Hadrosaur Symposium Abstract Volume

Drumheller , A lberta , Ca nada September 22 – 23, 2011
Abstract
Volume
INTERNATIONAL
HADROSAUR SYMPOSIUM
at the Royal Tyrrell Museum of Palaeontology, September 22 – 23, 2011
PROGRAM & ABSTRACTS Compiled by:
Dennis R. Braman, David A. Eberth, David C. Evans, Wendy Taylor
Sponsors:
Royal Tyrrell Museum · Royal Ontario Museum · Royal Tyrrell Museum Cooperating Society
Royal Tyrrell Museum of Palaeontology Box 7500 Drumheller, Alberta, Canada T0J 0Y0
PH: 403-823-7707 F X: 403-823-7131 www.tyrrellmuseum.com
1
Organizing Committee
Co-convenors:
David A. Eberth
David C. Evans
AV Support:
Ken Elsbett
Warren Nicholls
Program:
David A. Eberth
David C. Evans
Posters:
Rhian Russell
Marilyn Laframboise
Luke Webster
Field Trip:
Dave A. Eberth
David C. Evans
Donald B. Brinkman
Becky Kowalchuk
Display Specimens:
David C. Evans
Jim McCabe
Luke Webster
Publications and Printing:
Dennis R. Braman
David A. Eberth
Wendy Taylor
Kelly Kuhl
Graphic Design, Artwork, and Signage:
Kelly Kuhl
Wendy Taylor
Becky Kowalchuk
RTMP Design Studio
Registration:
Wendy Laughlin
Becky Kowalchuk
Web Support, Promotion, and Information:
Lisa Making
Kelly Kuhl
Wendy Laughlin
Hospitality and Conference Organization:
Becky Kowalchuk
David Lloyd
Product Development:
Amie Courtenay
The organizing committee thanks the contributors, participants, sponsors, and the
volunteers who helped to make the symposium a success.
2
Symposium Events at a Glance
date & time
location
event
Wednesday, Sept. 21
6:00 PM – 8:00 PM
Royal Tyrrell Museum
Lobby
Icebreaker, Behind-the-Scenes
Tours, Presentation Drop-Off
Learning Centre
Poster Set-Up
Thursday, Sept. 22
8:00 AM – 5:00 PM
5:30 PM – 8:00 PM
Royal Tyrrell Museum
Auditorium
Oral Sessions
Learning Centre
Posters
Dinosaur Trail Golf
and Country Club
(2km west of the Museum)
Symposium Supper
Friday, Sept. 23
8:00 AM – 5:00 PM
Royal Tyrrell Museum
Auditorium
Oral Sessions
Learning Centre
Posters
Dinosaur Provincial Park
Field Trip
(Depart/Return Ramada Inn)
Saturday, Sept. 24
8:00 AM – 8:00 PM
3
ORAL PROGRAM at a Glance
Thursday, Sept. 22
Friday, Sept. 23
8:00 – 8:20 AM
Welcome
8:20 – 9:00
Weishampel
Coria
9:00 – 9:20
Norman
Sullivan
9:20 – 9:40
McDonald
Ramírez-Velasco
9:40 – 10:00
Larson
Gates
10:00 – 10:20
break
10:20 – 10:40
Tsogtbaatar
Freedman
10:40 – 11:00
Dalla Vecchia
Evans
11:00 – 11:20
Cruzado-Caballero
Farke
11:20 – 11:40
Godefroit
McGarrity
11:40 – 12:00
Godefroit
Getty
12:00 – 1:20 PM
lunch
1:20 – 1:40
Lauters
Servín-Pichardo
1:40 – 2:00
Erickson
Fricke
2:00 – 2:20
Nabavizadeh
Ryan
2:20 – 2:40
Maidment
McCrea
2:40 – 3:00
Persons, IV
Tanke
3:00 – 3:20
break
3:20 – 3:40
Henderson
Brink
3:40 – 4:00
Bell
Bailleul
4:00 – 4:20
Clayton
Campione
4:20 – 4:40
Manning
Horner
4:40 – 5:00
—
Horner
bold = Keynote speakers
4
Hadrosaur Symposium Oral Program
Thursday Morning, Sept. 22 — Auditorium
Moderators: David A. Eberth and David C. Evans
8:00 – 8:20
Andrew G. Neuman, David A. Eberth, Welcome
David C. Evans
8:20 – 9:00
David B. Weishampel
Keynote : A history of scientific
works on hadrosaurs and how are
we to understand their phylogeny
9:00 – 9:20
David B. Norman
Basal iguanodontians in the Wealden
of England
9:20 – 9:40
Andrew T. McDonald
The phylogeny, taxonomy, and
biogeography of basal iguanodonts
(Dinosauria: Ornithischia)
9:40 – 10:00
Derek W. Larson, Nicolás E.
A hadrosauroid from the Santonian
Campione, C. Marshall Brown,
Milk River Formation of Alberta,
David C. Evans, and Michael J. Ryan Canada.
10:00 – 10:20
break
10:20 – 10:40 Khishigjav Tsogtbaatar, David B.
Weishampel, and Mahito Watabe
Keynote : Phylogenetic and
biogeographic importance of an
early Late Cretaceous (Cenomanian
- Campanian) hadrosauroid
(Ornithopoda) newly described
from Mongolia
10:40 – 11:00
Fabio Marco Dalla Vecchia, Rodrigo The hadrosaurid record in the
Gaete, Violeta Riera, Oriol Oms,
Maastrichtian of the eastern Tremp
Albert Prieto-Márquez, Bernat Vila,
Syncline (northern Spain)
Albert Garcia Sellés, and Angel
Galobart
11:00 – 11:20
Penélope Cruzado-Caballero,
J.I. Canudo, M. Moreno-Azanza,
and J.I. Ruiz-Omeñaca
The complex fauna of European
Maastrichtian hadrosaurids:
contributions of the lambeosaurines
from the Iberian Peninsula
11:20 – 12:00
Pascal Godefroit, Yuri Bolotsky,
Lina Golovneva, Wu Wenhao,
and Pascaline Lauters
Keynote : New data on latest
Cretaceous hadrosaurids from
Russia and north-eastern China
12:00 – 1:20
lunch
5
Thursday Afternoon, Sept. 22 — Auditorium
Moderators: François Therrien and Nicolás E. Campione
1:20 – 1:40
Pascaline Lauters, Martine
Vercauteren, and Pascal Godefroit
Brain of ornithopods and new
characters for phylogenetic analyses
1:40 – 2:00
Gregory M. Erickson and Mark A.
Norell
The osteohistology of hadrosaurid
dinosaur teeth—reptiles that
exceeded mammals in dental
complexity?
2:00 – 2:20
Ali Nabavizadeh
The functional significance of the
predentary bone in ornithopod jaw
mechanisms
2:20 – 2:40
Susannah C.R. Maidment, Karl Bates, Stance and gait in hadrosaurs:
and Paul M. Barrett
3D computational modelling of
locomotor muscle moment arms
in Edmontosaurus
2:40 – 3:00
W. Scott Persons, IV
3:00 – 3:20
6
Duckbills on the run: comparing the
cursorial abilities of hadrosaurs and
tyrannosaurs
break
3:20 – 3:40
Donald M. Henderson
Hopeful hadrosaurs and cursed
ceratopsians—the floating fates of
Dinosaur Provincial Park herbivores
during large-scale flooding events
3:40 – 4:00
Phil R. Bell and Philip J. Currie
The integument of the Laurasian
hadrosaur, Saurolophus, and a new
terminology for scale description
4:00 – 4:20
Katherine E. Clayton, Randall B.
Irmis, Michael A. Getty, Eric K. Lund,
William J. Nicholls, and Mark A.
Loewen
Non-osseous dermal scutes and
integument impressions from an
exceptionally preserved hadrosaurid
dinosaur skeleton, Upper Cretaceous
Kaiparowits Formation of Utah
4:20 – 4:40
Phillip L. Manning, R.A. Wogelius,
M. Buckley, B.E. van Dongen, T.
Lyson, U. Bergmann, S. Webb,
and W.I.S. Sellers
A multidisciplinary approach to
the analysis of fossil hadrosaur
integument and the taphonomic
role of skin pigment in exceptional
preservation
Friday Morning, Sept. 23 — Auditorium
Moderators: Donald B. Brinkman and Phil R. Bell
8:20 – 9:00
Rodolfo Coria
Keynote : South American
hadrosaurs: considerations on their
diversity
9:00 – 9:20
Robert M. Sullivan, Spencer G.
Lucas, and Joshua Fry
Hadrosaurid biostratigraphy of the
Upper Cretaceous Fruitland, Kirtland
and Ojo Alamo formations, San Juan
Basin, New Mexico
9:20 – 9:40
Ángel Alejandro Ramírez-Velasco
and René Hernández-Rivera
Review of the osteology record
of Mexican hadrosauroids
9:40 – 10:00
Terry A. Gates, Zubair Jinnah,
Michael A. Getty, and Carolyn G.
Levitt
Hadrosaurid dinosaurs from the
Upper Cretaceous (Campanian)
Wahweap Formation of southern
Utah: implications for biogeography
and biostratigraphy
10:00 – 10:20
break
10:20 – 10:40
Elizabeth Anne Freedman
10:40 – 11:00
David C. Evans, Philip J. Currie,
A new low-crested lambeosaurine
Larry M. Witmer, and John R. Horner hadrosaurid from the Dinosaur Park
Formation of Sandy Point, eastern
Alberta.
11:00 – 11:20
Andrew A. Farke
A juvenile lambeosaurine
(?Parasaurolophus) skull and skeleton
from the Kaiparowits Formation of
southern Utah, and developmental
timing in lambeosaurine ontogeny
11:20 – 11:40
Christopher T. McGarrity, David C.
Evans, and Nicolás E. Campione
Cranial anatomy and systematics of
Prosaurolophus maximus
11:40 – 12:00
Michael A. Getty
New Gryposaurus material from
the Kaiparowits Formation of
Grand Staircase Escalante National
Monument to be featured in the New
Natural History Museum of Utah in
Salt Lake City, Utah.
12:00 – 1:20
A new species of Brachylophosaurus
(Ornithischia: Hadrosauridae)
from the Judith River Formation
(Late Cretaceous: Campanian) of
northcentral Montana
lunch
7
Friday Afternoon, Sept. 23 — Auditorium
Moderators: Donald M. Henderson and Derek W. Larson
1:20 – 1:40
Ricardo Servín-Pichardo, René
Hernández-Rivera, and Ángel
Alejandro Ramírez-Velasco.
Ichnological hadrosaurian record
from Mexico
1:40 – 2:00
Henry C. Fricke
Stable isotope approaches to the
study of hadrosaurid behavior
2:00 – 2:20
Michael J. Ryan, David A. Eberth,
David C. Evans, Donald B. Brinkman,
and M. Clemens
Taphonomy and behavioral
implications of Edmontosaurus
(Ornithischia: Hadrosauridae)
bonebeds from the Horseshoe
Canyon Formation (Upper
Campanian), Alberta, Canada
2:20 – 2:40
Richard T. McCrea and
Lisa G. Buckley
Preliminary observations and
interpretations on a hadrosaur
(Lambeosaurinae) associated
with an abundance of juvenile
tyrannosaur (Albertosaurinae)
teeth from the Upper Cretaceous
(Campanian/Maastrichtian) Wapiti
Formation of northeastern British
Columbia
2:40 – 3:00
Darren H. Tanke and David C. Evans
Relocating the lost 1918 Royal
Ontario Museum’s Gryposaurus
incurvimanus quarry, Dinosaur
Provincial Park, Alberta, Canada
with comments on Gryposaurus
biostratigraphy
3:00 – 3:20
8
break
3:20 – 3:40
Kirstin S. Brink, Darla K. Zelenitsky,
David C. Evans, John R. Horner,
and François Therrien
Hypacrosaurus stebingeri: an
exceptional record of dinosaurian
cranial ontogeny
3:40 – 4:00
Alida M. Bailleul and John R. Horner
Early ossification and calcified
tissues in the skull of Hypacrosaurus
stebingeri (Ornithischia,
Lambeosaurinae)
4:00 – 4:20
Nicolás E. Campione and David
C. Evans
Body size variation and evolution
in hadrosauroid dinosaurs
4:20 – 5:00
John R. Horner and Holly N.
Woodward
Keynote: Riddle of the humongous
hadrosaurs: What these giants reveal
about dinosaur ontogeny, evolution,
and ecology
Posters (Atco Tyrrell Learning Centre Classrooms)
#
Authors
Title
1
Phil R. Bell, Federico Fanti, Robin
L. Sissons, Michael E. Burns, and
Philip J. Currie
A possible new hadrosaurine from
the Wapiti Formation (CampanianMaastrichtian), northwestern Alberta
2
Donald B. Brinkman
The size-frequency distribution of
hadrosaurs from the Dinosaur Park
Formation of Alberta, Canada
3
David A. Eberth and David C. Evans
First documented hadrosaurid bonebed
from the Belly River Group (Campanian)
at Dinosaur Provincial Park, Alberta,
Canada: importance and implications
4
Becky Gould, Allan Ashworth,
and Ron Nellermoe
Determining individual Edmontosaurus
from a disarticulated bonebed using
Principal Components Analysis
5
Merrilee Guenther, Mateusz Wosik,
and Stephanie McCarthy
Adding to hadrosaurid diversity in New
Mexico through the reexamination
of a historic collection
6
Shantungosaurus giganteus: the
B.P. Hedrick, Phillip L. Manning, A.T.
McDonald, E. Morschhauser, P. Dodson, implications of body size on bipedality
L. Margetts, K.A. Stevens, and W.I.S.
Sellers
7
Lucia Herrero and Andrew A. Farke
Morphological variation in the skull roof
of Gryposaurus from the Kaiparowits
Formation (late Campanian) of southern
Utah
8
Naoki Ikegami and Yukimitsu Tomida
Hadrosaurid remains from the early Late
Cretaceous Mifune Group in Kumamoto
Prefecture, Japan: implications to the
early radiation of hadrosaurids
9
Derek J. Main, Christopher R. Noto,
David B. Weishampel, and Christopher
R. Scotese
New basal hadrosauroid postcrania from
the Cretaceous (Cenomanian) Woodbine
Formation at the Arlington Archosaur Site,
North Texas
10
Jordan C. Mallon, Robin S. Cuthbertson,
and Alex Tirabasso
Hadrosaurid jaw mechanics as revealed
by cranial joint limitations and dental
microwear analysis
11
Tomoyuki Ohashi
An investigation on the feeding
mechanisms of the basal hadrosaur
(Hadrosauroidea) using the 3D finite
element method
9
Posters (Atco Tyrrell Learning Centre Classrooms) continued
10
12
Albert Prieto-Márquez and Jonathan R.
Wagner
New insights into the narial anatomy
of saurolophine hadrosaurids revealed
by a “mummified” specimen of
Edmontosaurus annectens
13
Masateru Shibata and Yoichi Azuma
Iguanodontian dentaries from the Lower
Cretaceous Kitadani Formation, Fukui,
central Japan
14
Shayda Spakowski, Brandon Strilisky,
and Rhian Russell
Why paleo-conservation is important:
an examination of the techniques used
to prepare and conserve a portion of a
neglected hadrosaur skeleton
15
Daisuke Suzuki and Tomoyuki Ohashi
Evaluation of bone-tendon morphology
of hadrosaur skeletons based on recent
crocodilian histology.
16
Darren H. Tanke and Bruce M. Rothschild Osteopathy in Hadrosauridae from
Alberta, Canada
17
François Therrien, Darla K. Zelenitsky,
Kohei Tanaka, and Wendy J. Sloboda
18
Collin S. VanBuren and Matthew F. Bonnan Quantifying forelimb posture in
hadrosaurs: a morphometric approach
First hadrosaur trackway from the Upper
Cretaceous (late Campanian) Oldman
Formation, southeastern Alberta
EARLY OSSIFICATION AND CALCIFIED TISSUES IN THE SKULL OF
HYPACROSAURUS STEBINGERI (ORNITHISCHIA, LAMBEOSAURINAE)
Alida M. Bailleul1 and John R. Horner2
1
Montana State University - Museum of the Rockies, 600 West Kagy Boulevard, Bozeman, Montana, 59717; <alida.
[email protected]>
2
Museum of the Rockies, Bozeman, Montana, USA; <[email protected]>
From a histological perspective, the early phases of dinosaur skull development remain poorly
understood. Here we describe the different calcified tissues present in craniofacial elements from a
perinate Hypacrosaurus from the Upper Cretaceous of Montana. Every element is highly cancellous,
vascularized, and mostly composed of primary woven bone trabeculae. This indicates a rapid growth due
to early ontogeny, fast brain development and metabolism. In some areas (e.g. the sutural edges of the
surangular, frontal and parietal, and in alveolar processes of the dentary and the premaxilla) the tissues
show a “chondroid-like” organization, morphologically intermediate between bone and cartilage: a
calcified extracellular matrix with numerous cellular lacunae showing the appearance of non-hypertrophic
chondrocytes. Despite the early ontogenetic stage of this specimen, secondary reworking has already
begun (e.g. the parietal shows an extensive secondary endosteal spongiosa). Six endochondral bones
show remnants of primary cartilage on their sutural edges: the basisphenoid, the prootic, the quadrate the
supraoccipital, the exoccipital and the basioccipital. The chondrocyte lacunae are rounded, hypertrophic
and organized into nodules or papillae. Patches of hypertrophic cartilage are also found on three
membrane bones: the surangular, the dentary and the maxilla. This suggests the existence of secondary
chondrogenesis in Hypacrosaurus, which is also observed in extant avian and mammalian membrane
bones. This first report of secondary cartilage in a non-avian dinosaur is interesting because this tissue
is critical to understanding growth, physiology and phylogeny. This sheds light on the early craniofacial
histogenesis of a dinosaur and emphasizes the importance of investigating the bone microstructure of
skulls, in parallel with the more widely studied postcranial elements.
11
The integument of the Laurasian hadrosaur, Saurolophus,
and a new terminology for scale description
Phil R. Bell1 and Philip J. Currie2
1
2
Pipestone Creek Dinosaur Initiative, Clairmont, Alberta, Canada.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Hadrosaurid skin impressions are relatively well known, yet few attempts have been made to synthesise
what is currently known of scale morphology, distribution (of scale morphotypes), or taxonomic utility.
Integumentary impressions pertaining to Saurolophus osborni and Saurolophus angustirostris, permit,
for the first time, a look at intrageneric variability of scale architecture. This serves as a proxy for softtissue-based identification of closely related taxa. Two general scale types are recognised: 1. ‘matrixscales’ are small (2–7mm), somewhat uniform in size, and constitute the major part of the integumentary
covering; 2. ‘Feature-scales’ are notably larger (7­–>30mm) than the surrounding matrix-scales, are
sparsely distributed, and may be absent altogether. Matrix- and feature-scales can be further broken
down into subcategories based on their outlines, surface features, and imbrication. Saurolophus is
characterised by a solid posterodorsally-oriented cranial crest, and species of this genus have the same
osteological bauplan in both cranial and postcranial anatomy. Analysis of integumentary impressions,
however, can be used to distinguish the two species based solely on scale morphology and patterns. S.
angustirostris is differentiated from S. osborni by the presence of tabular midline feature-scales along
the length of the tail and a banded pattern of scales at the base of the tail. The hindlimb and proximal part
of the tail of S. angustirostris were covered in circular shield feature-scales that were set in a grid-like
arrangement. Preliminary results suggest these patterns were ontogenetically stable. Skin impressions
from S. osborni are less well known; however, it apparently shared similarities with Edmontosaurus in the
presence of cluster areas of similar-sized scales on the tail. Comparisons with other hadrosaurids suggest
widespread morphological variability in scale architecture, especially in the caudal region, which is best
represented. Soft-tissue variation (including colour, size, and shape of integumentary features) is central
to the traditional taxonomic identifications of extant organisms, including crocodilians and birds, the
closest living relatives of dinosaurs. However, identification of dinosaurian taxa based only on soft-tissue
anatomy has not been previously possible. The presence of distinctive scale distributions and patterns in
species of Saurolophus confirms the taxonomic utility of scale architecture within this genus and hints at
a wider application of scale-based identifications within the Hadrosauridae. Although more specimens are
required before they can be fully incorporated into species diagnoses, closer attention should be paid to the
standardised description of scale morphology, which should accompany osteological descriptions where
possible.
12
A possible new hadrosaurine from the Wapiti Formation
(Campanian-Maastrichtian), northwestern Alberta
Phil R. Bell1, Federico Fanti2, Robin L. Sissons3, Michael E. Burns4, and Philip J. Currie4
1
Pipestone Creek Dinosaur Initiative, Clairmont, Alberta, Canada.
Dipartimento di Scienze della Terra e Geologico-Ambientali, Università di Bologna, Italy
3
Grande Prairie Regional College, Grande Prairie, Alberta, Canada.
4
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
2
A possible new hadrosaurine is identified from the Late Cretaceous Wapiti Formation (west-central
Alberta) based on an incomplete skull. Articulated-to-associated cranial and postcranial remains were
collected from a sandy channel lag that crops out on Red Willow Creek approximately 7km northeast of Elmworth (Fig. 1). Cranial elements include the right prefrontal, left maxilla, both jugals, right
quadratojugal, left quadrate, left dentary, and ?left angular. The skull is unusual in being relatively short
and deep, typical of immature hadrosaurs, yet the size of the animal suggests an age at which juvenile
morphology would no longer be expected. A phylogenetic analysis of 137 cranial characters recovers the
Red Willow taxon at the base of the Hadrosaurinae. The phylogenetically basal position may be a reflection
of the immature morphology of the specimen, highlighting the need for the careful study of the effects
of age and size in phylogenetic analyses of hadrosaurines. The Red Willow taxon comes from the Red
Willow Coal Zone at the top of Unit 4 of the Wapiti Formation, placing it on or close to the CampanianMaastrichtian boundary. This is equivalent in age to unit 2 of the Horseshoe Canyon Formation and to
the Drumheller Marine Tongue, a time at which there is a faunal turnover between the hadrosaurines,
Edmontosaurus and Saurolophus in the Horseshoe Canyon Formation. The Red Willow taxon differs from
both Edmontosaurus and Saurolophus (including immature individuals) in the absence of a well-developed
diastema on the dentary. The Red Willow specimen is the most complete hadrosaurid skeleton from highpalaeolatitudes in North America and contributes to the faunal diversity of the Wapiti Formation, which
remains largely unknown at the generic or species level.
13
Hypacrosaurus stebingeri: an exceptional record of
dinosaurian cranial ontogeny
Kirstin S. Brink1, Darla K. Zelenitsky2, David C. Evans3, John R. Horner4, and François Therrien5
1
University of Toronto, Toronto, ON, Canada, [email protected]
University of Calgary, Calgary, AB, Canada, [email protected]
3
Royal Ontario Museum, Toronto, ON, Canada, [email protected]
4
Museum of the Rockies, Bozeman, MT, USA, [email protected]
5
Royal Tyrrell Museum, Drumheller, AB, Canada, [email protected]
2
The lambeosaurine Hypacrosaurus stebingeri (Ornithischia: Hadrosauridae) is known from complete
and articulated skulls from embryonic to adult stages, collected from the Campanian aged Two Medicine
and Oldman formations of Montana and Alberta, respectively (Horner and Currie, 1994). This growth
series represents one of the most complete records of ontogeny in non-avian dinosaurs, and is therefore
important for understanding developmental dynamics in this clade. Here we present the first detailed
analysis of the cranial ontogenetic series of this taxon at all five growth stages (embryo, nestling, juvenile,
sub-adult, and adult). Results show that major changes occurring through ontogeny include a relative
decrease in orbit size, steepening of the facial profile, relative heightening of the prefrontal, relative
shortening of the upper temporal region of the skull, closure of the premaxilla-nasal fontanelle, and doming
of the premaxilla and nasal to form the cranial crest. The emergent crest is formed by the nasal in subadult H. stebingeri, yet the crest in adult individuals is formed predominantly by the premaxilla due to
expansion of the nasal cavities. No autapomorphies have been recognized for this taxon, and adult skulls
are diagnosed by a unique suite of shared characters: the nasal forms a small, plate-like portion of the
external crest surface (49% or less) with a shortened internasal joint along caudoventral margin of crest, as
in Lambeosaurus, and the shape of the crest is dome-like, as in Corythosaurus.
A comparison of the ontogenetic trajectory of H. stebingeri to that of Corythosaurus sp., Lambeosaurus
sp., and Hypacrosaurus altispinus (Evans, 2010) reveals that the development of the crest of H. stebingeri
and Corythosaurus is very similar (Fig. 1). Sub-adults of H. stebingeri and Corythosaurus both possess
a bifurcated nasal with processes of similar length that form an interdigitate suture with the premaxilla
and a premaxilla-nasal fontanelle that remains partially open late into ontogeny (Brink et al., 2011). A
comparison of ontogenetic changes below the sub-adult growth stage is more difficult, as such specimens
are rare, and all lambeosaurines in these age classes have similar morphologies. Furthermore, the
taxonomic assignment of the well-known embryonic individuals from Devil’s Coulee, Alberta, is tenuous,
as re-examination of the embryos reveals that the diagnostic nasals are less complete than previously
suggested, and the specimens are biostratigraphically intermediate between Corythosaurus in Alberta and
H. stebingeri in Montana. A quantitative analysis of the embryonic, nestling, juvenile, and sub-adult cranial
material reveals little differentiation among taxa, stressing the lack of diagnostic quantitative features
exclusive of the cranial crest. A similar analysis performed on adult specimens only reveals differentiation
between Lambeosaurus sp. and the corythosaurins, further reinforcing that taxonomically distinct
morphologies are expressed only late in ontogeny.
References
Brink, K. S., D. K. Zelenitsky, D. C. Evans, F. Therrien, and J. R. Horner. 2011. A sub-adult skull of Hypacrosaurus
stebingeri (Ornithischia: Lambeosaurinae): anatomy and comparison. Historical Biology 23:63-72.
Evans, D. C. 2010. Cranial anatomy and systematics of Hypacrosaurus altispinus, and comparative skull growth in
lambeosaurine hadrosaurids (Dinosauria: Ornithischia). Zoological Journal of the Linnean Society 159:398-434.
Horner, J. R., and P. J. Currie. 1994. Embryonic and neonatal morphology and ontogeny of a new species of
Hypacrosaurus (Ornithischia, Lambeosaurinae) from Montana and Alberta; pp. 312-336 in K. Carpenter, K. F.
Hirsch, and J. R. Horner (eds.), Dinosaur Eggs and Babies. Cambridge University Press.
14
Fig. 1. Cranial ontogenetic series of: a) Hypacrosaurus stebingeri, b) Hypacrosaurus altispinus, c) Corythosaurus
casuarius, and d) Lambeosaurus lambei. Specimens are arranged based on percentage of maximum skull
length. Modified from Evans, 2010.
15
The Size-frequency Distribution of Hadrosaurs from the
Dinosaur Park Formation of Alberta, Canada
Donald B. Brinkman
Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, Alberta, T0J 0Y0
Introduction
Size-frequency distributions can be an important source of data for estimating biological attributes of
fossil vertebrates. In extant populations of reptiles and amphibians that have a seasonal breeding period
and seasonally high mortality, age classes may be represented by distinct size classes. When this is the
case, size classes can be used to establish the age structure of a population and to infer growth rates (eg.
Andrews, 1982; Halliday and Verrell, 1988). Examples of the use of size-frequency distributions of fossil
assemblages to establish growth rates and mortality patterns include studies of fish (Wilson, 1984) and
pterosaurs (Bennett, 1993).
In studies of hadrosaur remains from a series of bonebeds in Montana, Varricchio and Horner (1993)
observed that three size classes are present. The smallest is the embryo-hatchling size class dominated by
individuals with a total length of about 1.5 meters. The second size class consists of juvenile individuals
that are 3.0-3.5 meters long, and the third is dominated by animals of adult size. They propose that the most
likely explanation of this pattern is that these size classes are age classes and that an adult size was reached
after two years growth. However, they recognized that the possibility that a more juvenile age class is not
represented in their sample because individuals of that age lived separately could not be excluded and that
to resolve whether or not an additional sub-adult size class extists further data from taphonomically and
geographically more diverse localities is needed.
In this study, the hypothesis that the size-classes that Varricchio and Horner (1993) recognize are age
classes is tested by examining the size-frequency distribution of hadrosaurs from Dinosaur Park Formation
of Alberta. The geographic area sampled is much larger, especially considering that this area would have
undergone changing environmental conditions associated with the transgression of the Bearpaw Sea.
The taphonomic setting of the hadrosaurs collected from Dinosaur Provincial Park differs from those
represented by the bonebeds studied by Horner and Varicchio (1993) in that the material is generally
preserved in the sands deposited by meandering rivers rather than in pond deposits associated with drought
conditions. As well, the taxonomic composition of the hadrosaurs of the Dinosaur Park Formation differs
since a diverse assemblage of five genera of hadrosaurs is present (Table 1). Given these differences, the
presence of a size-frequency distribution matching that documented by Varricchio and Horner (1993)
provides strong support for the hypothesis that the two sub-adult size classes they identify are age classes
and suggest the life-history parameters that give rise to this pattern are common to hadrosaurs, rather than
being taxon specific.
Methods
Linear measurements of the tibia and femur are used to evaluate the size of hadrosaurs from the
Dinosaur Park Formation of Alberta. In order to incorporate data from both elements in a single histogram,
measurements were standardized by reference to a single, complete articulated skeleton and are presented
as a percentage of the length of the corresponding element in that skeleton. Specimen TMP 98.58.1 was
chosen as a reference specimen since it includes a complete tibia, fibula and femur. Measurements were
taken from specimens in the collections of the Royal Tyrrell Museum and the Royal Ontario Museum.
Measurements from specimens housed in other institutions published by Lull and Wright (1942) were also
included in the data set. In general, the isolated elements included in this data set were found as isolated
specimens or from bonebeds that show evidence of extensive transportation. Thus, each element was
assumed to be from different individuals. In the case of articulated specimens, the length of the tibia was
taken as the measure of the size of that specimen. If the tibia was absent, the femur was used. The resulting
database included 58 specimens (Tables 1 and 2). This included nineteen articulated specimens (Table 1),
twenty isolated tibiae, and nineteen isolated femora (Table 2).
16
Results
The elements in this data set range from 19% to 219% the length of comparable elements in specimen
TMP 98.58.1. A histogram showing the size-frequency distribution of these remains (Fig. 1) shows two
well-defined subadult peaks and a broad cluster of adult individuals with two ill-defined peaks.
The smallest size class includes 21 individuals that range from 19% to 38% linear dimensions of TMP
98.58.1 with a peak in the 21-30 % size range. This size range includes elements equal in size to the embryo
and hatchling elements from nests in the Devil’s Coulee locality of Southern Alberta. Thus, following,
Varricchio and Horner (1993), this size class is interpreted as consisting of hatchling individuals and
individuals that had recently left the nest, rather than a first year age class. Not surprisingly, the elements in
this size class all show clear morphological evidence that they are at a very immature stage of development.
These include the presence of a punctuate surface texture and the presence of poorly defined articular
surfaces.
The second peak includes 13 individuals that range from 63% to 117% the linear dimensions of TMP
98.58.1 with a peak in the 81-90% size range. The bones in this peak generally have a striated texture
and their articular ends are not strongly rugose. The length of articulated individuals represented by the
elements in this peak is approximately 3 meters, the size that Varricchio and Horner (1993) recognized as
their possible one-year-old size class.
The third size class contains 24 individuals that range from 181% to 219% of the linear dimensions of
TMP 98.58.1 with a peak in the 191-200% size range. All the articulated specimens that are included in
this size class have been considered to be adult, including one of the smallest individuals in this group, a
Gryposaur, specimen TMP 1980.22.1, with a tibia that is 81% of the tibia is specimen TMP 98.58.1. Isolated
elements are also considered to be from adults because they have a smooth, finished external texture and
rugose articular surfaces. The lack of distinct size classes in adults suggests that growth had slowed so
successive age classes were piling up in a single broad size class.
The relative heights of the peaks formed by the three size classes on the size-frequency distribution
graph is also potentially of biological significance since it will reflect mortality patterns. Although this
variable is sensitive to biases, it is striking that the peak including the hatchling elements is particularly
high. This is consistent with the assumption that when individuals left the nest it was a time of particularly
high mortality.
Discussion
The occurrence of size/age clusters in the sample of hadrosaurs from Dinosaur Park Formation is
initially surprising since this assemblage constitutes an attritional assemblage accumulated over an
approximately 1.5 million year time period. Numerous sources of variation in size of animals in such an
assemblage are present that could swamp age-related size clusters. One of the sources is taxonomic, since
at least 6 genera are included in this assemblage and differences in the adult size of these taxa are present.
Thus for distinct age/size classes to be present, the taxa included must have similar growth rates and
mortality patterns. Variation in growth rates over time is another source of variation that could swamp the
age-based size clusters. Again, for size classes to be present, the growth rates and mortality patterns must
have been constant over the approximately 1.5 million years documented by the sample.
The presence of size/age clusters in attritional assemblages in dinosaurs is initially surprising since it
has generally been assumed that these will be obscured by random mortality events. However Craig and
Obertal (1966), using computer simulations, showed that size classes should be preserved in an attritional
assemblage given seasonality in the time of hatching and a seasonal period of high mortality. Thus the
presence of distinct size classes in hadrosaurs from the Dinosaur Park Formation implies that there are
annual cycles of high birth rate and high mortality rates in this region. Since the climate was generally
warm and there is no evidence for freezing temperatures, it has generally been assumed that seasonality
was reduced. However, Dinosaur Provincial Park was located at approximately 58o N paleolatitude so
major changes in the amount of daylight over the course of the year would have been present. At 58 o N the
day length during mid summer is about 18 hrs and in mid winter it is about 6 hrs. This difference in the
17
number of day-light hours would have resulted in seasonality in primary productivity, which could have
resulted is seasonal stress on a population of herbivores. As well, sedimentological evidence has suggested
the presence of seasonal periods of intense tropical storms and that these had a major impact on the biota
(Eberth and Getty, 2005).
The hypothesis that hadrosaurs of the mid Campanian shared a similar growth pattern can be further
tested by comparing the size-frequency patterns documented here with populations from other regions. Of
particular interest is the pattern in high-latitude assemblages, particularly those from Alaska and Bylot
Island in the Canadian Arctic. Subadult individuals are abundant in these assemblages. If these individuals
fall within the intermediate-size class, it would reinforce the interpretation that this is an age class and
suggest that in the high latitudes this size class was subject to a much higher mortality rate than in more
southern regions.
The hypothesis that the size-clusters recognized here are age clusters and that hadrosaurs reached an
adult size after two years of growth can be further tested by histological approaches to aging individuals.
Histological studies by Horner et al. (2000) suggested that the late juvenile stage represented by individuals
of about three meters length was reached after one to two years of growth. The size-frequency data
documented here suggests that the one-year estimate is correct. However, Horner et al. (2000) suggest that
an adult size was reached in 6 to 8 years, a much longer time that that suggested by the size-frequency
distribution seen here. Resolving the difference in these interpretations will undoubtedly provide new
insights into the biology of hadrosaurs, and by extension, other dinosaurs.
Acknowledgements
This study was made possible by the many collectors who recognized the importance of isolated limb
elements of hadrosaurs and spent considerable effort in collecting and preserving these. Thanks also to the
collection managers who have ensured that this material is available for study. In particular, I would like
to thank Brandon Strilisky for his work in care of the collections of the Royal Tyrrell Museum and Kevin
Seymour for his work on the collections of the Royal Ontario Museum. Finally I would like to thank David
Eberth for extensive discussions that aided in the development of ideas presented here and to David Eberth
and David Evans for encouragement for including this presentation in the Hadrosaur Symposium.
References
Andrews, R.M. 1982. Patterns of growth in reptiles. In: Biology of the Reptilia. Edited by Gans, C. and Pough, F.H.
Volume 13, Academic Press, London, p. 273-320.
Bennett, S.C. 1993. The ontogeny of Pteranodon and other pterosaurs. Paleobiology, 15: 92-106.
Craig, G.Y. and Oertel, G. 1966. Deterministic models of living and fossil populations of animals. Quarterly Journal
of the Geological Society of London, 122: 315-355.
Eberth, D.A., and Getty, M.A. 2005. Ceratopsian bonebeds: Occurrence, origins, and significance. In: Dinosaur
Provincial Park: A Spectacular Ancient Ecosystem Revealed. Edited by P.J. Currie and E.B. Koppelhus. Indiana
University Press, Bloomington, pp. 501-536.
Halliday, T.R. and Verrell, P.A., 1988. Body size and age in amphibians and reptiles. Journal of Herpetology, 22: 253265.
Horner, J.R., Ricklès, A.J. de, and Padian, K. 2000. Long bone histology of the hadrosaurid dinosaur Maiasaura
peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements. Journal of
Vertebrate Paleontology, 20: 115-129.
Lull, R.S., and Wright, N.W. 1942. Hadrosaurian dinosaurs of North America. Geological Society of America Special
Papers, 40: 1-242.
Varricchio, D.J. and Horner, J.R., 1993. Hadrosaurid and lambeosaurid bone beds from the Upper Cretaceous Two
Medicine Formation of Montana. Canadian Journal of Earth Sciences, 30: 997-1006.
Wilson, M.V.H., 1984. Year classes and sexual dimorphism in the Eocene catostomid fish Amyzon aggregatum.
Journal of Vertebrate Paleontology, 3: 137-142.
18
Table 1. Measurements of limb elements of articulated hadrosaur specimens from the Dinosaur Park Formation
of Alberta, Canada.
specimen
TMP 98.58.1
ROM 4670
TMP 83.64.3
AMNH 5461
AMNH 5340
TMP 80.22.1
ROM 787
ROM 4991
ROM 764
ROM 1218
AMNH 5338
ROM 4514
ROM 845
TMP 82.38.1
NMC 8532
AMNH 5240
NMC 8703
TMP 66.4.1
ROM 5859
identification
gen. indet.
Parasaurolophus
Prosaurolophus
Corythosaurus
Lambeosaurus
Gryposaurus
Prosaurolophus
Prosaurolophus
Gryposaurus
Lambeosaurus
Corythosaurus
Gryposaurus
Corythosaurus
Lambeosaurus
Corythosaurus
Corythosaurus
Lambeosaurus
Lambeosaurus
Gryposaurus
femur (cm)
52
102
59
52
59
85
99
101
104
105
99
105
104
105
104
108
102
110
114
tibia (cm)
47
-51
51
55
79
82
88
90
91
92
94
94
98
98
100
100
102
103
Table 2. Measurements of isolated hadrosaurs femora and tibiae from the Dinosaur Park Formation of Alberta, Canada.
isolated tibiae
length ( cm)
isolated femora
length (cm)
TMP 89.39.113
TMP 94.19.822
TMP 92.36.536
TMP 84.67.60
TMP 94.45.8
TMP 85.36.138
TMP 67.20.239
TMP 67.8.63
TMP 81.19.128
TMP 67.10.82
TMP 83.180.10
TMP 79.14.308
TMP 65.16.4
TMP 66.42.23
TMP 65.10.18
TMP 81.19.126
ROM 26032
ROM 655
TMP 94.12.840
TMP 97.12.216
10
11
11
11
12
12
18
38
39
39
42
43
71
74
92
93
97
98
40
14
TMP 92.36.920
TMP 92.36.921
TMP 89.36.415
TMP 92.36.600
TMP 90.36.412
TMP 89.36.173
ROM 706
TMP 94.12.465
TMP 94.666.82
TMP 90.36.73
TMP 87.78.5
TMP 84.1.1
TMP 90.2.28
TMP 87.62.29
TMP 96.12. 172
TMP 96.12.175
TMP 97.12.173
TMP 99.55.350
TMP 2001.12.89
10
10
11
12
12
13
13
19
33
38
51
90
95
100
16
12
13
11
20
19
Fig. 1. Size-frequency diagram of hadrosaurs from the Dinosaur Park Formation of Alberta, Canada.
20
Body size variation and evolution in hadrosauroid
dinosaurs
Nicolás E. Campione1 and David C. Evans2
1
University of Toronto, Toronto, Ontario, Canada <[email protected]>
Royal Ontario Museum, Toronto, Ontario, Canada, [email protected]
2
Introduction
Dinosaurs exhibit an incredible range of body sizes, and are important for understanding patterns of
body size evolution in terrestrial vertebrates as it relates to climate and geographic changes during the
Mesozoic, a dynamic period in Earth history. Although body size evolution has been studied on a broad
scale in dinosaurs (Carrano, 2006), as well as in more detail in sauropod and theropod dinosaurs (Carrano,
2005; Turner et al., 2007; Sanders et al., 2010), other diverse dinosaurian clades, such as ornithopods, have
received less attention. Hadrosauroid ornithopods (closer to Parasaurolophus than to Iguanodon (Sereno,
1997)) represent one of the most diverse clades of non-avian dinosaurs, and are numerically abundant in
Cretaceous deposits. In addition, they include multiple occurrences of large bodied taxa, and at least one
hypothesized case of dwarfism (Benton et al., 2010). As a result, hadrosauroids are a model clade to assess
patterns of body size evolution in dinosaurs.
In order to provide the requisite framework to reconstruct the patterns of body size evolution in
Hadrosauroidea, we compiled a database of limb measurements for virtually all known hadrosauroid
species. We examined inter- and intraspecific patterns of limb scaling in the clade, and estimated their body
mass based on regression equations derived from extant mammals and reptiles (Campione and Evans, in
prep). Here we report new data on body size variation in hadrosauroids and conduct preliminary analyses
of body size evolution based on published ornithopod phylogenies (Weishampel et al., 2004; Sues and
Averianov, 2009; McDonald et al., 2010; Prieto-Márquez, 2010).
Results and Discussion
Results of limb scaling analyses indicate isometric humerus to femur length scaling patterns within
hadrosauroid ornithopods; a pattern shared with other non-hadrosauroid ornithopods (except Iguanodon
(Campione and Evans, 2009)). At the upper bounds of the hadrosauroid dataset, Shantungosaurus
represents the largest exemplar. This taxon has long been considered to be the largest hadrosaurid, and
examination of the femora show an upper length limit of 1700 mm, 40% larger longer than Edmontosaurus,
one of the largest hadrosaurids known from North America. The humerus is equally as large, with a length
of 980 mm compared 690 in Edmontosaurus. Such limb proportions, as indicated by the bivariate plots,
place Shantungosaurus within the range of large sauropods.
Body mass estimates based on humeral and femoral circumference suggest most hadrosaurids fall
within the 2 to 5 tonne range. Non-hadrosaurid hadrosauroids, such as Probactrosaurus and Bactrosaurus,
are generally considerably smaller (1 to 2 tonne range). Shantungosaurus is by far the largest hadrosauroid,
and likely largest ornithischian, with estimates in excess of 10 tonnes, higher than that observed in the
diplodocid Diplodocus based on limb circumference.
Body mass estimates presented here for some hadrosaurioids suggest that they reached body sizes
that fall within the range of most large sauropod taxa, including dipodocids and camarasaurs. When
interpreted in a phylogenetic context, gigantism (> than 7 tonnes) appears to have evolved at least twice
in hadrosauroids, and more specifically within hadrosaurids, though the latter may well show numerous
trends towards body size increase. Within hadrosaurines, body size increases occurred in the ancestor of
Shantungosaurus, Saurolophus, and Edmontosaurus. Within Lambeosaurinae body size appears conserved,
however, the remains of large lambeosaurine material from California (Morris, 1972, 1981) suggests that
gigantism may have occurred in this clade as well. A preliminary assessment of Cope’s rule, based on
comparisons of body mass and clade-rank, suggests a significant, albeit weak, trend towards body size
increase in hadrosauroids. Future work will elucidate on more detailed body size patterns within this clade
21
and other ornithopods, provide the framework on which to hypotheses of island dwarfism in this clade
(Weishampel et al., 1993; Benton et al., 2010), and examine patterns of body size within the context of a
dynamic environmental landscape during the Cretaceous period.
References
Benton, M. J., Z. Csiki, D. Grigorescu, R. Redelstorff, P. M. Sanders, K. Stein, and D. B. Weishampel. 2010.
Dinosaurs and the island rule: the dwarfed dinosaurs from Hateg Island. Palaeogeography, Palaeoclimatology,
Palaeoecology 293:438-454.
Campione, N. E., and D. C. Evans. 2009. Limb scaling and body-mass of the iguanodontian ornithopod Iguanodon.
