.1-F-35
D6(NE)-8-13
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
CMH
MgVo-1
MgVo-1
MgVo-1
MgVo-2
MgVo-2
MgVo-2
MgVo-2
MgVo-2
MgVo-3
MgVo-3
MgVo-3
MgVo-1
Upper M1r-2
Upper M3l
Upper
P3l
Upper M3r
Upper
P3r
Upper M2l
Upper M1r
Upper
P3l
Upper M1r
Upper M1l
Upper
P4r
Lower m3l
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
T3-21-84
CMH
MgVo-1
Lower p4r-3
Pre-/Full-glacial
T3-21-86
C3(E)-3-2
C3(E)-3-2
C3(E)-3-2
C3(E)-3-2
L7-7-3
M7-2-18
CMH
CMH
CMH
CMH
CMH
CMH
CMH
MgVo-1
MgVo-2
MgVo-2
MgVo-2
MgVo-2
MgVo-1
MgVo-1
Lower
Lower
Lower
Lower
Lower
Upper
Upper
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
Pre-/Full-glacial
m2r-3
m3r-4
m3l-4
p3l-5
m3l-5
P3r
M1r
Postglacial
Postglacial
1l
0
1b
0
1b
0b, NA l
0b, NA l,
0
0
0b, NA l
0b (what is exposed)
2l
2b, 2p (same events), 1l, 1a
(same as lower b and p)
0l, NA b
0l, NA b,
1l, NA b
1p
2b
0b, NA l
0b, NA l
4
3
3
4
2b, NA l
4b, 5l
4b, 5l
2b, 3l
1b, 2l
4b, 5l
4b
0l (what is exposed)
4b, 3l
4l, 5b
3l, 5b
4l, 5b
4l, 5b
4l, 5b
4b, NA l
4b, 5l
354
Equus ferus scotti
Alberta
Equus ferus lambei
Bluefish Caves
Table A 9, continued. Hypoplasia data of late Pleistocene equid and bison samples studied. Number and location of hypoplastic
defects: b = buccal, l = lingual, a = anterior, p = posterior. CMH = Canadian Museum of History, RAM = Royal Alberta Museum.
Species Specimen
Inst.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
M7-1-1
CMH
MgVo-1
Upper
M3r
Postglacial
2b, 2l
4
L8(N)-7-24
CMH
MgVo-1
Upper
P3r
Postglacial
At least 4b, NA l
4b, 5l
L8(N)-8-2
CMH
MgVo-1
Upper
M1r
Postglacial
0b, NA l
4b, 5l
L8(N)-7-4
CMH
MgVo-1
Upper
M3l
Postglacial
NA
5
L7-5-2
CMH
MgVo-1
Upper
M2l
Postglacial
3l, 3b (same events)
3
2l, 2b (lower b same as
CMH
MgVo-1
Upper
M3l
Postglacial
L7-2-1
2
lower l)
5b, 6a (5 anterior events
CMH
MgVo-1
Upper
P3l
Postglacial
M7-2-21
4
correspond to 5b)
I8(S)-12-7
CMH
MgVo-1
Upper
M3l
Postglacial
4l, 4b (same events)
4
L8(N)-5-2
CMH
MgVo-1
Lower
m1r
Postglacial
1b
3
D6-SHL-5
CMH
MgVo-1
Lower
m1l
Postglacial
0
3
L8(N)-7-19
CMH
MgVo-1
Lower
p4r
Postglacial
0
3
L8(N)-11-10
CMH
MgVo-1
Lower
m2l
Postglacial
0l, NA b
4l, 5b
4b, 3a (same as first 3 b),
P83.4.2
RAM
Villenueve
Upper P3/P4l Preglacial
2
2l (upper same as lower b)
P95.2.75
RAM Apex Evergreen Upper
M2r
Preglacial
1l
2
P95.2.54
M2l
Preglacial
0
0
1
(a and p sides
P3r
Preglacial
1b
P95.2.42
weathered)
P90.6.38
M1r
Preglacial
1l
0
Apex
Evergreen
P95.2.1
RAM
Upper
P4r
Preglacial
1a, 2l (different events)
2
P95.2.24
M1l
Preglacial
0
2
P93.8.47
RAM Pit 45
Upper
M3r
Preglacial
1b, 1l (different events)
0
P91.10.16
RAM Pit 45
Upper
P4?l
Preglacial
0
0
P89.6.5
RAM Pit 46
Upper
M3r
Preglacial
0
2
P91.11.1
RAM Pit 46
Upper
M1r
Preglacial
0
0
P91.11.8
RAM Pit 46
Upper
M1l
Preglacial
1b
1 (weathered)
P89.9.1
RAM Pit 45
Upper
M2l
Preglacial
1l, 0a,p; NA b
1 l,a,p; NA b
355
Equus ferus scotti
Alberta
defects: b = buccal, l = lingual, a = anterior, p = posterior. RAM = Royal Alberta Museum.
Species Specimen
Inst.
Locality Tooth position
Time int.