Journal of Vertebrate Paleontology 29:75A.
Carrano, M. T. 2005. The evolution of sauropod locomotion: morphological diversity of a secondarily quadrupedal
radiation; pp. 229-251 in K. C. Rogers and J. A. Wilson (eds.), The Sauropods: Evolution and Paleobiology.
University of California Press, Berkeley, CA.
Carrano, M. T. 2006. Body-size evolution in the Dinosauria; pp. 225-268 in M. T. Carrano, R. W. Blob, T. J. Gaudin,
and J. R. Wible (eds.), Amniote Paleobiology: Perspectives on the Evolution of Mammals, Birds, and Reptiles.
University of Chicago Press, Chicago, Illinois.
McDonald, A. T., J. I. Kirkland, D. D. DeBlieux, S. K. Madsen, J. Cavin, A. R. Milner, and L. Panzarin. 2010. New
basal iguanodonts from the Cedar Mountain Formation of Utah and the evolution of thumb-spikes dinosaurs.
PLoS ONE 5:e14075.
Morris, W. J. 1972. A giant hadrosaurian dinosaur from Baja California. Journal of Paleontology 46:777-779.
Morris, W. J. 1981. A New Species of Hadrosaurian Dinosaur from the Upper Cretaceous of Baja California:
?Lambeosaurus laticaudus. Journal of Paleontology 55:453-462.
Prieto-Márquez, A. 2010. Global phylogeny of hadrosauridae (Dinosauria: Ornithopoda) using parsimony and
Bayesian methods. Zoological Journal of the Linnean Society 159:435-502.
Sanders, P. M., A. Christian, M. Clauss, R. Fechner, C. T. Gee, E.-M. Griebeler, H.-C. Gunga, J. Hummel, H.
Mallison, S. F. Perry, H. Preuschoft, O. W. M. Rauhut, K. Remes, T. Tütken, O. Wings, and U. Witzel. 2010.
Biology of the sauropod dinosaurs: the evolution of gigantism. Biological Reviews.
Sereno, P. C. 1997. The origin and evolution of dinosaurs. Annual Review of Earth and Planetary Science 25:435-489.
Sues, H.-D., and A. Averianov. 2009. A new basal hadrosauroid dinosaur from the Late Cretaceous of Uzbekistan and
the early readiation of duck-billed dinosaurs. Proceedings of the Royal Society B 276:2549-2555.
Turner, A. H., D. Pol, J. A. Clarke, G. M. Erickson, and M. A. Norell. 2007. A basal dromaeosaurid and size evolution
preceding avian flight. Science 317:1378-1381.
Weishampel, D. B., D. B. Norman, and D. Grigorescu. 1993. Telmatosaurus transsylvanicus from the Late Cretaceous
of Romania: the most basal hadrosaurid dinosaur. Palaeontology 36:361-385.
Weishampel, D. B., P. Dodson, and H. Osmolska. 2004. The Dinosauria. 2 Edition. University of California Press, 861
pp.
Addendum
Results of limb scaling analyses indicate two patterns within Iguanodontia. Non-iguanodontian
ornithopods share similar isometric fore to hind limb scaling patterns with hadrosaurids. In comparison,
Iguanodon, and likely close relatives Lurdusaurus and Ouranosaurus, exhibits strong positive allometry of
the forelimbs relative to the hind limbs. At its largest size, Iguanodon has limb proportions comparable to
large sauropods. Shantungosaurus has long been considered to be the largest hadrosaurid, and examination
of the femora show an upper length limit of 1700 mm a 40% difference from Edmontosaurus, one of the
largest hadrosaurids known from North America. The humerus is equally as large, with a length of 980
mm compared 690 in Edmontosaurus. Such limb proportions place this taxon within the range of large
sauropods.
Body mass estimates based on humeral and femoral circumference suggest most hadrosaurids fall
within the 2 to 5 tonne range. Basal taxa such as Probactrosaurus and Bactrosaurus are generally
considerably smaller (1 to 2 tonne range). Two taxa are notable for their huge body size. Estimates indicate
a 12 – 20 tonne range for Shantungosaurus and an 11 – 19 tonne range for Iguanodon. These estimates are
higher than that observed in the diplodocid Diplodocus (7 – 13 tonnes) based on limb circumference.
22
NON-OSSEOUS DERMAL SCUTES AND INTEGUMENT IMPRESSIONS
FROM AN EXCEPTIONALLY PRESERVED HADROSAURID DINOSAUR
SKELETON, UPPER CRETACEOUS KAIPAROWITS FORMATION OF
UTAH
Katherine E. Clayton1,2, Randall B. Irmis1,2, Michael A. Getty2, Eric K. Lund2, William J. Nicholls2, and
Mark A. Loewen1,2
1
Department of Geology and Geophysics, Salt Lake City, Utah 84112
Utah Museum of Natural History, University of Utah, Salt Lake City, Utah 84112
2
Introduction
Dinosaur skin impressions are typically rare in the fossil record, but renewed interest in the Late
Cretaceous of western North America over the last few decades has yielded many skin impressions from
hadrosaurid ornithischian dinosaurs. Over the past ten years, sustained fieldwork in the Upper Cretaceous
(Campanian) Kaiparowits Formation of southern Utah has discovered numerous, well-preserved
hadrosaurid skin impressions, from hatchling-size juveniles to massive, 12 meter long adults. This
relatively recent abundance of described integument and skin impressions from different taxa throughout
multiple formations in the Western Interior, including the Kaiparowits Fm, allows us to make comparative
observations regarding the phylogenetic distribution of integumentary patterns and other characters across
a variety of hadrosaurid species. These observations provide important insight into the animal’s overall
appearance, and could potentially be useful in identifying specimens found without diagnostic cranial
material. We report a partial adult hadrosaurine hadrosaurid skeleton (likely Gryposaurus sp.) from the
Kaiparowits Fm, UMNH VP 12265, with exquisitely preserved integument impressions and unusual
integumentary features that are closely associated with portions of the pelvis and tail.
Depositional Environment
The specimen (UMNH VP 12265) is preserved in a medium-grained, well-sorted, upward-fining fluvial
sandstone. This sandstone is highly indurated, resulting in exceptional preservation. Mudstone rip-up clasts
0.5-2 cm in diameter at the sandstone’s base indicates rapid burial in a high-energy environment. Portions
of the sacrum and tail are articulated and preserve largely complete sections of skin impressions in quasilife position across both the animal’s right and left sides. Skin impressions are primarily preserved on the
underside, or stratigraphic base of the animal, in a fine-grained, muddy sandstone. Portions of articulated
posterior skeleton lay on the higher end of a paleo-slope in the sandstone. However, the more anterior
skeleton, found in siltier sediment, is largely disarticulated and has only a few isolated skin impressions.
The animal may have been oriented with its distal body on a point or sand bar and rapidly buried. Later,
its anterior extremities were perhaps exhumed and exposed to a current that then winnowed away many
upper body elements. This scenario is consistent with the relative lack of skull and anterior-most skeletal
material from this specimen whereas the close association of such large areas of skin preservation and lack
of folds or breaks to the tubercles indicates minimal disturbance to the posterior portion of the body prior
to burial. Likewise, the skin’s lack of dramatic folding or warping, and fairly large distance from bone (~3
cm) suggest rapid burial without the long periods of exposure and desiccation implied in many descriptions
of dinosaur “mummies.”
Methods
Large blocks of skin impressions were meticulously collected from the field, many jacketed in their
original orientation associated with skeletal material. Loose blocks of skin impressions were reassembled
in the lab by seeking fits in the blocks and matching tubercle patterns. Ultimately, large sections of the
tail’s negative and positive skin impressions were paired together. These skin blocks were examined both
qualitatively and quantitatively. Measurements of the tubercles and dermal scutes were taken from both
23
types of skin impressions with digital calipers. We counted tubercle density and the number of ridges per
tubercle for a variety of areas across the skeleton.
Description
There are two major morphologies of impressions. Along the dorsal ridge of the tail there is a single row
of large, raised, non-osseous dermal scutes that range in length from 7-11 cm; these are heart-shaped with
radiating grooves that meet along the scute’s midline. Though the scutes do not correspond one-to-one with
each vertebral neural spine, they are directly associated with the spines’ dorsal surfaces. Strangely, there
is no definitive trend in the distance between these scutes or in their size across the body. Slightly larger
or smaller scutes occur randomly in sequence. However, distal-most scutes tend to be smaller than those
found on the proximal tail.
The rest of the skin is dominated by ridged, polygonal tubercles ranging in diameter from 5-12 mm,
with occasional patches of tightly-packed, flat pavement tubercles. Both types of tubercles were more often
fairly uniformly distributed with small, rare patches of clustered, smaller tubercles around progressively
larger, even occasional oversized tubercles up to 12-15 mm in diameter. Each ridged tubercle contains 9 to
15 radiating grooves and irregularly scalloped edges. There is a definite trend in tubercle size; the average
diameter increases distally along the tail. On the proximal tail, the largest tubercles are on the dorsal part of
the tail, whereas they are ventral on the distal tail.
Discussion and Conclusions
This specimen’s non-imbricated, polygonal tubercles are similar to many hadrosaurids including both
lambeosaurines (Corythosaurus, Parasaurolophus, Lambeosaurus) and closely related hadrosaurines like
Edmontosaurus. However, scalloped tubercle edges are absent in Edmontosaurus specimens described
from Montana, Wyoming and Alberta, whereas they are present in both the Kaiparowits specimens and
a specimen (BYU 13258) found in the Neslen Formation of the Book Cliffs, Utah. Similarly, overall
tubercle patterns consisting of uniformly distributed tubercles more closely resemble specimens described
from more southern localities and contrast with clusters described from Edmontosaurus. Ridge counts
of the scalloped tubercles are comparable with counts reported from the Books Cliffs specimen, though
the maximum number observed from UMNH VP 12265 is significantly lower. Overall, the tubercles’
appearance and patterns of UMNH VP 12265 are nearly identical to other hadrosaurid skin impressions,
NMMNH P-2611 from the Ringbone Formation of New Mexico, and BYU 13258 from the Books Cliffs of
Utah, which is also referred to Gryposaurus.
The large, non-osseous dermal scutes are unlike any integument described for hadrosaurids. These
scutes contrast with the continuous or segmented epidermal frills along the dorsal ridge of the tail
described for other hadrosaurids such as Edmontosaurus. At this point, it is impossible to determine if
these scutes are unique to Gryposaurus, hadrosaurines from the Kaiparowits Fm, or simply this specimen,
as this is the first Gryposaurus to preserve skin so closely associated with articulated vertebral material.
24
25
26
27
SOUTH AMERICAN HADROSAURS: CONSIDERATIONS ON THEIR
DIVERSITY
Rodolfo A. Coria
CONICET-University of Río Negro-Museo Carmen Funes, Av. Córdoba 55 (8318) Plaza Huincul, Neuquén,
Argentina.
The South American hadrosaurid record is, up to now, solely represented by findings made in Argentina,
where their remains, relatively abundant in variable preservational stages, have been collected from several
Late Cretaceous (Campanian-Maastrichtian) units extensively exposed in the Patagonian provinces of
Chubut (Bajo Barreal Fm or Laguna Palacio Fm), Río Negro (Angostura Colorada Fm/ Coli Toro Fm, Los
Alamitos Fm and Allen Fm) and La Pampa (Allen Fm) (Brett-Surman, 1979; Casamiquela, 1964; Bonaparte
et al., 1984; Powell, 1987; González Riga and Casadío, 2000). As the presence of remains of this group in
the mentioned units is relatively consistant, our knowledge about their taxonomic diversity has remained
very poor, mainly due the notorious scarcity of well-preserved specimens.
The diversity of hadrosaurids of Argentina would be represented by at least five taxa: Secernosaurus
koerneri, “Kritosaurus” australis, Willinakaqe salitralensis, some indeterminate specimens of
Lambeosaurinae and a possible new genus and species from the province of La Pampa (Brett-Surman,
1979; Bonaparte et al., 1984; Juárez Valieri et al., 2010; Coria et al., in press).
Secernosaurus koerneri
Secernosaurus koerneri has been confirmed as a Hadrosauridae more derived than Telmatosaurus
(Prieto-Márquez and Salinas, 2010; Coria, 2010), challenging previous assumptions (Brett-Surman, 1979),
and is diagnosed by a supracetabular crest less developed than in other hadrosaurids and a postacetabular
process of the ilium with parallels lateral and medial borders (Fig.1A-B). A detailed analysis of the
holotype material of Secernosaurus allowed us to access that it was based upon at least two hadrosaurid
individuals and one small non-hadrosaurid ornithopod. Nevertheless, the adult condition of the hadrosaurid
material is confirmed based on the fully fused neural arches and centra, which leads to the recognition
of a form smaller than other hadrosaurid taxa from Patagonia. In addition, a probable diagnostic feature
could be the presence of a crest supracetabular of modest development, compared with the broad and
well-developed supracetabular crests of other hadrosaurids. Recently, the hadrosarid material from Los
Alamitos Fm, previously identified as Kritosaurus australis (Bonaparte et al., 1984), was recognized as
a junior synomyn of Secernosaurus koerneri (Prieto-Márquez and Salinas, 2010). However, some of the
features that distinguish Secernosaurus from “Kritosaurus” australis is, for example, that in the latter, the
postacetabular process is strongly projected posteriorly and the lateral and medial borders are strongly
concave (Fig.1C-D). On the contrary, the ilium of Secernosaurus postacetabular process has their lateral
and medial borders slightly curved, and the distal expansion, though noticeable, is very poorly developed.
In this way, the lateral and medial borders are virtually parallel (Fig.1B). Other diagnostic features
proposed to unite Secernosaurus and Kritosaurus australis (sensu Prieto-Márquez and Salinas, 2010) are
features only found in elements assigned to the latter, which would indicate a taxonomic differentiation
between both forms. The presence of Secernosaurus in the late Cretaceous of Patagonia represents the
unequivocal southernmost record of hadrosaurids in South America. The discovery of new materials of
this form will enable a better understanding of their phylogenetic relationships with other members of
Hadrosauridae and the erection of hypotheses about the distribution and dispersal routes of members of this
group in the higher latitudes of South America.
“Kritosaurus” australis
The species “Kritosaurus” australis is here recognized as representing a valid taxonomic entity and
different to Secernosaurus koerneri (see Prieto-Márquez and Salinas, 2010 for a different opinion),
28
although rejecting its relationship with the genus Kritosaurus, leaving open the possibility of proposing a
new generic term (see Discussion). The species is characterized by having frontals projected anteriorly and
separated by a triangular area to receive posterior processes of nasals, predentary with denticles dorsally
convex, ventrally flat with sharp lateral edges; anteriorly converging lateral and medial borders of the
preacetabular process; ilium with postacetabular process strongly strangled at its medium sector (Fig.1C-F).
The analysis conducted of this species places it closer to lambeosaurine hadrosaurids like
Corythosaurus and Lambeosaurus than to other genera traditionally considered hadrosaurines (e.g.
Edmontosaurus, Gryposaurus, Kritosaurus, sensu Weishampel and Horner, 1990; Horner et al., 2004).
However, this hypothesis is preliminary due to the current lack of knowledge about important parts of the
skeleton, such as the rostral and nasal area of the skull.
Willinakaqe salitralensis
Recently, this form was proposed as comprising all hadrosaurid specimens collected from the Allen
Formation (Campanian-Maastrichtian) from Río Negro and La Pampa provinces (Juárez Valieri et al.,
2010). The diagnosis is based on a single premaxilla (holotype) (Fig. 1G) and several cranial and postcranial
elements (paratype). However, the claimed association of all these fossils is questionable because they
were not collected in association nor come from the same localities. Also, at least two different humeral
morphologies are known from the area (Fig.1H-I), including an almost complete and articulated specimen
(Powell, 1987). In sum, although the putative autopomorphies present in the holotype premaxilla could
represent a suite of unique characters, ascribing all other hadrosaurid material from Allen Formation to
Willinakaqe salitralensis casts several methodological and taxonomic inconveniences.
New genus and species from La Pampa Province
Materials previously identified as Hadrosauridae indet. from the Allen Fm. in La Pampa Province
(González Riga and Casadío, 2000) and assigned recently to Willinakaqe salitralensis (Juárez Valieri
et al., 2010), are interpreted as representatives of a new genus and species diagnosed by the presence of
pneumatic foramina located on the sides of the base of the neural spines, on the basis of the diapophyses in
anterior cervical vertebrae, and a scapula with a very sharp deltoid crest (Coria et al., in press) (Fig.1J-K).
Nevertheless, the analysis of the phylogenetic relationships of this new form among the Hadrosauridae
remain uncertain at the moment, due the fragmentary condition of the specimen.
Lambeosaurinae indet.
Materials previously identified as Lambeosaurinae indet. from the Allen Fm. (Powell, 1987) and the
Colitoro/Angostura Colorada formations in the province of Río Negro (Casamiquela, 1964; Coria, 2010)
are preliminarily distinguished from the rest of the recognized forms from Argentina on the basis of the
combination of several features that include very robust apendicular skeleton and long and robust caudal
neural spines.
Discussion
On the basis of previous phylogenetic analysis (Weishampel et al.,1993; Head, 1998; Hai-lu et al., 2003;
Horner et al., 2004; Prieto-Márquez et al. , 2005; Gates and Sampson, 2007), a matrix of 125 cranial,
dental and postcranial characters distributed among 26 taxa of Ornithischian dinosaurs were scored
using TNT (Goloboff et al., 2003). The data matrix was integrated by a basal Ornithischian as outgroup
(Heterodontosaurus), four non-hadrosaurid ornithopods (Gasparinisaura Anabisetia, Camptosaurus
and Iguanodon), five basal hadrosauroids (Probactrosaurus, Equijubus, Protohadros, Telmatosaurus
and Equijubus), 12 Laurasian hadrosaurids (Prosaurolophus, Maiasaura, Hadrosaurus, Edmontosaurus,
Saurolophus, Corythosaurus, Brachylophosaurus, Gryposaurus, Hypacrosaurus, Lambeosaurus,
Parasaurolophus and Kritosaurus) and the Argentine taxa Secernosaurus koerneri, “Kritosaurus”
29
australis, the Lambeosaurinae indet. From the Allen Fm. (equivalent to Willinakaqe salitralensis), the
Lambeosaurine indet. from Colitoro/Angostura Colorada formations of Río Negro province, and the
new genus and species of Hadrosauridae of the Allen Fm. from La Pampa province. The result was 60
most parsimonious trees of 225 steps, with a CI = 0,627 and an IR = 0,836. The reduced strict consensus
yields as a result three most parsimonious trees of 219 steps in length with a CI = 0,644 and an RI = 0,
847. The cladogram here presented (Fig.2) shows Secernosaurus koerneri, the new form from La Pampa
and the Coli Toro Fm. materials located as an unresolved politomy in the Euhadrosauria node. In turn,
“Kritosaurus” australis and the Lambeosaurinae indet. from Salitral Moreno are nested as a monophyletic
group closer to the node of Parasaurolophus + (Corythosaurus, Hypacrosaurus, and Lambeosaurus). The
general cladogram is consistent with the hypothesis that the forms of South American hadrosaurids were
present on this continent as a result of dispersal from North America, which eventually would have allowed
the arrival of hadrosaurids to Antarctica. This concurs with several previous proposals (Casamiquela, 1964;
Bonaparte et al, 1984; Prieto-Márquez, 2010; Coria, 2010) and at the same time contradicts the hypothesis
of the alleged vicarianza of South American forms from ancestors closer to Telmatosaurus (Salinas et al.
2004, 2006; Juárez Valieri et al. 2007).
The entrance of the hadrosaurids in South America has been proposed as a phenomenon that would
have significantly affected the composition and characteristics of the Gondwanan fauna. The environmental
impact generated in a relatively short time, undoubtedly determined a recapitulation of the biotic balance.
However the potential competitors of hadrosaurids in the niche of large herbivores, the titanosaurian, do not
reflect a significant reduction in their fossil record. The diversification of the saltasaurins (Saltasaurinii and
Aeolosaurinii) and the direct or indirect correlation with the arriving (and also diversification, taking into
account the results proposed here) of hadrosaurids in Patagonia, is one of the most fascinating questions
of the evolution of the dinosaurs of Patagonia that will be eventually be resolved with the discovery of
more remains of sauropods and hadrosaurs, which allow us to infer ecological information on the type of
interspecific relationship that both groups developed.
References
Bonaparte, J.F., Franchi, M.R., Powell, J.E. y Sepulveda E.C. 1984. La Formación Los Alamitos (CampanianoMaastrichtiano) del sudoeste de Río Negro, con descripción de Kritosaurus australis nov.sp. (Hadrosauridae).
Significación paleobiogeográficade los vertebrados. Revista de la Asociación Geológica Argentina 39: 284-299
Brett-Surman, M.K. 1979. Phylogeny and paleobiogeography of hadrosaurian dinosaurs. 642 Nature, 277: 560-562.
Casamiquela, R.M 1964. Sobre un dinosaurio hadrosaurio de la Argentina. Ameghiniana 3: 285-308.
Coria, R.A., González Riga, B. and Casadío, S. in press. Un nuevo hadrosáurido (Dinosauria,
Ornithopoda) de la Formación Allen, Provincia de La Pampa, Argentina. Ameghiniana.
Gates, T.A. y Sampson, S.D. 2007. A new species of Gryposaurus (Dinosauria: Hadrosauridae) from the Late
Campanian Kaiparowits Formation, southern Utah, USA. Zoological Journal of Linnean Society, 151: 351-376.
Gonzalez Riga, B. y Casadío, S. 2000. Primer registro de Dinosauria (Ornithischia, Hadrosauridae) en la Provincia
de La Pampa (Argentina) y sus implicancias paleobiogeográficas. Ameghiniana 37: 341-351.
Hai-lu, Y., Luo, Z. Shubin, N.H., Witmer, L.W., Tang, Z. y Fang, T. 2003. The earliest-known duck-billed dinosaur
from deposits of the late Early Cretaceous age in northwest China and hadrosaur evolution. Cretaceous Research,
24: 347-355.
Head, J.J., 1998. A new species of basal hadrosáurido (Dinosauria, Ornithischia) from the Cenomanian of Texas.
Journal of Vertebrate Paleontology, 18: 718-738.
Horner, J.A., Weishampel, D.B. y Forster, C.A., 2004. Hadrosauridae. In The Dinosauria. Edited by D.B. Weishampel,
P. Dodson and H. Osmolska, University of California Press, Berkeley, Los Angeles, Londres, pp. 438-463.
Juárez Valieri, R.D., Calvo, J.O., Muñoz, J.C., Salinas, G.C. y Fiorelli, L.E., 2007. New hadrosaur materials from
Salitral Moreno, Allen Formation, Río Negro province, Argentina. Ameghiniana, 44 (4): 23R.
Juárez Valieri, R.D., Haro, J.A., 2, Fiorelli, L.E. and Calvo, J.O., 2010. A new hadrosauroid (Dinosauria: Ornithopoda)
from the Allen Formation (Late Cretaceous) of Patagonia, Argentina Rev. Mus. Argentino Cienc. Nat., n.s.12 (2):
217-231.
30
Goloboff, P., Farris, J., y Nixon, K., 2003. T.N.T.: Tree Analysis Using New Technology. Program and documentations
available from the authors and at http://www.zmuc.dk/public/phylogeny.
Powell, J.E., 1987. Hallazgo de un dinosaurio hadrosáurido (Ornithischia, Oritopoda) en la Formación Allen
(Cretácico Superior) de Salitral Moreno, Provincia de Río Negro, Argentina. X Congreso Geológico Argentino,
Actas 3: 149-152.
Prieto-Márquez, A., 2005. New information on the cranium of Brachylophosaurus Canadensis (Dinosauria:
Hadrosauridae) with a revision of its phylogenetic position. Journal of Vertebrate Paleontology, 25: 144-156.
Prieto-Márquez, A. y Salinas, G.C. 2010. A re-evaluation of Secernosaurus koerneri and Kritosaurus australis
(Dinosauria, hadrosauridae) from the Late Cretaceous of Argentina. Journal of Vertebrate Paleontology 30:
813–837.
Salinas, G.C. y Juárez Valieri, R.D., 2004. Breve comentario acerca de los hadrosauriformes de América del Sur y
sus implicancias paleobiogeográficas. Ameghiniana, 41 (4): 19R.
Salinas, G.C., Juárez Valieri, R.D. y Fiorelli, L.E., 2006. Reestudio de Kritosaurus australis Bonaparte et al., 1984 y
su interés paleobiogeográfico. Ameghiniana, 43 (4): 54R.
Weishampel, D.B., Norman, D.B. y Grigorescu, D., 1993. Telmatosaurus transsylvanicus from the Late Cretaceous of
Romania: The most basal hadrosaurid dinosaur. Palaeontology, 36: 361-385.
Weishampel, D.B. y Horner, J. R., 1990. Hadrosauridae. In The Dinosauria. Edited by D.B. Weishampel, P. Dodson y
H. Osmólska, University of California Press, Berkeley, pp. 534-561.
31
Fig. 1. Secernosaurus koerneri (FMNH P13423), ilium in lateral (A) and ventral (B) views; “Kritosaurus” australis
(MACN-RN-02), ilium in (C) lateral and (D) ventral views, skull roof in (E) dorsal view, reconstructed
predentary in (F) ventral view; Willinikaqe salitrensis (MPCA-Pv SM 8, Holotype), right premaxilla in
(G) lateral view; two humeral morphotypes (MPCA-SM-33, H; MPCA-SM-4, I) assigned to Willinikaqe
salitrensis in caudolateral views; posible new genus and species from La Pampa Province (MPHN-PV-1),
anterior cervical vertebra in (J) lateral view and reconstructed scapulo-coracoid in (K) lateral view. Not to
scale.
Fig. 2. General cladogram including South American hadrosaurids.
32
The complex fauna of European Maastrichtian
hadrosaurids: contributions of the lambeosaurines
from the Iberian Peninsula
Penélope Cruzado-Caballero1, J.I. Canudo1, M. Moreno-Azanza1, and J.I. Ruiz-Omeñaca1, 2
1
Grupo Aragosaurus-Instituto Universitario de Ciencias Ambientales (http://www.aragosaurus.com). Universidad de
Zaragoza. 50009 Zaragoza, Spain. [email protected], [email protected], [email protected]
2
Museo del Jurásico de Asturias. 33328 Colunga, and Departamento de Geología, Universidad de Oviedo, c/ Jesús
Arias de Velasco s/n, 33005 Oviedo. Spain. [email protected]
* Corresponding author: Penélope Cruzado-Caballero ([email protected])
Introduction
The Iberian hadrosauroid fauna was very diverse and complex during the latest Cretaceous. It was
composed of non-hadrosaurid hadrosauroids, hadrosaurines and lambeosaurines (Dalla Vecchia, 2009;
Pereda-Suberbiola et al., 2009a, 2009b; Cruzado-Caballero et al., 2010a, 2010b). Up to four new genera
and species of lambeosaurines have been described in the provinces of Lleida and Huesca (northeastern
Spain, Fig. 1): Pararhabdodon isonensis Casanovas-Cladellas, Santafé-Llopis and Isidro-Llorens 1993 in
the Sant Romà d’Abella site (Lleida); Koutalisaurus kohlerorum Prieto-Márquez, Gaete, Rivas, Galobart
and Boada, 2006 in the Les Llaus site (Lleida); and Arenysaurus ardevoli Pereda-Suberbiola, Canudo,
Cruzado-Caballero, Barco, López-Martínez, Oms and Ruiz-Omeñaca, 2009b and Blasisaurus canudoi
Cruzado-Caballero, Pereda-Suberbiola and Ruiz-Omeñaca, 2010a in Arén (Huesca; the Blasi 3 and Blasi 1
sites, respectively). The objective of this work is to introduce these lambeosaurines and try to establish their
phylogeny and paleobiogeographical implications.
Geological frame
The Tremp Basin is located in the South-Central Pyrenees in the provinces of Huesca and Lleida (in
the autonomous regions of Aragón and Catalonia, respectively). It has some excellent continuous outcrops
with numerous hadrosaurid dinosaur sites. Stratigraphically, the sites of Sant Romà d’Abella and Les
Llaus are in the Lower Red Unit of the Tremp Formation (or the Conques Formation of the Tremp Group).
Biostratigraphic data (based on rudists, ostracods, charophytes and palynomorphs) give a Maastrichtian
age to this unit (see references in Riera et al., 2009). Both sites are probably late Maastrichtian (PrietoMárquez and Wagner, 2009). The Blasi sites are in the Arén Formation (Blasi 1) and the Grey Unit of the
Tremp Formation (Blasi 3) (or La Posa Formation of the Tremp Group). Magnetostratigraphically, the Blasi
sites are located in the upper part of a normal polarity chron correlated to chron C30n (late Maastrichtian,
Oms and Canudo, 2004; Pereda-Suberbiola et al., 2009b: fig. 2), i.e. they are considerably younger than 67.7
Ma and slightly older than 65.8 Ma (Ogg et al., 2008). These rocks are transitionally overlain by lagoonal/
marsh marls and red beds of the Lower Red Unit of the Tremp Formation, which is slightly younger in the
Arén section (see references in López-Martínez et al., 2001).
Catalonian taxa
The first Catalonian taxon, Pararhabdodon, was initially classified as an iguanodontid, subsequently
as a lambeosaurine and finally as a basal hadrosaurid (Casanovas-Cladellas et al., 1993; Casanovas et al.,
1999; Prieto-Márquez et al., 2006). Its phylogenetic position is very problematic. Nowadays, it is considered
to be a basal lambeosaurine on the basis of the following characters: the maxilla forms an acute embayment
extending ventral to the jugal process between the jugal facet and the ectopterygoid shelf; the jugal facet
of the maxilla is anteroposteriorly foreshortened, likely with a correspondingly anteroposteriorly narrow
anterior jugal; the anterior dentary has a symphysial process projecting medially such that the distance
between the symphysis and the lateral surface of the dentary is three times the labiolingual thickness of
the alveolar chamber. Moreover, Pararhabdodon shares with the Chinese hadrosaurid Tsintaosaurus an
33
elevation of the jugal facet of the maxilla that extends well above the level of the lateral margin of the
ectopterygoid shelf, though they differ in the broader, subrectangular anterodorsal region of the maxilla
(Prieto-Márquez and Wagner, 2009).
The second Catalonian taxon, Koutalisaurus, was described with a dentary that had previously been
assigned to Pararhabdodon (Casanovas et al, 1999; Prieto-Márquez et al, 2006). Recently, PrietoMárquez and Wagner (2009) have reviewed Pararhabdodon, Koutalisaurus and Tsintaosaurus remains
and concluded that Koutalisaurus is most probably the junior synonym of Pararhabdodon. These authors
argue that the dentaries of Koutalisaurus and Tsintaosaurus are indistinguishable, despite the posterodorsal
orientation of the coronoid process, which appears to be an artifact of preparation (Prieto-Márquez et al.,
2006).
As a result of these revisions, both Catalonian taxa are closer to Tsintaosaurus, forming a clade of
basal lambeosaurines defined by three synapomorphies: the long medial projection of the symphysial
region of the dentary; the nearly straight anterior edentulous region of the dentary for articulation with
the predentary; and a dorsally elevated maxilla-jugal joint; as well as one ambiguous synapomorphy: the
ventral deflection of the anterior edentulous region of the dentary greater than 25º.
Aragonian taxa
In the province of Huesca the genera Arenysaurus and Blasisaurus have recently been described
as basal lambeosaurines. Of these, Arenysaurus ardevoli preserves the most complete skeleton, which
includes the first articulated partial skull of a European lambeosaurine. This skull is characterized
by a very prominent frontal dome, more developed than in other adult specimens, and by the nearly
vertical prequadratic process of the squamosal and jugal process of the postorbital. It differs from other
lambeosaurines in having a unique combination of characters: a short frontal, with a posterior length/
width ratio estimated at 0.5; the midline ridge of the parietal approximately at the level of the postorbitalsquamosal bar; the parietal not interposed between the squamosals in the occipital surface of the skull;
and the lateral side of the squamosal relatively low above the cotyloid cavity. Other characters of the
cranial and post-cranial remains are: a robust jugal with the anterior process expanded dorsally, a straight
dorsoposterior end of the jugal; maxilla with the ectopterygoid ridge ventrally turned; dentary with its
anterior portion modestly deflected ventrally, a moderate diastema, and the presence of a mesial secondary
ridge in maxillary and dentary teeth; glenoid and coracoid facets of the scapula forming an angle of 135°;
straight humerus with deltopectoral crest oriented anteriorly, and pubis of type 5 sensu Brett-Surman and
Wagner (2006; i.e. Parasaurolophus and Bactrosaurus; Pereda-Suberbiola et al., 2009b).
Blasisaurus canudoi is characterized by a jugal with an autapomorphy resulting from the combination
of a hook-like dorsal posterior process and a relatively narrow and D-shaped infratemporal fenestra. This
jugal also presents a unique combination of characters: the posterior edge of the anterior process wellprojected ventrally in a straight line (as in Parasaurolophus), a concave posteroventral edge beneath the
infratemporal fenestra (as in Sahaliyania and hadrosaurines), and a very short jugal: the length/height ratio
lower than 1.2 [only Olorotitan, Velafrons and Tsintaosaurus have such a low ratio, in these genera due to
the height of the postorbital process (see Cruzado-Caballero et al., 2010a)].
According to Cruzado-Caballero et al. (2010a), Blasisaurus and Arenysaurus are closely related and are
united by two synapomorphies: 1) a short dentary diastema, whose length between the first dentary tooth
and the predentary is less than one-fifth the total length of the tooth row (the diastema is even shorter in
Arenysaurus than in Blasisaurus, character 80 of Sues and Averianov, 2009); and 2) the dentary portion
anterior to the tooth row in lateral view is approximately straight (character 79 of Sues and Averianov,
2009). On the other hand, these taxa differ in the dentary in several characters: in dorsal view, the dentary
of Blasisaurus is rather straight, while that of Arenysaurus is concave lateromedially; the distance between
the first dentary tooth and the inflection point of the symphysis is approximately 15.5% of the total length
of the dental battery in Blasisaurus, while in Arenysaurus it is only 4.5%; the dorsal side of the coronoid
process is convex in Blasisaurus and tip-like in Arenysaurus; the coronoid process of Blasisaurus extends
anteriorly but not so much as in Arenysaurus; the dental battery of Blasisaurus is made up of 35 tooth
34
positions, as opposed to the 37 tooth positions of Arenysaurus (Pereda-Suberbiola et al., 2009b). Several
characters in the dentary teeth are also different: in Blasisaurus they have no secondary ridges, unlike
in Arenysaurus (Pereda-Suberbiola et al., 2009b); the height/length ratio of the dentary teeth in the
anterior positions is greater in Blasisaurus (3.65) than in Arenysaurus (3.15). Finally, they differ in several
characters in the jugal: the dorsoposterior side of the anterior process in Arenysaurus is straight unlike in
Blasisaurus; the maxillary process of Blasisaurus is projected less laterally and more anteriorly than in
Arenysaurus; the postorbital process of Blasisaurus is more posterodorsally oriented with regard to the long
axis of the jugal (60º) than that of Arenysaurus (45º); the orbital fenestra is V-shaped in Arenysaurus unlike
in Blasisaurus.
Phylogeny and paleobiogeographical implications
A cladistic study of the Aragonian taxa has been conducted. This followed the Evans and Reisz (2007)
matrix and included character 82 from Sues and Averianov (2009) and the addition of Arenysaurus,
Blasisaurus (this study) and Velafrons (data from Gates et al., 2007). We have not included the Catalonian
taxa (Pararhabdodon and Koutalisaurus) due to the problematic assignation of the referred material of both
species. Arenysaurus and Blasisaurus are placed within the tribe Parasaurolophini, and are more derived
than Charonosaurus and basal to the node that includes the three Parasaurolophus species. In contrast to
what is suggested by the previous analysis (Cruzado-Caballero et al., 2010a), Arenysaurus and Blasisaurus
do not form a clade together, but are successive outgroups to the genus Parasaurolophus, Blasisaurus being
more derived than Arenysaurus.
Paleobiogeographically, the presence of Arenysaurus and Blasisaurus and their relationships with other
lambeosaurines, with the addition of Pararhabdodon and Tsintaosaurus as “tsintaosaurs” following PrietoMárquez and Wagner (2009), suggest several geodispersal events (Fig. 2): 1) a dispersal event from Asia to
Europe (Pararhabdodon or its ancestors), no later than the middle to late Campanian; 2) a second dispersal
event from Asia to Europe (Arenysaurus or its ancestors) no later than the middle to late Campanian,
as in the case of event 1; 3) a dispersal event from Europe to North America (Parasaurolophus spp. or
its ancestors), probably beforehand or in the early Campanian; 4) a dispersal event from Asia to North
America (Velafrons and Lambeosaurus spp. or their ancestors), beforehand or in the early Campanian, as in
the case of event 3; and 5) a last dispersal event from North America to Asia (Olorotitan or its ancestors), in
the mid- late Campanian-early Maastrichtian.
Acknowledgements
Research supported by the Ministerio de Ciencia e Innovación of Spain (project CGL2010-16447/
BTE) and the Gobierno de Aragón (Dirección General de Patrimonio y Grupos Consolidados). JIR-O also
thanks the Consejería de Cultura y Turismo of the Principado de Asturias (protocol CN-04-226) and the
Universidad de Oviedo. MM-A is supported by the Spanish Ministry of Science and Innovation, grant FPI
BES-2008-005538
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Cruzado-Caballero, P., Pereda-Suberbiola, X. and Ruiz-Omeñaca, J. I. 2010a. Blasisaurus canudoi gen. et sp. nov.,
35
a new lambeosaurine dinosaur (Hadrosauridae) from the Latest Cretaceous of Arén (Huesca, Spain). Canadian
Journal Earth Science, 47 (12): 1507-1517.
Cruzado-Caballero, P., Ruiz-Omeñaca, J. I., and Canudo, J. I. 2010b. Evidencias de la coexistencia de dinosaurios
hadrosaurinos y lambeosaurinos en el Maastrichtiano superior de la Península Ibérica (Arén, Huesca, España).
Ameghiniana, 47 (2): 153-164.
Dalla Vecchia, F. M. 2009. European hadrosauroids. In: Actas de las IV Jornadas Internacionales sobre Paleontología
de Dinosaurios y su Entorno. Edited by Colectivo Arqueológico-Paleontológico de Salas, Salas de los Infantes,
Burgos, Spain, pp. 45-74.
Evans, D. C., and Reisz, R. R. 2007. Anatomy and relationships of Lambeosaurus magnicristatus, a crested
hadrosaurid dinosaur (Ornithischia) from the Dinosaur Park Formation, Albert. Journal of Vertebrate
Paleontology, 27 (2): 373-393.
Gates, T.A., Sampson, S.D., Delgado de Jesús, C.R., Zanno, L.E., Eberth, D., Hernández-Rivera, R., Aguillón
Martínez, M.C., and Kirkland, J.I. 2007. Velafrons coahuilensis, a new lambeosaurine hadrosaurid (Dinosauria:
Ornithopoda) from the Late Campanian Cerro del pueblo Formation, Coahuila, México. Journal of Vertebrate
Paleontology, 27(4): 917–930
López-Martínez, N., Canudo, J. I., Ardévol, L., Pereda-Suberbiola, X., Orue-Etxebarria, X., Cuenca-Bescós, G.,
Ruiz-Omeñaca, J. I., Murelaga, X. and Feist, M. 2001. New dinosaur sites correlated with Upper Maastrichtian
pelagic deposits in the Spanish Pyrenees: implications for the dinosaur extinction pattern in Europe. Cretaceous
Research, 22 (1): 41–61.
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York.
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(Maastrichtiense superior) de Arén (Huesca, Unidad Surpirenaica Central). Geo-Temas, 6 (5): 51–54.
Pereda-Suberbiola, X., Canudo, J. I., Company, J., Cruzado-Caballero, P., Ruiz-Omeñaca, J. I. 2009a. Hadrosaurids
from the latest Cretaceous of the Iberian Peninsula: new interpretations. Journal of Vertebrate Paleontology, 29
(3): 946-951.
Pereda-Suberbiola, X., Canudo, J. I., Cruzado-Caballero, P., Barco, J. L., López-Martínez, N., Oms, O., and RuizOmeñaca, J. I. 2009b. The last hadrosaurid dinosaurs of Europe: a new lambeosaurine from the uppermost
Cretaceous of Arén (Huesca, Spain). Comptes Rendus. Palévol, 8 (6): 559–572.
Prieto-Márquez, A., and Wagner, J. R. 2009. Pararhabdodon isonensis and Tsintaosaurus spinorhinus: a new clade
of lambeosaurine hadrosaurids from Eurasia. Cretaceous Research, 30(5): 1238–1246.
Prieto-Márquez, A., Gaete, R., Rivas, G., Galobart, A., and Boada, M. 2006. Hadrosauroid dinosaurs from the Late
Cretaceous of Spain: Pararhabdodon isonensis revisited and Koutalisaurus kohlerorum, gen. et sp. nov. Journal
of Vertebrate Paleontology, 26(4): 929–943.
Riera, V., Oms, O., Gaete, R. and Galobart, A. 2009. The end-Cretaceous dinosaur succession in Europe: The Tremp
Basin record (Spain). Palaeogeography, Palaeoclimatology, Palaeoecology, 283, 160-171.
Sues, H.D., and Averianov, A. 2009. A new basal hadrosauroid dinosaur from the Late Cretaceous of Uzbekistan and
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(1667): 2549–2555.
36
Fig. 1. Map showing the location of sites in Huesca and Lleida provinces (Spain). Gray lines show the outlines of the
autonomous regions of Aragón and Catalonia.
Fig. 2. Biogeopraphic implications of the lambeosaurine phylogenetic analysis ruled out in this paper. The relative
position of Pararhabdodon is based on the phylogenetic analysis of Prieto-Márquez and Wagner (2009).
37
The hadrosaurid record in the Maastrichtian of the
eastern Tremp Syncline (northern Spain)
Fabio Marco Dalla Vecchia1, Rodrigo Gaete2, Violeta Riera3, Oriol Oms4, Albert Prieto-Márquez5, Bernat
Vila6, Albert Garcia Sellés7, and Angel Galobart8
1
Grup de Recerca del Mesozoic — Institut Català de Paleontologia (ICP) “M. Crusafont”, Escola Industrial 23,
E-08201 Sabadell, Spain.
2
Museu de la Conca Dellà, C/ del Museu 4, Isona, E-25650, Spain
3
Universitat Autònoma de Barcelona, Departament de Geologia, Cerdanyola del Vallès, Barcelona, E-08193, Spain
4
Universitat Autònoma de Barcelona, Departament de Geologia, Cerdanyola del Vallès, E-08193, Spain
5
Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, D-80333 Munich, Germany
6
Grup de Recerca del Mesozoic — Institut Català de Paleontologia (ICP) “M. Crusafont”, Escola Industrial 23,
E-08201 Sabadell, Spain.
7
Grup de Recerca del Mesozoic — Institut Català de Paleontologia (ICP) “M. Crusafont”, Escola Industrial 23,
E-08201 Sabadell, Spain.
8
Cap Grup de Recerca del Mesozoic — Institut Català de Paleontologia (ICP) “M. Crusafont”, Escola Industrial 23,
E-08201 Sabadell, Spain.
Derived hadrosauroids, considered here for practical purposes as those iguanodontoid dinosaurs more
derived than Bactrosaurus johnsoni (see Prieto-Márquez 2010), appear in the European fossil record
possibly in the upper Campanian and are the most common dinosaurs in the Maastrichtian (Dalla Vecchia
2006, 2009a). Their remains are reported from Spain, France, The Netherlands, Belgium, Germany,
Italy, Slovenia, Romania, Bulgaria, and Ukraine (Fig. 1). The basal, non-hadrosaurid (sensu PrietoMárquez 2010) Telmatosaurus transsylvanicus (Nopcsa 1900) and Tethyshadros insularis Dalla Vecchia
2009b are found in the lower Maastrichtian of Romania (see Panaiotu and Panaiotu, 2010 for dating by
paleomagnetism) and upper Campanian-lower Maastrichtian of Italy, respectively. The lambeosaurine
Pararhabdodon isonensis Casanovas-Cladellas, Santafé-Llopis, and Isidro-Llorens 1993, Arenysaurus
ardevoli Pereda-Suberbiola, Canudo, Cruzado-Caballero, Barco, López-Martínez, Oms and Ruiz-Omeñaca
2009b, and Blasisaurus canudoi Cruzado-Caballero, Pereda-Suberbiola and Ruiz-Omeñaca 2010b are
described from the upper Maastrichtian of Spain.
The richest region in Europe for the remains of those dinosaurs is without doubt the Tremp Syncline
of the southern Pyrenees, located in the Aragón and Catalunya regions of northern Spain (Figs 1-2A). The
western part of the syncline occurring in Aragón yielded a relatively limited sample of late Maastrichtian
age in three bone-bearing sites (five fossil-bearing levels) and one footprint site. However, that sample was
studied in detail and presents high hadrosaurid diversity with at least two lambeosaurines - Arenysaurus
ardevoli and Blasisaurus canudoi – and an indeterminate ‘hadrosaurine’ (Cruzado-Caballero et al. 2010a).
A higher number of sites occur in the eastern part of the syncline located in Catalunya, but most
of the abundant material collected to date (much more abundant than it can be evinced from literature,
e.g., Pereda-Suberbiola et al. 2009a) has not been published yet. Thirty-four sites with hadrosauroid
bone remains and at least nineteen with footprints have been identified to date, occurring mostly in the
easternmost portion of the syncline known as Conca Dellà (Isona i Conca Dellà, Abella de la Conca, Gavet
de la Conca and Tremp municipalities). All sites are located in the Tremp Formation; nearly all are in
the ‘lower red unit’ (sensu Rosell et al. 2001; Fig. 2B) of late Maastrichtian age (Riera et al. 2009a; Riera
2010; Oms et al., 2010) and only three (Els Nerets, Barcedana and Moror) are in the underlying ‘gray unit’
(Fig. 2B), also Maastrichtian in age (ibidem). The stratigraphic position of the fossil-bearing sites has
been located in the composite stratigraphic column of the lower part of the Tremp Formation and their age
was constrained by biostratigraphy, paleomagnetism and correlation with the stratigraphic sections of the
western part of the Tremp Syncline, and the close Àger and Vallcebre Synclines (Riera et al. 2009a; Riera
2010; Oms et al., 2010). To date, about one thousand skeletal remains and eight footprints collected in those
sites and referred to hadrosauroids are deposited in public institutions. The complete census of the footprint
sites is not available yet, but those fossils appear to be relatively frequent in the fluvial sandstones.
38
Hadrosauroid bones as well as footprints are common in the upper portion of the ‘lower red
unit’ referred to the magnetochron 29r, thus very close to the K/Pg boundary. The type material of
Pararhabdodon isonensis comes from this upper part of the ‘lower red unit’ (Sant Romà d’Abella site).
The ‘Koutalisaurus kohlerorum’ dentary, most probably belonging to Pararhabdodon isonensis (see PrietoMárquez and Wagner 2009) comes from the topographically and stratigraphically close Les Llaus site.
The first hadrosaurid bonebed in Europe occurs in the Basturs Poble site, which is located somewhat
lower in the ‘lower red unit’ (possibly in the lower part of C30n). The bonebed has yielded at least 250
hadrosaurid skeletal elements to date (the prepared material, including 11 partial to complete dentaries),
but possibly over 750 according to preliminary field identifications of still unprepared fossils.
Unfortunately, all the hadrosauroid material from the Tremp Formation, with the exclusion of a segment
of caudal vertebral column, is made of disarticulated elements. Although a complete and detailed study of
this large amount of specimens including the comparison with the taxa identified in the western part of the
syncline is in progress, three conclusions can already be drawn from the data currently available from the
sample.
First, hadrosauroids are relatively infrequent in the ‘grey unit’, where the titanosaurian sauropod
record is relatively abundant and rare ankylosaurian and theropod remains are also present. Hadrosauroids
become dominant in the “upper red unit”, where the other dinosaurian clades are only represented by a
few theropod teeth, a sauropod cervical vertebra and a femur, and some footprints referred to sauropods.
At least seven sites have yielded skeletal elements that can be referred to lambeosaurines. This faunal
turnover has been explained as a change from a transitional environment (marine to coastal plain) during
the deposition of the “grey unit” to a continental environment for the ‘upper red unit’ (Riera et al. 2009a).
However, most of the hadrosaurid record occurs in the marine-transitional Arén Formation (Blasi 1 level)
and in the overlying ‘grey unit’ (= La Posa Formation; Blasi 2-3 levels) in the western (Aragonian) part
of the Syncline, where the limit between the units is younger than in the eastern part because of facies
migration in a regressive context (Riera et al. 2009a). This suggests a time/event-related change in the
faunal composition rather than an ecological shift. Also the hadrosauroids from the close Àger and
Vallcebre Synclines of Catalunya, those from València Province of Spain (La Solana and Loma Cortada
sites), and those from southern France are late Maastrichtian in age (Dalla Vecchia 2009a). A faunal
change affecting the Ibero-Armorican Island close to the lower-upper Maastrichtian boundary was already
hypothesized by Le Loeuff et al. (1994), Buffetaut et al. (1997) and Company et al. (2009).
Secondly, egg remains are abundant in the eastern Tremp Syncline, being reported from at least 31 sites
located in the uppermost part of the underlying Arén Formation (Fig. 2B; at least 14 sites), ‘gray unit’ of the
Tremp Formation (six sites), and ‘lower red unit’ of the Tremp Formation (eleven sites) (López-Martínez,
1999; A. G. Sellés, pers. obs). They are nearly all referred to the Megaloolithus oogenus that is supposed
to be laid down by sauropod dinosaurs, while the Spheroolithidae oofamily that is usually referred to
hadrosaurids is unrepresented. This is unexpected, mainly for the ‘lower red unit’ where hadrosauroid
bones and footprints are far more common than sauropod ones.
Finally, the size of the hadrosauroid individuals represented by skeletal remains and footprints is, on
average, smaller than that of hadrosaurids found in Late Campanian-Maastrichtian sites of North America
and Asia (see Lull and Wright 1942; Figs 3-4). This is also the case of the hadrosaurids reported from the
western part of the Tremp Syncline (e.g., Cruzado-Caballero et al. 2010b), and those more or less coeval
in the French northern side of the Pyrenees (Laurent 2003). This supports the hypothesis of the influence
of insularism on hadrosauroid body size (island rule) (Dalla Vecchia 2006, 2009a, b; Benton et al. 2010).
Although histological studies are needed to establish the maturity or immaturity of the bones in the sample,
it appears rather improbable that so many specimens from 45 sites, both bones and footprints, all belong to
immature individuals.
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Fig. 1. Location of the Tremp Syncline (asterisk, including also the close Àger and Vallcebre Synclines) in the late
Maastrichtian European Archipelago (based on Philip et al. 2000). Other localities yielding latest Campanian
and Maastrichtian hadrosauroid remains in Europe are also reported (dots): 1) Laño (Spain), 2) La Solana
and Loma Cortada (Spain), 3) Southern France localities (Lestaillats, Jadet, Auzas, Peyrecave, Tricouté,
Cassagnau, Mérigon, Larcan, and Le Bexen), 4) Limburg localities (The Netherlands and Belgium), 5)
Bad Adelholzen (Germany), 6) Villaggio del Pescatore (Italy) and Kozina (Slovenia) sites, 7) Haţeg and
Transilvanian Basins (Romania), 8) Labirinta Cave (Bulgaria), 9) Mt. Besh-Kosh, Crimean peninsula
(Ukraine). White = emergent land, pale gray = shallow sea, gray = Chalk-sea, dark gray = deep sea, black =
oceanic basins (oceanic crust).
Fig. 2. The Tremp Formation. A) emergence of the Formation (gray) in the Tremp Syncline and other synclines of the
south-eastern Pyrenees (Spain). Based on Riera et al. (2009b), redrawn and modified. B) stratigraphy. 1) Arén
41
Sandstone; 2) Tremp Formation: 2a) ‘gray unit’, 2b) ‘lower red unit’, 2c) equivalent to the ‘Vallcebre limestone’,
2e) ‘upper red unit’.
Fig. 3. Selected hadrosaurid limb bones from the Tremp Formation of the eastern Tremp Syncline, compared for size
to a femur of Parasaurolophus, ROM 768a (A). (B) Femur (IPS-N-3) and (C) distal portion of a femur (IPS-
42
896) from Els Nerets site, (D) femur (MCD, without inventory number) from Lo Bas site, (E) femur (MCD
4766) from Casa Fabà site, (F) femur from Magret site (MCD, without inventory number), (G) the largest
femur from the sample of the Basturs Poble site (MCD 5011), (H) the largest humerus from the sample of the
Basturs Poble site (MCD 4825), (I) tibia (MCD 4737) from Cabana de Gori 2 site, (J) metatarsal II (MCD,
without inventory number) from Els Pous site, (K) tibia (MCD 4733) and (L) partial fibula (MCD 4733) from
Molí del Baró 1 site, (M) femur and (N) humerus (both MCD, without inventory number) from Costa de la
Serra 1 site, (O) proximal and (P) distal part of two femora from Serrat del Sanguin site (MCD, both without
inventory number), (Q) femur (IPS-931) from Sant Romà d’Abella II site, (R) humerus of Pararhabdodon
isonensis (IPS SRA 15) from Sant Romà d’Abella site, and (S) partial femur (MCD 5123) from the northern
flank of the Tossal de la Doba. All specimens are from the “lower red unit” with the exclusion of (B) and (C).
IPS = Institut Català de Paleontologia M. Crusafont, Sabadell; MCD = Museu de la Conca Dellà, Isona.
43
Fig. 4. Selected hadrosaurid footprints from the “lower red unit” of the Tremp Formation, eastern Tremp Syncline.
From (A) Tossal del Gassó, (B) Barranc de Guixers 3, (C) Serrat del Sanguin, (D) Barranc de Torrebilles, and
(E) Orcau. Specimens are deposited at the MCD, without inventory number. Hammer for scale in C and D is
11 inches (279 mm) long.
44
First documented hadrosaurid bonebed from the Belly
River Group (Campanian) at Dinosaur Provincial Park,
Alberta, Canada: Importance and Implications
David A. Eberth1 and David C. Evans2
1
Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta T0J 0Y0; [email protected]
University of Toronto,Toronto, Ontario;[email protected]
2
Bonebeds are important potential sources of paleoecological, paleobiological, and biostratigraphic
information (Rogers et al. 2007). They also provide unique opportunities to expand our knowledge of
basin evolution and preservational controls influencing a variety of resources. The Belly River Group at
Dinosaur Provincial Park (the Park) in southern Alberta, Canada, is famous for preserving large numbers
of fossil vertebrates and many hundreds of bonebeds (Eberth and Currie 2005). Although multitaxic
bonebeds (comprising the remains of many different kinds of vertebrates) represent more than 90% of
bonebed occurrences at the Park (Eberth and Currie 2005), it is the Park’s monodominant bonebeds that
have attracted most of the scientific and popular attention during the past 30 years (Currie and Dodson
1984; Ryan et al. 2000; Eberth and Getty 2005; Eberth and Currie 2005; Eberth et al. 2010). Monotaxic and
monodominant bonebeds continue to be the focus of research at the Park and elsewhere because of their
unique potential to provide insights into the paleobiology of individual taxa (Fiorillo and Eberth 2004;
Brinkman et al. 2007; Eberth and Currie 2010).
Until now, the Park’s monodominant dinosaur bonebeds (~20 known occurrences) have been known to
comprise skeletal material from only three centrosaurine ceratopsian (horned) dinosaurs -- Centrosaurus
apertus, Centrosaurus brinkmani, and Styracosaurus canadensis. Given that there are more than 42
species of dinosaur documented from the Park’s strata, and that dinosaur remains are unusually abundant,
this preservational pattern has been proposed as persuasive, though only partial evidence that these three
taxa were naturally gregarious (Currie 1981; Currie and Dodson 1984; Eberth and Getty 2005; Eberth et al.
2010). Conversely, the abundant fossil record at the Park coupled with the apparent absence of monotaxicmonodominant bonebeds comprising hadrosaurs has been regarded as an interesting paradox: the apparent
absence of monotaxic to monodominant hadrosaur bonebeds at the Park stands out as unusual given how
common hadrosaur bonebeds are elsewhere in Upper Cretaceous strata throughout the Western Interior and
globally (e.g., Lauters et al. 2008).
Here we document the first monodominant hadrosaur bonebed from the Park – the Princess Bonebed
(TMP L2369; BB: JR300). We propose that the perception that hadrosaurid bonebeds are absent at
the Park is simply an artifact of our historical approach to understanding the Park’s abundant fossil
resources. Specifically, we conclude that most field surveys that previously have assessed taphonomic and
preservational modes at the Park have relied on anecdotal and casual assessments of the resources rather
than quantification. Because dinosaur fossil resources are unusually abundant throughout the Park’s strata
and because hadrosaurs are the most common macrofossil preserved there (Dodson 1971; Brinkman
1990), it has been difficult to recognize hadrosaur bonebeds as distinct from the ‘background’ richness of
macrofossil remains. Hadrosaur bonebeds, although probably quite common in these beds, always contain
the remains of other taxa, and thus have been lumped together and categorized as multitaxic bonebeds. In
short, the Park’s unique fossil richness has made it more difficult to see the forest for the trees, especially in
the case of hadrosaurs.
References
Brinkman, D. B. 1990. Paleoecology of the Judith River Formation (Campanian) of Dinosaur Provincial Park,
Alberta, Canada: evidence from microfossils localities. Palaeogeography, Palaeoclimatology, Palaeoecology, 78:
37-54.
Brinkman, D.B., Eberth, D.A. and Currie, P.J. 2007. From bonebeds to paleobiology: applications of bonebed data.
In Bonebeds: Genesis, analysis, and paleobiological significance. Edited by R.R. Rogers, D.A. Eberth and A.R.
Fiorillo. University of Chicago Press, Chicago, pp. 221−263.
45
Currie, P.J. 1981. Hunting dinosaurs in Alberta’s great bonebed. Canadian Geographic, 10(4): 34-39.
Currie, P.J. and Dodson, P. 1984. Mass death of a herd of ceratopsian dinosaurs. In Third Symposium of Mesozoic
Terrestrial Ecosystems. Edited by W.E. Reif and F.Westphal. Attempto Verlag, Tubingen, pp. 52-60.
Dodson, P. 1971. Sedimentology and taphonomy of the Oldman Formation (Campanian), Dinosaur Provincial Park,
Alberta (Canada). Palaeogeography, Palaeoclimatology, Palaeoecology, 10: 21-74.
Eberth, D.A. and Currie, P.J. 2005. Vertebrate taphonomy and taphonomic modes. In Dinosaur Provincial Park: A
Spectacular Ancient Ecosystem Revealed. Edited by P.J. Currie and E.B. Koppelhus. Indiana University Press,
Bloomington, pp. 453-477.
Eberth, D.A. and Currie, P.J. 2010. Stratigraphy, sedimentology, and taphonomy of the Albertosaurus Bonebed (upper
Horseshoe Canyon Formation; Maastrichtian), southern Alberta, Canada. Canadian Journal of Earth Sciences,
47: 1119-1143.
Eberth, D.A., Brinkman, D.B., Barkas, V. 2010. A centrosaurine mega-bonebed from the Upper Cretaceous of
southern Alberta: Implications for behaviour and death events. In New Perspectives on Horned Dinosaurs: The
Ceratopsian Symposium at the Royal Tyrrell Museum, September 2007. Edited by M.J. Ryan, B. ChinneryAllgeier, and D.A. Eberth. Indiana University Press, Bloomington, pp. 495–508.
Eberth, D.A., and Getty, M.A. 2005. Ceratopsian bonebeds: Occurrence, origins, and significance. In Dinosaur
Provincial Park: A Spectacular Ancient Ecosystem Revealed. Edited by P.J. Currie and E.B. Koppelhus. Indiana
University Press, Bloomington, pp. 501-536.
Fiorillo, A.R., and D.A. Eberth 2004. Dinosaur taphonomy. In The Dinosauria. Edited by D.B. Weishampel, P.
Dodson, and H. Osmolska. University of California Press, Berkeley, pp. 607-613.
Lauters, P., Bolotsky, Y.L., Van Itterbeeck, J., and Godefroit, P. 2008. Taphonomy and Age Profile of a Latest
Cretaceous Dinosaur Bone Bed in Far Eastern Russia. Palaios, 23:153-162.
Rogers, R.R., Eberth, D.A., and Fiorillo, A.R. (editors) 2007. Bonebeds: Genesis, Analysis, and Paleobiological
Significance. University of Chicago Press, Chicago, 499 p.
Ryan, M.J., Russell, A.P., Eberth, D.A., and Currie, P.J. 2001. The taphonomy of a Centrosaurus (Ornithischia:
Ceratopsidae) bonebed from the Dinosaur Park Formation (Upper Campanian), Alberta, Canada, with comments
on cranial ontogeny. Palaios, 16: 482-506.
46
The Osteohistology of Hadrosaurid Dinosaur Teeth–
Reptiles that Exceeded Mammals in Dental Complexity?
Gregory M. Erickson1 and Mark A. Norell2
1
Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295; [email protected]
Division of Palontology, American Museum of Natural History, New York, NY 10024-5192;
[email protected]
2
Horses, bison, and elephants have grinding dentitions for finely titrating extremely tough and abrasive
plants. Their teeth are among the most sophisticated ever to evolve, being composed of intricate multitissue complexes that self wear to create the coarse chewing surfaces. Reptile teeth are considerably more
simplistic. Nevertheless, one group, the duck-billed dinosaurs (Hadrosauridae) evolved a similar dentition.
This innovation allowed them to become the first animals to broadly exploit flowering plants and dominate
Laurasian herbivorous niches for over 35 million years. Did these reptiles somehow evolve advanced
mammal-like dental sophistication? We used modern histological techniques to reveal that hadrosaurid
cheek teeth were much more complex that previously realized, and actually exceeded mammals in
complexity. Six tissues were present on the occlusal surfaces of their dental batteries. These include coronal
cementum, a tissue often cited as evidence for the advancement of mammalian dentitions beyond those of
reptiles. Variance in the distributions of these tissues within teeth and between taxa allowed for changes in
form and function relevant to feeding ecology.
47
A new low-crested lambeosaurine hadrosaurid from the
Dinosaur Park Formation of Sandy Point, eastern Alberta
David C. Evans1, Philip J. Currie2, Larry M. Witmer3, and John R. Horner4
1
Department of Natural History (Palaeobiology), Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario,
M5S 2C6, Canada; [email protected]
2
University of Alberta, CW405 Biological Sciences Building, Edmonton, Alberta T6G 2E9, Canada
3
Ohio University, Ohio, USA
4
Museum of the Rockies, Montana State University, Bozeman, Montana, USA
Lambeosaurinae is a diverse clade of ornithopod dinosaurs characterized by hypertrophied nasal
passages and associated cranial crests. Lambeosaurines were common in many Late Cretaceous
ecosystems of the northern hemisphere, and large sample sizes, taxonomic diversity, and increasing
control on their chronostratigraphic and paleoecological contexts make Lambeosaurinae a suitable model
clade to test hypotheses of Late Cretaceous dinosaur evolution and historical biogeography. The known
geologic range of Lambeosaurinae extends from the ?Turonian (Aralosaurus) through to near the end of
the Maastrichtian. All of the earliest known members of the clade are from south central Asia and are
represented by fragmentary material; Phylogenetic analyses posit these taxa as successive sister taxa
to the large clade formed of fan-crested (Corythosaurini) and tube-crested (Parasaurolophini) groups.
Lambeosaurines appear abruptly in Campanian-aged deposits of North America. The first occurrences
of Corythosaurus casuarius and Parasaurolophus walkeri at the base of the Dinosaur Park Formation of
southern Alberta are the oldest definitive records of lambeosaurines from North America published to date.
Here we report a new taxon of lambeosaurine from Belly River Group strata along the South
Saskatchewan River at Sandy Point, Alberta, approximately 70 km east of Dinosaur Provincial Park.
The new taxon was found at base of the Dinosaur Park Formation in this area, and therefore represents
one of the oldest diagnosable lambeosaurines from North America. It is represented by two largely
complete, articulated skeletons, each of which includes a complete skull and crest. The large database
of morphometrically described cranial growth series of Corythosaurus and Lambeosaurus provides a
framework for assessing the new specimens in an allometric context. The crest of the Sandy Point taxon
is notable for its relatively low, dome-like morphology combined with a prominent, posteriorly-projected
spike. In some respects, the crest superficially resembles juvenile specimens of Lambeosaurus in its cranial
anatomy. As in Lambeosaurus, the dorsal process of the premaxilla extends to form the dorsomedial region
of the posterior spike. However, the crest is not procumbent and the lateral premaxillary process does not
expand anterodorsally as in all known specimens of Lambeosaurus within the equivalent size range. The
apex of the crest is above the orbits, as in Corythosaurus. CT scanning and 3D visualization of the bestpreserved skull reveal that the nasal passage configuration is similar to that of Corythosaurus, and that
the dorsal fan, or ‘cocks-comb’, is truly poorly developed compared with those of Corythosaurus and
Lambeosaurus of similar size.
Preliminary phylogenetic analysis of the systematic position of the Sandy Point taxon within
Lambeosaurinae suggests that it occupies an important position in Corythosaurini, and forms the sister
taxon to a clade that includes Corythosaurus, Hypacrosaurus, and Lambeosaurus. It is differentiated
from these taxa in that it lacks a dorsal ‘cockscomb” above the nasal passages, and as a result lacks the
‘fan-shaped’ cranial crest of more derived corythosaurins. In virtually all previous analyses, fan-crested
(corythosaurin) and tubular crested (parasauroloph) clades are sister taxa, with out-group taxa known
from fragmentary crest material, making inferences about the plesiomorphic condition of the crest in
either group difficult. The new taxon is interesting because it has a relatively low, dome-like crest that may
approach the plesiomorphic condition for lambeosaurines, and suggests that the elaborate crests of derived
corythosaurins and parasaurolophins may have been derived independently from a more generalized,
dome-like ancestral condition. The resemblance of the crest to those in juvenile Corythosaurus and
Lambeosaurus emphasizes the importance of heterochrony in the evolution of the lambeosaurine crest.
48
Virtually all of the articulated skulls and skeletons of lambeosaurines from the Dinosaur Park Formation
have been recovered from Dinosaur Provincial Park (DPP). The chronostratigraphic distribution of the
new taxon indicates that it was contemporaneous with Corythosaurus from the lower faunal assemblage
zone in DPP, yet it occurred geographically closer to the coastline of the Western Interior Seaway. The
identification of this new lambeosaurine in a more coastally influenced environment and apparently
segregrated from other closely related taxa at DPP supports the hypothesis that the high faunal turnover
rates of lambeosaurines at the DPP are associated with habitat specificity and environmental change
affected by marine transgression.
49
A juvenile lambeosaurine (?Parasaurolophus) skull and
skeleton from the Kaiparowits Formation of southern
Utah, and developmental timing in lambeosaurine
ontogeny
Andrew A. Farke
Raymond M. Alf Museum of Paleontology, 1175 West Baseline Road, Claremont, California 91711-2199 USA (email:
[email protected])
Introduction
The late Campanian-aged Kaiparowits Formation of Grand Staircase-Escalante National Monument,
southern Utah, USA, has yielded a rich assemblage of hadrosaurid dinosaurs, including the hadrosaurine
Gryposaurus monumentensis, a second, unnamed species of Gryposaurus, and the lambeosaurine
Parasaurolophus sp. Although numerous isolated postcranial elements from juvenile individuals are
known, as well as an articulated juvenile hadrosaurine postcranial skeleton (Gates et al. 2006), juvenile
lambeosaurine crania from this formation have proven scarce to date. A small lambeosaurine hadrosaurid
(RAM 14000; ~2 m estimated body length) preserves a nearly complete skull (Fig. 1E), skeleton (with all
elements represented except for the forelimb below the elbow), and associated soft tissue impressions, and
thus provides important new data on the ontogeny of lambeosaurines.
Institutional abbreviations
CMN, Canadian Museum of Nature, Ottawa, Ont.; RAM, Raymond M. Alf Museum of Paleontology,
Claremont, Calif.; ROM, Royal Ontario Museum, Toronto, Ont.
Description
The humerus of RAM 14000 measures 180 mm in length, approximately one-third the length of the
humerus in the holotypes of Parasaurolophus walkeri and P. cyrtocristatus (Ostrom 1963), and the total
body length of the animal is estimated as ~2 m. Impressions of the scales along the toe pad were found in
association with the pedal digits. Additional details of the postcranial skeleton await complete preparation
of the specimen.
The skull (Fig. 1E) measures 255 mm from the tip of the premaxilla to the caudal extremity of the
exoccipital (compared to 810 mm for the same measurement in the holotype of P. walkeri; Evans et al.
2007) and 207 mm from the tip of the premaxilla to the end of the quadrate. The quadrate and dentary
measure 112 mm and 146 mm in length, respectively. A partial cast of the internal surface of the upper
beak shows that soft tissue (presumably keratin) extended 2.5 to 3 cm beyond the end of the premaxilla
(Fig. 1E). Thus, the profile of the oral margin was markedly different than indicated by the bone alone. As
seen in previously described examples of Edmontosaurus and Corythosaurus (Morris 1970), the internal
surface of the beak had vertical corrugations.
The cranial crest projects 38 mm above the top of the orbit and is thus relatively much more developed
than seen in previously described juvenile lambeosaurine skulls of larger size (e.g., Corythosaurus,
Hypacrosaurus, and Lambeosaurus; Evans 2010; Fig. 1A-D). In lateral view, the crest is semicircular,
arising well ahead of the orbit and terminating at approximately the mid-point of the orbit. The premaxillanasal fontanelle is open, and its ventral border terminates at the level of the midpoint of the orbit. The nasalfrontal suture is horizontal as in juvenile corythosaurins, rather than oriented dorsally as in larger juvenile
specimens of Parasaurolophus. Additionally, the frontal is interpreted to be approximately as long as wide
in dorsal view, unlike adult Parasaurolophus (Evans et al. 2007).
50
Discussion
The young ontogenetic age of the animal, as well as poor preservation of the sutures on the crest,
preclude a confident identification of RAM 14000. Among hadrosaurids, the jugal of RAM 14000 is most
similar to Parasaurolophus in the narrow angle between the postorbital process and the caudal blade,
resulting in a very narrow infratemporal fenestra. Additionally, the large size of the crest is also consistent
with Parasaurolophus; a previously described braincase from a subadult shows that the crest grew much
more quickly in this taxon than in corythosaurins (Evans et al. 2007). Finally, Parasaurolophus is the only
lambeosaurine currently known from the Kaiparowits Formation (Gates et al. 2006), and referral to this
taxon is thus most parsimonious.
Assuming that the assignment to Parasaurolophus is correct, RAM 14000 confirms that the
development of the crest in this taxon began far earlier ontogenetically than in other lambeosaurines. In
Corythosaurus, Lambeosaurus, and Hypacrosaurus, an incipient crest does not appear until individuals
reach ~50% of maximum adult skull length (Fig. 1B-D; Dodson 1975; Evans 2010); RAM 14000 is only
~30% of maximum adult skull length. Regardless, this appearance of incipient cranial ornamentation at
such a small size differs markedly from the cassuary, which does not develop its crest until it reaches 6580% of maximum skull length (Dodson 1975). Extremely late onset of development for bony ornamentation
is apparently typical for many birds, but contrasts with the condition in all ornamented ornithischian
dinosaurs (e.g., hadrosaurs, ceratopsians, and pachycephalosaurs). Although ornamentation may not reach
its final adult form until late in ontogeny, horns, frills and crests appear comparatively early. This is similar
to the ontogenetic trajectory of bovids, where horns occur even in the youngest animals (<25% adult size)
and may undergo considerable changes in shape and relative size. In at least some bovids, horn size is a
strong correlate with social status within a population (e.g., Geist 1966), and a similar pattern may have
applied in hadrosaurs (previously suggested for dinosaurs by Padian et al. 2011). Although allometric
trends and ontogenetic changes are frequently invoked in tests of evolutionary mechanisms behind cranial
ornamentation (e.g., Padian and Horner 2011a, 2011b; Knell and Sampson 2011), the developmental timing
of the initial appearance of ornamentation may be equally significant.
Acknowledgements
This project never would have happened without the chance discovery of the specimen by K. Terris. D.
Lofgren, M. Stokes, and numerous students, volunteers and faculty from The Webb Schools assisted in
the collection of the specimen. T. and S. Terris and the David B. Jones Foundation supported the airlift of
the specimen from the field, and G. Augustyn and family funded preparation of the specimen. M. Stokes
is gratefully acknowledged for his skillful excavation and preparation of RAM 14000. D. Evans, T. Gates,
M. Loewen, and S. Sampson offered helpful discussion, and S. Foss and A. Titus assisted with permitting.
The specimen was collected under United States Department of the Interior Bureau of Land Management
permit UT10-006E-Gs.
References
Dodson, P. 1975. Taxonomic implications of relative growth in lambeosaurine hadrosaurs. Systematic Zoology, 24(1):
37–54.
Evans, D.C. 2010. Cranial anatomy and systematics of Hypacrosaurus altispinus, and a comparative analysis of skull
growth in lambeosaurine hadrosaurids (Dinosauria: Ornithischia). Zoological Journal of the Linnean Society,
159(2): 398–434.
Evans, D.C., Reisz, R.R., and Dupuis, K. 2007. A juvenile Parasaurolophus (Ornithischia: Hadrosauridae) braincase
from Dinosaur Provincial Park, Alberta, with comments on crest ontogeny in the genus. Journal of Vertebrate
Paleontology, 27(3): 642–650.
Gates, T.A., Lund, E.K., Getty, M.A., Kirkland, J.I., Titus, A.L., DeBlieux, D.D., Boyd, C.A., and Sampson, S.D.
2006. Late Cretaceous ornithopod dinosaurs from the Kaiparowits Plateau, Grand Staircase-Escalante National
Monument, Utah. In Grand Staircase-Escalante National Monument Science Symposium Proceedings, Cedar City,
Utah, pp. 159–172.
51
Geist, V. 1966. The evolutionary significance of mountain sheep horns. Evolution, 20(4): 558–566.
Knell, R.J., and Sampson, S. 2011. Bizarre structures in dinosaurs: species recognition or sexual selection? A
response to Padian and Horner. Journal of Zoology, 283(1): 18–22.
Morris, W.J. 1970. Hadrosaurian dinosaurs bills–morphology and function. Los Angeles County Museum
Contributions in Science, 193: 1–14.
Ostrom, J.H. 1963. Parasaurolophus cyrtocristatus: a crested hadrosaurian dinosaur from New Mexico. Fieldiana
Geology, 14(8): 143–168.
Padian, K., and Horner, J.R. 2011a. The evolution of “bizarre structures” in dinosaurs: biomechanics, sexual selection,
social selection or species recognition? Journal of Zoology, 283(1): 3–17.
Padian, K., and Horner, J.R. 2011b. The definition of sexual selection and its implications for dinosaurian biology.
Journal of Zoology, 283(1): 23–27.
Padian, K., Horner, J., Fowler, D., and Scannella, J. 2010. How a synergy of species recognition and social signaling
explains cranial anatomy and ontogeny in several groups of dinosaurs. Journal of Vertebrate Paleontology, SVP
Program and Abstract Book, 2010: 143A.
Fig. 1. Schematics of skulls of juvenile lambeosaurine hadrosaurids in right lateral view (modified after Evans 2010),
drawn to scale: (A) RAM 14000 (reversed); (B) Corythosaurus casuarius (ROM 759); (C) Hypacrosaurus
altispinus (CMN 2247); (D) Lambeosaurus lambei (ROM 758). Note that although RAM 14000 is of
absolutely smaller skull size, its crest is relatively larger. (E) Skull of RAM 14000 in left lateral view, showing
sutural relationships. The rostral sutural margin of the jugal is mirrored from the contralateral element. Scale
bars = 10 cm; the bar at left is for (A-D), and the bar at right is for (E). Abbreviations: b, preserved extent of
impression of upper beak (indicated by arrows and shading); d, dentary; ex, exoccipital; j, jugal; m, maxilla;
pd, predentary; pm, premaxilla; pnf, premaxilla-nasal fontanelle; po, postorbital; q, quadrate; sa, surangular;
sq, squamosal.
52
A new species of Brachylophosaurus (Ornithischia:
Hadrosauridae) from the Judith River Formation
(Late Cretaceous: Campanian) of northcentral Montana
Elizabeth Anne Freedman
Museum of the Rockies and Department of Earth Sciences, Montana State University, 600 W Kagy Blvd, Bozeman,
Montana 59717, [email protected]
MOR 2919 is a new species of Brachylophosaurus, represented by an incomplete skull and postcrania
of a large individual from the Judith River Formation (Late Cretaceous: Campanian) of Hill County,
northcentral Montana. Exposures in Kennedy Coulee, the locality where the specimen was collected, are
equivalent to the uppermost Foremost Formation and lowermost Oldman Fm of Alberta, according to
multiple lines of evidence. The base of the coulee exposes a thick coal equivalent to the top of the Taber
Coal Zone of the Foremost Fm, capped by a white-gray amalgamated channel sandstone equivalent to the
Herronton Sandstone Zone at the top of the Foremost Fm. The upper portion of Kennedy Coulee, where
MOR 2919 was collected, is dominated by mudstones and corresponds to the pale beds of the lowermost
Oldman Fm. Radiometric dates constrain the age of MOR 2919 between 78.5 Ma and 78.2 Ma (Goodwin
and Deino, 1989), consistent with the range of ash dates from the lower Foremost (79.1 Ma) and upper
Oldman Fms (76.5 Ma) of Alberta (Eberth, 2005). Ray teeth collected from microsites throughout the
coulee, from the Herronton Sandstone to the pale beds of the lower Oldman, possess smooth crowns, and
are thus referable to Myledaphus sp. (sensu Peng et al., 2001). In Alberta, Myledaphus sp. are only found
in the Foremost and lowermost Oldman Fms (Brinkman et al., 2004), supporting the assignment of MOR
2919’s locality to the lowermost Oldman Fm.
The majority of known Brachylophosaurus canadensis specimens, notably a complete adult skeleton
(MOR 794) and a bonebed containing individuals of varying sizes (MOR 1071), were collected from
the Judith River Fm of Malta, Montana, 200 km east of Kennedy Coulee, and thus more distal along the
depositional wedge. In the Malta area, the base of the Judith River Fm is the shoreface Parkman Sandstone,
which is directly overlain by tan colored, quartz-rich sandstones (LaRock, 2001) equivalent to the Comrey
Sandstone Zone of the middle Oldman Fm. Strata equivalent to the Foremost Fm and lower Oldman Fm
are not present in the distal wedge deposits of Malta. Ray teeth collected with MOR 1071 are referable
to Myledaphus bipartitus, which, in Alberta, are only found in the Comrey Sandstone and higher units,
supporting the assignment of the Malta B. canadensis localities to the Comrey Sandstone of the Oldman
Fm. Brachylophosaurus canadensis specimens from Alberta were collected from the upper Oldman Fm
(Ryan and Evans, 2005). Thus, MOR 2919 is stratigraphically older than B. canadensis (MOR 794, MOR
1071, CMN 8893).
MOR 2919 is the sister taxon to B. canadensis, sharing nearly all character states. MOR 2919 is referable
to Brachylophosaurus based on the following synapomorphies: solid nasal crest extending posteriorly and
slightly dorsally, overhanging dorsal region of skull; extremely elongated, rod-like anterodorsal process of
maxilla. MOR 2919 is the largest known Brachylophosaurus individual: quadrate height of MOR 2919 is 37
cm, MOR 794 32.5 cm, MOR 1071 32.5 cm (largest specimen); dentary length MOR 2919 47 cm, MOR 794
46-47 cm, MOR 1071 42 cm (largest specimen), FMNH 40.5 cm and 42 cm; fibula length MOR 2919 112
cm, MOR 794 103 cm, MOR 1071 94 cm (largest specimen).
In B. canadensis, the nasal crest elongates posteriorly ontogenetically, and the posterior margin of
the nasofrontal suture migrates posteriorly as well. In MOR 2919, the nasofrontal suture is anteriorly
placed as in a juvenile canadensis, and the nasal crest is the shortest known for the species, overhanging
the supratemporal fenestrae by <1 cm. Yet, MOR 2919 is not a juvenile; in addition to its large size, the
braincase elements are completely fused, with most sutures obliterated. In “gracile” adult B. canadensis
(MOR 1071), which possess paddle-shaped nasal crests overhanging approximately 50% of the
supratemporal fenestrae (Prieto-Márquez, 2005), cranial sutures are still clearly defined. The “robust”
morphology of adult B. canadensis (MOR 794) displays a greatly flattened paddle-shaped nasal crest
completely overhanging the supratemporal fenestrae, and still possesses visible cranial sutures. In all
53
collected vertebrae of MOR 2919 (cervicals, dorsals, and caudals), the neural arches are fully fused to the
centra, with the suture lines completely obliterated. Small vertebrae from the MOR 1071 bonebed have
unfused neural arches found disarticulated from their centra.
Dentary teeth marginal papillae in MOR 2919 are slightly more pronounced than in B. canadensis
(MOR 1071 and FMNH 862). The primary ridge of the maxillary tooth crowns is often sinuous, as in at
least one B. canadensis (CMN 8893), but not Maiasaura peeblesorum. MOR 1155, a hadrosaurine from
the lower Two Medicine Formation, represents the sister taxon to the Brachylophosaurus-Maiasaura clade,
and possesses the sinuous primary ridge, suggesting that this character was reversed in Maiasaura but
persisted in both species of Brachylophosaurus (Prieto-Márquez 2010). MOR 2919 possesses a relatively
shorter proximal edentulous slope of the dentary than B. canadensis. Maiasaura and B. canadensis
are unique in possessing a dentary coronoid process with a horizontally straight dorsal margin leading
to a pointed caudodorsal process. MOR 2919 has the horizontally straight dorsal margin, but entirely
lacks the caudodorsal process. This process develops ontogenetically in Maiasaura and B. canadensis;
juveniles have the straight coronoid dorsal margin with no caudodorsal process, similar to the state of the
stratigraphically older MOR 2919. MOR 2919 has a relatively deeper caudal constriction of the jugal than
do B. canadensis and Maiasaura.
In Brachylophosaurus canadensis, the nasal crest continues to migrate posteriorly, elongate, and flatten
as the animal reaches adult size. Although the “gracile” and “robust” morphotypes are very similar in
size, the “gracile” specimens are consistently smaller than the “robust” specimens, suggesting that the
nasal crest continued growing significantly even as the animal’s overall growth rate was slowing. The
“gracile” and “robust” morphologies are not discrete; FMNH 862 and the holotype of Brachylophosaurus
canadensis (CMN 8893) display nasal crests intermediate in size between the “gracile” and “robust” forms
(Cuthbertson and Holmes, 2010). MOR 2919 is the largest individual of Brachylophosaurus, and displays
the greatest degree of sutural fusion, yet possesses the smallest nasal crest as an adult. Because MOR
2919 is stratigraphically older than all B. canadensis specimens, it is hypothesized to represent a more
basal Brachylophosaurus morphology. Thus, MOR 2919’s incipient crest would represent a transitional
nasal morphology between a non-crested ancestor (such as MOR 1155), and the larger crests of adult B.
canadensis.
References
Brinkman, D.B., Russell, A.P., Eberth, D.A., and Peng, J. 2004. Vertebrate palaeocommunities of the lower
Judith River Group (Campanian) of southeastern Alberta, Canada, as interpreted from vertebrate microfossil
assemblages. Palaeogeography, Palaeoclimatology, Palaeoecology, 213:295-313.
Cuthbertson, R.S., and Holmes, R.B. 2010. The first complete description of the holotype of Brachylophosaurus
canadensis Sternberg, 1953 (Dinosauria: Hadrosauridae) with comments on intraspecific variation. Zoological
Journal of the Linnean Society, 159:373-397.
Eberth, D.A. 2005: The Geology. In Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Edited
by P.J. Currie and E.B. Koppelhus, Indiana University Press, Bloomington, Indiana. pp. 54-82.
Goodwin, M.B., and Deino, A.L. 1989. The first radiometric ages from the Judith River Formation (Upper
Cretaceous), Hill County, Montana. Canadian Journal of Earth Sciences, 26:1384-1391.
LaRock, J.W. 2001. Sedimentology and taphonomy of a dinosaur bonebed from the Upper Cretaceous (Campanian)
Judith River Formation of north central Montana. Unpublished M.S. thesis. Pp. 61. Department of Earth Sciences.
Montana State University, Bozeman.
Peng, J.-H., Russell, A.P., and Brinkman, D.B. 2001. Vertebrate microsite assemblages (exclusive of mammals)
from the Foremost and Oldman Formations of the Judith River Group (Campanian) of Southeastern Alberta: an
illustrated guide. Provincial Museum of Alberta Natural History Occasional Paper, 25:1-54.
Prieto-Márquez, A. 2005. New information on the cranium of Brachylophosaurus canadensis (Dinosauria,
Hadrosauridae), with a revision of its phylogenetic position. Journal of Vertebrate Paleontology, 25:144-156.
Prieto-Márquez, A. 2010. Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and
Bayesian methods. Zoological Journal of the Linnean Society, 159:435-502.
Ryan, M.J., and Evans, D.C. 2005: Ornithischian Dinosaurs. In Dinosaur Provincial Park: A Spectacular Ancient
Ecosystem Revealed. Edited by P.J. Currie and E.B. Koppelhus, Indiana University Press, Bloomington, Indiana.
pp. 312-348.
54
Stable isotope approaches to the study of hadrosaurid
behavior
Henry C. Fricke
Department of Geology, Colorado College, Colorado Springs, CO, 80903 USA [email protected]
Traditionally paleontologists have relied on the morphology, taphonomy and sedimentological context
of hadrosaurid remains to investigate the behavior of these animals. Stable isotope ratios preserved
in hadrosaurid tooth enamel also record information related to animal behavior, and thus provide a
complementary means of research. Isotopic studies takes advantage of variability in carbon isotope
ratios of plant matter and in oxygen isotope ratios of surface waters that exists over any given landscape
due to differences in environmental conditions such as rainfall, temperature, evaporation, etc. When
animals ingest plant matter and surface waters, isotopic signatures reflective of the environment they are
occupying are incorporated into apatite [Ca5(PO4)3(OH, CO3)] that makes up their tooth enamel. Therefore
by comparing stable isotope ratios of different populations of hadrosaurids, or by comparing isotopic data
among hadrosaurids and other co-existing taxa, it is possible to study aspects of behavior such as migration
and ecological niche preference/niche partitioning.
To illustrate how stable isotope-based methods can be used, several different case studies (both
published and unpublished) are reviewed. For example, a comparison of isotopic data among Campanianage hadrosaurids that lived over a wide region along the Western Interior Seaway indicates that they
were limited in their migratory behavior (Fricke et al., 2009). A similar project looking at Maastrichtianage hadrosaurids from Wyoming, North Dakota and Alberta is ongoing, but suggests similar behavior.
Focusing on samples from a single location, a comparison of isotopic data from Maastrichtian-age
hadrosaurids and ceratopsians from North Dakota provides evidence for niche partitioning and a
hadrosaurian preference for riparian habitats (Fricke and Pearson, 2008). A similar comparison of
hadrosaurids and ceratopsians of Campanian-age from Alberta also reveals isotopic differences among
taxa, but with different absolute values and thus possibly different animal behaviors. Finally an ongoing
study of hadrosaurid teeth from these same sediments in Alberta reveals isotopic differences between those
found in river channel deposits and those found in crevasse splay deposits, which implies that hadrosaurid
populations themselves partitioned resources on the channel-floodplain scale.
Although these case studies provide excellent examples of how stable isotope geochemistry can be
applied to the study of behavior, a great deal of intriguing research remains to be done. For example,
intra-hadrosaurid niche partitioning inferred above could be occurring within a sub-family, between subfamilies, or perhaps between animals of different ages. With sampling of appropriate fossil material, these
and a host of other paleobehavioral questions, can be addressed.
References
Fricke H.C. and Pearson DA. 2008. Stable isotope evidence for variable dietary niche partitioning among
Hadrosaurian and Ceratopsian dinosaurs of the Hell Creek Formation, North Dakota. Paleobiology 34: 534-552.
Fricke H.C., Rogers R., and Gates T. 2009. Hadrosaurid migration: inferences based on stable isotope comparisons
among Late Cretaceous dinosaur localities. Paleobiology 35: 270-288.