Hypoplastic defects
Cementum score
P04.3.40
RAM Pit 48
Upper
M2l
Preglacial
0
3
P89.13.267
RAM Pit 48
Upper
M2l
Preglacial
2l
1
P89.13.396
RAM Pit 48
Upper
P4l
Preglacial
0
3
P89.13.269
RAM Pit 48
Upper
M1r
Preglacial
0
1
P89.13.270
RAM Pit 48
Upper
M3r
Preglacial
3a, 1l (same as lowermost a)
1
P89.13.223
RAM Pit 48
Upper
M1r
Preglacial
0
0
P98.5.142
RAM Pit 48
Upper M1/2r Preglacial
0
3
P89.13.397
RAM Pit 48
2b
2
P89.13.398
RAM Pit 48
Upper
M2l
Preglacial
0
1
P98.5.21
RAM Pit 48
Upper
P3r-1 Preglacial
3b
4
P98.5.19
RAM Pit 48
Upper
P4l-1 Preglacial
1l, 1b (same) 1p (different)
4
P98.5.20
RAM Pit 48
Upper
P3l-1 Preglacial
3b
4
4b, 3a (same as first 3b), 2a
P98.5.234
RAM Pit 48
Upper
P4l
Preglacial
1
P98.5.191
P98.5.483
P98.5.462
P94.1.726
P94.1.467
P89.13.4
P89.13.60
P89.13.123
P99.3.6
P89.13.392
P89.13.393
P89.13.614
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
M1r
P3l
P3?l
P2r
P2r
P3l
M1l
M2?r
P4?l
M3r
P3/P4r
M3l
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
P89.13.611
RAM
Pit 48
Upper
P3r
Preglacial
(upper same as lowermost b)
1b, 1a (same event), 3l
0
3b, 1l (separate events)
0
0
3b, 3a (same events)
1l
0
0
1l
0
1l
4b, 6a (2nd and 3rd same as 1st
and 2nd b; 4th and 5th same as
3rd b; 6th same as lowermost b)
3
3
2
0
3
1
1
1
1
2
1
2
1
356
Equus ferus scotti
Alberta
Species Specimen
Inst.
Locality Tooth position
Time int.
Hypoplastic defects
Cementum score
P89.13.610
RAM Pit 48
Upper
P4r
Preglacial
3b, 2a (1st same as upper b)
0
P89.13.613
RAM Pit 48
Upper
M1l
Preglacial
0
1
P89.13.618
RAM Pit 48
Upper
M2r
Preglacial
0
1
P89.13.617
RAM Pit 48
Upper
P3l
Preglacial
0
0
P89.13.616
RAM Pit 48
Upper
M2r
Preglacial
2b, 2l (same events)
3
P95.6.41
RAM Pit 48
Upper
M2l
Preglacial
2l
1
P95.6.40
RAM Pit 48
0
2
P95.6.89
RAM Pit 48
Upper
M2l
Preglacial
1a
2
P94.1.557
RAM Pit 48
Upper
P3r
Preglacial
3b
3
P94.1.866
RAM Pit 48
Upper P3/P4r Preglacial
3b, 1a (same as upper b)
1
P94.1.282
RAM Pit 48
Upper
P3r
Preglacial
0
4
P94.1.18
RAM Pit 48
Upper
P2l
Preglacial
2b
1
P94.1.533
RAM Pit 48
Upper
P4r
Preglacial
0
2
P94.1.498
RAM Pit 48
Upper
P4r
Preglacial
0
1
P94.1.242
RAM Pit 48
Upper
P3r
Preglacial
3b, 1l (same as lowest b)
2
P89.13.400
RAM Pit 48
Upper
P4l
Preglacial
1a
3
P94.1.747
RAM Pit 48
Upper
P3l
Preglacial
4b, 3a (same as last 3b)
4
P94.1.470
RAM Pit 48
Upper
P3l
Preglacial
3b
3
2b, 1a, 1p, 1l (lower buccal
P94.1.259
RAM Pit 48
Upper
P4l
Preglacial
1
same as other sides)
P94.1.583
P02.10.125
P94.1.892
P94.1.141
P89.13.612
P89.13.615
P99.3.136
P94.1.479
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
P3l
P3l
P3/P4r
M2r
P4/P3l
P3/P4l
M3l
M1?l
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
0
0
0
1l
0
0
0
0
4
1
0
2
3
1
1
3
357
Equus ferus scotti
Alberta
Species Specimen
Inst.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
P94.1.518
RAM Pit 48
Upper M3l
Preglacial
1a
2
P94.1.584
RAM Pit 48
Upper M3l
Preglacial
0
0
P94.1.634
RAM Pit 48
Upper M2r
Preglacial
0
1
P94.1.468
RAM Pit 48
Upper M1r
Preglacial
0
1
P94.1.613
RAM Pit 48
Upper M1l
Preglacial
0
4
P94.1.765
RAM Pit 48
Upper M2l
Preglacial
1l
2
P94.1.599
RAM Pit 48
Upper P2l
Preglacial
2b
0
P94.1.884
RAM Pit 48
Upper M2r
Preglacial
0
3
P94.1.444
RAM Pit 48
Upper M1r
Preglacial
0
3
P94.1.388
RAM Pit 48
Upper M2r
Preglacial
2l
3
P94.1.556
RAM Pit 48
Upper M1r
Preglacial
2b, 2l (same events)
2
P94.1.497
RAM Pit 48
Upper M2r
Preglacial
0
3
P94.1.478
RAM Pit 48
Upper M2r
Preglacial
3b
1
3b, 1a and 1l (these last two
P94.1.342
RAM Pit 48
Upper M2r
Preglacial
2
same event as upper b)
P94.1.248
RAM Pit 48
Upper M2r
Preglacial
2l, 1a (same event as upper l)
2
P94.1.727
RAM Pit 48
Upper M2l
Preglacial
0
1
P94.1.633
RAM Pit 48
Upper M1?l
Preglacial
0
0
P94.1.560
RAM Pit 48