55
Hadrosaurid dinosaurs from the Upper Cretaceous
(Campanian) Wahweap Formation of southern Utah:
Implications for biogeography and biostratigraphy
Terry A. Gates1, Zubair Jinnah2, Michael A. Getty3, and Carolyn G. Levitt4
1
Department of Geology, Field Museum of Natural History, 1400 S. Lakeshore Drive, Chicago, Illinois 60640, USA
School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, 2050, Johannesburg, South Africa
3
Utah Museum of Natural History, 1390 East Presidents Circle, Salt Lake City, Utah 84112, USA
4
Department of Geology and Geophysics, University of Utah, 115 South 1460 East, Salt Lake City, Utah 84112, USA
2
Hadrosaurid fossils from the Campanian Wahweap Formation of southern Utah offer the opportunity
to study the morphology and diversity of this group within a section of the Cretaceous that has previously
been depauperate of dinosaurs in North America. Radiometric dates derived from volcanic ashes within
the middle member of the 400 m thick formation provide a date of 80.1 ± 0.3 Ma (Jinnah et al. 2009). The
same study estimated the base of the Wahweap at 82-83 Ma derived from detrital zircon analysis. As such,
the Wahweap Formation is contemporaneous with several fossiliferous formations throughout the Western
Interior Basin (WIB), but most notably most of the Two Medicine and Judith River formations of Montana
and the Oldman, Foremost, and Pakowki formations of Alberta (Jinnah et al. 2009). Of these rock units,
only the Two Medicine and Oldman have produced identifiable hadrosaurid fossils for comparison with the
Wahweap fauna.
To date, there are two definitive taxa of hadrosaurid dinosaurs recognized from the Wahweap Formation,
one new species of lambeosaurine and one hadrosaurine of the Brachylophosaurini clade (Gates et al. in
press-b). Gates et al. (in press-a) described the hadrosaurine taxon Acristavus gagslarsoni, which is closely
related to Maiasaura and Brachylophosaurus but has no cranial ornamentation. Acristavus is found in the
middle member of the Wahweap Formation and lower Two Medicine Formation and is currently the oldest
hadrosaurid known from the WIB. Higher in section an isolated maxilla (UMNHVP 9548) was attributed
by Gates et al. (in press-b) to cf. Brachylophosaurus. This designation was based on similar morphology
between the Wahweap element and that of Brachylophosaurus. However, more recent comparisons have
cast doubt on the previous assignment and instead, we here attribute this element to cf. Acristavus. Most
specifically are the robustness of the ectopterygoid shelf and the straight rather than curved ventral margin
of the jugal articulation facet. Acristavus has a straight ventral margin as opposed to Brachylophosaurus
that possesses a sigmoidal ventral border. The maxilla from Maiasaura also has a straight ventral margin
of the jugal articulation facet, but several other features of the dorsal process, ectopterygoid shelf, and oral
margin preclude assignment to this taxon.
A single lambeosaurine maxilla (UCMP 152028) likely represents a new taxon. The element bears
the classic lambeosaurine morphology of a mediolaterally expanded premaxillary shelf and a high dorsal
process. Some of the unique features present on the maxilla include a large jugal process and a tall medial
wall that elevates the palatine process to nearly the height of the dorsal process.
Several hadrosaurid bonebeds have been excavated from the Wahweap Formation (Gates et al. in
press-b). Here we describe the skeletal material and taphonomy of one of the multi-individual bonebeds,
UMNHVP Locality 324, a site that to date, has yielded the most complete hadrosaurid skeleton from the
formation as well as a juvenile individual of the same species. Species-level identification of these skeletons
is currently unavailable. However, further study may reveal new information that will allow insight into
alpha taxonomy. Based on the preserved skeletal elements, we can identify the individuals to a species
that is likely a member of the Brachylophosaurini clade. More specifically, the only skull element from
the adult skeleton, a right postorbital, does not appear to have the unique morphology of the postorbital on
Acristavus, but it is too poorly preserved to gain more information. The remainder of the adult skeleton is
typical of hadrosaurid dinosaurs, although the neural arches of the cervical, dorsal, and caudal vertebrae
appear to have more unusual features. The juvenile skeleton preserves several other skull bones including
a maxilla, jugal, surangular, and partial postorbital. Most useful is the jugal that possesses an anterior
56
process with a long, triangular maxillary articulation facet, a feature that in hadrosaurids is found only in
the Brachylophosaurini clade. However, one confounding morphological feature on the jugal is that the
posteroventral flange is not drastically offset as in other specimens of the clade. Given the small size of the
element, this may just be an ontogenetic consideration.
The taphonomy of UMNHVP Locality 324 is similar to some other hadrosaurid sites in the Wahweap,
but differs in the amount of skeletal preservation. The site has yielded over 200 elements from the adult
and juvenile individuals, which are dispersed over an area of ~34 m2. However, there is little spatial overlap
between the adult and juvenile elements. Toothmarks are apparently absent from the preserved elements
and evidence of pre-burial breakage is minimal.
The bonebed is hosted in a horizontally-laminated mudrock that forms part of a 5 m thick upward-fining
succession. Fish scales, crab claws, carbonized wood and coal stringers are also present in the fossiliferous
layer, indicating subaqueous deposition in a waterlogged proximal floodplain setting. Long bones are
dominantly oriented SW-NE, suggesting some fluid flow prior to final burial. This orientation follows an
overall NE paleoflow postulated for the middle member of the Wahweap Formation (Lawton et al. 2003).
References
Gates, T.A., Horner, J.R., Hanna, R.R., and Nelson, C.R. in press-a. New unadorned hadrosaurid (Ornithopoda:
Dinosauria) from the Campanian of North America. Journal of Vertebrate Paleontology.
Gates, T.A., Lund, E.K., Boyd, C.A., DeBlieux, D.D., Titus, A.L., Evans, D.C., Getty, M.A., Kirkland, J.I., and Eaton,
J.G. in press-b. Ornithopod dinosaurs from the Grand Staircase-Escalante National Monument region, Utah
and their role in paleobiogeographic and macroevolutionary studies. In Advances in Late Cretaceous Western
Interior Basin Paleontology and Geology. Edited by A.L. Titus and M.A. Loewen, University of Indiana Press,
Indianapolis.
Jinnah, Z.A., Roberts, E.M., Deino, A.L., Larsen, J.S., Link, P.K., and Fanning, C.M. 2009. New 40Ar-39Ar and
detrital zircon U-Pb ages for the Upper Cretaceous Wahweap and Kaiparowits formations on the Kaiparowits
Plateau, Utah: implications for regional correlation, provenance, and biostratigraphy. Cretaceous Research, 30:
287-299.
Lawton, T.F., Pollock, S.L., and Robinson, R.A.J. 2003. Integrating Sandstone Petrology and Nonmarine Sequence
Stratigraphy: Application to the Late Cretaceous Fluvial Systems of Southwestern Utah, U.S.A. Journal of
Sedimentary Research, 73(3): 389-406.
57
New Gryposaurus material from the Kaiparowits
Formation of Grand Staircase Escalante National
Monument to be featured in the New Natural History
Museum of Utah in Salt Lake City, Utah
Michael A. Getty
Utah Museum of Natural History, University of Utah, 1390 E. Presidents Circle, Salt Lake City, UT 84112.
Email: [email protected]
In November 2011, the Utah Museum of Natural History (UMNH) will reopen to the public as the
Natural History Museum of Utah (NHMU) in a brand new home at the Rio Tinto Center on the University
of Utah campus in Salt Lake City. This facility will feature a number of new paleontology exhibits,
including several significant Gryopsaur specimens collected from the Upper Campanian Kaiparowits
Formation of Grand Staircase Escalante National Monument (GSENM), over the past twelve years.
New exhibits will feature mounted original skeletons of several Gryopsaur specimens collected in the
Kaiparowits Formation, including nearly complete skeletons of two adults and one very young juvenile, and
cast and original skulls of two additional individuals. These specimens were collected between 2001 and
2009, from remote wilderness areas of the Kaiparowits plateau in GSENM. Preparation of these specimens
has taken a team of more than 80 volunteer and professional preparators nearly 15,000 man hours to
complete, spanning over the past decade. Preparation of this material was complicated by both exceedingly
hard matrix, and extensive skin impressions.
One adult specimen (UMNH VP12665) was preserved with skin impressions covering nearly all of its
articulated tail and was prepared and mounted in a manner to exhibit the association of skin and bone. This
specimen is mounted into the floor in an “in situ” style, recreating how the skeleton was preserved in the
field. The second adult specimen (UMNH VP 20121) is the most complete large hadrosaur ever collected
in Utah, and was prepared out entirely from its matrix and ultimately mounted in a life-like position. This
mounted specimen is nearly 40 feet long, 12 feet high, and consists of more than 80% original skeletal
material. Although the nearly complete skull was collected from UMNH VP 20121, it is still in preparation,
and so we opted to use a reconstructed cast of the holotype of Gryposaurus monumentsis (RAM 6797) in
its place.
A second, original skull from another Gryposaur specimen (UMNH VP 18568) is also be mounted
in the exhibit, including a string of articulated cervical vertebrae and a large patch of skin impressions
from the neck. This specimen remains undescribed, but appears to represent a distinct morphology from
the holotype of Gryposaurus monumentensis. Also on exhibit is the nearly complete infant skeleton of
a hadrosaurine (UMNH VP 16677), which is likely Gryposaurus, but has not been positively identified
as such, due to the complete lack of cranial material. This specimen was prepared in matrix to maintain
the high level of articulation and associated soft tissue impressions. This exceptionally well preserved
specimen was preliminarily described at SVP in 2010, and is still under study for more detailed description
in the future.
The collection, preparation and mounting of these exceptional new specimens highlights the extremely
effective collaboration between the UMNH and the BLM administered GSENM, as well as the significance
of a highly motivated and dedicated team of volunteers in the field and lab.
58
New data on latest Cretaceous hadrosaurids from Russia
and north-eastern China
Pascal Godefroit1, Yuri Bolotsky2, Lina Golovneva3, Wu Wenhao4, and Pascaline Lauters5
1
Royal Belgian Institute of Natural Sciences, Department of Palaeontology, rue Vautier 29, B-1 000 Brussels,
Belgium, [email protected]
2
Palaeontological Laboratory of the Institute of Geology and Nature Management, Far East Branch, Russian
Academy of Sciences, per. Relochny 1, 675000 Blagoveschensk, Russia, [email protected]
3
Botanical Institute of the Russian Academy of Sciences, Prof. Popov street 2, St. Petersburg 197 376, Russia,
[email protected]
4
Research Center for Paleontology and Stratigraphy, Jilin University, Changchun 130061, P. R. China, paleovert@
jlu.edu.cn.
5
Department of Palaeontology, Royal Belgian Institute of Natural Sciences, rue Vautier 29, 1000 Bruxelles, Belgium,
[email protected], and Département d’Anthropologie et de Génétique humaine, Université
Libre de Bruxelles, avenue F.D. Roosevelt 50, 1050 Bruxelles, [email protected].
Four dinosaur-bearing sites have been investigated in latest Cretaceous deposits along the Amur
River, on the border between Russia and China: Jiayin and Wulaga (Yuliangze Formation) in China,
Blagoveschensk and Kundur (Udurchukan Formation) in Russia. More than 90% of the bones discovered
in these localities belong to hollow-crested lambeosaurine hadrosaurids: Charonosaurus jiayinensis at
Jiayin, Sahaliyania elunchunorum at Wulaga, Amurosaurus riabinini at Blagoveschensk, and Olorotitan
arharensis at Kundur. Flat-headed saurolophine hadrosaurids are much less numerous, but appear well
diversified as well: Wulagasaurus dongi at Wulaga, Kerberosaurus manakini at Blagoveschensk, and two
new genera respectively at Kundur and Jiayin. Palynological studies suggest that these sites are probably
synchronous with the ‘Lancian’ vertebrate localities in western North America. However, the latest
Cretaceous dinosaur assemblages are completely different in the Amur region (lambeosaurines abundant,
ceratopsids absent) and in western North America (ceratopsids abundant, lambeosaurines extremely rare
or absent). This probably reflects some kind of geographical barrier between both areas by Maastrichtian
time rather than strong differences in palaeoecological conditions. Recent advances in the study of the
hadrosaurids from the Amur region, including unpublished material from Jiayin, Blagoveschensk, and
Wulaga, will be presented during this communication.
A new Late Maastrichtian dinosaur fauna was also recently described in Chukotka region (north-eastern
Russia), close to the Bering Strait. In this locality, dinosaur remains are represented by isolated bones
and teeth, but allow reconstructing the biodiversity of the dinosaur fauna in arctic regions just before the
Cretaceous-Tertiary mass extinction event. Unlike in the Amur region, but like in western North America,
hadrosaurids lived together with ceratopsids in the Kakanaut area. Dinosaur eggshell fragments, belonging
to hadrosaurids and non-avian theropods, indicate that these taxa could reproduce in polar region and were
probably year-round residents of high latitudes. Palaeobotanical data suggest that these polar dinosaurs
lived in a temperate climate (mean annual temperature about 10°C), but the climate was apparently too
cold for ectothermic tetrapods. The high diversity of Late Maastrichtian dinosaurs in high latitudes, where
ectotherms are absent, indicates that dinosaur extinction was not a result of temperature decline, caused or
not by the Chicxulub impact.
59
Determining Individual Edmontosaurus From a
disarticulated bone bed using Principal Components
Analysis
Becky Gould1, Allan Ashworth2, and Ron Nellermoe3
1
North Dakota Geological Survey, [email protected]
North Dakota State University, [email protected]
3
Concordia College, [email protected]
2
Caudal vertebrae from numerous individuals of Edmontosaurus were examined for morphological
variation using Principal Components Analysis (PCA). The vertebrae were from a disarticulated,
monospecific bone bed in Corson County, South Dakota. Results of the PCA showed a minimum of 50
parallel lines which are interpreted to represent the existence of complete sections of tails from individual
animals within the bone bed. These lines showed a range in size from large to small animals, as well
as large to small vertebrae. This arrangement also facilitated examining fusion characteristics between
the vertebral centrum and associated processes. The results suggest that the fossil assemblage represents
an accumulation over a short, rather than long period of time, as well as a possible method for locating
individual animals or numbers of animals in other disarticulated bone beds.
60
Adding to Hadrosaurid Diversity in New Mexico Through
the Reexamination of a Historic Collection
Merrilee Guenther, Mateusz Wosik, and Stephanie McCarthy
Elmhurst College, Department of Biology, 190 Prospect Avenue, Elmhurst, IL 60126;
[email protected]
Understanding hadrosaurid diversity in the San Juan Basin can be difficult due, in part, to limitations
on the number and quality of specimens. In most cases, this fauna is not represented by complete, well
preserved skeletons as in Alberta. A reexamination of specimens collected in New Mexico in 1922 by the
Sternbergs sheds new light on hadrosaurid diversity and population dynamics in the San Juan Basin. The
collection, housed at the Field Museum of Natural History, is composed of disarticulated elements from the
Kirtland Formation of McKinley County, New Mexico, approximately 85 miles northeast of Thoreau, New
Mexico.
This collection represents individuals from a wide range of growth stages from juvenile to adult. The
smallest individuals are represented by isolated elements. The juvenile elements consist of postcrania
including ribs, femora, scapulae, and fragmentary skull elements, such as a partial quadrate and
quadratojugal. The smallest element, a scapula (PR 1295) that is approximately 66 mm in length, is
comparable in size to those of hatchling hadrosaurids of other genera known from Alberta and Montana. At
the opposite extreme are adult elements that appear to represent hadrosaurid individuals that are among the
largest known. A large humerus, hadrosaurine based on deltopectoral crest proportions, measures 861 mm
in length, approximately twenty five percent larger than individuals of Edmontosaurus.
In addition to the variation in growth stages, taxonomic variation is represented in this collection. Both
diagnostic cranial and postcranial elements have been preserved. Most of the postcranial elements are
hadrosaurine and have a generally gracile morphology, though several humeri appear lambeosaurine in
proportion. Based on postcranial elements, including the morphology of the pubis and humerus, there may
be at least three different genera of hadrosaurids represented in this collection. Cranial material is more
limited; however there are a number of disarticulated skull elements. Several well preserved dentaries
with predentaries that are not laterally expanded suggest individuals of basal hadrosaurine affinity. Several
jugals with angular and rostrally directed rostral margins are also present in the collection. In general, this
long overlooked collection of hadrosaurids provides the opportunity to add to the hadrosaurid data set of
New Mexico.
61
Shantungosaurus giganteus: the implications of body size
on bipedality
B.P. Hedrick1, P.L. Manning1,2*, A.T. McDonald1, E. Morschhauser1, P. Dodson3, L. Margetts2, K.A. Stevens4,
and W.I.S. Sellers5
*corresponding author email: [email protected]
1
School of Earth and Environmental Science, Hayden Hall, University of Pennsylvania, USA.
2
School of Earth, Atmospheric & Environmental Science, Williamson Building, University of Manchester, UK.
3
Penn Veterinary Medicine, Department of Animal Biology, University of Pennsylvania, USA.
4
Department of Computer and Information Science. University of Oregon, USA.
5
Faculty of Life Sciences, Stopford Building, University of Manchester, UK.
The colossal hadrosaur Shantungosaurus giganteus has been found in large numbers in the
Xingezhuang Formation of the Wangshi series in the Eastern Shandong Basin (Hu et al., 2001). The
Wangshi series was considered to be Late Cretaceous in 1923 when the geology was originally described
(Tan, 1923), and this interpretation has been supported through subsequent analyses (Hu, 1973; Zhao, 1979;
Dong, 1980; Hu et al., 2001; Liu et al., 2010; Ji et al., 2011).
The comprehensive analysis of hadrosaurid relationships performed by Prieto-Márquez (2010) found
Shantungosaurus and Edmontosaurus to be successively more derived outgroups of a clade of derived
saurolophines; Saurolophinae exhibited the following topology in the strict reduced consensus cladogram
(Prieto-Márquez 2010: fig. 6): ((Two Medicine OTU (Brachylophosaurus, Maiasaura)), (Shantungosaurus
(Edmontosaurus (more derived saurolophines)))). As a taxonomic aside, we follow the conclusions of Ji et al.
(2011) and consider Zhuchengosaurus maximus (Zhao et al. 2007) a junior synonym of Shantungosaurus
giganteus (Hu 1973).
Scaling a virtual model of Edmontosaurus to a larger body length (14.72 meters) to represent
Shantungosaurus is morphologically feasible due to the gross similarity between the two taxa (BrettSurman 1989), with the caveat that the mounted holotype skeleton of Shantungosaurus is a composite
of several individuals (Hu 1973; Brett-Surman 1989). Edmontosaurus and Shantungosaurus are also
phylogenetically close, though they are not sister taxa.
Fig. 1. Musculoskeletal model of Edmontosaurus sp. used by Sellers et al. (2009) to generate plausible gait patterns
using Gaitsym. Here the model generated a hopping gait!
62
Scaling an existing model is considerably easier than creating a new model de novo. Our existing
hadrosaur model (Sellers et al., 2009) is based on laser scanning an Edmontosaurus skeleton followed
by CAD based reconstruction (Figure 1). Muscles have been added using literature based myologies
(Dilkes 2000; Schachner 2005) and the size based on a proportion of total body mass using our established
methodology (Sellers and Manning 2007). This can therefore be rescaled to Shantungosaurus relatively
straightforwardly using basic measurement of the skeleton and a new estimate of body mass. Once the new
morphology has been established we used our standard genetic algorithm based gait generation software
GaitSym (Sellers et al., 2003) to generate the muscle activation patterns required for locomotion. This
system is able to generate gait optimised for arbitrary combinations of speed or economy. Kinematic and
dynamic analysis of the appendicular skeleton also permits the reconstruction of potential quadrupedal
and bipedal gait cycles, as well as transitional postures and gaits. The forelimb and pectoral girdles, in
particular, suggest postural adaptations for bipedality, while comparison of fore- vs. hindlimb ranges of
motion and associated stride lengths constrain the transition from quadrupedal to bipedal locomotion.
The main advantage of our approach to determine fossil gait reconstruction over others, is that ours
requires no a priori assumptions about gait kinematics and the gaits it produces are all both physically and
physiologically possible. This is particularly important when considering the locomotion of an animal, such
as Shantungosaurus, that might be considered at the very limit of possible body size for a biped.
References:
Brett-Surman, M. K. 1989. A revision of the Hadrosauridae (Reptilia: Ornithischia) and their evolution. Ph.D.
Dissertation, The George Washington University. 192 pp.
Dong, Z. 1980. Chinese dinosaur faunas and their stratigraphic position. Journal of Stratigraphy 4: 256-263.
Hu, C., Cheng, Z., Pang, Q., Fang, X. 2001. Shantungosaurus giganteus. Beijing: Geological Publishing House: 1-139.
Hu., C. 1973. A new hadrosaur from the Cretaceous of Zhucheng, Shantung. Acta Geologica Sinica 2: 179-206.
Ji, Y., Wang, X., Liu, Y., and Ji, Q. 2011. Systematics, behavior, and living environment of Shantungosaurus
giganteus (Dinosauria: Hadrosauridae). Acta Geologica Sinica 85: 58-65.
Liu, Y., Kuang, H., Peng, N., Ji, S., Wang, X., Chen, S., Zhang, Y., and Xu, H. 2010. Sedimentary facies and
taphonomy of Late Cretaceous Deaths of Dinosaur, Zhucheng, Eastern Shandong. Geological Review 56: 457-468.
Prieto-Márquez, A. 2010. Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and
Bayesian methods. Zoological Journal of the Linnean Society, 159: 435-502.
Schachner, E.R. 2005. Pectoral and Forelimb Musculature of the Basal Iguanodontid Tenontosaurus tilletti
(Dinosauria- Ornithischia), MSC Thesis, University of Bristol.
Sellers, W. I., Dennis, L. A. Crompton, R. H. 2003. Predicting the metabolic energy costs of bipedalism using
evolutionary robotics. Journal of Experimental Biology 206: 1127 .
Sellers, W. I. and Manning, P. L., 2007. Estimating dinosaur maximum running speeds using evolutionary robotics.
Proceedings of the Roal Society of London B 274: 2711.
Sellers, W.I., Manning, P. L., Lyson, L., Stevens, K., Margetts, L. 2009. Virtual palaeontology: gait reconstruction of
extinct vertebrates using high performance computing. Palaeontologia Electronica 12: 11A.
Tan, H. C. 1923. New research on the Mesozoic and Early Tertiary geology in Shantung. Bulletin of the Geological
Survey of China 5: 95-135.
Zhao, Z. 1979. Progress in the research of dinosaur eggs. Mesozoic and Cenozoic Red Beds of South China: Selected
papers from the “Cretaceous Tertiary Workshop,” Nanxiong, Guangdong Province, Science Press.
63
Hopeful hadrosaurs and cursed ceratopsians – the
floating fates of Dinosaur Provincial Park herbivores
during large-scale flooding events
Donald M. Henderson
Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada T0J 0Y0
Ceratopsian bonebeds are relatively common in Dinosaur Provincial Park, and are attributed to mass
mortality events during flooding (Eberth and Getty 2005). In contrast, hadrosaur bonebeds are rare within
the Park (Eberth and Currie 2005). To investigate the hypothesis that hadrosaurs were more resistant
to drowning when compared to ceratopsians, three-dimensional, digital models of representatives of
both groups were created. These models were then analyzed using some specially written software used
previously to examine buoyancy and stability in living and extinct tetrapods (Henderson 2003a,b; 2010).
Examples of crested and non-crested hadrosaurs were used - Lambeosaurus lambei and Gryposaurus
notabilis, respectively; along with short-frilled and long-frilled ceratopsians - Centrosaurus apertus, and
Chasmosaurus belli, respectively. The models include air-filled lung cavities equal to approximately 8% of
body volume as seen in extant reptiles (Milsom 1975). Axial body densities were set to 1,000 gm/l for the
post-cervical region, while the limbs were set to 1,050 gm/l. The head and neck densities were set to 900
gm/l to account for the spaces occupied by the trachea and esophagus, and the oral and sinus cavities in
the heads. It was found that both the hadrosaurs and ceratopsians were able to float passively with the body
sub-horizontal, but the hadrosaurs had their heads clear of the water surface, thus enabling the animals to
breathe. In contrast, the ceratopsians floated with their heads fully immersed and would have struggled
to elevate their heads to breathe. All models showed that the centres of buoyancy were slightly below the
centres of mass, indicating a potential instability. The relatively slender bodies and longer limbs of the
hadrosaurs may have made it easier for them to propel themselves through water when compared to the
rotund and short-limbed ceratopsians. Based on the results of these modeling studies, it is proposed that
hadrosaurs were better able to cross rivers and to have better survivorship during flooding events. The
exceptional abundances of hadrosaur remains in the Park may be a reflection of their better adaptive fit
with the well-watered landscape recorded in the rocks of the Park.
References
Eberth, D.A. and Currie, P.J. 2005. Vertebrate taphonomy and taphonomic modes. In Dinosaur Provincial Park: A
Spectacular Ancient Ecosystem Revealed. Edited by P.J. Currie and E.B. Koppelhus. Indiana University Press,
Bloomington, IN. pp.453-477.
Eberth, D.A. and Getty, M.A. 2005. Ceratopsian bonebeds: occurrence, origins, and significance. In Dinosaur
Provincial Park: A Spectacular Ancient Ecosystem Revealed. Edited by P.J. Currie and E.B. Koppelhus. Indiana
University Press, Bloomington, IN. pp.501-536.
Henderson, D. M. 2003a. Effects of stomach stones on the buoyancy and equilibrium of a floating crocodilian: a
computational analysis. Canadian Journal of Zoology, 81: 1346-1357.
Henderson, D.M. 2003b. Tipsy punters: sauropod dinosaur pneumaticity, buoyancy and aquatic habits. Proceedings
of the Royal Society of London B (Supp.)
Henderson, D.M. and Naish, D. 2010. Predicting the buoyancy, equilibrium and potential swimming ability of
giraffes by computational analysis. Journal of Theoretical Biology, 265: 151-159.
Milsom, W. K. 1975. Development of buoyancy control in juvenile Atlantic loggerhead turtles, Caretta c. caretta.
Copeia 1974: 758-762.
64
Morphological variation in the skull roof of
Gryposaurus from the Kaiparowits Formation (late
Campanian) of southern Utah
Lucia Herrero1* and Andrew A. Farke2
1
The Webb Schools, 1175 West Baseline Road, Claremont, California 91711-2199 USA.
2
Raymond M. Alf Museum of Paleontology, 1175 West Baseline Road, Claremont, California 91711-2199 USA, (email:
[email protected])
*Current address: Stanford University, 450 Serra Mall, Stanford, CA 94305 USA, (email: [email protected])
Fieldwork in the Kaiparowits Formation (late Campanian) of Grand Staircase-Escalante National
Monument, southern Utah, has yielded numerous hadrosaur specimens, representing Parasaurolophus sp.
and two species of Gryposaurus. A partial skull of Gryposaurus (RAM 12065; Raymond M. Alf Museum
of Paleontology, Claremont, California), including the braincase, parietals, squamosals, frontals, and
postorbitals, was recently collected from a channel sandstone within the upper part of the middle unit of
the formation. RAM 12065 can be definitively assigned to Gryposaurus, based on a prong of the nasals
inserting between the frontals, but a species determination cannot be made in the absence of the nasals
themselves. Nevertheless, the morphology of the supratemporal fossae and postorbitals differs from other
Gryposaurus specimens from the Kaiparowits Formation. In all known specimens of G. monumentensis,
the caudal portion of the postorbital is sharply angled dorsally, providing a kinked profile to the skull roof
in lateral view. In RAM 12065, the dorsal surface of the postorbital, and thus the profile of the skull roof,
is straight in lateral view. Gryposaurus incurvimanus shows intraspecific variability in this trait, with
smaller and presumably ontogenetically younger specimens showing a straight postorbital, contrasting
with a kinked postorbital in larger and presumably older specimens. Thus, we suggest that the profile of
the postorbital changed ontogenetically in Gryposaurus. The stratigraphic position, morphology, and small
size of the specimen relative to the holotype of G. monumentensis suggest that RAM 12065 most likely
represents a young G. monumentensis.
65
Riddle of the Humongous Hadrosaurs: What these giants
reveal about dinosaur ontogeny, evolution, and ecology
John R. Horner and Holly N. Woodward
Museum of the Rockies, Montana State University, Bozeman, MT 59717
The ultimate size and age of skeletally mature dinosaurs is largely unknown despite osteohistologic
evidence that indicates determinate growth in dinosaurs and other archosaurs. Current osteohistologic
studies provide important information concerning dinosaur growth rates, mass accumulation, and age at
death, but reveal precious little about skeletal maturity. Recent dinosaur census data from the Hell Creek
Formation reveal the crux of the problem, showing that terminal size individuals are amongst the rarest
of specimens in that “ecosystem.” Other Late Cretaceous formations reveal similar patterns, particularly
involving hadrosaurids, suggesting a variety of evolutionary, ecologic, or taphonomic possibilities.
Historically, paleontologists have considered dinosaur specimens representative of adults if the
specimens were “large” and articulated. Apparent cranial and vertebral fusion was used as a proxy for an
individual’s maturity, and terminal size was therefore implied. Later discoveries of even larger specimens
with minor differences were considered separate genera primarily because they were larger. This
interesting philosophy disregarded the possibility of allometric growth, but more importantly based its
premise on preconceived (untested) definitions of maturity despite the fact that an ontogenetic pattern of
fusion of cranial elements or vertebral neural arches has not been demonstrated in any dinosaur taxon.
Hadrosaurid specimens from the Hell Creek Formation of Montana seem to exemplify the problem
of misidentifying skeletal maturity. The average length of an “adult” Edmontosaurus skull from the
Hell Creek Formation is 100 cm whereas the three known skulls of Anatotitan are approximately 110
cm. However, an anomalous maxilla and jugal (MOR 1609) possessing shared characteristics of both
Edmontosaurus and Anatotitan represents a skull with a length of 150 cm, and an articulated specimen
(MOR 1142) with pelvis, partial hind legs, and complete tail is 7.6 meters in length, therefore representing
an animal with a total length of nearly 15 meters. Based solely on size, the traditional approach would be to
assign new genera to these specimens.
However, an osteohistological analysis of various hadrosaur specimens from the Hell Creek Formation
reveals the predictable: The smaller individuals possess immature bone tissues, while the largest specimens
possess the most mature tissues. Specifically, the eight to nine meter long Edmontosaurus specimens
possess tissues indicative of rapid, active growth, suggesting that they will indeed reach much larger
proportions. Conversely, the bone microstructure of the fifteen-meter long specimen reveals a cessation of
growth in body length. Therefore, it is likely that body size differences in hadrosaur specimens from the
Hell Creek Formation are ontogenetic rather than taxonomic indicators.
Census data from the Hell Creek Formation also allows for inferences regarding survivorship and
environmental preference. As has been recently demonstrated, several subadult dinosaur taxa possess
medullary tissues indicating that sexual maturity preceeded skeletal maturity. It is likely that hadrosaurs
followed a similar pattern, as the large number of subadult-size individuals preserved suggests that
hadrosaurs endured high mortality rates, and skeletal maturity was a rare event. Interestingly, however, this
scenario is only evident in terrestrial sediments as the percentage of giant, skeletally mature hadrosaurs
found in marine deposits is surprisingly high. Although finding the remains of terrestrial animals within
marine deposits is especially rare, the high frequency of abnormally large hadrosaurs suggests the pattern
of high subadult mortality rates observed in the Hell Creek Formation is instead a result of ontogenetic
environmental preference.
66
Hadrosaurid remains from the early Late Cretaceous
Mifune Group in Kumamoto Prefecture, Japan:
implications to the early radiation of hadrosaurids
Naoki Ikegami1 and Yukimitsu Tomida2
1
Mifune Dinosaur Museum, Kumamoto, Japan
Department of Geology and Paleontology, National Museum of Nature and Science, Tokyo, Japan.
2
Duck-billed dinosaurs are one of the well known groups of dinosaurs in the Late Cretaceous, and
abundant material has been discovered from the Campanian–Maastrichtian deposits in Asia and North
America. However, fossil records of the early Late Cretaceous hadrosaurids are still poor, and their
evolution in early stage is not well understood.
The Mifune Group, which lies in Kyushu, Japan, contains various vertebrate fossils of Cenomanian–
Santonian, and some elements of hadrosaurid ornithopod were found from the “Upper Formation”
(Coniacian–Santonian) of the group. A cranial material, as well as some postcranial elements, was found
from a coarse sandstone bed. This sandstone bed is covered by reddish mudstone of floodplain deposits,
and this sequence is considered to be fluvial deposits. Several hadrosaurid teeth and a fragment of maxilla
have also been found in the multi-taxic bonebed preserved in the channel-fill deposits.
The partial skull element is slightly compressed and deformed. Although the major part of the parietal
is eroded, the posterolateral portion of the right parietal is preserved. The parietal is broad laterally, and the
squamosal has elevated lateral wall above the cotylus, showing an affinity with lambeosaurines from the
Campanian–Maastrichtian of North America and Asia. The facet for the caudal ramus of the postorbital
elongates above the cotylus. The dorsal surface of postorbital is flat. Posterolateral part of the basicranial
is well preserved. The median ramus of squamosal reaches the center of parietal. The exoccipitals connect
together. The supraoccipital is excluded from participation to form the upper edge of the foramen magnum.
The occipital condyle is semicircular in outline with the dorsal surface concave. The basioccipital is
mediolaterally wider than anteroposterior length. The paroccipital process is posteroventrally and laterally
directed, and the basipterygoid processes project ventrolaterally. The alar processes are well developed.
These cranial elements differ from those of derived iguanodontians from the Early Cretaceous of Asia
and North America and Bactrosaurus johnsoni from Inner Mongolia in the short and wide basioccipital.
This partial skull is rather similar to Jaxartosaurus aralensis from the Santonian of Kazakhstan in Central
Asia in wide parietal, short caudal ramus of the postorbital, and the mediolaterally wide basioccipital.
However, the Mifune specimen differs from J. aralensis in having a strong depression on the ventral
surface of basioccipital. Therefore, characters described above suggest that Mifune specimen probably
represents a new taxon of lambeosaurine.
The maxillary teeth have a strong primary ridge, whereas secondary ridge is missing, and the crowns
are symmetrical on the either side of the primary ridge. The primary ridge is more prominent, and the
occlusal surface is pentagonal in outline as in the derived hadrosauroids. This situation is different from
those of non-hadrosauroid iguanodontian. The lingual enamel of dentary teeth from the Mifune Group
bears a single median carina and secondary longitudinal ridge. However, they have narrower diamondshaped crowns, and the prominent primary ridge lies near the center of the lingual surface as in the derived
hadrosauroids and lambeosaurines.
These specimens extend the temporal range of the lambeosaurines in Japan to Coniacian–Santonian.
This fact supports that the early radiation of the lambeosaurines has occurred during this age in Asia.
67
A hadrosauroid from the Santonian Milk River
Formation of Alberta, Canada
Derek W. Larson1, Nicolás E. Campione1, C. Marshall Brown1, David C. Evans2, and Michael J. Ryan3
1
Department of Ecology and Evolutionary Biology, University of Toronto
Department of Natural History, Royal Ontario Museum
3
Cleveland Museum of Natural History, Cleveland, Ohio
2
The Milk River Formation preserves some of the oldest terrestrial fossils from Alberta, and as such
is important for interpreting the structure of early Late Cretaceous communities that gave rise to the
well-known Late Cretaceous dinosaur faunas typical of the Belly River Group (e.g., Dinosaur Park
Formation; Currie and Koppelhus 2005). Presently, the Milk River Formation preserves a well-documented
microvertebrate fossil assemblage of latest Santonian age (e.g., Fox 1972;Larson 2008), but in comparison,
the remains of large terrestrial vertebrates, including the megaherbivorous fauna, are poorly documented
and limited to a single study (Russell, 1935). Hadrosaurids represent some of the most common vertebrates
in the later deposits of the Belly River Group (Ryan and Evans 2005), and are therefore likely to be one of
the most important primary consumers. The occurrence of these large taxa is expected in the Milk River
Formation. Presently, the fossil record of hadrosaurids from this formation is limited to teeth assigned
to cf. Kritosaurus sp. (Russell 1935), though based on our current understanding of tooth morphology, a
specific identification of hadrosauroid teeth is here regarded as dubious. We report on several cranial and
postcranial isolated elements of varying completeness that can be confidently assigned to Hadosauroidea,
and discuss both their phylogenetic and biogeographic implications.
These cranial elements include an almost complete frontal, partial jugal, prootic, quadrate, dentary,
and complete surangular. Postcranial elements include numerous vertebrae, a humerus, a femur, three
tibiae, a fibula, metatarsals, and phalanges. All elements were recovered as isolated material or from
mixed bonebeds, but all are from roughly the same stratigraphic horizon within the Milk River Formation.
Based on the morphology of the various elements, it is likely that they represent a single species; however,
at this time, we cannot unequivocally reject the possibility of multiple taxa. Elements are from a range
of individual sizes. The frontal, jugal, and surangular exhibit notable diagnostic attributes. The frontal
appears to be domed, has a broad suture for the postorbital, and a small contribution to the orbit, consistent
with the morphology seen in Lophorhothon (Langston 1960) and Aralosaurus (Rozhdestvenskiy 1968),
and unlike Bactrosaurus (Prieto-Márquez 2011). Only the rostral region of the jugal is preserved, and it
does not exhibit the dorsoventral expansion of the rostral process, typical of hadrosaurids. Rather, the jugal
exhibits a slight rounded dorsoventral expansion, similar to that of other non-hadrosaurid hadrosauroids
(Langston 1960;Sues and Averianov 2009;Prieto-Márquez and Norell 2010). The surangular is typical of
hadrosauroids; it is dorsoventrally flattened, expands laterally, and lacks a surangular foramen.
Based on the combination of characters present on the cranial elements, as well as others present
in the postcranial bones, we coded the Milk River Formation taxon into the ornithopod matrix of Sues
and Averianov (2009). The analysis recovered 73 most parsimonious trees of 288 steps (CI=0.542
RI=0.86 RC=0.466) and supports the hypothesis that the Milk River material is phylogenetically closer
to Hadrosauridae than to Protohadros. Its ambiguous placement outside of both hadrosaurid clades
(Hadrosaurinae and Lambeosaurinae) supports the notion that it shares similarities with stem hadrosaurids
and non-hadrosaurid hadrosauroids, such as Aralosaurus, Bactrosaurus, Gilmoreosaurus, Levnesovia,
Lophorhothon, Telmatosaurus, and Tanius.
Although the present material is not complete or diagnostic enough to be named, it provides evidence
of a basal hadrosauroid in the Santonian of western North America, immediately prior to the Campanian
diversification of hadrosaurid taxa in this region. At this time, further specimens need to be collected
to make strong conclusions; however, based on the similarity with taxa such as Lophorhothon and
Aralosaurus, as well as its Santonian age, it is clear that the study of ornithopods from the Milk River
Formation has important implications for the biogeography and evolutionary history of hadrosaurids.
68
References
Currie, P.J., and Koppelhus, E.B., (eds.). 2005. Dinosaur Provincial Park: A Spectacular Ancient ecosystem Revealed.
Indiana University Press, Bloomington, Indiana, 648 pp.
Fox, R.C. 1972. A primitive therian mammal from the Upper Cretaceous of Alberta. Canadian Journal of Earth
Sciences, 9: 1479-1494.
Langston, W., Jr. 1960. The vertebrate fauna of the Selma Formation of Alabama Part VI: The Dinosaurs. Fieldiana:
Geology Memoirs, 3(6): 317-361.
Larson, D.W. 2008. Diversity and variation of theropod dinosaur teeth from the uppermost Santonian Milk River
Formation (Upper Cretaceous), Alberta: a quantitative method supporting identification of the oldest dinosaur
tooth assemblage in Canada. Canadian Journal of Earth Sciences, 45: 1455-1468.
Prieto-Márquez, A., and Norell, M.A. 2010. Anatomy and relationships of Gilmoreosaurus mongolensis (Dinosauria:
Hadrosauridae) from the Late Cretaceous of Central Asia. American Museum Novitates, 3694: 49 pp.
Prieto-Márquez, A. 2011. Cranial and appendicular ontogeny of Bactrosaurus johnsoni, a hadrosauroid dinosaur
from the Late Cretaceous of Northern China. Palaeontology:
Rozhdestvenskiy, A.K. 1968. Hadrosaurs of Kazakhstan. In Upper Paleozoic and Mesozoic Amphibians and Reptiles.
Edited by L.P. Tatarinov, and et al. Akademia Nauk S.S.S.R., Moscow, Russia. pp. 97-141.
Russell, L.S. 1935. Fauna of the upper Milk River beds, Southern Alberta. Transactions of the Royal Society of
Canada, IV: 115-128.
Ryan, M.J., and Evans, D.C. 2005. Ornithischian Dinosaurs. In Dinosaur Provincial Park: A spectacular Ancient
Ecosystem Revealed. Edited by P.J. Currie, and E.B. Koppelhus. Indiana Univeristy Press, Bloomington. pp. 312348.
Sues, H.D., and Averianov, A. 2009. A new basal hadrosauroid dinosaur from the Late Cretaceous of Uzbekistan and
the early readiation of duck-billed dinosaurs. Proceedings of the Royal Society B, 276: 2549-2555.
69
Brain of Ornithopods and new characters for
phylogenetic analyses
Pascaline Lauters1, Martine Vercauteren2, and Pascal Godefroit3
1
Royal Belgian Institute of Natural Sciences, Department of Palaeontology, rue Vautier 29, B-1000 Brussels, Belgium,
[email protected]; and Département d’Anthropologie et de Génétique humaine, Université Libre
de Bruxelles, avenue F.D. Roosevelt 50, B-1050 Brussels, Belgium, [email protected]
2
Département d’Anthropologie et de Génétique humaine, Université Libre de Bruxelles, avenue F.D. Roosevelt 50,
B-1050 Brussels, Belgium, [email protected]
3
Royal Belgian Institute of Natural Sciences, Department of Palaeontology, rue Vautier 29, B-1000 Brussels, Belgium,
[email protected]
The brain is generally lost before any fossilization, being subject to rapid decay after death. That doesn’t
actually prevent its study. In fact, we have the possibility to describe the endocranial cavity, and thus the
supposed shape of the brain of extinct animals, through two techniques: endocranial casts made from
yielding materials (silicone or latex rubber), and 3D reconstructions generated from the processing of CT
scan data. Thanks to these techniques, we looked at endocranial volumes of a variety of ornithopods from
the Cretaceous of Europe and Asia. The access to the endocranial cavity leads to the establishment of new
characters potentially interesting for the phylogeny of hadrosaurid dinosaurs.
70
Stance and gait in hadrosaurs: 3D computational
modelling of locomotor muscle moment arms in
Edmontosaurus
Susannah C.R. Maidment1, Karl Bates2, and Paul M. Barrett1
1
Department of Palaeontology, Natural History Museum, London, United Kingdom; [email protected]
Department of Musculoskeletal Biology, University of Liverpool, United Kingdom
2
Introduction
Although the hadrosaurian postcranial skeleton has been studied for well over a century (e.g. Cope 1883;
Lambe 1914), consensus remains to be reached regarding stance and gait. For example, hadrosaurs have
been considered bipeds (e.g. Ostrom 1964; Galton 1970; Maryańska & Osmólska 1984), quadrupeds (e.g.
Lockley and Wright 2001) or somewhere in between (facultative quadrupedality; e.g. Carrano 2001; Horner
et al. 2004; Sellers et al. 2009).
Maidment & Barrett (2010) reconstructed the pelvic myology of various quadrupedal and bipedal
ornithischians and suggested that hadrosaurs, despite being quadrupedal, possessed a different stance than
other quadrupedal ornithischians. They suggested that hadrosaurs retained crouched hind limbs and placed
their feet on the midline during locomotion, similarly to a biped. In contrast, stegosaurs, ceratopsids and
ankylosaurs possessed columnar hind limbs and were relatively ‘wide-gauge’.
These inferences of stance and locomotion were derived from musculofunctional hypotheses based
on qualitative comparative anatomy. Herein, we use a combination of comparative anatomy, myological
reconstruction, and three-dimensional computational modelling of pelvic muscle moment arms to
quantitatively test the above musculofunctional hypotheses, and to provide a preliminarily examination of
stance and gait in hadrosaurian dinosaurs relative to those of other ornithischians.