Upper M2l
Preglacial
0
2
P94.1.449
RAM Pit 48
Upper P3/P4l
Preglacial
0
4
P94.1.378
RAM Pit 48
Upper M1l
Preglacial
0
2
P94.1.150
RAM Pit 48
Upper P3/P4l
Preglacial
2b
2
P94.1.390
RAM Pit 48
Upper M2r
Preglacial
0
3
P96.2.43
RAM Pit 48
Upper P2r
Preglacial
0
4
P04.3.40
RAM Pit 48
Upper M2l
Preglacial
0
3
P94.8.161
RAM Riverview Upper P4l
Preglacial
3b
3
P94.8.14
RAM Riverview Upper M2l
Preglacial
0b, p; NA a, l
2b, 0p weathered
P94.8.84
RAM Riverview Upper M1r
Preglacial
2l
3
358
Equus ferus scotti
Alberta
Species Specimen
Inst.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
P94.8.101
RAM Riverview
Upper P3r
Preglacial
0
0
P89.15.2
RAM Riverview
Upper M1/M2r Preglacial
0
2
P94.8.159
RAM Riverview
Upper P3r
Preglacial
0
2
P94.8.52
RAM Riverview
Upper M3r
Preglacial
0
1
P94.8.38
RAM Riverview
Upper M2r
Preglacial
0
4
Preglacial
2b, 2p (upper same as
P90.6.49
RAM Apex Evergreen Lower m2l
1
lower b)
P90.6.50
Preglacial
1l
1
Preglacial
1a, 1l, 1p (all three same
P90.6.37
event), 2b (separate events)
1
P02.2.5
RAM Apex Evergreen Lower m1r
Preglacial
0l, other sides NA
0l, weathered
P95.2.90
RAM Apex Evergreen Lower p3r
Preglacial
0
3
P02.2.4
RAM Apex Evergreen Lower p3/p4l
Preglacial
0
3
P92.11.3
Preglacial
0
2
P94.5.5
RAM Pit 45
Lower p4/m1r
Preglacial
0b, a; NA l, p
1b, 0a; weathered
P91.11.2
RAM Pit 46
Lower p4r
Preglacial
0
0
P94.4.7
RAM Pit 46
Lower m1r
Preglacial
1b
0 (weathered)
P98.5.484
RAM Pit 48
Lower p3/4l
Preglacial
0
0
P98.5.444
RAM Pit 48
Lower m2r
Preglacial
1b, 1a, (different events)
0
P89.13.50
RAM Pit 48
Lower p3/p4r
Preglacial
0
1
P89.13.391 RAM Pit 48
Lower m1l
Preglacial
0
2
P89.13.395 RAM Pit 48
Lower m1l
Preglacial
0
2
P94.1.213
RAM Pit 48
Lower p3/p4l
Preglacial
1l
2
P94.1.113
RAM Pit 48
Lower m1l
Preglacial
0
1
P05.10.46
RAM Pit 48
Lower m2l
Preglacial
2p
4
P89.13.619 RAM Pit 48
Lower m1/m2r
Preglacial
0
2
P89.13.399 RAM Pit 48
Lower p2r
Preglacial
1b
1
P94.1.486
RAM Pit 48
Lower p3l
Preglacial
1l
3
359
Equus ferus scotti
Alberta
Species Specimen
Inst.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
P94.1.632
RAM Pit 48
Lower p4l
Preglacial
0
2
P94.1.585
RAM Pit 48
Lower p3r
Preglacial
0
0
P94.1.347
RAM Pit 48
Lower m1r
Preglacial
1p
4
P89.13.394 RAM Pit 48
Lower m1?r
Preglacial
0
0
P05.10.26
RAM Pit 48
Lower m3r
Preglacial
0
3b, 0l, a and p
P94.1.582
RAM Pit 48
Lower p4/m1l
Preglacial
0
1
P94.1.519
RAM Pit 48
Lower m2l
Preglacial
2a
1
P94.1.308
RAM Pit 48
Lower m1/p4l
Preglacial
0
0
P94.1.614
RAM Pit 48
Lower m1/p4l
Preglacial
0
0
P94.1.343
RAM Pit 48
Lower p4/m1l
Preglacial
0
1
P94.1.341
RAM Pit 48
Lower m1/p4l
Preglacial
3b
0
P94.1.715
RAM Pit 48
Lower m1l
Preglacial
0
1
P94.1.349
RAM Pit 48
Lower m3/m2r
Preglacial
1b, 1a, 1l (same event)
2
P94.1.397
RAM Pit 48
Lower m3r
Preglacial
0
0
P94.1.348
RAM Pit 48
Lower m3r
Preglacial
2l
1
P94.1.344
RAM Pit 48
Lower m2r
Preglacial
0
3
P94.1.212
RAM Pit 48
Lower m2?r
Preglacial
0
0
P94.1.635
RAM Pit 48
Lower m3l
Preglacial
0
4
P94.1.558
RAM Pit 48
Lower m2r
Preglacial
0 b, p, and a; NA l
0 (weathered)
P94.1.751
RAM Pit 48
Lower m1/m2r
Preglacial
0
3
P94.1.686
RAM Pit 48
Lower m1/m2r
Preglacial
0 l, p, and a; NA b
1 l, p, and a; 5 b
P94.1.306
RAM Pit 48
Lower m1?r
Preglacial
0
2
P94.1.970
RAM Pit 48
Lower m1/p4r
Preglacial
0
4
P94.1.372
RAM Pit 48
Lower m2r
Preglacial
1p, 1a
2
P94.1.124
RAM Pit 48
Lower m2r
Preglacial
1a, 1p (same event)
4
P96.2.21
RAM Pit 48
Lower m2l
Preglacial
2b
1
P96.2.45
RAM Pit 48
Lower p2l
Preglacial
0
1
P05.10.103 RAM Pit 48
Lower p3r
Preglacial
0
3
360
Equus ferus scotti
Alberta
defects: b = buccal, l = lingual, a = anterior, p = posterior. RAM = Royal Alberta Museum. Associated teeth indicated by a sequential
Species Specimen
Inst.