Materials and Methods
The postcranial skeletons of 17 hadrosaurs were examined for gross morphology and muscle scars
(Table 1). Myological reconstructions used the extant phylogenetic bracket, whereby the reconstruction of
unpreserved anatomical features in non-avian dinosaurs can be inferred by their presence in crocodiles
and birds (Bryant & Russell 1992; Witmer 1995). We dissected numerous extant archosaurs and drew
additional information from the literature (e.g. Romer 1923; Norman 1986; Dilkes 2000; Hutchinson 2001a,
b) to inform our myological reconstruction, which was set in an evolutionary context by examination of
extinct archosaurs and over 150 ornithischian specimens (Maidment & Barrett 2010, in review). Despite
this, there is still some uncertainty regarding the exact origin and insertion of several pelvic muscles, so
sensitivity analyses were carried out using alternative myological reconstructions.
Edmontosaurus material from the Sternberg Collection of the Natural History Museum, London
(NHMUK) was used to build a three-dimensional model. An ilium (NHMUK R6862), ischium (NHMUK
R14368), pubis (NHMUK R5915) and femur (NHMUK R14369) were laser scanned using a Viuscan handheld laser scanner. Although the scanned specimens come from individuals of different sizes, the laser
scans were rescaled using ratios from other well-preserved Edmontosaurus skeletons. All of the specimens
came from the same locality and likely represent the same population of animals.
Laser scans were imported into the computer-aided design software Maya (www.autodesk.com) and
the pelvis and hind limb were manually articulated in a ‘neutral’ posture (e.g. Hutchinson et al. 2005). The
hip joint was modelled as a ball and socket joint. The model was imported into the dynamic locomotion
software GaitSym (www.animalsimulation.org), and origin and insertion points of pelvic muscles
specified. Intermediate or ‘via’ points and wrapping cylinders (Sellers et al. 2003) were used to guide 3D
muscle paths from origin to insertion (Figure 1). Analysis of the model was carried out in GaitSym. The
effective moment arm for each muscle at a range of hip joint angles was recorded. Results were compared
with similar models of the bipedal basal ornithischian Lesothosaurus, and the quadrupedal stegosaur
Kentrosaurus.
71
Results
Hadrosaurs as obligate bipeds
The forelimb morphology of hadrosaurs provides numerous lines of evidence to suggest that they were
obligate quadrupeds (Figure 2). The development of an anterolateral process of the proximal ulna (Fig.
2B, C: lp; Brett-Surman & Wagner 2007; Prieto-Márquez 2007; Cuthbertson & Holmes 2010) is a feature
present in other quadrupedal ornithischians and quadrupedal sauropodomorphs (Bonnan 2003) and results
in the radius articulating with the ulna anteromedially. Distally, the ulna bears a concave, cup-like facet
medially for the radius in hadrosaurs (Fig. 2B: rf; Cuthbertson & Holmes 2010), while the radius bears a
facet laterally for the ulna. When the elements are articulated the distal end of the radius is located medially
to the ulna. In basal dinosaurs (Bonnan 2003), the radius was located anterior to the ulna and the manus
was supinated, a feature presumably required for grasping. Medial movement of the ulna would have
resulted in pronation of the manus (Bonnan 2003), a feature important in quadrupedal locomotion. The
cup-like articular facet of the distal ulna (Fig. 2B) would have prevented rotation of the distal end of the
radius around the ulna, so that supination of the manus would have been impossible (Bonnan 2003).
The morphology of the manus provides further evidence for obligate quadrupedalism. Metacarpals
II–IV are elongate and closely appressed (Fig. 2D; Evans & Reisz 2007; Prieto-Márquez 2007). Proximal
phalanges are cylindrical, while the distal ends of the metacarpals and all phalanges lack roller joints
(Fig. 2D; Brett-Surman & Wagner 2007). The unguals of digits II and III are hoof-like (Fig. 2D, hu; BrettSurman & Wagner 2007; Prieto-Márquez 2007), a feature observed in all other obligate quadrupedal
ornithischians. The columnar nature of the metacarpals and proximal phalanges suggests that they
functioned like a single unit and the lack of roller joints between phalanges suggests that bending of the
digits would have been impossible. Finally, the hoof-like unguals are clearly adapted for weight-bearing
and it is difficult to envisage the potential function of these structures in a biped. These features were also
used to indicate weight-bearing in Iguanodon bernissartensis (Norman 1980). The inability to supinate
the manus and bend the digits indicates that the hadrosaurian forelimb would not have been capable of
grasping. This evidence suggests that hadrosaurs were obligate quadrupeds and is in agreement with
reports of quadrupedal hadrosaur trackways (e.g. Lockley & Wright 2001) and evidence from soft tissue
(Sellers et al. 2009).
Moment arms in Edmontosaurus
Of the 15 hip muscles modelled (Fig. 1; abbreviations for all muscles given in Table 2), seven possessed
leverage for hip flexion (PIFI1&2, ISTR, ITBA, IFMA, IFMP, AMB) while eight possessed leverage for hip
extension (ADD1&2, CFB, CFL, FTI3, IFB, ITBP, FTE). Muscles originating posterior to the hip joint have
moment arms for extension, while those originating anterior to the hip are flexors. Flexors and extensors
experienced maximum moment arms at a wide range of hip joint angles, from strongly flexed to strongly
extended.
Originating dorsal to the hip joint and inserting ventral to it, 11 of the 15 muscles possess moment arms
for abduction (AMB, CFB, FTE, FTI3, IFB, IFMA, IFMP, ITBA, ITBP, PIFI1&2) while four are adductors
(ADD1&2, ISTR, CFL). Peak moment arms occurred at a wide range of hip flexion-extension angles.
In long axis rotation, most muscles had peak moment arms at highly extended or highly flexed hip joint
angles. Nine muscles, mostly those originating posterior to the hip joint, possess moment arms for lateral
rotation (ADD1&2, CFL, CFB, FTE, FTI3, IFB, ISTR, ITBP) while six muscles are medial rotators (AMB,
IFMA, IFMP, ITBA, PIFI1&2).
Most muscles have the greatest leverage for flexion-extension. IFMA and IFMP have highest moment
arms for abduction, while ISTR has highest leverage for lateral rotation.
72
Sensitivity analyses
Alternative reconstructions for ADD1&2 and PIFI2 resulted in little change to the patterns above. A
more distal origin of ADD1&2 resulted in an increase in peak moment arms, while a more proximal origin
resulted in a decrease in moment arms. PIFI2 originating on the sacral ribs had the same moment arms as
it did originating on the medial side of the preacetabular process. A PIFI2 insertion on the anterior femur
resulted in a decrease in abduction-adduction moment arms, but an increase in long axis rotation moment
arms.
Comparisons with other taxa
Changes in moment arm with hip flexion-extension angle were generally similar across the three
ornithischian taxa, although there were some more significant variations in some muscle groups. IFMP was
a flexor in Kentrosaurus and Edmontosaurus, but was an extensor at most joint angles in Lesothosaurus
(Fig. 3A). This is because Lesothosaurus possesses the primitive origin of IFMP dorsal to the acetabulum,
but in both Edmontosaurus and Kentrosaurus, the origin has migrated anteriorly. The more posterior
origin of IFMP in Lesothosaurus also resulted in a much higher moment arm for lateral rotation than in
Edmontosaurus and Kentrosaurus.
ISTR had a moment arm for extension in Kentrosaurus and Lesothosaurus, while it was a flexor in
Edmontosaurus (Fig. 3B). This is because Kentrosaurus and Lesothosaurus possess the primitive insertion
of ISTR below the greater trochanter on the posterolateral femur, while Edmontosaurus possesses a
derived insertion on the ‘posterior trochanter’, a posterior extension of the greater trochanter observed in
ornithopods related to the insertion of this muscle (Maidment & Barrett in prep.).
Abduction-adduction moment arms showed some differences in magnitude between taxa, although changes
in moment arm magnitude with hip angle were similar. For the majority of abductors, Kentrosaurus
possessed higher moment arms than the other taxa (e.g. Fig. 4A), and this is to be expected because of the
transverse expansion of the ilium. Long axis rotation moment arms also varied between taxa. Muscles
originating on the ilium and inserting on the lower limb, such as AMB, FTE and FTI3 were lateral rotators
at flexed joint angles in all taxa, but in Kentrosaurus their moment arms for lateral rotation decreased at
extended joint angles and they became medial rotators (e.g. Fig. 4B) due to the lateral expansion of the
pelvis.
Discussion
Despite abundant evidence for quadrupedalism in hadrosaurs, hip muscle leverage suggests more
functional similarities with bipedal ornithischians than with quadrupeds. Several extensors (ADD1
& 2, FTE, FTI3) show similar variation in moment arm with hip joint angle in Edmontosaurus and
Lesothosaurus. In Kentrosaurus, the moment arms of these muscles are lower (e.g. Fig. 3C).
In contrast, several flexors have higher leverage (e.g. PIFI1&2, AMB) in Kentrosaurus than in
Edmontosaurus and Lesothosaurus (Fig. 3D). The flexion moment arm of AMB shows similar variation
in moment arm with hip joint angle in Edmontosaurus and Lesothosaurus, but PIFI1&2 show differences
between all three taxa. This is related to the migration of PIFI onto the preacetabular process of the ilium
and a resulting increase in moment arms for flexion during ornithischian evolution.
In bipedal taxa with a slightly crouched hind limb, the locomotory power stroke is driven by the
powerful extensors (Gatesy 1990). Maidment and Barrett (2010) suggested that in a quadruped with a more
columnar hind limb, additional hip flexion would be required to draw the leg forward during the swing
phase, because the femur is not protracted to the same degree, and hip flexors such as PIFI1&2 have higher
moment arms (Maidment and Barrett 2010). Higher extensor moment arms and lower flexion moment arms
in Edmontosaurus in comparison with Kentrosaurus support the proposal that hadrosaurs had crouched
hind limbs similar to bipedal taxa (Maidment & Barrett 2010), and used powerful extensors to drive the
locomotory power stroke. However, moment arms are only one factor that contributes to the way muscles
work during locomotion. Differences in the centre of mass, muscle size, and muscle architecture between
Edmontosaurus and Kentrosaurus may also have contributed to the observed differences in moment arms.
Conclusions
An inability to pronate the manus or flex the digits, along with weight-bearing adaptations of the ungual
73
phalanges, provides clear evidence for obligate quadrupedality in adult hadrosaurs. However, examination
of hip muscle moment arms suggests that muscle organization and leverage was more similar to bipedal
ornithischians than it was to other quadrupedal ornithischians. This seems to indicate that hadrosaurs
retained an essentially bipedal bauplan despite quadrupedality. Further work on the relationships between
centre of mass and changes in musculature in extant bipeds and quadrupeds may shed light on the
differences between quadrupedal ornithischians; however, they differ in their locomotor strategies from
all extant tetrapods because of constraints caused by the imposition of quadrupedality on the primitively
bipedal body plan, which may hinder attempts to find suitable extant analogues.
Acknowledgements
The following people allowed access to specimens and hospitality during research trips: D. Evans,
K. Seymour, and B. Iwama (ROM), M. Currie, K. Shepherd, A. Macdonald, and C. Kennedy (CMN),
D. Henderson (TMP). SCRM is funded by Natural Environment Research Council grant number NE/
G001898/1 awarded to PMB.
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Brett-Surman, M.K., and Wagner, J.R. 2007. Discussion of character analysis of the appendicular anatomy in
Campanian and Maastrichtian North American hadrosaurids—variation and ontogeny. In Horns and Beaks.
Edited by K. Carpenter. Indiana University Press, Bloomington, pp. 135–170.
Bryant, H. N., and Russell, A. P. 1992. The role of phylogenetic analysis in the inference of unpreserved attributes of
extinct taxa. Philosophical Transactions of the Royal Society of London, Series B, 337:405–418.
Carrano, M.T. 2001. Implications of limb bone scaling, curvature and eccentricity in mammals and non-avian
dinosaurs. Journal of Zoology, London, 254: 41–55.
Cope, E.D. 1883. On the characters of the skull in Hadrosauridae. Proceedings of the Acadmey of Natural Sciences of
Philadelphia, 35: 97–107.
Cuthbertson, R.S., and Holmes, R.B. 2010. The first complete description of the holotype of Brachylophosaurus
canadensis Sternberg, 1953 (Dinosauria: Hadrosauridae) with comments on intraspecific variation. Zoological
Journal of the Linnean Society, 159: 373–397.
Dilkes, D.W. 2000. Appendicular myology of the hadrosaurian dinosaur Maiasaurua peeblesorum from the Late
Cretaceous (Campanian) of Montana. Transactions of the Royal Society of Edinburgh, Earth Sciences, 90: 87–125.
Evans, D.C., and Reisz, R.R. 2007. Anatomy and relationships of Lambeosaurus magnicristatus, a crested
hadrosaurid dinosaur (Ornithischia) from the Dinosaur Park Formation, Alberta. Journal of Vertebrate
Paleontology 27: 373–393.
Galton, P.M. 1970. The posture of hadrosaurian dinosaurs. Journal of Paleontology, 44, 464–473.
Gatesy, S.M. 1990. Caudofemoral musculature and the evolution of theropod locomotion. Paleobiology, 16:170–186.
Horner, J.R., Weishampel, D.B., and Forster, C.A. 2004. Hadrosauridae. In The Dinosauria (second edition). Edited
by D.B. Weishampel, P. Dodson , and H. Osmólska. University of California Press, Berkeley. pp. 438–463.
Hutchinson, J.R. 2001a. The evolution of pelvic osteology and soft tissues on the line to extant birds (Neornithes).
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Zoological Journal of the Linnean Society, 131: 169–197.
Hutchinson, J.R., and Gatesy, S.M. 2000. Adductors, abductors, and the evolution of archosaur locomotion.
Paleobiology, 26: 734–751.
Hutchinson, J.R., Anderson, F.C., Blemker, S.S., and Delp, S.L. 2005. Analysis of hindlimb muscle moment arms in
Tyrannosaurus rex using a three-dimensional musculoskeletal computer model: implications for stance, gait, and
speed. Paleobiology 31: 676–701.
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428–442.
Maidment, S.C.R., and Barrett, P.M. 2010. The evolution of locomotor musculature in ornithischian dinosaurs.
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Maidment, S.C.R., and Barrett, P.M. In review. The locomotor musculature of basal ornithischian dinosaurs. Journal
of Vertebrate Paleontology.
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75
Table 1. Hadrosaur specimens examined. CMN, Canadian Museum of Nature, Ottawa, Canada; NHMUK, Natural
History Museum, London, U.K.; ROM, Royal Ontario Museum, Toronto, Canada; TMP, Royal Tyrrell Museum of
Palaeontology, Drumheller, Canada.
Taxon
Specimen number
Brachylophosaurus canadensis
Brachylophosaurus canadensis
Corythosaurus casuaris
Corythosaurus casuaris
Corythosaurus casuaris
Edmontosaurus annectens
Edmontosaurus annectens
Edmontosaurus regalis
Edmontosaurus sp.
Edmontosaurus sp.
Edmontosaurus sp.
Edmontosaurus sp.
Gryposaurus incurvimanus
Gryposaurus sp.
Hadrosauridae indet.
Hypacrosaurus altispinus
Hypacrosaurus sp.
Lambeosaurus lambei
Lambeosaurus magnicristatus
Parasaurlophus walkeri
CMN 8893
TMP 1990.104.01
ROM 1947
TMP 1980.40.01
ROM 845
ROM 801
CMN 8839
CMN 2289
NHMUK R6862
NHMUK R5915
NHMUK R14368
NHMUK R14369
ROM 764
TMP 1980.22.01
TMP 1998.58.01
CMN 8501
TMP 2007.10.02
ROM 1218
TMP 1966.04.01
ROM 768
Table 2. Abbreviations of muscles used in the text.
76
Abbreviation
ADD
AMB
CFB
CFL
FTE
Muscle
Adductor
Ambiens
Caudofemoralis brevis
Caudofemoralis longus
Femorotibialis externus
FTI3
Femorotibialis internus, part 3
IFB
IFMA
IFMP
ISTR
ITBA
ITBP
Iliofibularis
Iliofemoralis, anterior part
Iliofemoralis, posterior part
Ischiotrochantericus
Iliotibialis, anterior part
Iliotibialis, posterior part
PIFI
Puboischiofemoralis internus
Fig. 1. GaitSym model of the pelvis of Edmontosaurus with muscles reconstructed and mapped on to the threedimensional laser scans of the pelvic elements.
77
Fig. 2. Quadrupedal adaptations in the forelimb of hadrosaurian dinosaurs. A–C, Brachylophosaurus canadensis
CMN 8893. D, Edmontosaurus annectens ROM 801. A, left radius in anterior view; B, left ulna in anterior
view; C, left ulna in proximal view; D, right manus in anterior view. Abbreviations: hu, hoof-like ungual
phalanges; lp, lateral process of proximal ulna; mc, metacarpals; mp, medial process of proximal ulna; op,
olecranon process of ulna; rf, facet for the radius on the distal ulna. Scale bar equals 10 cm.
78
Fig. 3. Flexion-extension moment arms of selected muscles across a range of hip flexion and extension angles,
compared between Edmontosaurus, the bipedal basal ornithischian Lesothosaurus, and the quadrupedal
stegosaur Kentrosaurus. Flexion-extension moment arms are normalized by femoral length. Positive numbers
on the Y-axes indicate the muscle has leverage for hip extension, while negative numbers indicate leverage
for hip flexion. Positive numbers on the X-axes indicate the hip was extended (femur retracted), while
negative numbers indicate the hip was flexed (femur protracted) as shown by the models in graphs C and D.
A, Iliofemoralis, posterior part (IFMP). moment arms for flexion occur in Edmontosaurus and Kentrosaurus
while in Lesothosaurus, IFMP has a moment arm for extension across most hip joint angles. This is because
of the derived, anteriorly located origin of this muscle in Edmontosaurus and Kentrosaurus.
B, Ischiotrochantericus (ISTR). Leverage for extension occurs in Lesothosaurus and Kentrosaurus but for
flexion in Edmontosaurus because of the derived insertion present in ornithopods. C, Adductor 2 (ADD2).
The adductor of Edmontosaurus and Lesothosaurus have very similar moment arms for extension, while
that of Kentrosaurus is lower. D, Puboischiofemoralis internus 1 (PIFI1). PIFI1 in Kentrosaurus has a higher
moment arm for flexion than those of Edmontosaurus and Lesothosaurus.
79
Fig. 4. Moment arms of selected muscles across a range of hip flexion and extension angles, compared between
Edmontosaurus, the bipedal basal ornithischian Lesothosaurus, and the quadrupedal stegosaur Kentrosaurus.
Moment arms are normalized by femoral length. Positive numbers on the X-axes indicate the hip was
extended (femur retracted), while negative numbers indicate the hip was flexed (femur protracted) as shown
by the models in graph A. A, abduction-adduction moment arms of the iliofemoralis, anterior part (IFMA).
Positive numbers on the Y-axis indicate the muscle has leverage for abduction, while negative numbers
indicate leverage for adduction. B, long axis rotation moment arms of the ambiens (AMB). Positive numbers
on the Y-axis indicate a moment arm for lateral long axis rotation of the femur, while negative numbers
indicate medial femoral long axis rotation. In both A and B, Kentrosaurus is rather different from the other
taxa due to transverse enlargement of the ilium.
80
NEW BASAL HADROSAUROID POSTCRANIA FROM THE CRETACEOUS
(CENOMANIAN) WOODBINE FORMATION AT THE ARLINGTON
ARCHOSAUR SITE, NORTH TEXAS
Derek J. Main1, Christopher R. Noto2, David B. Weishampel3, and Christopher R. Scotese1
1
Department of Earth and Environmental Sciences, University of Texas at Arlington, 500 Yates St., Box 19049,
Arlington, Texas 76019, USA
2
Department of Biological Sciences, University of Wisconsin–Parkside, P.O. Box 2000, Kenosha, Wisconsin 53141,
USA
3
Center for Functional Anatomy & Evolution, Johns Hopkins University School of Medicine, 1830 E Monument St
RM 303, Baltimore, Maryland 21205, USA
Introduction
All fossil material was recovered from a productive fossil locality in north-central Texas named the
Arlington Archosaur Site (AAS; Fig. 1). This material is currently housed in the Earth and Environmental
Sciences Department at the University of Texas at Arlington (UTA). The AAS is part of the Lewisville
Member of the Woodbine Formation (Dodge 1952; 1968; 1969; Johnson 1974; Main 2005; Oliver 1971) and
is Cenomanian in age (95-100 My) (Kennedy and Cobban 1990). Woodbine deposits preserve nearshore
terrestrial and shallow marine depositional systems, and include fluvial, deltaic and shelf deposits (Dodge
1952; Main 2005; Oliver 1971). The AAS represents a coastal ecosystem from a delta plain that was once
situated along the southeastern margin of the Western Interior Seaway (Fig. 2). The diverse biota recovered
so far includes lungfish, gar, shark, ray, turtle, dinosaur (ornithopod and theropod), and crocodyliform
remains along with numerous invertebrates and carbonized logs (Main 2009; Main et al. in press). The
taphonomy of this layer indicates it is an attritional assemblage formed in a low-energy environment.
Bones are largely disassociated with little evidence of abrasion or transport, however some ornithopod
bones show signs of postdepositional deformation. Remains of several species and individuals are mixed
and widespread throughout the exposed area.
Description of Fossil Material
Ornithopod fossils identified to date include a partial dentary and isolated teeth; cervical, dorsal and
caudal vertebrae; a scapula and coracoid; and ilium, ischium and pubis. In addition, two humeri and a
femur are known from juvenile individuals. Based on the elements recovered, at least four individuals are
represented from juvenile, subadult and adult growth stages.
Skull
Very little cranial material has been discovered thus far save for a single dentary fragment from
a juvenile individual. The dentary fragment contains the close-packed alveolar grooves typical of
hadrosaurid dental batteries. The teeth possess relatively straight roots with wide crowns that taper distally.
The buccal surface of each crown contains a single, prominent median carina and denticulate margin.
Axial Skeleton
The axial skeleton is represented by approximately twenty five vertebrae from the axial column;
including numerous partial centra. The axis is strongly opisthocoelous with a pronounced dens and broad
median keel on the ventral surface (Fig. 3). The prezygapophyses sit flush with the sides of the neural
spine but do not extend beyond the dens. The neural arch and spine are robust; the cranial-dorsal margin is
blade-shaped in lateral view and thins dorsally to a rounded point. The neural arch bifurcates caudally into
separate broad postzygopohyses. All other post-axial cervicals are roughly equal in length with strongly
opithocoelus centra, typical of hadrosauroids (Horner et al. 2004). The centra are broad mediolaterally
and elongate craniocaudally. The cervical ribs are similar to those of Tethyshadros and Iguanodon (Dalla
81
Vecchia 2009; Norman 1980). In dorsal vertebrae the centrum is mildly opisthocoelous or amphiplatan.
The stout transverse processes and neural spine point posteriorly, especially as one moves caudally, similar
to Gryposaurus. Neural spines are tall and have a square border. Proximal caudal vertebrae are axially
compressed with very tall (3x centrum height), narrow neural spines.
Appendicular Skeleton
The scapula is a broad, robust element and missing the distal blade (Fig. 4). The preserved blade is
straight in lateral aspect with a mild medial curvature. It is ovoid proximally and thins distally. The rostral
edge of the blade rises gently into the acromion process. The proximal blade expands ventrally to produce
a pronounced glenoid process. The glenoid is a robust depression that terminates in a broad buttress that
projects caudolaterally from the body. This extensive glenoid-buttress form is similar to Camptosaurus,
Gilmoreosaurus and Probactrosaurus (Norman 2004).
The coracoid is subtriangular in planar view, and convexoconcave in lateral view with a pronounced
foramen sitting at the junction of the humeral glenoid and the scapular suture. The glenoid suture is a
concave, rugose process. The scapular suture is an elongate surface that thins proximaly, terminating into
a thin acromion ridge. The coracoidal ridge gently deflects proximaly, curving in towards the sternum, and
lacks the hooklike process typical of hadrosaurs (Brett-Surman and Wagner 2007).
The ilium is broad and robust (Fig. 5). The preacetabular process is incomplete anteriorly, but gently
deflects ventrolaterally, similar to Bactrosaurus, Camptosaurus and Cedrorestes. The preacetabular
notch is open. The pubic peduncle is short, subrounded with a slight inclination to the anterior, similar to
Probactrosaurus, Zalmoxes and Altirhinus. The ischial peduncle is broad and rectangular in shape a trait
typically associated with lambeosaurines, including Eolambia (Brett-Surman and Wagner 2007). The
suprailiac crest rises above the preacetabular process at a near perpendicular angle. It thickens dorsally
appearing triangular in caudolateral view, distinctive of early hadrosaurids (Brett-Surman and Wagner
2007). The dorsal surface of the supracetabular process is relatively flat, similar to Cedrorestes and
Probactrosaurus, yet has a unique anterior dorsal deflection that forms a near perpendicular rise from the
preacetabular process in lateral view.
The ischium is nearly complete, missing only the distal most end. The pubic peduncle is smaller than
the iliac peduncle, similar to the ratios seen in Camptosaurus, Mantellisaurus and Gilmoreosaurus. On
the caudoventral part of the proximal blade, the obturator process is subrounded and small, with a shallow
obturator foramen. The obturator process is proximally placed, a character typical of iguanodontians. A
ridge extends dorsolaterally away from the obturator process down the length of the shaft, flattening
distally. This tapering ridge is similar to the ischial ridge noted in Probactrosaurus, although less
pronounced (Norman 2004).
The pubis is represented by the prepubic blade. The prepubis is shallowly concave along the ventral
margin and relatively flat along the dorsal margin. It is wide, flattened and thins cranially with an axelike anterior margin that thins dorsally, similar to Gilmoreosaurus and Altirhinus. The prepubic neck is
relatively long and thin, similar in form to Altirhinus and Tethyshadros. The postpubis bows ventrally with
much of the pubic bar broken and missing.
The humerus is gently sigmoidal and wider proximally than distally. The deltopectoral crest is a low,
thickened ridge that extends about half way down the shaft. The overall morphology is reminiscent of
Iguanodon, however this may be due to ontogentic immaturity of the individual.
The proximal end of a right element represents the femur. Enough of the shaft is preserved though
to indicate it was straight and not bowed. Remnants suggest the head was offset on a distinct neck. The
greater trochanter is large, taking up the entire dorsal border of the proximal end, while the cranial
trochanter was much smaller and located on the anteromedial surface of the shaft. It is separated from the
grater trochanter by a shallow cleft. The fourth trochanter is broken at its base, though this shows it was
a long and narrow, most likely triangular, process. The overall morphology of the proximal femur is most
similar to Telmatosaurus and Iguanodon (Norman 2004).
82
Evolutionary and Paleobiogeographic Significance
New fossil material recovered from the Woodbine Formation represents the most complete ornithopod
postcrania recovered from this area and adds important insight to the morphological transition between
iguanodontians and hadrosaurids. The postcrania demonstrate a unique mix of plesiomorphic hadrosaurid
characters with derived iguanodontian features, suggesting that this may be the most basal hadrosauroid
yet recovered. This unusual combination of characters suggests biogeographic isolation or endemism.
Weishampel et al. (1993) noted the isolated nature of Telmatosaurus in Europe and related the species
primitive characters to its endemism. Dalla Vecchia (2009) noted a similar pattern in Tethyshadros, which
was isolated on a carbonate platform in the Tethys Ocean. The relatively primitive nature of other AAS
specimens also supports this hypothesis. The primitive tooth plate morphology of the Woodbine lungfish
C. carteri is reminiscent of earlier North American ceradontids (Main et al, in press). Theropod dinosaur
remains recovered from the site include cf. Acrocanthosaurus, typically an Early Cretaceous theropod,
suggesting that this group endured as a part of southern North American faunas well into the Cenomanian
(Noto and Main In review).
The AAS ecosystem may be representative of a broader ecological pattern present in the Cretaceous
fossil record, in which late-surviving southern relics mixed with recent Eurasian migrants and were
later isolated by Cenomanian eustatic high stands. Thus, the endemic nature of AAS taxa provides an
evolutionary bridge between Early and Late Cretaceous terrestrial ecosystems.
References
Brett-Surman, M., and Wagner, J.R. 2007. Discussion of character analysis of the appendicular anatomy in
Campanian and Maastrichtian North American hadrosaurids-variation and ontogeny. In Horns and Beaks,
Ceratopsian and Ornithopod Dinosaurs. Indiana University Press, Bloomington. pp. 135-169.
Dalla Vecchia, F.M. 2009. Tethyshadros insularis, A New Hadrosauroid Dinosaur (Ornithischia) from the Upper
Cretaceous of Italy. Journal of Vertebrate Paleontology, 29(4): 1100-1116.
Dodge, C.F. 1952. Stratigraphy of the Woodbine Formation in the Arlington area. Tarrant County, Texas: Field and
Laboratory, 20(2): 66-78.
Dodge, C.F. 1968. Stratigraphic Nomenclature of the Woodbine Formation Tarrant County, Texas In Field trip
Guidebook, South Central Section, Stratigraphy of the Woodbine Formation. Geological Society of America. pp.
107-125.
Dodge, C.F. 1969. Stratigraphic nomenclature of the Woodbine Formation Tarrant County, Texas. Texas Journal of
Science, 21: 43-62.
Horner, J.R., B., W.D., and Forster, C.A. 2004. Hadrosauridae. In The Dinosauria, 2nd edition. University of
California Press, Berkeley. pp. 438- 463. .
Johnson, R.O. 1974. Lithofacies and depositional environments of the Rush Creek Member of the Woodbine
Formation (Gulfian) of North Central Texas, University of Texas, Arlington.
Kennedy, W.J., and Cobban, W.A. 1990. Cenomanian ammonite faunas from the Woodbine Formation and lower part
of the Eagle Ford Group, Texas. Palaeontology, 33(1): 75-154.
Main, D.J. 2005. Paleoenvironments and Paleoecology of the Cenomanian Woodbine Formation of Texas,
Paleobiogeography of the Hadrosaurs (Dinosauria: Ornithischia), University of Texas, Arlington.
Main, D.J. 2009. Delta Plain Environments and Ecology of the Cretaceous (Cenomanian) Woodbine Formation at the
Arlington Archosaur Site, North Texas. Geological Society of America, Abstracts with Programs, 41(7): 103.
Main, D.J., Parris, D., Grandstaff, B., and Carter, B. in press. A New Lungfish (Dipnoi: Ceratodontidae) from the
Cretaceous Woodbine Formation, Arlington Archosaur Site, North Texas. Texas Journal of Science.
Norman, D.B. 1980. On the ornithischian dinosaur Iguanodon bernissartensis from the Lower Cretaceous of
Bernissart (Belgium). Institut Royal des Sciences Naturelles de Belgique Memoire (178).
Norman, D.B. 2004. Basal Iguanodontia. In The Dinosauria, 2nd Edition. University of California Press, Berkeley.
pp. 413-437.
Noto, C.R., and Main, D.J. In review. Paleoecologic and paleobiogeographic implications of new theropod material
from the Cretaceous (Cenomanian) Woodbine Formation of North Central Texas. Cretaceous Research.
Oliver, W.B. 1971. Depositional systems in the Woodbine Formation (Upper Cretaceous), northeast Texas: The
University of Texas at Austin. Bureau of Economic Geology Report of Investigations, 73: 28.
83
Scotese, C.R. 2005. Polar Paleogeographic projections; Cretaceous, North America. Unpublished, Paleomap Project.
Weishampel, D., Norman, D., and Grigorescu, D. 1993. Telmatosaurus transsylvanicus from the Late Cretaceous of
Romania: the most basal hadrosaurid dinosaur. Palaeontology, 36(2): 361-385.
Fig. 1. Woodbine Formation exposures in North Texas and location of the Arlington Archosaur Site (AAS). At right
is a composite stratigraphic column for the site. The lowermost horizon represents the peat bed containing the
crocodyliform, turtle, and juvenile ornithopod remains. The horizon immediately above contained the adult
and subadult ornithopod bone in a paleosol complex, which also contained carbonate nodules (white shapes),
charcoal fragments (small black shapes), and whole charcoalified stumps (large black shape).
84
Fig. 2. Arlington Archosaur Site denoted with star on a paleogeographic map of the Western Interior Seaway in
North America, Cenomanian (90-95Mya) (Scotese 2005).
Fig. 3. Axis in anterior, left lateral, and posterior views (from left). Scale bar equals 5 cm.
85
Fig. 4. Left scapula in lateral and medial views (from left). Scale bar equals 5 cm.
Fig. 5. Left ilium in lateral view. Scale bar equals 5 cm.
86
Hadrosaurid Jaw Mechanics as Revealed by Cranial Joint
Limitations and Dental Microwear Analysis
Jordan C. Mallon1, Robin S. Cuthbertson1, and Alex Tirabasso2
1
Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, T2N 1N4,
Canada
2
Information Management and Technology Services, Canadian Museum of Nature, PO Box 3443 STN “D” Ottawa,
ON, K1P 6P4, Canada
Pleurokinesis is a long established hypothesis that explains the jaw mechanics of ornithopod dinosaurs
(Weishampel, 1983; 1984; Norman and Weishampel, 1985). Among hadrosaurids, the pleurokinetic model
proposes a series of primary movements that include: (1) vertical adduction of the mandible; (2) lateral
rotation of the maxilla at the maxilla-premaxilla joint; (3) lateral rotation of the jugal-maxilla complex at
its contact with the lacrimal; and (4) caudolateral rotation of the quadrate at its contact with the squamosal.
As a consequence of these primary movements, a series of secondary movements are also compelled,
including: (1) translation between the postorbital and the jugal; (2) rotation and/or translation between
the quadratojugal and the quadrate; (3) rotation and translation between the pterygoid process of the
basisphenoid and the pterygoid; (4) rotation of the mandibles about the symphysis; (5) rotation between
the pterygoid and the palatine-ectopterygoid-maxilla complex; and (6) rotation of the ventral head of the
quadrate about the mandibular component of the jaw joint.
Contrary to the pleurokinetic model, recent interpretations of the kinetic limitations of the intracranial
joints of Brachylophosaurus and Edmontosaurus have identified two units within the skull: an immobile
upper unit (formed by the maxilla, jugal, palatine, pterygoid, quadratojugal, and quadrate), and a mandible
that appears capable of limited movement at the jaw joint (Cuthbertson, 2007). Based on the kinetic
limitations of the upper unit, potential movements associated with the mandibular ramus were further
explored as an alternate hypothesis to pleurokinesis.
Despite exhibiting wear along their entire lengths, the upper and lower tooth rows of the holotype
of Brachylophosaurus canadensis differ by approximately 10 mm, suggesting that at least 10 mm of
propalinal movement occurred during the chewing cycle. Due to the inferred immobility of the upper
unit, the propalinal component of the chewing cycle is herein interpreted to have occurred at the jaw joint
(representing the only other point in the skull that a for-aft component could have been accommodated),
similar to the akinetic skull of Sphenodon punctatus (Gorniak et al., 1982).
The occlusal surface of the hadrosaurid dentary tooth row has previously been described as concave
(Ostrom, 1961; Weishampel, 1984; Horner et al., 2004). This morphology is formed by a vertical and
horizontal facet in both Brachylophosaurus and Edmontosaurus (Fig. 1). A curved transition (longitudinal
groove) occurs between the facets, likely resulting from the physical interaction between the upper and
lower tooth rows during occlusion, and indicates at least minimal rotation of the mandibular ramus about
its long axis.
To date, the involvement of the vertical and horizontal facets in relation to the power stroke of the
chewing cycle remains poorly explored. One possibility is that both facets were functional and involved in
the power stroke. However, for the maxillary teeth to occlude with both the vertical and horizontal facets,
11 degrees of mandibular rotation would be required in Edmontosaurus regalis. This degree of rotation is
unlikely and would result in disarticulation of the mandible from the jaw joint. An alternative scenario is
that only the lingual portion of the horizontal facet was involved in the powers stroke, and that the labial
extent of the horizontal facet had migrated out of occlusion. A more conservative (and plausible) 3 degrees
of mandibular rotation in Edmontosaurus is necessary to employ the vertical facet and lingual third of the
horizontal facet as part of the power stroke, resulting in a curved transition between the facets.
In addition to the consideration of cranial joint limitations, we also investigated hadrosaurid jaw
mechanics using low magnification dental microwear analysis. This refers to the study of the microscopic
pits and scratches left on teeth, usually as a result of feeding. Although dental microwear is regularly used
to provide information about the mechanical properties of an animal’s diet, it can also be used to inform
87
interpretations of jaw mechanics. Williams et al. (2009) recently provided statistical evidence for the
existence of four discrete classes of microwear scratch orientations in Edmontosaurus, and noted that the
absence of curved scratches in this taxon precluded the possibility of rotation about the long axes of the
mandibular rami (although curved scratches would likely also result from transverse flaring of the maxillae
under the pleurokinetic model). The authors concluded that flexion along a pleurokinetic hinge, resulting in
a high-angle oblique adduction and an isognathous oblique transverse power stroke, best fit the evidence.
Our investigation of hadrosaurid jaw mechanics was done with the aid of rose diagrams depicting
the length and orientation of scratches on dental wear facets. Our sample comprised 18 hadrosaurid
dentitions of the genera Corythosaurus, Gryposaurus, Lambeosaurus, and Prosaurolophus, all from the
upper Campanian Dinosaur Park Formation of Alberta. Although the confounding effects of taphonomy
were often prohibitive, some general patterns emerged. The vertical facets of the best preserved dentary
teeth appear to show a bimodal distribution (Fig. 2) in which most scratches (usually the longest) are
oriented dorsocaudally to sub-vertically, in line with the presumed vector resultant of the external adductor
musculature. We interpret this as evidence for the direction of the power stroke, effecting a shearing motion
of the teeth. In the second mode, scratches are orientated rostrocaudally. We interpret this as evidence
for secondary jaw motions, effected by the pterygoideus and posterior adductor musculature to produce
a propalinal motion, corroborating the aforementioned evidence from gross tooth wear. Contrary to the
interpretation of Williams et al. (2009), the regular presence of curved scratches suggests that rotation of
the mandibular ramus about its long axes was possible. Although sample size is still low, these patterns do
not appear to vary systematically.
Finally, we used microwear to test two alternative hypotheses concerning the functionality of those
dentary teeth labial to the longitudinal groove, which bear sub-horizontal wear facets. The first hypothesis
states that these teeth served a crushing function during arcilineal jaw movements, and predicts that their
wear facets should exhibit heavy pitting relative to those teeth lingual to the longitudinal groove. The
second hypothesis states that these teeth served a grinding function during propalinal jaw movements,
and predicts that their wear facets should exhibit scratches oriented primarily mesiodistally. The first
hypothesis was rejected by a Mann-Whitney U test of the arcsine-transformed data (n = 14, U = 20.5, p >
0.05). The second hypothesis was rejected by visual inspection of rose diagrams, which demonstrate that
teeth labial to the longitudinal groove do not possess more mesiodistally oriented scratches relative to the
more lingually positioned teeth (Fig. 3). Therefore, we accept the null hypothesis that these teeth were
mostly non-functional; rather, they represent the remnants of teeth that were once functional and have since
migrated out of occlusion.
References
Cuthbertson, R. 2007. Pleurokinesis revisited, kinematic limitations of cranial joints in hadrosaurine dinosaurs.
Journal of Vertebrate Paleontology 27(3, Suppl.): 64A.
Gorniak, G. C., Rosenberg, H. I., and Gans, C. 1982. Mastication in the Tuatara, Sphenodon punctatus (Reptilia:
Rynchocephalia): structure and activity of the motor system. Journal of Morphology 171: 321-353.
Horner, J. R., Weishampel, D. B., and Forster, C. A. 2004. Hadrosauridae. Pp. 438-463 in D. B. Weishampel, P.
Dodson, and H. Osmólska (eds), The Dinosauria (2nd edition). University of California Press, Berkeley.
Norman, D. B., and Weishampel, D. B. 1985. Ornithopod feeding mechanisms: their bearing on the evolution of
herbivory. American Naturalist 126: 151-164.
Ostrom, J. H. 1961. Cranial morphology of the hadrosaurian dinosaurs of North America. Bulletin of the American
Museum of Natural History 122: 33-186.
Rybczynski, N., Tirabasso, A., Bloskie, P., Cuthbertson, R., and Holliday C. 2008. A three-dimensional animation
model of Edmontosaurus (Hadrosauridae) for testing chewing hypotheses. Palaeontologia Electronica 11(2)9A.
14 pgs.
Weishampel, D. B. 1983. Hadrosaurid jaw mechanics. Acta Palaeontogica Polonica 28: 271-280.
Weishampel, D. B. 1984. Evolution of jaw mechanisms in ornithopod dinosaurs. Advances in Anatomy, Embryology
and Cell Biology 87: 1-110.
Williams, V. S., Barrett, P. M., and Purnell, M. A. 2009. Quantitative analysis of dental microwear in hadrosaurid
dinosaurs, and the implications for hypotheses of jaw mechanics and feeding. Proceedings of the National
Academy of Sciences 106: 11194-11199.
88
Fig. 1. Posterior aspect of the left dentary tooth row of Edmontosaurus regalis (CMN 2289). Labial to the left, apical
to the top. The longitudinal groove extends normal to the plane of this page.
Fig. 2. Rose diagrams depicting scratch orientation at three points along the left dentary of Corythosaurus (CMN
8505). Angles have been reflected so that they correspond to those of the right dentary. The rostral direction is
to the right (0°), apical is to the top of the page (90°). 95% confidence intervals shown. (A) third tooth family,
apicalmost (first) tooth position; (B) ninth tooth family, first tooth position; (C) 18th tooth family, second tooth
position.
89
Fig. 3. Rose diagrams comparing scratch orientations from teeth lingual (top) and labial (bottom) to the longitudinal
groove of the dental battery. Angles have been reflected where necessary so that they correspond to those of
the right dentary. The rostral direction is to the right (0°), apical is to the top of the page (90°). 95% confidence
intervals shown. (A) Lambeosaurus (YPM 3222), left dentary, 26th tooth family; (B) Corythosaurus (ROM
868), left dentary, 18th tooth family; (C) Corythosaurus (TMP 1982.037.0001), right dentary, 32nd tooth family.
Although the distributions of scratch orientation often differ within a single tooth family, there is no evidence
that teeth located labial to the longitudinal groove served a grinding function.
90
A multidisciplinary approach to the analysis of fossil
hadrosaur integument and the taphonomic role of skin
pigment in exceptional preservation
P.L. Manning1,2,3, R.A. Wogelius1,3, M. Buckley3, B.E. van Dongen1,3, T. Lyson4, U. Bergmann5, S. Webb5,
and W.I.S. Sellers6
1
School of Earth, Atmospheric and Environmental Sciences, University of Manchester, UK. 2Department of Earth
and Environmental Science, University of Pennsylvania, USA.
3
Williamson Research Centre for Molecular Environmental Science, University of Manchester, UK
4
Peabody Museum of Natural History, Yale University, USA
5
SSRL, Stanford University, Menlo Park, USA.
6
Faculty of Life Sciences, University of Manchester, Manchester, UK.
The recognition of both structure and composition in dinosaur soft tissues has been revolutionised
by the application of sophisticated new analytical techniques to fossil material (see Schweitzer 2011 for
review). The identification of mineralized soft tissue has not been restricted to that contained within
bones and claws. The structure and macromolecular composition of dinosaur skin has also been identified
(Manning et al. 2009). The suite of techniques available for the study of soft tissue in the fossil record is
now extending to infrared spectroscopy (Edwards et al. 2011) and synchrotron based x-ray fluorescence
(Bergmann et al. 2010; Wogelius et al. 2011) yielding impressive results. Here we review the application of
multi-analytical techniques applied to the exceptionally preserved remains of the hadrosaurine dinosaur
MRF-03 (cf. Edmontosaurus sp.) found in the Hell Creek Formation (Upper Cretaceous) of North Dakota
(USA) (Manning et al. 2009). In addition to the techniques applied by Manning et al. (2009), synchrotronbased spectroscopic techniques are applied to skin samples from MRF-03 for the very first time. When
combined with the results from earlier work (Manning et al. 2009), the synchrotron-based results in this
study provide evidence for the presence of endogenous pigments that might have played a taphonomic role
in the spectacular soft tissue preservation shown by MRF-03.