Locality
Tooth position
Time int.
Hypoplastic defects Cementum score
P94.8.137
RAM Riverview
Lower m2l
Preglacial
1b
0
RAM
Lower
Preglacial
5b, 2l (same events
P89.15.1
Riverview
m3r
1
as lower b)
P94.8.87
RAM Riverview
Lower m1/p4r
Preglacial
0
1
P94.19.4
RAM TBG Pit 1042 Lower m1?r
Preglacial
1b
0
P92.8.11
RAM TBG Pit 1042 Upper p4l
Preglacial
0
1
P02.8.5
RAM TBG Pit 4
Upper M2l
Postglacial
0
1
P02.8.1
RAM TBG Pit 4
Upper M2r
Postglacial
0
1
P02.8.3
RAM TBG Pit 4
Upper M3l
Postglacial
0
0
P02.8.14
RAM TBG Pit 4
Upper P2l
Postglacial
1b
1
P02.8.21
RAM TBG Pit 4
Upper M1/M2l Postglacial
0
0
0 (portion parastyle
865.1 (Horse B) RAM Wally's Beach Upper P3l-2
Postglacial 2b exposed section; exposed, other sides
NA other sides
embeded in skull)
821 (Horse C) RAM Wally's Beach Upper P4r-3
Postglacial 0b; NA other sides
3
821 (Horse C) RAM Wally's Beach Upper M1r-3
Postglacial 0b, NA other sides
3
2990.1
RAM Wally's Beach Upper M1l
Postglacial
0
2b, 3l
3437.1 (Horse 2) RAM Wally's Beach Upper P3l
Postglacial 2a (NA other sides)
4a, 5 other sides
2l, 1b (same as
P98.8.85
RAM Gertzen Pit
Upper M1r
Postglacial
upper l)
4
P02.8.67
RAM TBG Pit 4
Lower p2r
Postglacial
1a
3
P02.8.48
RAM TBG Pit 4
Lower p4r-4
Postglacial
1b
2
P02.8.48
RAM TBG Pit 4
Lower m1r-4
Postglacial
0
3
Wally's
Beach
74.1 (Horse C) RAM
Lower m1l-3
Postglacial
0 a, l; NA p, b
0 what is exposed
74.1 (Horse C) RAM Wally's Beach Lower m2l-3
Postglacial
1l, 0b; NA a, p
0 what is exposed
69.1 (Horse D) RAM Wally's Beach Lower p4l-5
Postglacial
1b
0; from CT-scans
69.1 (Horse D) RAM Wally's Beach Lower m1l-5
Postglacial
1b
0; from CT-scans
864 (Horse A) RAM Wally's Beach Lower p4l-6
Postglacial
2b
0; from CT
361
Equus
ferus scotti
Alberta
Species Specimen
Inst.
Locality
Tooth position Time int.
864 (Horse A) RAM Wally's Beach
Lower m1l-6 Postglacial
4b
0; from CT
2b, 2p (same), 2a
0; from CT
(1st same as upper
Lower p4r-2 Postglacial
b), 1l (same as up b)
Lower m1r-2 Postglacial
0
0; from CT
P68.2.690
RAM Apex Evergreen Upper M1l-1 Preglacial
0l, NA b
1l, b (broken)
1l, b (broken and
P68.2.690
RAM Apex Evergreen Upper M2l-1 Preglacial
0l, NA b
Bison sp.
Alberta
weathered)
P68.2.690
P94.1.885
P95.6.88
P94.1.643
P95.6.2
P95.6.108
P95.6.1
P96.2.20
P96.2.42
P98.5.400
P68.2.667
P68.2.666
P68.2.666
P68.2.666
P89.13.207
P96.2.32
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Apex Evergreen
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Pit 48
Apex Evergreen
Apex Evergreen
Apex Evergreen
Apex Evergreen
Pit 48
Pit 48
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Lower
Lower
Lower
Lower
Lower
Lower
P94.1.938
RAM
Pit 48
P95.6.112
RAM
Pit 48
M3l-1
M1r
M3l
M3l
M1l
M1r
M3l
M3r
M3r
M1l
m2l
m1r-2
m2r-2
m3r-2
m1l
m2l
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
0l,p; NA b
0
1l
0
0
0
0
0
0
0
1b
0
0 (what is exposed)
0 (what is exposed)
0b,p; NA a,l
0
Lower m2r
Preglacial
0l; NA b, a, p
Lower m2l-3
Preglacial
0
1l,p; b (weathered)
0
2
1
1
0
1
1
1
0
1
1
1 and in dentary
1 and in dentary
1b,p; a and l broken
1
0l; b,a,p sides in
fragment of dentary
1 (< 25% in dentary)
362
Bison sp.
Alberta
Species Specimen
Inst.
Locality Tooth position Time int.
Hypoplastic defects
Cementum score
P95.6.112
RAM Pit 48
Lower m3l-3 Preglacial
1l
1 and in dentary
P89.13.324
RAM Pit 48
Lower m3r
Preglacial
5b
0
P94.1.122
RAM Pit 48
Lower m2l
Preglacial
0 b, NA l
0b; l weathered
P96.2.46
RAM Pit 48
Lower m2r
Preglacial
1l
0
P94.1.728
RAM Pit 48
Lower m2l
Preglacial
0
3
P95.6.109
RAM Pit 48
Lower m3l
Preglacial
1b, 1a (same event)
1
P96.2.35
RAM Pit 48
Lower m3r
Preglacial
0
0
P96.2.44
RAM Pit 48
Lower m2r
Preglacial
1l
0
P89.13.505
RAM Pit 48
Lower m3l
Preglacial
0
1
P94.1.17
RAM Pit 48
Lower m3r
Preglacial
0
0
P99.3.28
RAM Pit 48
0
1
P99.3.28
RAM Pit 48
0
1
P99.3.28
RAM Pit 48
0
2
P95.6.73
RAM Pit 48
Lower m1r-5 Preglacial
0
1
P95.6.73
RAM Pit 48
0
2
P89.13.326
RAM Pit 48
0
1
P89.13.326
RAM Pit 48
0 what is exposed
1 (lower portion in dentary)
P04.3.62
RAM Pit 48
0
2
P04.3.62
RAM Pit 48
0
3
P89.13.325
RAM Pit 48
0
3
P89.13.325
RAM Pit 48
0l, NAb
2b, 5l
P05.10.88
RAM Pit 48
Lower m3r
Preglacial
0
0
P89.13.158
RAM Pit 48
Lower m1r
Preglacial
0
1
P02.10.98
RAM Pit 48
Lower m1l
Preglacial
0
2
P09.7.10
RAM
P09.7.10
RAM
TBG Pit
1042
TBG Pit
1042
Lower m1l-9
Preglacial
0
1
Lower m2l-9
Preglacial
0
2
363
Bison sp.
Alberta
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
P09.7.10
RAM
P06.2.5
RAM
P02.8.12
P02.8.13
P02.8.23
P02.8.10
P02.8.39
RAM
RAM
RAM
RAM
RAM
TBG Pit
1042
TBG Pit
1042
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
P02.8.7
RAM
P02.8.4
P02.8.40
P02.8.6
P02.8.45
P02.8.9
P02.8.11
P02.8.25
P02.8.24
P90.4.1
P02.8.18
P02.8.33
P02.8.30
P02.8.19
P02.8.35
P02.8.17
P02.8.20
P02.8.43
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
RAM
Lower m3l-9
Preglacial
1b
2
Lower m2?l
Preglacial
1l
1
Upper
Upper
Upper
Upper
Upper
M2r
M2l
M1r
M1l
M3r
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
0
1
1
0
1
TBG Pit 4
Upper
M3l
Postglacial
0
0
0
0
1a
2l and 1b, p (likely same
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
TBG Pit 4
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
M3r
M1l?
M1l?
M1?r
M2l
M2r
M3r
M1r
M1l
m1?r
m3l
m2l
m1/m2r
m3r
m3l
m1r
m3?l
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
as lower b)
3p, 1b (same as upper p)
1p
0
1p
0
0
1b
0
0
0
0b, NAl
1l
0
0
0
0
0
1
1
0
0
0
0
0
1
1
2
1
2b, l side weathered
0
0
2
0
1
0
364
Equus conversidens
American Southwest
Bison sp.