The hadrosaur mummy MRF-03 displays large areas of un-collapsed skin ‘envelope’ around the
tail, parts of the torso, legs and arm. The preservation of the skin is 3D with clear raised scales and
interconnecting hinge areas (Figure 1).
Fig. 1. Lateral view of skin envelope from the lateral craniodorsal portion of tail of MRF-03 (scale bar 10 cm).
91
Polished thin-sections prepared from the skin (Figure 2) of MRF-03 were generated to provide
suitable samples for analysis within an Environmental Scanning Electron Microscope (ESEM) using it
in Backscattered Electron (BSE) mode (Manning et al. 2009). The same thin-sections were also used
in the most recent synchrotron rapid scanning x-ray fluorescence (SRS-XRF) analyses. The earlier BSE
microscopy provided information on both the structure and composition of the skin envelope. Given that
each element has a different number of electrons, there is a direct correlation between atomic number and
electron backscattering efficiency; a more dense electronic cloud yields more backscattering of an incident
electron beam. Thus, the BSE mode on an ESEM yields images that reflect the average surficial element
composition of a sample.
Fig. 2. Visible light image of polished thin section (left) and BSE image of MRF-03 skin envelope (right). The skin
envelope is delineated by the dashed line on the thin section. Accelerating voltage 15.0kV, working distance
9.8mm at 0.5 Torr (modified from Manning et al. 2009).
The skin samples from MRF-03 (taken from the ventral surface at the base of the tail) was ~2.5-3.5 mm
thick and preserved internal structure (Figure 2 blue box detail), that was visible in BSE mode (Manning
et al. 2009). Compositional data was also recovered using energy dispersive x-ray (EDX) analysis, but the
results were too crude to provide information on the spatial distribution of the elemental inventory of the
skin. However, the BSE data indicated the presence of organic compounds (that appear black in BSE mode)
restricted to within the upper and lower boundaries of the sectioned skin envelope, but EDX did not permit
their identification. The thin-section was then analyzed by both infrared and mass spectroscopic techniques
to further resolve the presence and identity of organic compounds within the skin.
Fourier Transform Infrared Spectroscopy (FTIR) was used as a screening tool by Manning et al.
(2009) to spatially map the presence of infrared active organic functional groups in skin, hoof and tendon
samples from MRF-03. FTIR exploits the fact that different molecules absorb specific infrared frequencies
reflecting their structure. The frequency of the absorbed infrared spectra matches that of the bond or group
that vibrates. FTIR of biomaterials recovered from the skin and terminal ungual phalanx of MRF-03
indicated the presence of compounds containing amide groups. These amide groups absorb infrared light
at two positions called amide I and amide II, and dominate the absorption spectrum of keratin. Amides
are the most stable of all carbonyl functional groups. The position and appearance of the FTIR bands of
the amide I and II groups present within the skin regions of MRF-03 were similar to what was measured
in extant beta-keratin samples taken for bird and reptile tissues, constraining analogous biomaterials used
by the Extant Phylogenetic Bracket (Manning et al. 2009; Witmer, 1995). The presence of Amide groups
was interpreted by the earlier study as a sign that intact proteins or their breakdown might possibly have
survived in MRF-03.
92
Proteins form one of the major building blocks of life, carrying out a range of different functions from
structural biomaterials to cell maintenance and the regulation of biosynthetic pathways. They are made up
of chemical units called amino acids of which there are 20 encoded for by the genetic code. Amino acid
composition analysis is a method used to hydrolyse (break up) proteins present in a given sample into its
constituent amino acid units in order to give a general impression of the dominant proteins within a sample
(or to screen fossils to see if any proteins could be present). Due to the asymmetric structure of most
amino acids (all except glycine), amino acids exist in two different ‘mirror-image’ configurations often
called D (dextro) and L (levo) amino acids, but only the L form are typically incorporated into proteins
during synthesis. However, once protein synthesis stops (i.e., death of an organism), L-amino acids start to
spontaneously convert to D-amino acids via a process called racemisation. Although various environmental
factors need to be taken into account, this amino acid racemisation process can be used to assess the state
of preservation of proteins in fossils. In both of the above methods the amino acids (both L and D forms)
are usually separated by some form of chromatography (in this case, Liquid Chromatography) and detected
by a variety of methods (in this case, fluorescence). The amino acid composition and racemisation analyses
of a skin envelope sample from MRF-03 exhibited a distinct composition clearly different from the
surrounding matrix. High glycine:alanine concentrations were observed, potentially indicative of fibrous
structural proteins such as collagens and keratins. After using amino acid composition and racemisation
analyses to confirm the presence of protein, there are a variety of protein isolation techniques that can be
used to study how intact the proteins are within the fossil.
The most common protein isolation technique is called Polyacrylamide Gel Electrophoresis (PAGE).
This involves taking a sample of proteins (i.e., not hydrolysed as with amino acid analyses) and applying
them to a polyacrylamide gel with a tracking dye. During electrophoresis the samples are induced to
separate according to size and charge (eletrophoretic mobility) using an electric field over a given amount
of time. Following electrophoresis the gel can be stained allowing for visualisation of how far each band
of separated proteins has travelled and, if used with molecular weight markers, can help estimate the
size of the protein. The PAGE protocol successfully removed beta keratin from extant samples in the
prior study, but was not able to repeat the same for skin and tendon samples from MRF-03 (Manning et
al. 2009). However, when the size exclusion was removed from the PAGE protocol, low molecular-weight
fractions (less than 12 kDa) were observable on the electrophoresis gel for MRF-03 samples, indicating the
organic material was present. Additional analyses using matrix assisted laser desorption/ionization-mass
spectrometry (MALDI-MS) and liquid chromatography-electrospray ionization (LC-ESI) were consistent
with the results produced by the PAGE protocol in that low-molecular-weight peaks at m/z 1100– 2200
were observed (Manning et al. 2009). Therefore the presence of intact proteins could not be confirmed
using protein mass spectrometry, even after such promising amino acid analysis, but breakdown products
of proteins were likely.
The application of Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS) was more successful
and revealed a substantial difference in the aliphatic polymer between the skin and associated sediment
of MRF-03 (Manning et al. 2009). Py-GCMS works on the principle that when a sample is rapidly heated
to decomposition it produces smaller molecules that are then separated by gas chromatography and then
subsequently may be detected using mass spectrometry.
The Py-GCMS of the skin generated n-alkanes/n-alken-1-ene homologues ranging in carbon number
from C9 to C36 with a trimodal distribution of n-alkanes (Figure 3a; maxima C11, C15 and C27). In
comparison, the n-alkane/n-alken-1-ene homologues distribution pattern in the enclosing sediment differed
considerably, ranging from C9 to C30 but dominated by the C10-C18 n-alkanes with a maximum at C11
(Figure 3b). The observed differences were inconsistent with an origin solely via migration from enclosing
sediment and must thus have been derived endogenously. This suggested that the organics present in the
skin consisted of a macromolecule that was in part aliphatic. Comparable to earlier studies on plant and
insect fossils these aliphatic components are presumably the result of in situ polymerisation (Gupta et
al. 2007a; Gupta et al. 2007b). The preservation of the organic material was probably caused by a rapid
burial in combination with intensely reducing pore waters causing oxidized iron species to be reduced and
feldspar and rock fragments to partially dissolve. The reduced iron in solution rapidly replaced the soft
93
tissue with carbonate minerals, outpacing microbial decay processes. Besides preservation of soft tissue
structures this ensured that some breakdown products of organic molecules were preserved within the
mineral matrix (Manning et al. 2009).
Fig. 3. Partial Py-GCMS total ion current chromatograms of (a) the skin envelope and (b) the surrounding sediment
associated with the skin envelop of MRF-03. The insets show the m/z 57 mass chromatograms revealing the
distribution of n-alkanes moieties with numbers indicating the carbon chain length (from Manning et al..,
2009).
94
The recent application of Synchrotron Rapid Scan X-ray Fluorescence (SRS-XRF) to specimens of
Archaeopteryx lithographica (Bergman et al. 2010; Wogelius et al. 2011; Manning et al. in review), Green
River Formation reptile skin (Edwards et al. 2011) and Confuciuornis sanctus (Wogelius et al. 2011) have
provided great insight to the chemistry and taphonomy of fossilized soft tissues. This powerful, but nondestructive, technique offers new insight to the mass-flow of elements and organic compounds within
specific sedimentary facies and provides high-resolution maps of chemistry within discrete biological
structures. When combined with supporting chemical data derived from the tissues of extant species that
phylogenetically bracket extinct samples being studied, it can offer great insight to potential endogenous
compounds and biosynthetic pathways. Samples of fossil skin from the hadrosaur mummy MRF-03 were
chemically mapped using SRS-XRF on beam line 3-2 at the Stanford Synchrotron Radiation Lightsource
(SLAC National Laboratory), see Figure 4.
Given EDX analysis did not yield detailed information on the elemental inventory of the skin of
MRF-03, SRS-XRF was applied to the polished thin-sections (Figure 2). SRS-XRF maps are generated
by collecting signals from multiple elements that are read out at intervals of only a few milliseconds per
pixel during bidirectional scans (Bergmann et al. 2010; Edwards et al. 2011). This dramatically reduces
scan times to ~30 seconds per cm2 at 100 μm resolution. Because of the intense nature of the incident
synchrotron X-ray beam, imaging is not only rapid enough to be practical for large objects but also can
successfully record spatial variation at even lower concentrations of an element than is typically possible
with standard electron beam methods; approximately an order of magnitude better sensitivity can be
achieved routinely with the current SSRL configuration (Wogelius et al. 2011). SRS-XRF applied to fossils
makes it possible to simultaneously probe elemental distributions of large specimens and their embedding
geological matrix, thus resolving the exchange of material between the organism and the surrounding
sediment during fossilization (Bergmann et al. 2010: Wogelius et al. 2011).
In addition to the SRS-XRF, Extended X-ray Absorption Fine Structure (EXAFS) analysis was also
undertaken with samples from MRF-03 on beam line 2-3 at SSRL. EXAFS spectroscopy is sensitive to
the electronic structure of the probed central absorber atom, and is especially able to accurately quantify
distances to shells of surrounding atoms, thus providing a great deal of information on biological or
geochemical context.
Fig. 4. SRS-XRF maps of polished thin-section (compare to Figure 2) from skin of MRF-03 undertaken at SSRL
beam line 10-2. The dashed white line delineates the boundary of the skin envelope and indicates the
concentration of mapped elements within the cross-section.
95
The EXAFS data can be used to diagnose whether trace metals such as Fe2+and Mn2+ are sequestered
within channels of eumelanin or melanin derived organic compounds. Given that divalent trace
metals are chelated by melanin pigments this may provide useful information about original pigment
distribution (Wogelius et al. 2011). We suggest that if suitable chemical conditions prevail during burial
then organometallic compounds may preserve evidence of original pigmentation in dinosaur skin. The
presence of trace metal-rich pigment in the skin of MRF-03 (Figure 4) would have formed a natural biocide
(Wogelius et al 2011), resistant to the bacteria that would consume the rest of the carcass. Thus the presence
of ‘indigestible’ pigmented skin is possibly an overlooked explanation to the exceptional preservation of
skin in dinosaurs and other pigmented organisms in the fossil record.
References
Bergmann, U., Morton, R. W., Manning, P. L., Sellers, W. I., Farrar, S., Huntley, K. G., Wogelius, R. A, and Larson,
P. 2010. Archaeopteryx feathers and bone chemistry fully revealed via synchrotron imaging, Proceeding of the
National Academy of Sciences, 107 (20), 9060-9065.
Edwards, N. P., Barden, B. E., Dongen, B. E. van., Manning. P. L., Bergman, U., Sellers, W. I., and Wogelius, R. A.
2011. Infra-Red mapping resolves soft-tissue preservation in 50 Million year old reptile skin. Proceedings of the
Royal Society, Series B., doi: 10.1098/rspb.2011.0135
Gupta, N. S., Briggs, D. E. G., Collinson, M. E., Evershed, R. P., Michels, R. & Pancost, R. D. 2007a Molecular
preservation of plant and insect cuticles from the Oligocene Enspel Formation, Germany: evidence against
derivation of aliphatic polymer from sediment. Organic Geochemistry 38, 404–418. (doi:10.1016/j.orggeochem.
2006.06.012).
Gupta, N. S., Michels, R., Briggs, D. E. G., Collinson, M. E., Evershed, R. P. & Pancost, R. D. 2007b Experimental
evidence for land plant lipids as a source of aliphaticrich kerogen. Org. Geochem. 38, 28–36. (doi:10.1016/
j.orggeochem.2006.09.014)
Manning, P. L., Morris, P. M., McMahon, A., Jones, E., Gize, A., Macquaker, J. H. S., Marshall, J., Lyson, T.,
Wolff, G., Buckley, M. and Wogelius, R. A. 2009. Preserved soft-tissue structures and organic molecules in a
mummified hadrosaur dinosaur from the Hell Creek Formation, North Dakota (USA). Proceedings of the Royal
Society Series B., 276 (1672), 3429-3437.
Schweitzer, M.H. (2011) Soft tissue preservation in terrestrial Mesozoic vertebrates. The Annual Review of Earth and
Planetary Sciences, 39, 187-216.
Witmer, L. M. 1995 The extant phylogenetic bracket and the importance of reconstructing soft tissue in fossils. In
Functional morphology in vertebrate palaeontology (ed. J. J. Thomason), pp. 19–33. Cambridge, UK: Cambridge
University Press.
Wogelius, R. A., Manning, P. L. Larson, P. L., Barden, H., Edwards, N. P., Webb, S. M., Sellers, W. I., Taylor, K. G.,
Dodson, P., You, H., Da-qing L. and Bergmann, U. 2011. Trace metals as biomarkers for eumelanin pigment in the
fossil record, Science, published online July 1st 20011.
96
Preliminary observations and interpretations on
a hadrosaur (Lambeosaurinae) associated with an
abundance of juvenile tyrannosaur (Albertosaurinae)
teeth from the Upper Cretaceous (Campanian/
Maastrichtian) Wapiti Formation of northeastern
British Columbia
Richard T. McCrea1,2 and Lisa G. Buckley1,3
1
Peace Region Palaeontology Research Centre; Box 1540; Tumbler Ridge, British Columbia; Canada; V0C 2W0
Department of Earth and Atmospheric Sciences; University of Alberta; Edmonton, Alberta; CANADA
3
Department of Biological Sciences; University of Alberta; Edmonton, Alberta; Canada
2
Remains of a partially articulated hadrosaur from the Peace Region of northeastern British Columbia
were discovered in July, 2007, thirteen kilometers west of the B.C./Alberta border in the Upper Cretaceous
Wapiti Formation. The Wapiti Formation of Alberta is well-known for fossil vertebrate remains
(Tanke, 2004; Currie et al., 2008), but the potential for B.C. finds, while predicted (Tanke, 2004), was
unknown until recently. The hadrosaur is associated with an unusually high number of shed tyrannosaur
(Albertosaurinae) teeth primarily from sub-adults (McCrea & Buckley 2010; 2011). The excavation of the
site began in 2008 and was resumed annually to the present (McCrea & Buckley, 2010; 2011).
The site is on the north side of a river bank that was exposed by recent, minor slumping. The excavation
has revealed 7.9 vertical metres of strata dipping 5 degrees to the northeast (40 degrees unadjusted). The
bottommost layer is a friable, grey siltstone which is at least 2.2 m thick before it disappears at the river’s
edge. The top boundary of this layer is well-defined but irregular, probably representing a localized
disconformity. The succeeding layer is the bone horizon which is 1.0m thick. It is composed of poorly
consolidated, organic-rich, silty sands and sideritized concretions which usually encase bone, although
not all bones occur in concretions. This layer contains in situ tree stumps rooted in the same horizon and
there is amber and 3-D seeds. Above this is a 0.50m thick layer of dense, blocky, silty-clay with large tree
trunks with roots penetrating into the excavation horizon. The next layer is 1.2 m thick grey, blocky silts
with some iron staining and containing grey balls of clay and a lot of organic plant fragments. This layer
is topped by a <10cm thick coal seam which is persistent for at least a kilometer in either direction (east
and west) and which contains the richest source of amber at this locality. The uppermost 3.0 m of exposed
Wapiti Fm. strata is grey silty sandstone which is dense and blocky with some sideritized concretions in
the upper half. This layer has produced some amber and seeds. The top of the Wapiti section at this site is
eroded and topped by 1.2m of unconsolidated glacial till of Pleistocene origin. The sedimentology of the
excavation site indicates a low energy depositional environment, likely a shallow swamp or the margin of a
lake. Based on geographic location and lithology it is likely that this site correlates with Unit 3 of the Wapiti
Formation (Fanti, and Catuneanu, 2009; 2010).
The current quarry is 40m2 with the articulated remains occupying only a few square metres. Single
elements and several small sections of articulated vertebrae (cervical, thoracic and caudal) are found in
varying concentrations in other areas of the quarry. The articulated portion of the hadrosaur begins with
the middle of the thoracic region of vertebrae leading to the hips (which are complete) and extends to the
middle of the caudal series. The carcass is resting on its right side with its anterior between two in situ tree
stumps. The morphology of the left ilium, pubis and ischium support the identification of the hadrosaur
as a lambeosaurine. With the exception of the left bones of the pelvis no elements from the left side of the
body (ribs or limb bones) remain in articulation. The condition of the majority of the right side of the body
is currently unknown; however the right femur is present and appears to be articulated with the pelvis.
The skull has not been discovered, but three hadrosaur teeth with roots were found, one near the anterior
region of the articulated specimen and two more anterior and ventral to the pubis. Preservation of the bones
is quite good, with little evidence of post-depositional deformation. There are many skeletal elements
97
scattered around the articulated specimen, with small bones mixed amongst larger bones. There are three
concentrations of disarticulated bones (large and small elements) within three metres of the articulated
specimen. There is nothing to indicate the presence of more than one hadrosaur at this site.
A large number (>40) of shed tyrannosaur teeth were found throughout the quarry, with some
teeth lying on top of the articulated hadrosaur carcass. All these teeth are from anterior jaw regions
(premaxillary, anterior maxillary and anterior dentary teeth). All but two tyrannosaur teeth from this site
are significantly smaller than those from typical adult specimens belonging to the Albertosaurinae. When
comparing this site’s tyrannosaur teeth with teeth of Albertosaurus sarcophagus collected from a single
population containing both juvenile and adult specimens (Buckley et al. 2010), the majority of the teeth
group statistically with those teeth from juvenile individuals due to size.
A single shed Dromaoesauridae indet. tooth, a possible tooth of a bonefish (Parabula sp.) and one small
unidentified caudal vertebra (possibly from a small lizard) have added to this site’s vertebrate diversity.
Small, poorly preserved gastropods were found in the bone horizon as well as a few plant remains (seeds
and small cones) and a few pieces of amber.
As the excavation and preparation of the recovered bones and teeth progresses, questions have arisen:
1) What could explain the state of the hadrosaur carcass and the distribution of the isolated elements?, and
2) What could explain the presence of so many shed anterior teeth of tyrannosaurs? Fluvial action was not
responsible for the distribution of the bones at this site given the low-energy depositional environment.
There is little evidence for directional orientation of isolated long bones (ribs, femur, radius, ulna) or fluvialinfluenced sorting of bones (sensu Voorhies, 1969; and Behrensmeyer, 1975). The low energy depositional
environment is unlikely to have been a factor in a fluvial concentration of the shed teeth of tyrannosaurs
at this site. Teeth of tyrannosaurs have been found lying on some of the isolated bones and upon the
articulated specimen, which would be unusual for a transport influenced scenario. The teeth were likely
concentrated at this site due to the feeding behaviour (scavenging or predation) of at least one adult and
several juvenile tyrannosaurs. Such behaviour would explain the state of the hadrosaur carcass including
the distribution of the isolated elements.
No tooth puncture or scrape marks have been identified on prepared specimens to date, although one
isolated hadrosaur metacarpal is laterally compressed. The undistorted state of all other isolated elements
suggests that the metacarpal compression may have been caused by a pre-depositional event and may even
have been due to the force of a bite. Most dinosaur bones from other suspected feeding sites do not bear
tooth marks (Abler, 1992), so the absence of tooth marked bone does not remove feeding by tyrannosaurs
as a differential.
As with several authors with other sites (Carpenter, 1998; Jerzykiewicz et al., 1993; Matthew, 1908;
Maxwell & Ostrom, 1995, Ryan, et al., 1998) we are curious to know whether the B.C. hadrosaur may
have succumbed to predation by one or more tyrannosaurs. There is compelling ‘direct’ evidence that
large theropod dinosaurs preyed on large herbivorous dinosaurs. One example is specimen DMNH 1493
of Edmontosaurus annectens with damage to its tail, interpreted by Carpenter (1998) as a healed bitemark from an attack by a Tyrannosaurus rex. Such evidence makes a strong case for attempted predation.
However, what if the predator, instead of wounding DMNH 1493, had been successful with its kill? How
could it be demonstrated that the hadrosaur had not died from old age, disease or other non-predatory cause
and then had its carcass scavenged?
In the case of the B.C. hadrosaur, the concentration of tyrannosaur teeth may have had nothing to
do with predation, and in the absence of other observations they alone may not be the best evidence for
feeding. No definitive bite marks have yet been observed on the articulated part of the body or on the
dissociated bones. If discovered, bite marks on the left side of the carcass would confirm feeding behavior,
but would not be definitive evidence of predation. If bite marks were to be discovered on the right side of
the articulated specimen they would provide much stronger evidence for predation, since such bite marks
would have to have been made before the hadrosaur came to rest on its right side. We feel that right side
bite marks could not have been made by feeding dinosaurs, but could have only been inflicted while the
animal was alive and upright. This is assuming that a multi-ton hadrosaur carcass was not moved or flipped
98
by fairly small (<2m tall) juvenile tyrannosaur (and at least one adult) during feeding. Upon the hadrosaur’s
death (if it was an act of predation), its fall would have removed the bulk of its right side from feeding
activities, leaving only the traces of predatory attack.
The authors consider the above speculation to be a testable hypothesis with this specimen as we, at the
time of this writing, are preparing for the final recovery of the articulated specimen from the field site. Of
course, there may be no tooth-marked bone on either the left or right sides of the body, and any predation or
scavenging may have involved soft tissues only. In that case evidence of predation is equivocal, but the case
for feeding which is based on other lines of evidence remains viable.
We cite several lines of evidence to support our hypothesis of feeding at this site as follows:
1. There are a large number (40+) of shed tyrannosaur teeth,
2. The shed teeth are derived exclusively from anterior jaw regions,
3. The tyrannosaur teeth are associated with a partially disarticulated hadrosaur carcass, and
4. The hadrosaur bones and tyrannosaur teeth are preserved in a very low energy environment.
The large number of shed teeth may suggest the carcass was visited by a group of juvenile tyrannosaurs
rather than a series of individuals. We are currently investigating methods to determine minimum numbers
of tyrannosaurs that may have been involved in the dismemberment of the carcass. For now we simply
note that the Albertosaurinae (juveniles and adults) have between 64-68 tooth positions (compiled from
Carr, 1999) and it is unlikely that a small number of tyrannosaurs shed the large number of anterior teeth
found at this locality. Also, a time-averaged accumulation of tyrannosaur teeth would be likely to include a
higher proportion of adult-sized teeth. However, we acknowledge that with the proposed high survivorship
of juvenile tyrannosaurids compared to that of adults (Erickson et al., 2006), an alternative interpretation
might be that there were simply several juvenile tyrannosaurids in the vicinity of the carcass. There are
three accumulations of bones between 1 and 3 metres away from the main carcass which could be evidence
that more than one tyrannosaur was feeding on the carcass. Some modern predators and scavengers jockey
for position at a carcass and quickly tear off a piece and then retreat a safe distance to eat their portion
in peace away from the throng of other scavengers. The three bone piles may be the traces of this sort of
group feeding behavior, as has been suggested for other sites (Erickson and Olson, 1996).
Many of the disarticulated hadrosaur bones (ribs, radius, ulna, etc.) are long and delicate, yet (with
the possible exception of the crushed metacarpal) lack obvious tooth punctures, scrapes or compression
features from bites. Most of these delicate bones are complete. Incomplete elements have been found at the
edge of the bank and were subject to recent erosion.
Juvenile tyrannosaurs may have had to adopt a feeding strategy which differed from that supposed for
adult tyrannosaurs (Reichel, 2011). With mouths and teeth proportionally smaller (and with presumably
decreased bite force and bite stress ability of the teeth) juvenile tyrannosaurs may have resorted to tearing
portions of the body and flesh off the carcass. This may have been accomplished by the anterior portions of
their jaws ‘nipping’ the carcass to pieces as opposed to using their teeth and jaws to bite and crush through
flesh and bone (Erickson and Olson, 1996). This method of dismembering the carcass and feeding may
account for the apparent lack of tooth marks at this site.
Although our interpretations relating to this excavation are of a preliminary nature we feel that there is
a unique opportunity to test the ideas stated herein as well as ideas published by others regarding evidence
and assumptions for interpretations of feeding, scavenging and predation in dinosaurs.
Acknowledgements
CGG Veritas and Ridge Rotors generously donated helicopter support for surveys of the Wapiti
Formation outcrop in 2006 and 2010 respectively. LaPrairie Crane, the North and South Peace Economic
Development Commissions, Peace River Coal, and Enbridge Northern Gateway provided financial support
for the excavation. We are grateful our volunteers and staff field assistants who helped with this excavation.
99
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18(2):161-183.
Behrensmeyer, A.K. 1975. The taphonomy and paleoecology of Plio-Pleistocene vertebrate assemblages east of Lake
Rudolph, Kenya. Bulletin of the Museum of Comparative Zoology, 146: 473-578.
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from the Upper Cretaceous of Alberta, Candada, pp. 1-108. In Currie, P.J., Langston, W. Jr., and Tanke, D.H.,
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correlative stratigraphy, sedimentary geology, and paleontology and comparisons with the type locality in the preAltai Gobi. Canadian Journal of Earth Sciences, 30: 2180-2195.
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(ed.), 9th British Columbia Paleontology Symposium/ 3rd Peace Region Palaeontology Symposium Abstracts
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implications inferred through 3-D models. Canadian Journal of Earth Sciences 47: 1253-1261.
Ryan, M.J., Currie, P.J., Gardner, J.D., Vickaryous, M.K., and Lavigne, J.M. 1998. Baby hadrosaurid material
associated with an unusually high abundance of Troodon teeth from the Horseshoe Canyon Formation, Upper
Cretaceous, Alberta, Canada, pp. 123-133. In Perez-Moreno, B.P., Holtz, T., Sanz, J.L., and Moratalla, J. (eds.),
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100
The Phylogeny, Taxonomy, and Biogeography of Basal
Iguanodonts (Dinosauria: Ornithischia)
Andrew T. McDonald
Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Introduction
Much as hadrosaurids are ubiquitous in latest Cretaceous faunas, their precursors, the basal iguanodonts,
are prevalent in Late Jurassic and Early Cretaceous dinosaur assemblages. Lower Cretaceous formations
of western North America, western Europe, and east-central Asia are especially prolific. Nearly 60 basal,
i.e. non-hadrosaurid, members of the clade Iguanodontia have been named, and yet until recently many
of these species had not been included in a phylogenetic analysis. In order to elucidate the relationships
among these taxa, they were included in the first comprehensive phylogenetic analysis of basal iguanodonts,
the latest iteration of which appeared in McDonald et al. (2010c) and McDonald (2011). The results of this
analysis carry ramifications for the taxonomy of some basal iguanodonts and prompt novel biogeographic
hypotheses.
Phylogenetic Analysis
The phylogenetic analysis of basal iguanodonts encompassed nearly all named non-hadrosaurid
members of Iguanodontia. This includes four new species recently named by the author and colleagues:
Jeyawati rugoculus (McDonald et al. 2010a), Kukufeldia tilgatensis (McDonald et al. 2010b),
Iguanacolossus fortis (McDonald et al. 2010c), and Hippodraco scutodens (McDonald et al. 2010c). Also
incorporated were numerous other taxa that had never before been placed in a quantitative phylogenetic
analysis, such as Callovosaurus leedsi, Elrhazosaurus nigeriensis, Uteodon (= “Camptosaurus”)
aphanoecetes, Cumnoria (= “Camptosaurus”) prestwichii, Osmakasaurus (= “Camptosaurus”) depressus,
Owenodon hoggii, Barilium dawsoni, and Hypselospinus fittoni.
The initial data matrix included 61 taxa (two outgroups, 56 basal iguanodonts, and three representative
hadrosaurids) and 131 morphological characters. Regarding character distribution among anatomical
regions, 28 (~ 21%) characters are in the mandibular elements, 52 (~ 40%) in the skull, 13 (~ 10%) in the
dentition, three (~ 2%) in the vertebrae, 13 (~ 10%) in the pectoral girdle and forelimb, and 22 (~ 17%)
in the pelvic girdle and hindlimb. The single most character-rich element is the dentary, with 17 (~ 13%)
characters.
The analysis was run in TNT (Goloboff et al. 2008). Wagner starting trees with a random seed of 1
and 10,000 replicates were used with the tree bisection reconnection algorithm, which saved 10 trees per
replication. This resulted in 13,080 most parsimonious trees (MPTs) of 358 steps. The matrix was then run
through the program TAXEQ3 (Wilkinson 2001a) for safe taxonomic reduction; a subsequent running of
the analysis found 11,850 MPTs of 358 steps. The matrix was finally run through the program REDCON
3.0 (Wilkinson 2001b) to find reduced consensus trees. Several of the resultant trees were combined
to produce the cladogram shown in Figure 1. Although this reduced consensus tree is moderately well
resolved, safe taxonomic reduction and calculation of reduced consensus trees a posteriori pruned 15
unstable basal iguanodonts from the tree, including Osmakasaurus, Owenodon, Barilium, Hypselospinus,
and Kukufeldia.
A new iteration of the analysis is currently being prepared and will be presented at the Hadrosaur
Symposium. It will incorporate additional information for several taxa, such as the postcranial anatomy of
Jinzhousaurus yangi (Wang et al. 2011), and new taxa, such as Xuwulong yueluni (You et al. 2011).
101
Taxonomic Revisions
The results of the phylogenetic analysis had major implications for the taxonomy of Camptosaurus
(McDonald 2011). “C.” aphanoecetes (Carpenter and Wilson 2008) and “C.” prestwichii (Hulke 1880)
were found to be more derived than the type species, Camptosaurus dispar (Marsh 1879) (Fig. 1). Thus,
the genus Cumnoria (Seeley 1888) was reinstated for “C.” prestwichii and a new genus, Uteodon, erected
for “C.” aphanoecetes (McDonald 2011). “Camptosaurus” valdensis was found to be an indeterminate
dryosaurid.
Although eliminated from the reduced consensus tree, “Camptosaurus” depressus (Gilmore 1909) was
also given a new generic name, Osmakasaurus (McDonald 2011). Such a taxonomic move was necessary
after reassessment of the putative horizontal postacetabular process that linked this species to Planicoxa
venenica (Carpenter and Wilson 2008) revealed that this feature exists due to crushing of the left ilium of
the holotype skeleton; the same conclusion was reached for the postacetabular process of the holotype ilium
of Planicoxa venenica. The holotype and only known skeleton of “C.” depressus lacks features that would
support referral to any existing genus of basal iguanodont, hence the creation of the new generic name
Osmakasaurus. The phylogenetic analysis revealed that the name Camptosaurus historically encompassed
a mixture of dryosaurid, basal ankylopollexian, and basal styracosternan taxa and should be restricted to
the type species, C. dispar.
Basal Iguanodont Biogeography
The phylogeny presented in Figure 1 allowed some preliminary biogeographic observations to be
made. Two possible instances of endemism are suggested by the cladogram: the clade composed of
Hippodraco scutodens and Theiophytalia kerri is known only from the Barremian-Albian of Utah and
Colorado (Brill and Carpenter 2007; McDonald et al. 2010c), and the clade including Jinzhousaurus yangi
and Penelopognathus weishampeli is known only from the Barremian-Albian of northeastern China
(Godefroit et al. 2005; Barrett et al. 2009). Furthermore, it appears that Early Cretaceous taxa from western
North America are more basal than contemporaneous taxa in Europe and Asia. For example, Hippodraco
scutodens from Utah is more basal than Jinzhousaurus yangi from China and Iguanodon bernissartensis
from Belgium and England. A quantitative analysis of basal iguanodont biogeography is now in preparation
using the program S-DIVA (Yu et al. 2010). The results will be presented at this conference.
Acknowledgements
I am very grateful to my advisor, Peter Dodson, for his advice, insights, and constant encouragement. I
thank Richard Butler for offering guidance on phylogenetic techniques and Victoria Egerton for discussions
of biogeographic analysis. I am also grateful to my chief collaborators, Paul Barrett, James Kirkland,
and Douglas Wolfe for allowing me to work on new iguanodonts from England, Utah, and New Mexico,
respectively, and for their confidence in me to carry out those projects well. My research was facilitated by
funds from the Jurassic Foundation, Evolving Earth Foundation, University of Pennsylvania Paleobiology
Summer Stipend, and Utah Friends of Paleontology.
References
Barrett, P.M., Butler, R.J., Wang X.-L., and Xu X. 2009. Cranial anatomy of the iguanodontoid ornithopod
Jinzhousaurus yangi from the Lower Cretaceous Yixian Formation of China. Acta Palaeontologica Polonica,
54(1): 35-48.
Brill, K., and Carpenter, K. 2007. A description of a new ornithopod from the Lytle Member of the Purgatoire
Formation (Lower Cretaceous) and a reassessment of the skull of Camptosaurus. In Horns and Beaks:
Ceratopsian and Ornithopod Dinosaurs. Edited by K. Carpenter. Indiana University Press, Bloomington, Indiana.
pp. 49-67.
Carpenter, K., and Wilson, Y. 2008. A new species of Camptosaurus (Ornithopoda: Dinosauria) from the Morrison
Formation (Upper Jurassic) of Dinosaur National Monument, Utah, and a biomechanical analysis of its forelimb.
Annals of the Carnegie Museum, 76(4): 227-263.
102
Gilmore, C.W. 1909. Osteology of the Jurassic reptile Camptosaurus, with a revision of the species of the genus, and
descriptions of two new species. Proceedings of the United States National Museum, 36: 197-332.
Godefroit, P., Li, H., and Shang, C.-Y. 2005. A new primitive hadrosauroid dinosaur from the Early Cretaceous of
Inner Mongolia (P. R. China). Comptes Rendus Palevol, 4: 697-705.
Goloboff, P.A., Farris, J.S., and Nixon, K.C. 2008. TNT, a free program for phylogenetic analysis. Cladistics, 24: 774786.
Hulke, J.W. 1880. Iguanodon prestwichii, a new species from the Kimmeridge Clay, founded on numerous fossil
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433-456.
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2783: 52-68.
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the Turonian of New Mexico. Journal of Vertebrate Paleontology, 30(3): 799-812.
McDonald, A.T., Barrett, P.M., and Chapman, S.D. 2010b. A new basal iguanodont (Dinosauria: Ornithischia) from
the Wealden (Lower Cretaceous) of England. Zootaxa, 2569: 1-43.
McDonald, A.T., Kirkland, J.I., DeBlieux, D.D., Madsen, S.K., Cavin, J., Milner, A.R.C., and Panzarin, L. 2010c.
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Jinzhousaurus yangi from the Lower Cretaceous Yixian Formation of western Liaoning, China. Earth and
Environmental Science Transactions of the Royal Society of Edinburgh, 101: 135-159.
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History Museum, London. Available from http://www.nhm.ac.uk/research-curation/research/projects/software/
mwphylogeny.html [cited 16 April 2010].
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History Museum, London. Available from http://www.nhm.ac.uk/research-curation/research/projects/software/
mwphylogeny.html [cited 5 October 2010].
You H., Li D., and Liu W. 2011. A new hadrosauriform dinosaur from the Early Cretaceous of Gansu Province, China.
Acta Geologica Sinica (English Edition), 85(1): 51-57.
Yu, Y., Harris, A.J., and He, X. 2010. S-DIVA (Statistical Dispersal-Vicariance Analysis): a tool for inferring
biogeographic histories. Molecular Phylogenetics and Evolution, 56: 848-850.
103
Fig. 1. Reduced consensus tree of 11,850 MPTs of 358 steps each, following ordering of 22 multistate characters
and safe taxonomic reduction. Numbers below and to the left of some nodes correspond to the following
clade names: 1, Ornithopoda; 2, Iguanodontia; 3, Rhabdodontidae; 4, Dryomorpha; 5, Dryosauridae; 6,
Ankylopollexia; 7, Styracosterna; 8, Hadrosauriformes; 9, Hadrosauroidea. Modified from McDonald (2011).
104
Cranial anatomy and systematics of Prosaurolophus
maximus
Christopher T. McGarrity1, David C. Evans2, and Nicolás E. Campione1
1
2
Department of Ecology and Evolutionary Biology, University of Toronto
Department of Natural History, Royal Ontario Museum
Hadrosaurids were the dominant large-bodied herbivores in Late Cretaceous ecosystems of North
America and Asia. Although they are a diverse and well-sampled clade, their evolutionary relationships
continue to be poorly resolved. The hadrosaurine Prosaurolophus maximus is known from numerous
articulated specimens from the Late Campanian Dinosaur Park Formation (DPF) of southern Alberta.
Therefore, it is an ideal taxon to reconstruct patterns of growth and variation in hadrosaurids, and improve
our understanding of their evolutionary relationships. Though well represented in the fossil record, P.
maximus has been poorly documented. It was named by Brown (1916) on the basis of a single incomplete,
articulated skull (AMNH 5386). Since the holotype description, at least nine more articulated P. maximus
skulls have been found in the DPF at the type locality of Dinosaur Provincial Park (including ROM 787,
Figure 1), representing a size range between presumably sub-adult (66% maximum size) to larger adult.
While the majority of the anatomy is well preserved in AMNH 5386, study of additional material reveals
valuable information about cranial variation in P. maximus, including that surrounding the morphology
of the putatively diagnostic crest. This study describes the cranial anatomy in P. maximus, quantitatively
examines its range of variation, and provides the first ontogenetic series for this taxon, with implications for
dinosaur diversity and evolution.
Prosaurolophus maximus is characterized by a solid nasal crest located above the rostrodorsal margin of
the orbit that is excavated laterally by the circumnarial depression. In his original description of this taxon,
Brown (1916) states that the crest is formed primarily by the frontal, and that the nasal only contributes the
rostral portion of the crest. However, all subsequent authors have agreed with the interpretation of Lull and
Wright (1942), who observed that the crest is formed exclusively by the nasal. Regression analyses indicate
that growth of the crest is positively allometric, consistent with hypotheses of a sexually selected structure,
as suggested for other crested hadrosaurids (Lull and Wright, 1942; Ostrom, 1961, 1962; Dodson, 1975;
Hopson, 1975; Evans, 2010). Additionally, the growth of the crest is shown to have occurred in stages as it
developed throughout ontogeny from small and incipient; to an intermediate stage with a dorsally directed
bowing of the nasal in the rostral portion of the crest, which became larger, more rugose, and more deeply
excavated by the circumnarial depression; and finally to a more robust and knob-like crest, with the dorsal
bowing occurring immediately rostral to the crest.
A second species, Prosaurolophus blackfeetensis, from the Two Medicine Formation of Montana, was
named by Horner (1992) on the basis of subtle differences from Prosaurolophus maximus pertaining to the
size and morphology of the crest; however, these proposed differences could not be observed in P. maximus
in this study. A recent study by Prieto-Márquez (2010) suggests that these taxa are synonymous. However,
this has not been tested using quantitative morphometric and phylogenetic methods. Morphometric results
in this study fail to quantitatively differentiate P. blackfeetensis from P. maximus.
A species-level phylogenetic analysis of hadrosaurids, the first to include both species of
Prosaurolophus, recovers a single most parsimonious tree with P. maximus and P. blackfeetensis as
sister taxa. Furthermore, P. maximus and P. blackfeetensis are scored identically for all phylogenetically
informative characters included in this taxon-character matrix where they could be evaluated for both
taxa. Based on both the morphometric and phylogenetic data, this study supports the previous hypothesis
of Prieto-Márquez (2010) that P. blackfeetensis is a junior synonym of P. maximus thereby increasing its
temporal range to 1.6 Ma, and suggests a long period of morphological stasis in this taxon.
Because hadrosaurs constitute a highly diverse group of dinosaurs with a well-sampled fossil record,
they have been important in the construction of large-scale hypotheses related to the macroevolutionary
patterns of Late Cretaceous dinosaurs in general. However, the species-level phylogenetic relationships
105
of hadrosaurine hadrosaurids are disputed and poorly resolved. When Brown originally described
Prosaurolophus maximus (1916), he hypothesized that it was the direct ancestor of Saurolophus osborni.
Since then, the evolutionary relationships of P. maximus within Hadrosauridae have been debated. BrettSurman (1979) was the first to formally propose a sister taxon relationship between Prosaurolophus
and Saurolophus, rather than an ancestor-descent relationship. Most analyses support this hypothesis
and recover Saurolophus and Prosaurolophus as sister taxa (Weishampel et al., 1993; Bolotsky and
Godefroit, 2004; Godefroit et al., 2004, 2008; Prieto-Márquez et al., 2006; Gates and Sampson, 2007;
Prieto-Márquez, 2010), while Horner et al. (2004) recover Prosaurolophus more closely related to a clade
that includes Gryposaurus. This analysis supports a monophyletic relationship between Saurolophus and
Prosaurolophus, consistent with the majority of previous studies.
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Natural History 35: 701–708.
Dodson, P. 1975. Taxonomic implications of relative growth in lambeosaurine hadrosaurs. Systematic Zoology 24:
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Hopson, J.A. 1975. The evolution of cranial display structures in hadrosaurian dinosaurs. Paleobiology 1: 21–43.
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new hadrosaurid species and an evaluation of hadrosaurid phylogenetic relationships. Museum of the Rockies,
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Museum of Natural History 122: 33–186.
Ostrom, J.H. 1962. The cranial crests of hadrosaurian dinosaurs. Postilla 62: 1–29.
Prieto-Márquez, A. 2010. Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and
Bayesian methods. Zoological Journal of the Linnean Society 159: 435- 502.
Prieto-Márquez, A., Gaete, R., Rivas, G., Galobart, A., and Boada, M. 2006. Hadrosauroid dinosaurs from Western
Europe: Pararhabdodon isonensis revisited and Koutalisaurus kohlerorum gen. et sp. nov. Journal of Vertebrate
Paleontology 26: 929–943.
Weishampel, D.B., Norman, D.B., Grigorescu, D. 1993. Telmatosaurus transsylvanicus from the Late Cretaceous of
Romania: the most basal hadrosaurid. Palaeontology 36: 361–385.
106
Fig. 1. ROM 787, Prosaurolophus maximus. Right lateral view. Scale bar equals 10 cm.
107
The Functional Significance of the Predentary Bone in
Ornithopod Jaw Mechanisms
Ali Nabavizadeh
The Johns Hopkins University School of Medicine, Center for Functional Anatomy and Evolution
The evolution of ornithopod jaw mechanisms has been subject to investigation for over a century, with
in-depth analyses of intra-cranial joints and dental microwear (Marsh, 1893; Nopsca, 1900; Versluys,
1910; 1912; 1923; Lambe 1920; von Kripp, 1933; Lull and Wright, 1942; Ostrom, 1961; Thulborn, 1971;
Galton, 1974; Hopson, 1980; Sues, 1980; Weishampel, 1984; Norman, 1984; Norman and Weishampel,
1985; Rybczynski et al., 2008; Williams et al., 2009; Bell et al., 2009). Their skulls, mandibles, and
dentition are of such unique structures that there is no modern analogue with which sufficiently to compare
them. For over two decades, the most accepted feeding mechanism proposed for most ornithopods has
been pleurokinesis (Weishampel, 1984; Norman, 1984; Norman and Weishampel, 1985), a novel style of
chewing using a unique form of cranial kinesis. Pleurokinesis involves movement of the quadrate against
the squamosal creating a domino effect of kinetic cranial elements causing the maxillae to be pushed and
rotate laterally as their teeth occlude. This accounts for their unusual horizontally-oriented tooth wear.