Alberta
defects: b = buccal, l = lingual, a = anterior, p = posterior. RAM = Royal Alberta Museum, TMM = Vertebrate Paleontology
Laboratory, University of Texas at Austin. Associated teeth indicated by a sequential number under tooth position.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
P02.8.8
RAM TBG Pit 4
Lower m3r
Postglacial
0
1
P02.8.26
RAM TBG Pit 4
Lower m2r
Postglacial
0
2
P02.8.28
RAM TBG Pit 4
Lower m1r
Postglacial
0b, NAl
2b, l side broken
P02.8.27
RAM TBG Pit 4
Lower m2?r
Postglacial
0
1
P02.8.42
RAM TBG Pit 4
Lower m3l
Postglacial
1a
2
P02.8.16
RAM TBG Pit 4
Lower m2l
Postglacial
0
0
P02.8.15
RAM TBG Pit 4
Lower m3l
Postglacial
0
1
P02.8.34
RAM TBG Pit 4
Lower m3r
Postglacial
1b, 1l (same event)
0
P02.8.49
RAM TBG Pit 4
0
1
P02.8.49
RAM TBG Pit 4
2b
2
P02.8.49
RAM TBG Pit 4
1b
3 and in dentary
0 posterior half, NA
P02.8.46
RAM TBG Pit 4
Lower m3l
Postglacial
3 and in dentary
anterior half
P02.8.47
RAM TBG Pit 4
0 what is exposed
1
P02.8.47
RAM TBG Pit 4
0 what is exposed
2 and in dentary
Preglacial
1b
1
41228-1026 TMM Dark Canyon Cave Upper m3r
41228-59 TMM Dark Canyon Cave Upper m2-m1l Preglacial
0
3
Preglacial
0
4
41228-221 TMM Dark Canyon Cave Upper m3l
Preglacial
0
4 (b side weathered)
Preglacial
2b
4
Preglacial
1b
4
41228-1051 TMM Dark Canyon Cave Upper p3r
Preglacial
0
4
Preglacial
0
4
41228-261 TMM Dark Canyon Cave Upper m1-m2l Preglacial
1a, 1b (different events)
4
41228-311 TMM Dark Canyon Cave Upper p4?r
Preglacial
0
1
41228-60 TMM Dark Canyon Cave Upper m1-p4l Preglacial
0
4
1b
1
41228-368 TMM Dark Canyon Cave Upper m2?r
Preglacial
365
defects: b = buccal, l = lingual, a = anterior, p = posterior. TMM = Vertebrate Paleontology Laboratory, University of Texas at Austin.
Associated teeth indicated by a sequential number under tooth position.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
Preglacial
1b
0
Preglacial
1l
4
Preglacial
0
3
Preglacial
0
1
75-31/75-29 TMM Dark Canyon Cave Upper p3r
Preglacial
0
4
41228-3857 TMM Dark Canyon Cave Lower m2r
Preglacial
0
3
41228-1031 TMM Dark Canyon Cave Lower p4r
41228-288 TMM Dark Canyon Cave Lower m3r
Preglacial
0
1
3
(buccal side
41228-3817 TMM Dark Canyon Cave Lower m2?l
Preglacial
0
Equus conversidens
American Southwest
broken)
TMM
41228-299 TMM
41228-254 TMM
41228-3888 TMM
41228-1025 TMM
41228-389 TMM
41228-367 TMM
41228-361 TMM
41228-235 TMM
41228-3841 TMM
41228-375 TMM
41228-3874 TMM
41228-3821 TMM
41228-3821 TMM
41228-252 TMM
41228-234 TMM
41228-386 TMM
41228-232 TMM
41228-1038
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Dark Canyon Cave
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
m2r
p4?r
m3r
m1l
m1l
p4r
p3r
m2l
m2?r
m2r
m1-m2l
m1-m2r
p4r-1
p3r-1
m3l
m2l
p3r
m2l
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
Preglacial
0
0
0
0
0
0
0
1p
0
3b
0
0
3
2
2
3
4
4
4
5
1
3
1
3
1l
0
0
0
0
0
5
3
3
2
4
4
366
Equus conversidens
American Southwest
defects: b = buccal, l = lingual, a = anterior, p = posterior. TMM = Vertebrate Paleo. Laboratory, University of Texas at Austin, UTEP
= University of Texas at El Paso. * indicates Dry Cave localities. Associated teeth indicated by a sequential number in tooth position.
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
41228-233 TMM Dark Canyon Cave Lower m2l
Preglacial
0
1
41228-239 TMM Dark Canyon Cave Lower p3-p4l
Preglacial
1l
2
41228-158 TMM Dark Canyon Cave Lower m1-m2r Preglacial
0
4
41228-272 TMM Dark Canyon Cave Lower m1?l
Preglacial
1l
2
41228-394 TMM Dark Canyon Cave Lower m2l
Preglacial
0
4
41228-247 TMM Dark Canyon Cave Lower m1-m2r Preglacial
0
1
Preglacial
1l, 1p (same event)
1
41228-uncat TMM Dark Canyon Cave Lower m2r
Preglacial
1l, 1b (same event)
1
41228-uncat TMM Dark Canyon Cave Lower m3r
41228-181 TMM Dark Canyon Cave Lower m1-m2l Preglacial
0
4
75-29
TMM Dark Canyon Cave Lower m2r
Preglacial
1l
4
75-30
TMM Dark Canyon Cave Lower m1/m2l Preglacial
0
4
Full-glacial 2l, 1b (same as upper l)
22-961
UTEP Charlies Parlor* Upper M1r
4
Full-glacial
22-1609
UTEP Animal Fair*
Upper M3l
1l
5
Full-glacial
22-669
UTEP Animal Fair*
Lower p2r-2
1a
4
Full-glacial
22-669
UTEP Animal Fair*
Lower p3r-2
1b
4
Full-glacial
22-682
UTEP Animal Fair*
Lower m3l
0
2
Full-glacial
22-955
UTEP Animal Fair*
Lower p2d
0 (what is exposed)
2 (in dentary)
Postglacial 3b, 1l (same as one of
937-uncat TMM Blackwater Draw Upper M3r
0
b)
937-203
937-195
937-194
937-322
937-918
937-504
937-504
TMM
TMM
TMM
TMM
TMM
TMM
TMM
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Upper
Upper
Upper
Upper
Upper
Upper
Upper
M2r
M2r
M1l
M1r
M1/P4r
P3/P4r-3
P3r-3
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
0
1l, 1a (same event)
0
0
0
2l
1l
3
0
3
1
4
4
4
367
Equus conversidens
American Southwest
Locality
Tooth position
Time int.
937-504
TMM Blackwater Draw Upper M2l-3
Postglacial
0
4 (weathered)
937-504
TMM Blackwater Draw Upper P3/P4l-3 Postglacial
0
4
TMM Blackwater Draw Upper P4/M1r Postglacial
3b
4
937-uncat
937-857
Postglacial
0
1
892-457
TMM Lubbock Lake
Upper P4l
Postglacial
1b
3 (cast)
892-458
TMM Lubbock Lake
Upper M3r
Postglacial
0
3 (cast)
998-7
TMM Scharbauer Ranch Upper P3l
Postglacial
2b
1
998-8
TMM Scharbauer Ranch Upper M2l
Postglacial
0
1
Scharbauer
Ranch
TMM
Upper M3l
Postglacial
0
1
998-uncat
31-47
UTEP Early man corridor* Upper P4l-4
Postglacial
1b
4b, NA l (in maxillary)
31-47
UTEP Early man corridor* Upper M1l-4
Postglacial
0
31-47
UTEP Early man corridor* Upper M3l-4
Postglacial
3b
4b NA l (in maxillary)
4-827
UTEP Bison Chamber* Upper M1r
Postglacial
1b
5
54-1212
UTEP TTII*
Upper P2l
Postglacial
0b, NA l
54-827
UTEP TTII*
Upper M1l
Postglacial
0
4
937-930
Postglacial
0
2
937-122
TMM Blackwater Draw Lower p4l
Postglacial
1p
0
937-123
TMM Blackwater Draw Lower p2r
Postglacial
0
2
937-944
Postglacial
1b
1
Blackwater
Draw
937-121
TMM
Lower m1r
Postglacial
0
2
937-692
Postglacial
1b
0 (weathered)
937-973
Postglacial
2b
0
1b, 1l (different
937-702
Postglacial
2
events)
998-9
TMM
Scharbauer Ranch
998-10
TMM
Scharbauer Ranch
Lower p3r
Postglacial
Lower m2r
Postglacial
1b
2b, 1a (different
events)
3l, NAb (in frag. dentary)
0
368
E.
conver
-sidens
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
23-65
UTEP Stalag 17*
Lower p3r
Postglacial
0
4
23-64
UTEP Stalag 17*
Lower m2r
Postglacial 1b, 1p (same event)
4
23-77
UTEP Stalag 17*
Lower m1l
Postglacial
0
3
4b, 2l (same as two
Full-glacial
22-1608
UTEP Charlie's parlor* Upper P4r-1
1
Equus ferus scotti
American Southwest
lower b)
22-1608
22-1608
22-1611
22-1611
22-1617
22-64
22-64
22-65
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
UTEP
Animal Fair*
Animal Fair*
Animal Fair*
Animal Fair*
Animal Fair*
Animal Fair*
Animal Fair*
Animal Fair*
Upper
Upper
Upper
Upper
Upper
Upper
Upper
Upper
P4l-1
M1l-1
M3r-2
M3l-2
P2l
M1l-3
M3l-3
M3l
Full-glacial
Full-glacial
Full-glacial
Full-glacial
Full-glacial
Full-glacial
Full-glacial
Full-glacial
22-981
UTEP
Charlie's parlor*
Upper
M3l
Full-glacial
22-985
22-1607
22-1616
22-1645
22-61
UTEP
UTEP
UTEP
UTEP
UTEP
Charlie's parlor*
Animal Fair*
Charlies Parlor*
Animal Fair*
Animal Fair*
Upper
Lower
Lower
Lower
Lower
M1l
m1r
m1r
m3l
m1l-4
Full-glacial
Full-glacial
Full-glacial
Full-glacial
Full-glacial
0l,p,a, NA b
0b (lingual side NA)
0
2l
0
22-61
UTEP
Animal Fair*
Lower p3l-4
Full-glacial
0l (what is exposed)
22-61
UTEP
Animal Fair*
22-648
937-738
UTEP
TMM
937-678
TMM
Lower p4l-4
0
0
0
0
1b
2b
0 (what is exposed)
2b,2l (same events)
0l, 0b (what is
exposed)
Full-glacial
0l
Animal Fair*
Lower m1/m2l
Blackwater Draw Upper P4?l
Full-glacial
0
0
Blackwater Draw Upper
Postglacial
P3r
Postglacial
2b, 1a (same as lower
b)
4 (partially in plaster)
4 (partially in plaster)
0
0
3
4
2
4
4 (partially In maxillary)
2 (buccal side in maxillary)
0b, 5l
4
4
4
4 (b and bottom of l in
dentary)
5 (b and bottom of l in
dentary)
4
0
0
369
Equus ferus scotti
American Southwest
defects: b = buccal, l = lingual, a = anterior, p = posterior. TMM = Vertebrate Paleo. Laboratory, University of Texas at Austin.
Locality
Tooth position
Time int.