Although this mechanism has recently been challenged due to proposed constraints within certain cranial
joints, there is yet to be proposed an alternative explanation for the horizontal tooth wear. Since neither
propalinal nor orthal chewing would explain this and the angle at which teeth occlude would not allow the
entire jaw to chew transversely as one unit, there is likely another aspect of the jaw mechanism that is not
well understood.
In modern herbivorous mammals, there are species with a fused mandibular symphysis, with
antagonistic opposing muscle forces through the symphysis, and species with an unfused mandibular
symphysis, allowing medial torsion or rotation of the dentary bones (Greaves, 1978). Since most, if not
all, ornithischian taxa do not fuse the two dentaries together anteriorly, the predentary bone to which
they both attach may assist in a jaw mechanism similar to an unfused symphysis. Weishampel (1984) and
Crompton and Attridge (1986) investigated the skull of Heterodontosaurus and proposed that there was a
separate lateral mobility at the predentary-dentary junction. This mechanism is almost unknown in other
vertebrates. The role of the predentary bone itself was not considered, but rather it was assumed that some
type of lateral kinesis of the mandibular corpora was used. Sereno (1991) proposed a similar mechanism
for Lesothosaurus with the observation that the dentaries were completely separate entities that did not
firmly articulate with the predentary, implying slight mobility. As Heterodontosaurus and Lesothosaurus
are considered among the most basal ornithischians (Butler et al., 2007), the evolutionary and functional
significance of the ornithischian predentary bone comes into question.
The predentary bone is a single bony mandibular element uniting all of Ornithischia (see Figure 1).
Located anteriorly at the midline of the mandibular symphysis, it occludes with the premaxilla (or rostral
bone in ceratopsians) and was likely covered by a keratinous bill. In many cases, there are numerous
foramina on the rostral surface, indicating neurovasculature to the keratinous sheath. It has been
universally accepted that the predentary was part of a plant-gathering beak used like the lower incisors of
herbivorous mammals in nipping vegetation (Padian, 1997). Its absence in fossil and extant herbivorous
mammals and many other fossil herbivores (including sauropodomorphs), however, indicates that the
functional significance of this element is yet to be understood. Why did ornithischians evolve this extra
mandibular element and why did it persist throughout 140 million years of ornithischian evolution?
As the morphologies of the predentary bone are highly diverse among ornithischian groups, it is helpful
to examine each clade separately. In this particular study, various ornithopod predentary and dentary
morphologies were investigated. The articular surfaces between the predentary and dentary and between
other mandibular elements were examined to assess any type of mobility that might have occurred at these
junctions. Tooth wear orientation of hadrosauroids was also examined under light microscopy to obtain
general information about directionality of mastication in more advanced ornithopods.
108
Primitive ornithopods such as Hypsilophodon have a triangular-shaped predentary reminiscent of
still more primitive ornithischians. There is a single median ventral process cradling the inferior border
of the dentaries as well as a groove on the posterior edge of two caudally bifurcating processes of the
predentary on which the anterior edge of the dentary rested. The dentary itself possesses leaf-shaped
teeth and is curved medially at the anterior tip, although to a minimal extent. Like Heterodontosaurus
and Lesothosaurus, there is potential mobility at the predentary-dentary junction likely accommodated
by cartilage. A similar structure holds true for Thescelosaurus, although its predentary is much more
anteroposteriorly elongate and the anteromedial tip is more pointed.
Zalmoxes shows the first signs of a dorsoventral heightening as well as more curvature of the anterior
end of the predentary. This curvature begins to form two more distinct bifurcating processes directed
caudally over the dentaries along with the same single ventral process that has evolved to become more
broadened. As ornithopod evolution progressed, iguanodontian predentaries evolved more distinct denticles
on the dorsal edge and the posterior bifurcating processes are widened and expanded to overlap the anterior
edge of the dentaries on either side. These widened expansions do not clasp onto the dentaries, but merely
allow the dentaries to rest up against them. The paired dentaries do not form a true symphysis but in fact
press up against each other. Pathological rugosities at this junction imply rubbing of the two dentaries
against each other during mastication. Most derived non-hadrosaurid iguanodontians evolve a bifurcation
of the ventral process of the predentary as well, likely providing more stability.
The derived hadrosauroids exhibit the most extreme cases of widening expansions of the caudally
bifurcating processes to the extent that they curve dorsally at an angle while still constraining a flat
articular surface. The median ventral bifurcating process is still present. There is no indication of a firm,
clasping junction at the predentary-dentary articulation (or between the dentaries themselves). There
are gaps between the predentary and dentary regardless of what orientation they are articulated. This is
indicative of significant mobility at this junction with a range of movement supported by cartilage (see
Figure 2).
Other aspects of hadrosauroid mandibular morphology also suggest significant predentary-dentary
mobility, specifically that of mediolateral rotation of each mandibular corpus. A distinct exaggerated
medial curvature of the anterior portion of the dentary indicates a plane on which the predentary would
rock back and forth as does a mediolateral arc curvature of the tooth battery from a superior view along the
long axis of the dentary. A slightly medially recurved coronoid process allows each side of the mandible to
be tucked underneath the jugal with rotation of the mandibular corpora. Also, a ball-and-socket articulation
between the quadrate and mandible (at the articular bone) suggests a rotating surface and range of
movement (see Figure 3). These along with the evolution of a large tooth battery with an outwardly angled
occlusal surface give evidence for a complex chewing style.
Two different orientations of tooth wear on the serrated edges and occlusal surfaces suggest both
propalinal jaw movement for initial shearing of vegetation and a bolt-cutter-like medial rotation of the
dentaries against the maxilla. This would maneuver the vegetation into the oral cavity independently
on both sides for more efficient processing. With these observations, a four-step feeding mechanism
is proposed for hadrosauroids: 1) occlusion of the tooth batteries with simultaneous palinal motion; 2)
stripping bark with palinal motion of the jaw; 3) dentary bones rotating medially with maxillary teeth
pressing against the dentary teeth as the jaw is pulled caudally, maneuvering vegetation into the oral cavity;
4) returning to resting position before repeating the process (see Figure 4).
In conclusion, many morphological aspects of the predentary-dentary junction as well as post-dentary
elements and dental microwear support the presence of independent kinesis of the paired dentary bones
relative to the predentary. The predentary would have served as an axial point for the paired dentaries to
simultaneously mediolaterally rotate. The pterygoideus and adductor muscles of the jaw (Ostrom, 1961)
would have accommodated this motion. Various other mandibular features also suggest a rotating surface
and range of movement with cartilage at the predentary-dentary junction, thus allowing medial torsion or
rotation of both dentary bones. Two orientations of tooth wear on the serrated edges and occlusal surfaces
suggest both palinal jaw movement to shear vegetation initially and a bolt-cutter-like medial rotation of the
dentary bones against the maxilla. This would maneuver the vegetation into the oral cavity independently
109
on both sides for more efficient processing (i.e. ability to work both sides of the jaw simultaneously rather
than one side at a time as in most herbivores). More in-depth analysis of the predentary bone and associated
jaw elements in ornithopods as well as all other ornithischians is essential (specifically more quantitative
analyses) as well as analysis of its implications toward pleurokinesis. This would help elucidate the
significance of the predentary bone in ornithischian evolution and its implications on the 140-million-year
success of the clade.
References
Bell, P.B., Snively, E., & Shychoski, L. 2009. A comparison of the jaw mechanics in hadrosaurid and ceratopsid
dinosaurs using finite element analysis. The Anatomical Record 292: 1338-1351.
Butler, R.J., Upchurch, P., & Norman, D.B. 2007. The phylogeny of the ornithischian dinosaurs. Journal of
Systematic Palaeontology 6 (1): 1-40.
Crompton, A.W., Attridge, J. 1986. Masticatory apparatus of the larger herbivores during Late Triassic and Early
Jurassic times. In The Beginning of the Age of Dinosaurs. Faunal Change Across the Triassic-Jurassic Boundary,
ed. Padian, K. Cambridge University Press, London, 223-236.
Galton, P.M. 1974. The ornithischian dinosaur Hypsilophodon from the Wealdon of the Isle of Wight. Bulletin of the
British Museum (Natural History) Geol. 25: 1-152.
Greaves, W.S. 1978. The jaw lever system in ungulates: a new model. Journal of Zoology in London 184: 271-285.
Hopson, J.A. 1980. Tooth function and replacement in early Mesozoic ornithischian dinosaurs: implications for
aestivation. Lethaia 13: 93-105.
Lambe, L.M. 1920. The hadrosaur Edmontosaurus from the Upper Cretaceous of Alberta. Memoir in Canadian
Geological Survey. 120: 1-79.
Lull, R.S., & Wright, N.E. 1942. Hadrosaurian dinosaurs of North America. Geological Society of America Special
Paper 40: 1-242.
Marsh, O.C. 1893. The skull and brain of Claosaurus. American Journal of Science (Series 3) 55: 83-86.
Nopsca, F.B. Dinosaurierreste aus Siebenbergen. I. Schadel von Limnosaurus transsyvanicus nov. gen. et spec.
Denkschr Akad Wiss Wien 68: 555-591.
Norman, D.B. 1984. On the cranial morphology and evolution of ornithopod dinosaurs. Symposium of the Zoological
Society in London 52: 521-547.
Norman, D.B., & Weishampel, D.B. 1985. Ornithopod feeding mechanisms: their bearing on the evolution of
herbivory. The American Naturalist 126: 151-164.
Ostrom, J.H. 1961. Cranial morphology of the hadrosaurian dinosaurs of North America. Bulletin of the American
Museum of Natural History 122: 39-186.
Padian, K. 1997. Ornithischia. In Currie, J.P. & Padian, K., eds. Encyclopedia of Dinosaurs. Academic Press, San
Diego, pp. 494-498.
Rybczynski, N., Tirabasso, A., Bloskie, P., Cuthbertson, R., & Holliday, C. 2008. A three-dimensional animation
model of Edmontosaurus (Hadrosauridae) for testing chewing hypotheses. Palaeontologica Electronica 11(9A).
Sereno, P.C. 1991. Lesothosaurus, “fabrosaurids,” and the early evolution of Ornithischia. Journal of Vertebrate
Paleontology 11: 168–97.
Sues, H.D. 1980. Anatomy and relationships of a new hypsilophodontid dinosaur from the Lower Cretaceous of
North America. Palaeontographica [A] 169: 51-72.
Thulborn, 1971. Tooth wear and jaw action in the Triassic ornithischian dinosaur Fabrosaurus. Journal of Zoology in
London 164: 165-179.
Versluys, J. 1910. Streptostylie bei Dinosauriern nebst Bemerkungen uber die Verwandtschaft der Vogel und
Dinosaurier. Zool Jahrb Abt Anat. 30: 175-260.
Versluys, J. 1912. Das Streptostylie-Problem und die Bewegung im Schadel bei Sauropsida. Zool. Jahrb [Suppl.] 15:
545-716.
Versluys, J. 1923. Der Schadel des Skeletts von Trachodon annectus im Senckenberg-Museum. Abh Senckenb Naturf
Ges. 38: 1-19.
von Kripp, D. 1933. Die Kaubewegung und Lebensweise von Edmontosaurus spec. auf Grund der mechanischkonstruktiven Analyse. Palaeobiologica 5: 409-422.
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Weishampel, D.B. 1984. Evolution of jaw mechanisms in ornithopod dinosaurs. Advances in Anatomy Embryology
and Cell Biology 87: 1-109.
Williams, V.S., Barrett, P.M., & Purnell, M.A. 2009. Quantitative analysis of dental microwear in hadrosaurid
dinosaurs, and the implications for hypotheses of jaw mechanics and feeding. Proceedings of the National
Academy of Sciences 106: 11194-11199.
Fig. 1. Superior view of a lambeosaurine predentary.
Fig. 2. A) Hypacrosaurus skeletal reconstruction with arrows indicating independent rotation of dentary bones
with predentary bone acting as an axial point. B) Anterior view of Edmontosaurus skull. C) Anterior view
of Edmontosaurus skull with premaxilla and predentary removed; arrows indicate rotational bolt-cutter
mechanism of dentary bones hypothesized after morphological examination.
111
Fig. 3. Lateral view of quadrate-articular junction in Parasaurolophus forming a ball-to-cup junction allowing long
axis rotation
Fig. 4. Anterior view of teeth showing four step feeding mechanism: A) occlusion; B) stripping bark palinally; C)
dentary bones rotating medially with maxillary teeth pressing against the dentary teeth as the jaw is pulled
caudally, maneuvering vegetation into the oral cavity like a bolt cutter; D) returning to resting position.
112
Basal iguanodontians in the Wealden of England
David B. Norman
Department of Earth Sciences & Sedgwick Museum, University of Cambridge, Cambridge CB2 3EQ, UK.
Email: [email protected]
Iguanodontian ornithopods were recovered from a number of Lower Cretaceous quarries and foreshore
outcrops scattered across the Weald of southern Britain, and also along the southwestern coast of the Isle
of Wight, during the 19th and early 20th centuries. The majority of these remains were disassociated and
often completely isolated bones; however, some partial skeletons were recovered (e.g. Norman 1993). It
was common practice, and perfectly understandable at that, to refer these remains to the historically
notable dinosaurian genus Iguanodon (Mantell 1825). This approach was essentially pragmatic in that it
tacitly acknowledged the difficulties encountered when trying to piece together isolated elements, many of
different size and some of a form that was not easy to recognise using the comparative method established
by Cuvier. Richard Owen was pre-eminent in this field of research for a considerable period of time during
the 19th century and published a number of exquisitely illustrated monographs on individual bones or
occasionally associated remains referred to as Iguanodon (often as I. Mantelli) in the Palaeontographical
Society series. However, despite the excellence of these reports, the inability to establish an anatomical
‘blueprint’, that is to say a definitive osteology for the type genus proved to be a critical stumbling-block.
In the absence of a defined anatomy for Iguanodon it was impossible to draw comparisons with any new
discoveries that might have provided the basis for new, and definitive, taxonomic proposals.
The potential solution to this problem of definitional taxonomy arrived in 1878, following the discovery
of abundant, fully articulated, iguanodontian skeletons in Lower Cretaceous clays at an active colliery
near the village of Bernissart (Belgium) on the European mainland (Norman 1987). Unfortunately, the
often-promised monographic description(s) of these specimens failed to materialize and instead a stream
of Dolloian ‘notes’, containing very little detailed anatomy, were published on the Bernissart dinosaurs
between 1882 and 1923 by Louis Dollo (1923). Dollo did however establish the existence of two taxa of
iguanodontian at Bernissart: a gracile species that he referred to I. mantelli (from comparison with the
partial skeleton from Maidstone [Norman 1993]) and a larger and more robust species that was named
I. bernissartensis.
The interest in Iguanodon-like dinosaurs (notably those from the English Wealden deposits) was
invigorated by the new Belgian discoveries and visits to Brussels by British scientists, in order to inspect
this material; the effect of this discovery is reflected in a decade of relatively intense publishing activity on
the British Wealden-aged discoveries of these animals by such luminaries as Harry Govier Seeley (18391909), John Whitaker Hulke (1830-1895) and Richard Lydekker (1845-1915). By the early 1890s their work
had established a significant number of new Iguanodon-like taxa: Vectisaurus valdensis, Iguanodon seelyi,
Sphenospondylus gracilis, Iguanodon dawsoni, Iguanodon fittoni and Iguanodon hollingtoniensis. The
issue of taxonomic identity and rank of specimens had also come to the fore as a result of the opposing
views held by the arch taxonomic ‘splitter’ Harry Seeley and his main protagonist the ‘lumper’ John Hulke
(Lydekker, judged by his published comments appears to have studiously ‘fence-sat’ over these issues).
Much of this gentlemanly dispute is preserved in the text of the original articles as well as in the reports of
the discussion that are appended to the scientific papers that were presented to formal Geological Society
meetings. Seeley (1887) was also notably critical of both the telegraphic style of Louis Dollo’s ‘notes’, as
well as the preliminary nature of his taxonomic conclusions (Seeley believed in contrast to Dollo that the
two taxa from Bernissart were sufficiently anatomically distinct that they deserved to be recognised as
separate genera).
Following the comparatively brief (1880s) flurry of intense interest in iguanodontians of the Wealden,
there was no further significant work produced on these animals until the genuinely monographic
publication by Reginald Hooley (1925) on a new and well-preserved skeleton recovered in the debris left
after a cliff collapsed near Atherfield Point on the Isle of Wight in 1914: Iguanodon atherfieldensis. Despite
113
the many notes produced by Dollo during the intervening years, the work by Hooley was the first, exactly a
century after the first publication by Mantell (1825) that named Iguanodon, to provide a coherent and wellillustrated anatomy of any Wealden-aged iguanodontian. And this remained as the only definitive account,
and consequently became the ‘default’ reference for all of these animals until the 1980s.
More detailed work on the Bernissart material led to the first monographic accounts of the small
(gracile) skeleton, referred to as Iguanodon atherfieldensis; and a larger (robust) iguanodontian, recognised
as Iguanodon bernissartensis (Norman 1980, 1986). These two taxa were demonstrably similar to gracile
and robust skeletal remains collected from the Isle of Wight (Upper Wessex Formation: Barremian) and
the Weald Basin (Lower Weald Clay Formation: Barremian). The Bernissart clays had proved very difficult
to date and a consensus date range based on biostratigraphic principles (Barremian-Lower Aptian) was
suggested by Norman (1986). More recently Yans et al. (2006) have proposed a middle Barremian-earliest
Aptian dating for the Sainte-Barbe Clays Formation (in which the Bernissart fauna was found) based upon
independent dating methods; this dating lends some support to the taxonomic assignments.
In recent years the taxonomy of these western European iguanodontians has been revisited. In the spirit
of the ‘splitter’ Harry Seeley, Iguanodon atherfieldensis has been re-named Mantellisaurus atherfieldensis,
but it was done so in a manner that would have deeply embarrassed Seeley. In addition, spurious arguments
and unsupportable diagnoses have been used to completely rename the Bernissart gracile taxon, and it has
been suggested by the same author that further changes are being planned for some of the Hastings Beds
Group taxa of the Weald. Norman (2010) reviewed the Hastings Beds Group taxa described originally by
Richard Lydekker (comprising I. dawsoni, I. fittoni and I. hollingtoniensis) and diagnosed, illustrated and
renamed these as just two taxa: Barilium dawsoni and Hypselospinus fittoni. McDonald et al (2010) shortly
afterward diagnosed and named a new taxon (Kukufeldia tilgatensis), following careful examination of the
material. A little later in the same year a further article was published; this attempted to rename these same
species (without the benefit of appropriate diagnoses or descriptions) as well as creating additional new taxa
on the basis of either no diagnostic evidence, or completely erroneous and/or unsupportable interpretations
of the original material.
While taxonomy of fossil species will always be a matter of opinion, it must be supported by careful
study and description of the original material and supportable statements concerning the anatomical
evidence used to diagnose each taxon. The practices employed by the uncited individuals alluded to in
these more recent ‘works’ does not conform to the requirements of good, or even appropriate, taxonomy
and, if this practice continues in publications that purport to be peer-reviewed, it will bring the entire
specialist field, particularly as it applies to dinosaurian taxonomy, into disrepute.
The Hasting Beds Group (Valanginian) taxa (B. dawsoni and H. fittoni) are known from reasonably
complete skeletal remains, which have been overlooked for more than a century (Norman, in press, and in
review). These two taxa are anatomically distinct and are separated by a substantial stratigraphic interval
from younger (middle Barremian-Lower Aptian) M. atherfieldensis and I. bernissartensis.
In recent discussions, focused on portions of the skeletal remains of both the Valanginian and Barremian
iguanodontian taxa, it has been claimed that some anatomical features exhibit strong similarities to those
described in the geologically younger and more derived hadrosaurian iguanodontians. Such suggestions, if
not substantiated by detailed study of the original specimens, may remain in the literature (unchallenged)
and risk being unwittingly utilized as characters or character-states in subsequent systematic analyses
of iguanodontian interrelationships. The anatomy of these Wealden-aged iguanodontians from Britain
is reviewed as a preliminary to a systematic analysis of basal iguanodontians. This new analysis will
explore their interrelationships as well the tree topology with respect to proximate, that is to say (basal)
hadrosaurids. The review will test’ these putative anatomical characters and evaluate some of the more
recent cladistic analyses applied to a range of basal iguanodontians.
114
References
Dollo, L. (1923). «La centenaire des Iguanodons (1822-1922).» Philosophical Transactions of the Royal Society of
London, Series B. CCXII: 67-78.
Hooley, R. W. (1925). “On the skeleton of Iguanodon atherfieldensis sp. nov., from the Wealden shales of Atherfield
(Isle of Wight).” Quarterly Journal of the Geological Society of London 81: 1-61.
Mantell, G. A. (1825). “Notice on the Iguanodon, a newly discovered fossil reptile, from the sandstone of Tilgate
forest, in Sussex.” Philosophical Transactions of the Royal Society of London CXV: 179-186.
McDonald, A. T., P. M. Barrett, et al. (2010). “A new basal iguanodont (Dinosauria: Ornithischia) from the Wealden
(Lower Cretaceous) of England.” Zootaxa 2569: 1-43.
Norman, D. B. (1980). “On the ornithischian dinosaur Iguanodon bernissartensis from Belgium.” Mémoires de
l’Institut Royal des Sciences Naturelles de Belgique 178: 1-105.
Norman, D. B. (1986). «On the anatomy of Iguanodon atherfieldensis (Ornithischia: Ornithopoda).” Bulletin de
l’Institut Royal des Sciences Naturelles de Belgique 56: 281-372.
Norman, D. B. (1987). “On the discovery of fossils at Bernissart (1878-1921) Belgium.” Archives of Natural History
13: 131-147.
Norman, D. B. (1993). “Gideon Mantell’s “Mantel-piece”: the earliest well-preserved ornithischian dinosaur.” Modern
Geology 18: 225-245.
Norman, D. B. (2010). “A taxonomy of iguanodontians (Dinosauria: Ornithopoda) from the lower Wealden Group
(Valanginian) of southern England.” Zootaxa 2489: 47-66.
Norman, D. B. (in press). “On the osteology of the lower Wealden Group (Valanginian) ornithopod Barilium dawsoni
(Iguanodontia: Styracosterna).” Special Papers in Palaeontology, Palaeontological Association.
Norman, D. B. (in review). “On the osteology, comparative morphology and systematics of the Hastings Beds Group
(Valanginian) ornithopod dinosaur Hypselospinus fittoni (Iguanodontia: Styracosterna).”
Seeley, H. G. (1887). “Mr Dollo’s notes on the dinosaurian fauna of Bernissart (parts 1 & 2).” Geological Magazine
Decade III, Vol. IV: 80-87, 124-130.
Yans, J., J. Dejax, et al. (2006). «The Iguanodons of Bernissart are middle Barremian to earliest Aptian in age.»
Bulletin Institut Royal des Science Naturelles de Belgique 76: 91-95.
115
An Investigation on the Feeding Mechanisms of the Basal
Hadrosaur (Hadrosauroidea) Using the 3D Finite Element
Method
Tomoyuki Ohashi
Kitakyushu Museum of Natural History and Human History, Higashida 2-4-1, Yahatahigashi-ku, Kitakyushu, 8050071, JAPAN; [email protected]
Hadrosauroid dinosaurs are known for succeeding herbivorous animals in the Late Cretaceous with an
effective food-processing mechanism called “pleurokinesis” (Norman and Weishampel 1985). Ever since
this mechanism was first advanced in the 1980s through careful observation of the morphological features
of the ornithopod skulls, several studies on this mechanism have been conducted, including morphological
descriptions, jaw muscle reconstructions, and reconstructions of jaw motions using 3D animation (e. g.,
Holliday and Witmer 2008; Rybczynski et al. 2008). A structural analysis has also been performed to test
pleurokinesis in a subadult Hypacrosaurus skull using the 3D finite element method (FEM) to determine
its feasibility and mechanical advantages (Ohashi 2006). FEM is a numerical simulation method for solving
complex field problems and has been mainly used in engineering and medical fields since the 1960s. In the
2000s, however, many useful studies in vertebrate paleontology also began to employ FEM (e. g., Rayfield
et al. 2001).
The present study applies finite element analysis to a basal hadrosauroid dinosaur skull and lower jaws.
The morphologies of the skull and lower jaws were obtained from X-ray CT images. The material property
and Young’s modulus of the cartilage and jaw articulation are not clear; hence, the Young’s modulus of
jaw articulation is a lower value and is represented as an elastic material. The point forces are applied at
the muscle origin with the direction of adductor and mPTs muscles. The origins and directions of these
muscles are based on previous studies (Holliday 2009). The magnitude of muscle force is irrelevant in
this study because the objective is not to examine the strength of the skull; instead, it is to determine the
internal force transfer within the skull and lower jaws during mastication. Virtual food is set between the
upper and lower jaws to direct the bite force from the lower to the upper jaws. To explain the basic chewing
motion of the hadrosaur and to avoid making the calculation unnecessarily complex, this study treats the
skull as a homogenous unit and dose not consider flexibility of the skull to be associated with pleurokinesis.
Results of a preliminary analysis reveal that the stress caused by the jaw-closing motion is widely
distributed in the lower jaws, and even extends into the anterior parts; however, it is not distributed into the
predentary. Furthermore, the stress is distributed into the temporal regions and the shaft of the quadrates,
but is not concentrated in the maxillary unit. This preliminary analysis is the first analysis in which lower
jaws have been taken into consideration. Despite the necessity to improve the modeling and boundary
conditions, this analysis suggests that the robust lower jaws in the basal hadrosauroid are useful to relieve
the stress for stable chewing from a mechanical standpoint.
References
116
Holliday, C. M. 2009. New insights into dinosaur jaw muscle anatomy. The Anatomical Record, 292: 1246-1265.
Holliday, C. M. and L. M. Witmer. 2008. Cranial kinesis in dinosaurs: intracranial joints, protractor muscles, and
their significance for cranial evolution and function in diapsids. Journal of Vertebrate Paleontology, 28(4): 10731088.
Norman, D. B. and D. B. Weishampel. 1985. Ornithopod feeding mechanisms: their bearing on the evolution of
herbivory. American Naturalist, 126: 151-164.
Ohashi, T. 2006. Structural analysis of derived ornithopod skull using 3D finite element method: reconstruction of
their feeding method. Journal of Vertebrate Paleontology, 26 (Supplement to 3) 107A.
Rayfield, E. J., D. B. Norman, C. Horner, J. Horner, P. Smith, J. Thomason, and P. Upchurch. 2001. Cranial design
and function in a large theropod dinosaur. Nature, 409: 1033-1037.
Rybczynski, N., A. Tirabasso, P. Bloskie, R. Cuthbertson, and C. Holliday. 2008. A three-dimensional animation
model of Edmontosaurus (Hadrosauridae) for testing chewing hypotheses. Palaeontologia Electronica, 11(2): 9A:
14p.
Duckbills on the run: comparing the cursorial abilities
of hadrosaurs and tyrannosaurs
W. Scott Persons, IV
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
Introduction
Throughout the Late Cretaceous, tyrannosauroids were the dominant large theropods across the
Northern Hemisphere and were the only likely terrestrial predators of adult hadrosaurs. Despite this
coexistence, Laurasian hadrosaur species flourished and were among the most abundant herbivorous
dinosaurs in many ecosystems. This success is remarkable considering that most hadrosaurs had no
obvious anti-predator defenses. Hadrosaurs lacked osteological armor and weapons – such as horns or
spikes – and the large size of adult hadrosaurs would likely have prevented concealment-based predator
avoidance. While some Asian forms may have been protected in adulthood by their enormous bulk, most
adult hadrosaurs were smaller than, or equal in size to, the tyrannosaurs that shared their environments.
Previous examinations of the relative cursoriality of both groups have failed to offer an explanation.
Tyrannosaurs appear to have been faster runners, with relatively longer tibiae and metatarsals and,
therefore, longer strides with biomechanical advantages for speed. Additionally, hadrosaurs lacked the
advanced arctometatarsus of tyrannosaurs, which has been interpreted as a critical cursorial adaptation
(Holtz, 1995).
This study takes the question of hadrosaur running capabilities a step beyond strict skeletal anatomy
and considers the arrangement of the primary hindlimb retractor muscle-set: the M. caudofemoralis. In
modern crocodilians, the M. caudofemoralis is the largest femoral retractor muscle and has been shown to
be the major contributor, in all gaits, to the locomotive power-stroke of the hindlimbs (Gatesy, 1997). The
M. caudofemoralis originates from the brevis fossa of the ilium and from the anterior caudal vertebrae
and chevrons, and it inserts, via the caudofemoral tendon, onto the fourth trochanter of the femur. Based
on the large size of the femoral fourth trochanter, a caudofemoral-dominated locomotive system has been
inferred for most non-avian dinosaurs, including ornithopods (Dollo, 1883; Romer, 1927; Gatesy, 1990).
Using comparisons with modern animals, osteological correlates, and digital modeling techniques, the
caudal musculature of hadrosaurs has been reconstructed. Compared with previous work on tyrannosaurs,
the results suggest that, under the right circumstances, adult hadrosaurs could have been successful at
outrunning potential tyrannosaur predators.
Modeling Methodology
The osteological muscle insertion correlates and digital muscle modeling techniques described in
Persons and Currie (2011) were applied to the hips and caudal series of TMP1982.038.0001 (Lambeosaurus
lambei) and TMP1998.058.0001 (a juvenile hadrosaur from the Dinosaur Park Formation, but of
indeterminate genus) (Figs. 1, 2). These methods have been shown to be accurate muscle mass predictors
in a variety of modern reptiles and have previously been applied to a range of theropod taxa (Persons and
Currie, 2011).
Gross Anatomy and Functional Significance
The chevrons and the caudal neural spines of adult hadrosaurs are more extensive than those of similarly
sized and more primitive ornithopods, such as iguanodontids and camptosaurids. The digital models
indicate large hypaxial musculature -- resulting from the proportions of hadrosaur chevrons – but, despite
the extended neural spines, only moderately-sized epaxial muscles. This result stems from the lack of a
corresponding elongation of hadrosaur caudal rids (caudal transverse processes), which are important in
determining the mass of the epaxial musculature (but not the hypaxial musculature). Unexpanded epaxial
117
muscles conflict with previous suggestions that hadrosaur tails were specifically adapted for swimming,
because large epaxial muscles (particularly the M. longissimus) are important in powering aquatic sculling
in modern crocodilians and swimming lizards. Comparisons of juvenile and adult hadrosaur skeletons
show that the proportions of the deep chevrons varied little through ontogeny, whereas the tall caudal
neural spines are an adult characteristic. This evidence supports the hypothesis that the tall neural spines
of adult hadrosaurs, which together dramatically increase the lateral profile, primarily served as display
structures.
Persons and Currie (2011) argued that the relative mass of the M. caudofemoralis of tyrannosaurs and
most other non-avian theropods was substantially greater than that of crocodilians and other modern
reptiles and, would have supported greater cursoriality. This conclusion was based on the recognition that
the anterior caudal ribs of most non-avian theropods are positioned high on the neural arches – well above
the dorsal edges of the caudal centra. Elevation of the caudal ribs in these theropods extended the lateral
attachment surfaces and permitted the expansion of the M. caudofemoralis. The digital modeling shows
that hadrosaurs also had larger caudofemoral muscles than modern reptiles. However, the caudal ribs of
hadrosaurs are not elevated and are positioned below, or level with, the dorsal edges of the caudal centra.
Instead, the increased size of the hadrosaur M. caudofemoralis was accomplished by extending the lateral
attachment surfaces ventrally, rather than dorsally, by deepening the anterior chevrons.
Because the M. caudofemoralis is a roughly symmetrical muscle, ventral expansion of the M.
caudofemoralis would result in a corresponding shift of the muscle’s centerline and the averaged force
vector of its contractions. Ideally, in order to maximize muscle efficiency, the average force vector of the
M. caudofemoralis contractions should be in line with the vector of pull on the femur. In the caudofemoral
complex, the vector of pull on the femur is equivalent to the orientation of the caudofemoral tendon, which
runs from the femoral fourth trochanter to the approximant dorsoventral-center of the most anterior extent
of the M. caudofemoralis. In tyrannosaurs and all other theropods, the fourth trochanter is positioned
proximally on the femur shaft (roughly 1/5 the way down the femur in Tyrannosaurus). In hadrosaurs,
the fourth trochanter is positioned at roughly the proximodistal center of the femur. Therefore, the
directionally-opposite expansions of the M. caudofemoralis inferred for tyrannosaurs and hadrosaurs are
consistent with the relative position of the femoral fourth trochanter in both groups – in tyrannosaurs the
dorsal expansion maintained a contraction force vector that was more in line with the high position of
the fourth trochanter, and in hadrosaurs the ventral expansion maintained a contraction force vector that
was more in line with the low position of the fourth trochanter. These simple differences in caudofemoral
arrangements imparted fundamentally different athletic abilities.
With a high caudofemoral complex, tyrannosaurs were capable of rapid femur retraction, because
the motion-arch that the fourth-trochanter had to travel through from the beginning to the end of each
retraction-stage of the step-cycle was relatively short and, therefore, required only a short and quick muscle
contraction. However, the high femoral attachment imparted poor leverage, and each retraction would
have required greater muscle exertion. In contrast, with a low caudofemoral complex, hadrosaurs were
capable of only relatively slow femoral retraction, because the motion-arch that the fourth-trochanter had to
travel through from the beginning to the end of each retraction-stage of the step-cycle was relatively long
and, therefore, required a long muscle contraction. But, the low femoral attachment gave the hadrosaur
arrangement superior leverage, and each retraction would have required less muscle exertion and would
have diminished the rate of muscular fatigue. The question, then, of whether a hadrosaur or a tyrannosaur
would have won a race is entirely dependant on the length of the race. In a brief sprint, tyrannosaurs had a
clear anatomical advantage, but, in a prolonged run, hadrosaurs held the athletic edge.
Conclusion
In recent years, advocacy for specific morphological traits having a direct function in dinosaur
predator/prey interactions has fallen out of general favor. Such attempts are intrinsically speculative and
also carry the stigma of sensationalism. Nevertheless, among mega-fauna, predator/prey interactions
are a reality in any modern ecosystem, and successful prey species must have strategies for dealing with
118
predators – although these strategies need not be violent. The findings of this study suggest that hadrosaurs
were equipped to employ the same strategy used today by many large and medium-sized mammalian
herbivores, best documented and demonstrated by the modern zebra. Like hadrosaurs, zebra lack defensive
weapons but are nonetheless one of the most common large herbivores in their environment. Among the
predators of zebra are large felines, including lions and cheetahs. These big cats have a maximum sprint
speed of 70 kph and 112 kph respectively, while a zebra at full gallop can reach a maximum of 55 kph
(Estes, 1990). However, zebra have superior endurance and can win predator-initiated chases even against
cheetahs, provided the zebra are vigilant to avoid breeching the cats’ short striking range (Kingdon,
1982; Estes, 1990). As in zebra, the good eyesight and herding behavior of hadrosaurs would have been
especially helpful in spotting and keeping predators at a safe distance. The endurance-runner strategy was
potentially even more viable for hadrosaurs than modern mammalian herbivores, because the sheer size of
tyrannosaurs would have made spotting stealthy ambushes and avoiding close encounters easier.
References
Dollo, L. 1883. Note sur le présence, sur les Oiseaux, du “troisième trochanter” des Dinosauriens et sur la fonction de
celui-ci. Musée Royal d’Histoire Naturelle de Belgique, Bulletin Tome II, 13.
Estes, R.D. 1990. “The Behavior Guide to African Mammals.” Los Angeles: The University of California Press.
Gatesy, S.M. 1990. Caudofemoral musculature and the evolution of theropod locomotion. Paleobiology, 16: 170-186.
Gatesy, S.M. 1997. An electromyographic analysis of hindlimb function in Alligator during terrestrial locomotion.
Journal of Morphology, 234: 197-212.
Holtz, T.R. Jr. 1995. The arctometatarsalian pes, an unusual structure of the metatarsus of Cretaceous Theropoda
(Dinosauria: Saurischia). Journal of Vertebrate Paleontology, 14: 480–519.
Kingdon, J.S. 1982. “East African Mammals.” New York: Academic Press.
Persons, W.S., and Currie, P.J. 2011. The tail of Tyrannosaurus: reassessing the size and locomotive importance of
the M. caudofemoralis in non-avian theropods. The Anatomical Record: Advances in Integrative Anatomy and
Evolutionary Biology, 294: 119–131.
Romer, A.S. 1927. The pelvic musculature of the ornithischian dinosaurs. Acta Zoologica, 8: 225-275.
119
Fig. 1. Stages in modeling the tail of a juvenile hadrosaur (TMP1998.058.0001) in lateral and dorsal views. Digital
reconstruction of the caudal skeleton (A). Digital reconstruction including the M. caudofemoralis longus (B).
Complete digital reconstruction, with M. spinalis and M. longissimus, and M. ilio-ischiocaudalis (C).
120
Fig. 2. Stages in modeling the tail of a Lambeosaurus lambei (TMP1982.038.0001) in lateral and dorsal views.
Digital reconstruction of the caudal skeleton (A). Digital reconstruction including the M. caudofemoralis
longus (B). Complete digital reconstruction, with M. spinalis and M. longissimus, and M. ilio-ischiocaudalis
(C).
121
New Insights into the Narial Anatomy of Saurolophine
Hadrosaurids Revealed by a “Mummified” Specimen of
Edmontosaurus annectens
Albert Prieto-Márquez1 and Jonathan R. Wagner2
1
Division of Paleontology, American Museum of Natural History, Central Park West at 79th St., New York, NY 100245192, U.S.A.; [email protected]
2
Jackson School of Geosciences, The University of Texas at Austin, 1 University Station C1100, Austin, Texas 787121101, U.S.A.; [email protected]
Along with ceratopsians, hadrosaurid dinosaurs are distinctive among ornithischians in possessing
greatly hypertrophied narial structures. In lambeosaurine hadrosaurids the nasal passages are enclosed
by thin sheets of bone, and they extend posterodorsally, arching in a broad loop to enter the skull dorsally
anterior to the orbits (Ostrom 1962); this enclosure of the narial structure permits comparative study of
the anatomy of the narial passage in fossils (Weishampel 1981; Evans 2006). In the other major clade of
hadrosaurids, Saurolophinae (sensu Prieto-Márquez 2010), the nasal passages remain anterior to the orbits
(Horner et al. 2004). While the bony external naris is surrounded by a circumnarial depression that varies
in depth and posterior extension among taxa, most of this structure is not enclosed in bone, and little is
known about the soft-tissue anatomy of the narial structure. Variation in the length, proportions, and the
number and placement of various foramina, ridges, and subordinate fossae of the circumnarial depression
have been documented within the group (Prieto-Márquez 2010). However, there has been no description of
the soft-tissue structures that must have been bound within the circumnarial fossa.
Here, we report on soft tissue structures preserved within the circumnarial fossa of an exquisitely
preserved specimen of Edmontosaurus annectens, AMNH 5060. This nearly complete skeleton is the
classic dinosaur “mummy” described by Osborn early in the twentieth century, and to date it remains one
of the best preserved and most complete dinosaur specimens ever collected. Close examination of the narial
region of AMNH 5060 reveals hitherto undescribed details of the circumnarial fossa of the specimen. The
observed structures are consistent with the presence of a soft-tissue structure within the circumnarial
fossa, as proposed by others (Hopson 1975; Wagner 2004). The posterodorsal margin of the narial fenestra
(or boney external naris) proper, set within the circumnarial fossa, is extended anteriorly by a flange of
soft-tissue that may represent a cartilaginous extension of the margin of the very large narial fenestra that
may have occluded some of the opening in life (Fig. 1). This suggests that the opening between the skull
and the circumnarial structure may have been in the posterior portion of the narial fenestra. The skull also
preserves the base of a thin septum that appears to have underlain an extracranial extension of the nasal
vestibulum across the circumnarial space and out to the fleshy external naris (Fig. 1).
The latter structure may be analogous or homologous to the only other known evidence of circumnarial
structure within saurolophines, the delicate, longitudinal boney septa in Saurolophus angustirostris
(Maryanska and Osmólska 1981). Regardless, these details reveal more complexity within the
saurolophine circumnarial fossa than previously assumed. Comparison with the circumnarial structures of
lambeosaurines supports previously proposed hard-tissue homologies (e.g., Wagner 2004), and reinforces
the interpretation of these structures as presented here.
References
Evans, D.C. 2006. Nasal cavity homologies and cranial crest function in lambeosaurine dinosaurs. Paleobiology, 32:
109–125.
Hopson, J. 1975. The evolution of cranial display structures in hadrosaurian dinosaurs. Paleobiology, 1: 21–43.
Horner, J.R., Weshampel, D.B., and Forster, C.A. 2004. Hadrosauridae. In The Dinosauria, second edition. Edited by
D. Weishampel, P. Dodson, and H. Osmólska. University of California Press, Berkeley, California. pp. 438–463.
Maryanska T., and Osmólska, H. 1981. Cranial anatomy of Saurolophus angustirostris with comments on the Asian
Hadrosauridae (Dinosauria). Palaeontologia Polonica, 42: 5–24.
122
Ostrom, J.H. 1962. The cranial crests of hadrosaurian dinosaurs. Postilla, 62: 1–29.
Prieto-Márquez, A. 2010. Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and
Bayesian methods. Zoological Journal of the Linnean Society, 159: 435–502.
Wagner, J.R. 2004. Hard-tissue homologies and their consequences for interpretation of the cranial crests of
lambeosaurine dinosaurs (Dinosauria: Hadrosauria). Journal of Vertebrate Paleontology, 24 (Suppl. 3):
125A–126A.
Weishampel, D.B. 1981. The nasal cavity of lambeosaurine hadrosaurids (Reptilia: Ornithischia): comparative
anatomy and homologies. Journal of Paleontology, 55: 1046–1057.
Fig. 1. Narial anatomy of the Edmontosaurus annectens skull AMNH 5060. (A), right lateral view of complete skull.
(B), line drawing with interpretation of the circumnarial and narial structures. (C), right lateral view of the
circumnarial region.
123
REVIEW OF THE OSTEOLOGY RECORD OF MEXICAN
HADROSAUROIDS
Ángel Alejandro Ramírez-Velasco1 and René Hernández-Rivera2
1
Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Circuito de
Investigación Científica, Ciudad Universitaria, Delegación Coyoacán, 04510 México, [email protected];
2
Instituto de Geología, Universidad Nacional Autónoma de México, Circuito de Investigación Científica, Ciudad
Universitaria, Delegación de Coyoacán, 04510 México.
The study of hadrosaurs on Mexico began in 1933 with the discovery of Taliaferro at the top of the
Snake Ridge Formation in the state of Sonora and identified from bones and teeth by Barnum Brown.
Since then there have been documented their presence in Baja California (Langstone and Oakes, 1954;
Morris, 1981; Morris, 1971; Molnar, 1974; Hilton, 2003), Coahuila (Murray, 1960; Hernández-Rivera,
1997; Aguillón et al., 1998; Rodríguez-de Rosa and Cevallos-Ferris, 1998; Kirkland et al., 2000; Eberth.,
2003; Kirkland et al. 2006; Serrano-Brañas, 2006; Serrano-Brañas, et al, 2006; Gates et al., 2007;
Rivera-Sylva, 2007; Monroy-Mújica, 2009; Rivera-Sylva et al, 2011), Sonora (Taliferro, 1933;) (Lucas
and González León, 1996), Chihuahua (Montaño et al., 2009) and recently in Michoacán (Benammi
et al., 2005; Mariscal-Ramos, 2006; Ramírez-Velasco, 2009) (Fig. 1). These discoveries were known
species such as Lambeosaurus laticaudus (Morris, 1981) from El Rosario as the largest known North
American lambeosaurinae (Morris, 1972) and recently suggested by Prieto-Márquez (2010) as a new
genus with affinity to Hypacrosaurus altispinus and Velafrons coahuilensis. The latter represented by
juvenile individual from the Cerro de los Dinosaurios, the most complete specimen of this subfamily
(Gates, et al. 2003). Within this subfamily highlights the specimen from Presa San Antonio which by its
distinct morphology could represent a new species different from those already mentioned as suggested
by Serrano-Brañas (2006). Within the saurolophinae stands the large size of the Mezquite and Presa San
Antonio specimens identified as Kritosaurus sp. (Kirkland et al., 2006), which could represent new genera
and species, and the Mezquite specimen could represent a basal saurolophinae as suggested by PrietoMárquez (2010). In addition to these, we known Gryposaurus sp. (Serrano-Brañas, 2006) from Presa
San Antonio known as “Isauria” (Hernández-Rivera, 1997), a endocast brain from Fraustro with notable
differences with the endocranium of the specimen from the Mezquite (Serrano-Brañas, et al. 2006), and
an elongated jaw with a coronoid process deflected caudally from the saurolophinae of the Cerro de los
Dinosaurs (Serrano-Brañas, 2006) which differs with the taxa mentioned above. In addition to this there
are a great number of hadrosaurs remains represented by fragmentary elements with great size like the
Icoteas specimen and La Esperanza specimen. Recently found at Fronteras a new specimen with great
size in study. Finally the southernmost basal hadrosauroidea of North America discovered in the Barranca
de los Bonetes with tall neural spines (Ramírez-Velasco, 2009). The study of Mexican hadrosaurs does
not end with its taxonomic assignation, recently a number of paleopathologies have been identified which
range from trauma, degenerative, probable neoplasms and other diseases of uncertain affinities, both in
sub-adult specimens as juvenile that they are in study. As already mentioned, Mexico shows a new picture
for the study of hadrosaurs, showing a greater diversity of what had been previously thought due to the
mixture of endemic species and others with affinities to the already known genera of North America. The
great abundance of fossils of hadrosaurs represented by young´s and adults, as larger individuals indicate
favourable environmental conditions to withstand the demands of these major phytophagous dinosaurs of
the Cretaceous.