Blackwater
Draw
937-170
TMM
Upper P3l
Postglacial
0
0
937-191
Postglacial
2l, 1a
0
937-738
Postglacial
0
0
3b, 1a (same as 2nd
937-253
TMM Blackwater Draw Upper P4l
Postglacial
1
b), 1l (same as 1st b)
937-uncat TMM Blackwater Draw Upper M1l
Postglacial
0
1
937-738
Postglacial
2l
0
937-968
Postglacial
0
0
937-799
Postglacial
0
0
Scharbauer
Ranch
998-26
TMM
Upper P2l
Postglacial
0
1
998-24
TMM Scharbauer Ranch Upper P2r
Postglacial
1b
1
Scharbauer
Ranch
998-25
TMM
Upper P3/P4r Postglacial
2b
1
998-uncat TMM Scharbauer Ranch Upper P2l
Postglacial
1b
3
998-25
TMM Scharbauer Ranch Upper P3/P4r Postglacial
0
4
998-26
TMM Scharbauer Ranch Upper M1r
Postglacial
0
4
937-931
Postglacial
0
0
937-848
Postglacial
2b
2
937-738
Postglacial
3 b,l,a,p (same)
0
937-969
Postglacial
0
2
937-760
Postglacial
2b
2
Blackwater
Draw
937-39
TMM
Lower m2l
Postglacial
0
1
937-952
Postglacial
0
3
937-956
TMM Blackwater Draw Lower m1/m2r Postglacial
0
1
937-955
TMM Blackwater Draw Lower p4/m1l Postglacial
2b
1
937-961
TMM Blackwater Draw Lower p3/p4l
Postglacial
1l
0
937-965
Postglacial
2b
0
937-953
TMM Blackwater Draw Lower m1/m2 Postglacial
0
0
937-949
Postglacial
3b
0
370
Equus ferus scotti
American Southwest
Locality
Tooth position
Time int.
Hypoplastic defects
Cementum score
Blackwater
Draw
937-950
TMM
Lower p4l
Postglacial
0
0
937-964
Postglacial
0
0
937-678
TMM Blackwater Draw Lower m1/m2r Postglacial
0
1
937-192
Postglacial
2b
0
937-169
Postglacial
0
0
937-781
Postglacial
0
3
937-246
Postglacial
2b
0
937-223
Postglacial
5b 1l (different from b)
0
937-254
Postglacial
0
0
2a,p; 1b,l (same as upper
937-933
Postglacial
0
a,p)
937-945
937-119
937-244
937-250
937-251
937-971
937-970
937-940
937-937
937-125
937-225
937-252
937-977
937-859
937-725
937-702
892-299
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
TMM
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Blackwater Draw
Lubbock Lake
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
Lower
p3l
m2r
p4l
p3l
p4/m1l
m2r
m3r
p4l
m1l
m3l
m2r
m1l
m3l
m1l
p4r
m1-m2r
m3r
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
Postglacial
1b
2b, 2a (same events)
0
0
1b
3b, 1p (same as 2nd b)
3b, 1l (same as lower b)
0
0
3b, 1l (same as upper b)
1b
2b, 1a (same as upper b)
0
3b, 3p (same events)
2b
3
0
0
0
0
0
1
1
2
0
1
0
2
0
1
1
4
371
Bison antiquus
American Southwest
Associated teeth indicated by a sequential number in tooth position.
Locality
Tooth position
Time int.
937-uncat. TMM Blackwater Draw Upper M2r-1
Postglacial
0
3 (l side covered by matrix)
Postglacial 2b, 2l (same events)
1
Postglacial
0
1
937-886
0
1
937-886
0
0
937-886
TMM Blackwater Draw Upper M3?l
Postglacial
0
0
937-907
TMM Blackwater Draw Upper M2/M3l Postglacial
0
1
937-492
TMM Blackwater Draw Upper M1/M2r? Postglacial
0
0
937-492
0
0
937-708
TMM Blackwater Draw Upper M3l-2
Postglacial
1b
0
Blackwater
Draw
937-582
TMM
Upper M2l?-3 Postglacial
0
0
937-708
TMM Blackwater Draw Upper M3r-2
Postglacial
0
0
937-580
Postglacial
0
0
937-582
Postglacial
0
0
937-582
Postglacial
1b
0
937-582
TMM Blackwater Draw Upper M1?r?-3 Postglacial
0
0
937-uncat. TMM Blackwater Draw Upper M3l
Postglacial
0
2
Scharbauer
Ranch
998-uncat. TMM
Upper M3l
Postglacial
0
3
998-uncat. TMM Scharbauer Ranch Upper M1?l
Postglacial
1l
2
Blackwater
Draw
937-667
TMM
Lower m3r
Postglacial
0
2
937-523
Postglacial
1b
2 (in dentary)
937-492
TMM Blackwater Draw Lower m1l-4
Postglacial
0
0 (extremely worn)
937-492
TMM Blackwater Draw Lower m2l-4
Postglacial
0
0 (extremely worn)
937-492
Postglacial
0
0 (extremely worn)
937-707
Postglacial
0
0
937-uncat. TMM Blackwater Draw Lower m??
Postglacial
0
2
998-194
TMM Scharbauer Ranch Lower m3r
Postglacial
0
0
372

The Late Pleistocene Extinction in North America: An Investigation of

Transcription

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