References
Aguillón-Martínez, M.C., Vallejo-González, I., Hernández-Rivera, R. and Kirkland, J.I. 1998. Dinosaur trackway
from the Cerro del Pueblo Formation, Difunta Group (Latest Campanian, Cretaceous), Coahuila, Mexico. Journal
of Vertebrate Paleontology, 18: 23A.
Benammi, M., Centeno-García, E., Martínez-Hernández, E., Morales-Gámez, M., Tolson, G., and UrrutiaFucugauchi, J. 2005. Presencia de dinosaurios en la barranca Los Bonetes en el sur de México (Región de
Tiquicheo, Estado de Michoacán) y sus implicaciones cronoestratigráficas. Revista Mexicana de Ciencias
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Geológicas 23:401–418.
Eberth, D.A., Sampson, S.D., Rodríguez-de la Rosa, R.A., Aguillón-Martínez, M.C., Brinkman, D.B., and LópezEspinoza, J. 2003. Las Águilas: An unusually rich Campanian-age vertébrate locality in southern Coahuila,
Mexico. Journal of Vertebrate Paleontology, 23: 47A.
Gates, T. A., Sampsom, S., Delgado de Jesús, C.R., Zanno, L.E., Eberth, D., Hernández-Rivera, R., AguillónMartínez, M.C., and Kirkland, J.I. 2007. A new genus and species of lambeosaurine hadrosaur (Dinosauria:
Ornithopoda) from the Late Campanian Cerro del Pueblo Formation, Coahuila, Mexico. Journal of Vertebrate
Paleontology, 27:917–930.
Hernández-Rivera, R. 1997. Mexican dinosaurs. In Encyclopedia of Dinosaurs. Edited by P.j. Currie and K. Padian.
Academic Press. USA. pp. 433-437.
Hilton, R. P. 2003. Dinosaurs and other Mesozoic Reptiles of California. University of California Press. Berkeley and
Los Angeles California.
Kirkland, J.L., Hernández-Rivera, R., Aguillón-Martínez, M.C., Delgado-de Jesús, C.R., Gómez-Nuñez, R., and
Vallejo-González, I. 2000. The Late Cretaceous Difunta Group of the Parras Basin, Coahuila, Mexico, and its
vertebrate fauna. Field Trip Guide Book, Society of Vertebrate Paleontology Annual Meeting. pp. 133-172.
Kirkland, J. I., Hernández-Rivera, R., Gates, T., Paul, G.S., Nesbitt, S. Serrano-Brañas, C.I., and García-de la Garza,
J.P. 2006. Large Hadrosaurine Dinosaurs from the Lastest Campanian of Coahuila, Mexico. Late Cretaceous
Vertebrates from Western Interior New Mexico. Museum of Natural History and Sciences Bulletin, 35: 299–315.
Langston, Jr. W., and Oakes, M.H. 1954. Hadrosaurs in Baja California. Geological Society of American Bulletin,
Abstracts, 65:1344.
Lucas S. G., and González-León, C.M. 1996. Dinosaurios del Cretácico Tardío del Grupo Cabullona, Sonora.
Geología del Noroeste 1: 20–25.
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(Tuzantla, Michoacán). Thesis, Facultad de Ciencias, Universidad Nacional Autónoma de México. Mexico.
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Monroy-Mújica, I.H. 2009. Microvertebrados fósiles cretácicos tardíos (Campaniano Tardío) de la Formación Aguja
en el Noroeste de Coahuila, México. Thesis, Facultad de Estudios Superiores Iztacala, Universidad Nacional
Autónoma de México, Mexico.
Montaño, M.I., Hernández-Rivera, R., and Montellano-Ballesteros, M. 2009. Hadrosaurios kritosaurinos del
Cretácico Tardío de Coahuila y Chihuahua, México. XI Congreso Nacional de Paleontología. Centro de
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?Lambeosaurus laticaudus. Journal of Paleontology, 55: 453–462.
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Basin, Coahuila, Mexico. Journal of Paleontology, 34: 368-373.
Prieto-Márquez, A. 2010. Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and
Bayesian methods. Zoological Journal of the Linnean Society, 159: 435–502.
Ramírez-Velasco, A.A. 2009. Descripción de los dinosaurios de la Barranca de los Bonetes (Tuzantla, Michoacán)
Cretácico Tardío (Coniaciano-Santoniano) y reporte de paleopatologías. Thesis, Facultad de Ciencias, Universidad
Nacional Autónoma de México, México.
Rivera-Sylva, H., Guzmán-Gutiérrez, J.R., Palomino-Sánchez, F.J., López-Espinosa, J., and De La Peña-Oviedo,
I. 2007. New vertebrate fossil localities from the Late Cretaceous of Northern Coahuila, Mexico. Journal of
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Rodríguez-de la Rosa, R., and Cevallos-Ferris, S. 1998. Vertebrates of Pelillal locality (Campanian, Cerro del Pueblo
Formation), southeastern Coahuila, Mexico. Journal of Vertebrate Paleontology, 18: 751–764.
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Superior de Coahuila, México. Thesis. Facultad de Ciencias, Universidad Nacional Autónoma de México.
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from the Western Interior. New Mexico Museum of Natural History and Science Bulletin. Edited by S.G. Lucas
125
and R.M. Sullivan.
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Geology, 41: 12–37.
FIG. 1. Map showing localities with osteological remains of hadrosaurs in Mexico. State of Baja California Norte:
1, Punta San Isidro, El Gallo Formation; 2, El Rosario, El Gallo Formation; 3, El Rosario, La Boca Roja
Formation; State of Sonora: 4, Corral de En medio Formation; 5, Camas Foramation; 6, Packard Formation;
7, Lomas Coloradas Formation; 8, Fronteras; 9, Snake Ridge Formation; State of Chihuahua: 10, Bengis
Bar, Aguja Formation; 11, Icoteas, Aguja Formation; 12, Pico de pato, Aguja Formation; 13, Arenales; 14,
Chamel; 15, Doctor; State of Coahuila: 16, Anizul, Aguja Formation; 17, Dueto Miseria, Aguja Formation;
18, Álamos de Márquez, Aguja Formation; 19, El Rebaje, Aguja, Formation; 20, La Salada, Aguja Formation;
21, Bell Brown, Aguja Formation; 22, Las Garzas, Aguja Formation; 23, La Esperanza, Aguja Formation; 24,
San Miguel, Aguja Formation; 25, El Mezquite, Olmos Formation; 26, Polvorín, Olmos Formation; 27, Palau,
Olmos Formation; 28, Phelan; 29, Altamira, Cerro Huerta Formation; 30, DINO 1960 Hipólito; 31, Pelillal,
Muerto Formation; 32, Fraustro, Cerro del Pueblo Formation; 33, Rancho Quintanilla, Cerro del Pueblo
Formation; 34, Cañon del Oso, Olmos Formation; 35, Hedionda, Cerro del Pueblo Formation; 36, Sierra
Mojada, Soledad beds; 37, B1 y B2, Cerro del Pueblo Formation; 38, Coah 14 Presa San Antonio, Cerro del
Pueblo Formation; 39, Tanque, Cerro del Pueblo Formation; 40, Rojas 1 y 2, Cerro del Pueblo Formation;
41, Coah 1 Cerro de los Dinosaurios, Cerro del Pueblo Formation; 42, Coah 20 Rincón Colorado, Cerro del
Pueblo Formation; 43, La Rosa, Cerro del Pueblo Formation; 44, Agua de Mula, Cerro del Pueblo Formation;
45, Palmar, Cerro del Pueblo Formation; 46, Cruce de Caminos; 47, Las Águillas, Cerro del Pueblo Formation;
State of Michoacán: 48, Barranca de los Bonetes.
126
TAPHONOMY AND BEHAVIORAL IMPLICATIONS OF
EDMONTOSAURUS (ORNITHISCHIA:HADROSAURIDAE) BONEBEDS
FROM THE HORSESHOE CANYON FORMATION (UPPER CAMPANIAN),
ALBERTA, CANADA
Michael J. Ryan1, David A. Eberth2, David C. Evans3, Donald B. Brinkman2, and Matthew E. Clemens1
1
Cleveland Museum of Natural History, Cleveland, Ohio
Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta
3
Department of Natural History, Royal Ontario Museum, Ontario
2
Monodominant hadrosaurine bonebeds are well known from the Upper Cretaceous of North America,
including Maiasaura from the Two Medicine Formation of Montana, Edmontosaurus from the of
Horseshoe Canyon Formation of Alberta and the Hell Creek, Lance, and Prince Creek formations of
north central USA, and Saurolophus from the Nemegt Formation of Mongolia. Despite being well-known,
hadrosaurine bonebeds have not been documented in detail in the scientific literature. Here we report on
three hadrosaurine (c.f. Edmontosaurus), bonebeds from strata of the Horseshoe Canyon Formation, below
the Drumheller Marine Tongue, in the upper Campanian (Edmonton Group) of Alberta. These bonebeds
were subject to multi-year excavations conducted as part of the Royal Tyrrell Museum’s Day Digs Program
designed to allow members of the general public to directly participate in the scientific excavation process.
Approximately 10,000 participants assisted with the excavation of the quarries, and an additional 50,000
visitors took part in guided tours of the sites.
The three excavated localities designated ‘Bleriot Ferry’ (BF; 1993-1998), ‘Fox Coulee’ (FC; 1999-2001)
and ‘Prehistoric Park ‘ (PP; 2002-2004) occur in Unit 1 of the Horseshoe Canyon Formation. Although
only material from the Bleriot Ferry locality can be positively referred to Edmontosaurus (based on the
morphology of isolated jugals), this taxon is the only hadrosaur known to occur below the Drumheller
Marine Tongue in this formation, and the morphology and size of the material is consistent with this taxon
at all sites.
Only small portions (20–100 m2) of each bonebed were excavated, however, at least two separate
areas were excavated at each site. The BF and PP bonebeds are laterally extensive (>1000 m2) and the
sampled areas at each of those sites exceeded 100 m2. In contrast, the FC bonebed is minimally exposed
and prevents us from estimating reliably the original extent of the bonebed. The FC bonebed is dominated
by small (<20 mm in length) fragments of ornithischian rib and vertebral elements, and is interpreted as
an attritional assemblage. The BF and PP quarries both occur at the base of an ~1 m thick, carbonaceous
mudstone in a stacked mudstone succession and are interpreted as being deposited during overbank
flooding events in a swampy, coastal lowland.
All three bonebeds are dominated (>90%) by disarticulated to associated remains that exhibit similar
taphonomic signatures. The majority of the hadrosaur elements (>95%) are from adult-sized animals,
although a few elements of small (<4 m) sized hadrosaurs are also preserved. The assemblages are
dominated by thoracic vertebrae and ribs (>80%), pelvic and pectoral elements (~5%), limb elements (~5%),
and miscellaneous teeth and fragments of tendons (10%). Long bones and vertebrae do not show current
alignment. Although most non-rib and vertebral elements are complete, they have been badly fragmented
by recent weathering, and exhibit at least abrasion class 1 rounding.
Over 10% of the fossils have theropod tooth marks, and isolated shed theropod teeth are common
in the deposits, indicating that the remains were scavenged prior to reworking and burial. Scavenging
is attributed to Albertosaurus, the only other common large vertebrate in the area at the time. Skeletal
remains of two dentaries represent at least one individual of Albertosaurus at the BF site. Several other
important ornithischian elements have been recovered from the BF bonebed, including the partial skull
and a few limb elements of Pachyrhinosaurus canadensis. Numerous isolated, shed small theropod teeth
from Troodon and Saurornitholestes were also recovered from all of these sites. Microvertebrate material is
127
rare at all sites. Screen-washing of matrix from the BF bonebed resulted in the recovery of Opisthotrition,
Scapherpeton, Myledaphus, Lepisosteus, and indeterminate turtle elements. The taxa in these bonebeds
were apparently derived from an inland terrestrial paleocommunity with input from local fresh water
communities.
Hadrosaurine and centrosaurine monotaxic bonebeds are common throughout upper Campanian
strata of Alberta, but monodominant bonebeds of these taxa rarely occur in contemporaneous sediments,
suggesting ecological partitioning in these taxa that may be related to seasonal variation in resource use.
Centrosaurine bonebeds are common in the more distal sediments of the lower Dinosaur Park Formation
(Centrosaurus) of Alberta and the Wapiti and St. Mary River formations of Alberta (Pachyrhinosaurus),
whereas hadrosaurine bonebeds occur in a number depositional setting throughout the Campanian
and Maastrichtian of western North America. The presence of these monotaxic bonebeds support the
hypothesis of gregarious behavior in these large ornithischians and suggests that they did not overlap in
time at any given locality.
128
Ichnological hadrosaurian record from Mexico
Ricardo Servín-Pichardo1, René Hernández-Rivera2, and Ángel Alejandro Ramírez-Velasco3.
Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica, Ciudad
Universitaria. Delegación Coyoacán, 04510 México D.F.
2
Instituto de Geología, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica, Ciudad
Universitaria. Delegación Coyoacán, 04510 México D.F.
3
Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Circuito de la
Investigación Científica, Ciudad Universitaria. Delegación Coyoacán, 04510 México D.F.
1
The ichnological hadrosaurian record in Mexico is well known in several states and has been reported
by many authors. These reports have increased in recent years.
The first extensive report was made by Bravo-Cuevas and Jiménez-Hidalgo (1996). They describe
ichnites from Late Cretaceous Mexcala Formation, Puebla State. This record shows small individuals
compared with his relatives from other parts of the world (Bravo-Cuevas & Jiménez-Hidalgo, 1996).
This could represent dwarfing by isolation, considering a possible Late Cretaceous island geography in
Central Mexico. The Late Cretaceous Arenisca Aguililla, Municipio Aguaje, Michoacán State, has high
paleoichnofauna diversity, including hadrosaur and theropod ichnites. However, part of this diversity could
be only variations from a single morphotype and/or extramorphologic variation (Ortiz-Mendieta, 2001;
Rodríguez-de la Rosa et al., 2004). The Michoacán and Puebla ichnofaunas are the unique Late Cretaceous
dinosaurichnites reported south to the Transmexican Volcanic Belt and the most austral hadrosaur evidence
in North America (Rodriguez-de la Rosa et al., 2004, Ortiz-Mendieta, 2001). The authors attributed the
ichnites to individuals with different sizes and ages in base of his sizes.
The Coahuila State has a broad record. Several localities with ichnites are known in the Late Cretaceous
Cerro del Pueblo Formation (Late Campanian). One of the most important places is known as Las Águilas,
Municipio General Cepeda, with about 5000 m2; being the biggest site documented with dinosaur ichnites
from Mexico (Rodriguez-de la Rosa et al., 2004). This site contains ichnites and natural casts, showing
individuals with biped and quadruped tendency (Rodríguez-de la Rosa et al. 2003; Rodríguez-de la Rosa
et al., 2004). In La Parrita tracksite, footprints indicate that some of the individuals were near to 12 m long
(Rodríguez-de la Rosa, 2007). In the same formation also occur skin impressions. Those have been found
associated to skeletal remains from hip, tail and limbs and negative relief impressions from other areas;
while other impressions are isolated (Hernández-Rivera & Delgado-de Jesús, 2000). The Rancho Soledad
from the Late Cretaceous Olmos Formation, southwest from Sabinas, has footprints attributed
to ornithopods (Meyer, et al. 2005).
In El Gallo Formation (Late Cretaceous), Baja California State, Morris (1981) mentioned cast of
scalation (large hexagonal and small rounded scales) with ossicles associated to ?Lambeosaurus laticaudus
anterior dorsal vertebrae, being the fist record in his kind for Mexico at that time. Eggshells founded in
the same formation shows characters that allows the identification to ornithopods and mainly, hadrosaurs
(Rodriguez de la Rosa, 1998).
In 2010, a great discovery was made in The Municipio de Fronteras Sonora State. The first dinosaur
footprints in the state were found within a lithologic unity belonging to Cabullona Group (Late Cretaceous).
The rock facies represents a lacustrine environment. Two tracks are present in different stratigraphic levels.
One of these tracks shows manual impressions. One isolated ichnite may be represents a juvenile individual
in base of his size. This ichnites still under study (Servín-Pichardo et al. 2011).
References:
Bravo-Cuevas, V. & Jiménez-Hidalgo, E. 1996. Las Dinosauricnitas de México: Su significación geológicopaleontológica. Tesis de Licenciatura, Facultad de Ciencias; Universidad Nacional Autónoma de México. 147 p.
Hernández-Rivera, R. and Delgado-de Jesús, C. R. 2000. Hadrosaur skin impressions and associated skeletal remains
from Cerro del Pueblo Fm (Uppermost Campanian) southeastern Coahuila, México. Journal of Vertebrate
Paleontology. 20:48A.
129
Meyer, C. A., Frey, E. D., Thüring, B., Etter, W. & Stinnesbeck, W. 2005. Dinosaur Tracks from the Late Cretaceous
Sabinas Basin (Mexico). Darmstädter Beiträge zur Naturgeschichte. 14: 41-45.
Morris, W. 1981. A New species of hadrosaurian dinosaur from the Upper Cretceous of Baja California
?Lambeosaurus laticaudus. Journal of Vertebrate Paleontology. 55:453-462.
Ortíz-Mendieta, J.A. 2001. Dinosauricnitas Cretácico-tardías de El Aguaje, Michoacán, región suroccidental de
México y sus implicaciones geológico-paleontológicas. Tesis de Licenciatura, Facultad de Ciencias, Universidad
Nacional Autónoma de México. 75 p.
Rodriguez-de la Rosa, R, Aguillón-Martínez, M. C., López-Espinoza, J., Eberth, D.A. 2004. The Fossil Record of
Vertebrate Tracks in México. Ichnos. 11: 27-37.
Rodríguez-de la Rosa, R. 1998. Cáscaras de huevo avianas (Neognathae) y de Ornithopoda (Dinosauria) del
Cretácico Tardío de Baja California. VI Congreso Nacional de Paleontología. México. Memorias: 59-60.
Rodríguez-de la Rosa, R. A., Eberth, D. A., Brinkman, D. B., Sampson, S. D. and López-Espinoza, J., 2003. Dinosaur
tracks from the Late Campanian Las Aguilas locality south-eastern Coahuila, México. Journal of Vertebrate
Paleontology: 90A.
Rodríguez-de la Rosa, R.A. 2007. Hadrosaurian Footprints from the Late Cretaceous Cerro del Pueblo Formation
of Coahuila, Mexico. In Díaz-Martínez E. & Rábano, I. (Eds.) 4thEuropean Meeting on the Palaeontology and
Stratigraphy of Latin America. Cuadernos del Museo Geominero, No. 8. Instituto Geológico y Minero de España,
Madrid. 339-343 pp.
Servín-Pichardo, R., Hernández-Rivera, R., González-León, C.M., Pacheco-Rodriguez, R. 2011. Primer registro
de dinosauricnitas en el Grupo Cabullona (Cretácico Tardío), Esqueda, Municipio de Fronteras, Sonora. XII
Congreso Nacional de Paleontología. México. Memorias: 130-131.
Fig. 1. Hadrosaur ichnological localities from México. 1, El Gallo Formation, Baja California; 2, Municipio de
Fronteras, Sonora (Cabullona Group); 3, Rancho Soledad, Olmos Formation, Coahuila; 4, 5, Las Águilas and
la Parrita, Cerro del Pueblo Formation, Coahuila; 6, Arenisca Aguililla, Municipio el Aguaje, Michoacán; 7,
Mexcala Formation, Puebla.
130
Iguanodontian dentaries from the Lower Cretaceous
Kitadani Formation, Fukui, central Japan
Masateru Shibata* and Yoichi Azuma
Fukui Prefectural Dinosaur Museum, Muroko 51-11, Terao, Katsuyama, Fukui, 911-8601 Japan. *Corresponding
author: [email protected]
The Lower Cretaceous Kitadani Formation has yielded an abundance of fossils, including plants,
molluscs, other invertebrates, and vertebrates (Azuma 2002 and so on). The excavation project launched
by Fukui Prefectural Dinosaur Museum (FPDM) has focused on the vertebrate remains, and produced
three dinosaurs named from this formation, a theropod Fukuiraptor kitadaniensis, the iguanodontian
Fukuisaurus tetoriensis, and a sauropod Fukuititan nipponensis (Azuma and Currie 2000; Kobayashi and
Azuma 2003; Azuma and Shibata 2010)
Although these Fukui dinosaurs were all disarticulated, the F. tetoriensis material included a relatively
large number of skull parts. Kobayashi and Azuma (2003) considered the combination of skull and
mandible characters as diagnosable of a new genus. Our re-examination of type material revealed a
previously unrecognized autapomorphy: a bowed ventral margin on the left dentary (FPDM-V40-9).
Presence of this same character on the right one indicates this is as an original feature and not the product
of deformation. In addition to these specimens, the 2007-2010 excavation project produced three additional
iguanodontian dentaries, all lacking the forementioned F. tetoriensis character. All of them exhibit a
relatively straight ventral margin of the ramus, distinguishing them from F. tetoriensis.
A small right dentary, 7.7 cm in length, is complete but lacks any observable teeth. Shibata (2009)
discussed the possibility that this represented a new species, rather than a juvenile F. tetoriensis, because
iguanodontia dentaries show no distinct shape change through ontogeny (Carpenter 1994; Horner and
Currie 1994).
The other two dentaries, a right and left both approximately 25 cm long likely represent one individual.
Furthermore, theses possess the straight ventral ramus margin as in the small dentary and distinct from F.
tetoriensis.
In conclusion, dentaries of F. tetoriensis show an autapomorphy, overlooked by Kobayashi and Azuma
(2003) and the absence of this character in newly discovered dentaries suggests a second, possible new
iguanodontian from the Kitadani Formation.
References
Azuma, Y. 2002. Early Cretaceous vertebrate remains from Katsuyama City, Fukui Prefecture, Japan. Memoir of the
Fukui Prefectural Dinosaur Museum, 2: 17-21.
Azuma, Y. and Currie, P.J. 2000. A new carnosaur (Dinosauria: Theropoda) from the Lower Cretaceous of Japan.
Canadian Journal of Earth Sciences, 37: 1735-1753.
Azuma, Y. and Shibata, M. 2010. Fukuititan nipponensis, a new titanosauriform sauropod from the Early Cretaceous
Tetori Group of Fukui Prefecture, Japan. Acta Geologica Sinica (English Edition), 84(3): 454-462.
Carpenter, K., 1994. Baby Dryosaurus from the Upper Jurassic Morrison Formation of Dinosaur National Monument.
In Dinosaur Eggs and Babies, Edited by Carpenter, K., Hirsch, K.F. and Horner, J.R. Cambridge University Press,
Cambridge. pp. 288-297.
Horner, J.R. and Currie, P.J., 1994. Embryonic and neonatal morphology and ontogeny of a new species of
Hypacrosaurus (Ornithischia, Lambeosauridae) from Montana and Alberta. In Dinosaur Eggs and Babies, Edited
by Carpenter, K., Hirsch, K.F. and Horner, J.R. Cambridge University Press, Cambridge. pp. 313-336.
Kobayashi, Y. and Azuma, Y. 2003. A new iguanodontian (Dinosauria: Ornithopoda) from the Lower Cretaceous
Kitadani Formation of Fukui Prefecture, Japan. Journal of Vertebrate Paleontology, 23(1): 166-175.
Shibata, M. 2009. Small-sized iguanodontian dentary from the Early Cretaceous Kitadani Formation in Fukui
Prefecture, central Japan. Abstracts with Programs, The 2009 Annual Meeting The Palaeontological Society of
Japan, p. 28.
131
Why Paleo-Conservation is Important: An Examination of
the Techniques used to Prepare and Conserve a portion of
a Neglected Hadrosaur Skeleton
Shayda Spakowski, Brandon Strilisky, and Rhian Russell
Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta
Introduction
The study, practice and execution of preventative conservation on museum artifacts is typically confined
to those items in which degradation through exposure to light, relative humidity (RH), moisture, molecular
degradation (i.e. rust) or pest infestation is evident and known to occur. Due to their apparent stability and
longevity, minimal conservational thought or practice is implemented when fossils are concerned. Though
fossils are more ‘stable’ than oil paintings, textiles or even metal tools and equipment, this characteristic
should not exclude them from conservation treatment. The use of improper solvents, adhesives, storage
techniques, handling and collection procedures, as well as general human neglect and carelessness will not
only cause problems such as cracking, missing elements, and irreversible procedures, but it may also cause
irreparable harm to the fossil itself, leaving it brittle, weakened or in some cases, completely disintegrated.
TMP1980.023.0001, part of an incomplete hadrosaur skeleton, was the victim of several neglectful events
that lead to extensive cracking, missing elements, disintegration and irremovable coatings that could have
easily been avoided. Fig 1 shows the initial condition of the jacketed TMP1980.023.0001 prior to any
treatment.
Materials and Methods
Standard paleontological preparation tools and materials were used to treat and consolidate
TMP1980.023.0001. The deteriorated field jacket was removed using kitchen knives and handsaws. In
preparing this specimen, air scribers, awls, hammers, and paintbrushes were used to mechanically remove
the surrounding sandstone. Acryloid of 20%-50% concentrations were used to consolidate broken and
unstable fossil elements and acetone, as applied with a toothbrush, and used in conjunction with a scalpel,
was used to remove polyurethane foam residue from the affected fossils. Personal Protective Equipment
(PPE) was worn for the majority of the time, including facemasks, nitril gloves, lab coats and protective eye
goggles.
Results
The jacket was removed in increments in order to maintain the structural integrity of the fractured block.
As the fossils were exposed, they were coated in a 20% acryloid mixture in order to prevent the fossils from
further breaking apart. A stronger concentration of acryloid (50%) was used to reassemble fragmented
and broken pieces. Acryloid was used extensively in this project as the main and only adhesive due to its
longevity, stability, and ease of removal.
Upon opening the jacket, the preparators discovered that black mold, one of the consequences of being
exposed to nearly 10 years of the environmental and seasonal conditions of the Alberta badlands, was
prevalent throughout the jacket as shown in Fig 2. Full PPE were worn in order to ensure the health and
safety of the preparators.
In addition to promoting mold growth, the seasonal temperatures and moisture of the badlands
subjected the fossils to freeze/thaw conditions, causing the fossils to become cracked, fractured and, in the
cases of the more fragile ribs and vertebrae, completely disintegrated. Prior to enveloping the fossils in a
plaster and burlap jacket, the field technicians of the 1980’s used an expanding foam similar to that used in
insulating houses in order to offer additional support to the fossils during transportation. A barrier, usually
aluminum foil as found in a standard household kitchen, is usually placed between the two elements in
132
order to prevent any residues from the foam adhering to the fossil. In this instance, the preparators did not
use a barrier, allowing the foam to come in contact with the surface of the fossil, leaving behind a thin,
sticky residue. The foam itself was removed by either breaking it or shaving it away in thin sections with a
scalpel. In order to remove the residue, however, acetone was applied by soaking a toothbrush in the solvent
and then scrubbing the surface of the fossil until the foam obtained a sticky, plastic consistency that could
be removed with a scalpel. Fig 3 illustrates a portion of the fractured matrix as well as the initial layers of
foam as met by the preparators.
The application of acetone did not guarantee results. In some cases the fossils were so fragile that the
amount of acetone used needed to be regulated. Too much and the fossil would soften and fall apart. Too
little and the foam would not soften enough to be removed easily. It seems that in addition to the residue,
the degree of foam expansion was also not taken into account. Fossils that were initially only intended to be
supported by the foam, ended up being displaced from their original positions as the foam seeped into preexisting cracks, further separating the elements by worsening the extent of the cracks as it is suspected that
after it was applied, the foam continued to expand over a period of 24 to 48 hours as is typical of housing
insulation. The long-term effects of the foam residue on the fossils have yet to be determined.
Throughout the excavation, caches of seeds were discovered, indicating rodent activity. On the 8th day
into the excavation, the fully articulated skeleton of a mouse (Mus musculus) was discovered. Theoretically,
the rodent most likely entered the jacket through the large missing section as viewed previously in Fig 1,
area C. There was no evidence of rodent feces present in the jacket.
Discussion
Preventative conservation not only ensures that the fossil will continue to exist in a complete and stable
structure, but it also prevents the waste of excessive time and use of resources and removes otherwise
potential health hazards towards the preparators. If preventative conservation had been undertaken with
this specimen, if a barrier had been placed between the foam and the fossil, if it had not been left out in the
badlands for approximately 10 years, subjected to the effects of the natural environment, it would not be the
broken and fractured specimen that it is. Time and resources needed to prepare and conserve it would have
been minimal and the potential health risks associated with the black mold would not have been an issue. It
is the responsibility of the technicians, preparators, conservators, researchers, and curators to ensure that
the fossils that are brought into their museums are all treated with the same respect and care. Conservation
towards paleontological fossils and remains may not be at the forefront of many paleontologists minds,
but it is a useful and necessary technique that needs to be implemented in the standard preparation and
treatment procedures of fossils if their safety and longevity is to be ensured.
Reference
Collins, Chris. “The Care and Conservation of Paleontological Material”. Butterworth-Heinemann. 1995. Oxford,
England.
Acknowledgements
I would like to thank Brandon Strilisky (Collections Manager for the Royal Tyrrell Museum), Rhian
Russell (Royal Tyrrell Museum Conservator), Daren Tanke (Royal Tyrrell Museum Technician), and
Martin Schilling (International Intern) for supporting and assisting me with the conservation and
preparation of TMP1980.023.0001; Dr. Don Brinkman and Dr. Mike Newbrey for providing invaluable
assistance and suggestions for designing and creating this poster; Fleming College, for supporting
me through the Collections Conservation and Management Program; and the Royal Tyrrell Museum
of Palaeontology for allowing me to conduct my internship with them during which I worked on this
hadrosaur.
133
Fig 1. TMP1980.023.0001 prior to removal of jacket. A, B, and C indicate areas of plaster disintegration and loss of
jacket elements. Area C indicates an area that has lost complete structural integrity and where a large hole
measuring approximately 1ft x 2ft existed.
Fig 2. Black mold (D) as found within the jacket layers of TMP1980.023.0001
Fig 3. Showing the severity of fractures (E) and foam presence (F) in TMP1980.023.0001
134
Hadrosaurid biostratigraphy of the Upper Cretaceous
Fruitland, Kirtland and Ojo Alamo formations, San Juan
Basin, New Mexico
Robert M. Sullivan1, Spencer G. Lucas2, and Joshua Fry3
1
Section of Paleontology and Geology, The State Museum of Pennsylvania, 300 North Street, Harrisburg, PA 17120
New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104
3
Department of Anthropology, Geography and Earth Sciences, Clarion University of Pennsylvania, 840 Wood Street,
Clarion, PA 16214
2
Hadrosaur fossils have been known from the Upper Cretaceous strata of the San Juan Basin, New
Mexico, for more than 100 years. Yet, their biostratigraphic distribution has been somewhat confused,
in part, due to imprecise stratigraphic record keeping in the earlier days of collecting and partly due to
taxonomic problems involving generic and specific identifications based on disarticulated and incomplete
material. Five hadrosaurid species have been named from the San Juan Basin: the hadrosaurines
Kritosaurus navajovius, Anasazisaurus horneri and Naashoibitosaurus ostromi; and the lambeosaurines
Parasaurolophus cyrtocristatus and P. tubicen. Specimens of these taxa are from the Kirtland Formation,
although some have been erroneously attributed to the Fruitland Formation. The Fruitland-Kirtland
transition is regarded as a nearly continuous depositional sequence, and there have been differing opinions
as to where to draw the boundary between the two lithostratigraphic units. A lambeosaurine, closely
allied to Corythosaurus, is present in the stratigraphically highest Upper Cretaceous unit, the Ojo Alamo
Formation (Naashoibito Member). Yet, no hadrosaurine has been positively confirmed in the Ojo Alamo
Formation, which is due to both relatively small sample size and the incomplete nature of the hadrosaurid
material that has been recovered from this unit. Large hadrosaur tracks (ichnogenus Caririchnium), mostly
likely from a very large hadrosaurine, are known from the upper part of the Fruitland Formation (Fossil
Forest Member).
Whereas the two lambeosaurines, Parasaurolophus cyrtocristatus and P. tubicen, are clearly
distinguished by their respective distinct narial crests, the validity of the three hadrosaurines continues
to problematic because of issues concerning inadequate type material, comparable ontogenetic stages,
intraspecific and interspecific variation. Moreover, whereas the lambeosaurines P. cyrtocristatus and
P. tubicen are separated stratigraphically, the occurrences of the hadrosaurines Kritosaurus navajovius,
Anasazisaurus horneri and Naashoibitosaurus ostromi are clustered together and, in part, overlap. These
three taxa are also of questionable taxonomic status. All may represent a single taxon, but this is not
agreed on. Of the San Juan Basin hadrosaurs, the only species-level taxon found outside of New Mexico is
P. cyrtocristatus, which is known from Judithian strata of the Kaiparowits Formation in Utah. The genus
Parasaurolophus is also known from the Judithian of Alberta, Canada. The Judithian hadrosaur genus
Parasaurolophus thus has its youngest records in the San Juan Basin, in strata of Kirklandian age.
135
Fig. 1. Biostratigraphic distribution of the Hadrosauridae within the upper Fruitland through Ojo Alamo formations.
136
Evaluation of bone-tendon morphology of hadrosaur
skeletons based on recent crocodilian histology
Daisuke Suzuki1 and Tomoyuki Ohashi2
1
Department of Anatomy, Sapporo Medical University School of Medicine
South 1 West 17, Chuo-ku, Sapporo 060-8556 JAPAN
2
Kitakyushu Museum of Natural History & Human History
Introduction
Fossils are mainly derived from bones those are including not only macroscopic characters but
microscopic characters. Some of one was lines of arrested growth (LAGs), and another one was
birefringence of bony matrix, which reflect stress environment of living time. The bony matrix was
occupied 60-70% as organic phase mainly hydroxyapatite and 25-30% as type I collagen as organic
component. Mineralization was started by deposition on collagen fibers. Accordingly, birefringence pattern
of bone under polarized microscope was regard as bony anisotrophy for optimized adaptation by stress on
the bones. For example, Ascenzi and Bonucci (1967, 1968) suggested the longitudinal oriented collagen
(and crystallites) withstands loading by tension, and transverse oriented withstands loading by compression
as classically known as Gebhardt’s (1905) theory.
Crocodilian bone where the tendon is attached surface is remarkable trace as collagen fibers continuing
from tendon (Suzuki et al 2003). This structure is well observed in the reptiles but not in mammals. In
mammalian osteogenesis, primary bones and lamellar bones those made by periosteum are rapidly
remodeled by Haversian bone (Osteonalization; Jaworski 1992). While reptiles including crocodiles are
known that the remodeling was started after grown or not occurred. Hence most part of the subperiosteal
region was remained as primary lamellar bone (e.g. Enlow 1969).
Dinosaurs were known higher bone metabolism and rich in osteons than recent reptiles, however
some primary bones were remained particularly bony surfaces. In this study, we made thin sections from
dinosaur hadrosaurid bones to observe bone anisotrophy derived from tendon attachment and to evaluate
the direction of the muscle action force.
Material & Method
We used hadrosaur isolated bones (Hadrosauridae indet.) stored Kitakushu Museum of Natural History
& Human History, from Judith River Formation. The fossils were included: the distal palanges (digit II) of
the foot, the fibular shaft and distal end, the rib and the humerus (1991Z01VP02). Based on recent reptilian
anatomy, we identified muscle origin/ insertion and described cutting plane (Figure 1).
The hadrosaur fossils were cut to include the possibly tendon attachment site. These cut materials
were embedded with epoxy resin (Epofix, Struers, Denmark) using the vacuum impregnation apparatus.
Embedded blocks were bonded to slide glass with high water resistance epoxy gull (type E-set, Konishi,
Osaka), after ground with green carborundum (#600) and polished with white alundum (#1000 and #2000).
The other side of block was cut 1-2mm thickness with diamond knife and ground with green carborundum
(#300-#600) and white alundum (#1000-#8000) until the section was made approximately 80 μm in
thickness. Finally the surface was polished diamond paste (#10000).
To compare the fossil section, we made both histological sections and polish section of crocodilian
limbs (Crocodylus niloticus). The histological section was followed as general pathological sections; the
specimens were dissected, were cut including both bones and soft tissues, and were decalcified with PlankRychlo solution (AlCl3•6H2O 7.0 %, HCl 3.6 %, and HCOOH 4.6 %; Wako, Tokyo). The specimens were
trimmed into 3-4 cm3 block and were dehydrated through a graded ethanol series. After embedding them
in paraffin, the specimens were cut into 6 µm in thickness with microtome and stained Hematoxylin and
Eosin, and Masson Trichrome. The method of the polished section of crocodiles was same as that of fossil
section. The observation was used the polarized light microscope (PLM, Eclipse 50iPOL, Nikon, Japan)
for the birefringence pattern and the light microscope (LM, Eclipse E800, Nikon, Japan) for the general
morphology.
137
The muscular term of forelimb was followed Meers (2003), which was detail description of the
crocodilian forelimb. In hindlimb, we followed Russell & Baur (2008), which was detail description of the
lepidosaurian hindlimb, because there are no adequate muscular descriptions of the archosaurians hindlimb.
Result
The polished section of crocodiles bone was also showed thick cortical bones and the cortical bone
had less osteons and the bony matrix was predominant lamellar bones. The appearance of decalcified
histological section was quite different from that of the polished thin sections (Figure 2), but their
birefringence pattern is very similar to that of polished thin section. It indicates the birefringence pattern
is derived from collagen fiber orientations. The polished sections of the hadrosaur limb bones have very
thick cortical bone and small cancellous bone even in epiphysis, which have very thin cortical bone and
was almost occupied cancellous bone in crocodiles. The shaft is occupied much thicker cortical bone with
highly remodeled than any other recent reptiles. The morphology is rather similar to mammalian bones,
in that the secondary osteon highly occupied the bony matrix. Each secondary osteon in the cortical bone
was almost uniform and is same direction; however, the osteons in superficial layer (lateralmost of external
fundamental system, EFS) are sparse and not uniform and different directions in some places. The area
was predominant primary bone and showed from perpendicular to oblique pattern in birefringence. We
defined that these birefringence pattern area is tendon/ muscle attachment part, based on recent crocodilian
polished and histological thin sections (Figure 2).
Non muscle/ tendon attachment part: The surface of non tendon insertion part is smooth even
microscopically. The uniformed osteons are occupied closely to the surface. These parts of the bone were
not shown birefringence except for the layers along the EFS or the lines of arrested growth (LAGs), and
the remodelling line (e.g. cement line of Haversian canal). The no birefringence area indicates that the
collagen fibers in bone matrix arranged along the longitudinal axis in bony matrix (figure 3). The polished
thin sections of crocodiles were also showed strong birefringence pattern along the EFS or LAGs, being
similar to those of hadrosaur sections except for low density of osteons. Those patterns were also observed
in histological section.
Muscle/ tendon attachment part: The tendon insertion part was showed different osteon orientation
and smaller number of osteons in near surface area. The non-osteon matrix, or primary bone was shows
perpendicular to oblique striation under the PLM. These striations are attribute to the collagen fiber
from tendon as known as the anchoring fibers (Oguma et al 2001) from comparison of the crocodilian
histological/ polished specimens (Figure 2). These structures are not observed internal area by active
remodeling like mammalian bones.
The humerus was investigated by three polished sections. The posterior part was probably
corresponding to the M. latissimus dorsi (figure 2) and M. scapulohumeralis. The anterior part was M.
deltoideus clavicularis, and the deltopectoral part was M. pectoralis, respectively.
The insertion of M. latissimus dorsi was located proximo-lateral side of the humeral and that of M.
scapulohumeralis caudalis was posterior margin; both corresponding part is the rough surface. The
birefringence of M. latissimus dorsi insertion was prominent; there are thin dark striations appeared by
birefringence pattern were perpendicular to the surface. The birefringence pattern at M. scapulohumeralis
insertion was oblique to the surface. These different patterns were suggested the difference of the tendon
attachment angle. We expected the insertion of M. deltoideus clavicularis was remain in the anterior
part, however we could not observe clear insertion traces. The insertion of M. pectoralis was observed
the deltopectoral part section. The M. pectoralis insertion was not prominent but it was identified by thin
primary bone with oblique osteon, and birefringence pattern under the PLM.
The rib has the origin and insertion of the M. intercostales externi and interni. The posterolateral side of
the rib was attributed to the attachment area of the M. intercostales e muscles; the surface was rough and
osteons in that area was obliquely inclined. The birefringence pattern is parallel to the osteon inclination
under the PLM. The anterolateral side was also seen muscle/ tendon attachment area, which is smaller than
that of posterolateral area. It is likely to the attachment of the M. intercostales interni.
138
The distal end of the fibula was origin of M. peroneus brevis and M. adductor hallucis dorsalis in
crocodiles in anterior side. The posterior side was no muscle attachment because of the articulation with
the distal tibia. There are small trace, probably correspond to the origin of the M adductor hallucis dorsalis.
It shows perpendicular to oblique birefringence pattern. There are no detectable traces attributable to
M. peroneus brevis: probably the muscles were weak fleshy insertion as in crocodile or we observed
inadequate part.
The digit II of the foot was medialmost digits in hadrosaur and the hadrosaur foot print showed clear
digit II outline (Currie 1983). It suggests that the M. flexor digitorum longus was functioned during their
gait as a flexion of distal interphalangeal joint. The proximal ventral surface of the distal phalange is
generally insertion of M. flexor digitorum longus. The observation of the polished section was showed
clearly tendon insertion area which showed oblique birefringence pattern. In addition, the insertion of M.
extensor digitorum longus was observed in dorsal surface (figure 3).
Discussion
Different from mammals bone tendon interface, the recent crocodilian bone tendon interface was lack
of the fibrocartilage and the collagen fibers from tendon or ligament were continuously to the bone matrix.
In this study, we suggested the dinosaur bone tendon interface was very similar to that of crocodiles. At
the same time, we suggest the dinosaur bone tendon interface could be preserved and detectable. The
birefringence pattern in tendon attachment area was variable in their angle, and thickness. These properties
are probably reflected the muscle action force and direction.
References
Ascenzi A., and Bonucci E. 1967. The tensil property of single osteons. Anat Rec, 158: 375-386
Ascenzi A., and Bonucci E. 1968. The compressive properties of single osteons. Anat Rec, 161: 377-392
Currie P.J. 1983. Hadrosaur trackways from the Lower Cretaceous of Canada. Acta Palaeont Pol, 28: 63- 73.
Enlow D.H. 1969. The bone of reptiles. In: Gans C. ed., Biology of the Reptilia, vol.1 Morphology A. 45-80.
Academic Press, New York.
Gebhardt W. 1905. Über funktionell wichtige Anordnungsweisen der feineren und gröberen Bauelemente des
Wirbeltierknochens. Archiv für Entwicklungsmechanik der Organismen, 20: 187-322.
Jaworski Z.F.G. 1992. Haversian systems and haversian bone. In: Hall B.K ed., Bone metabolism and mineralization,
vol. 4, 21-45. CRC Press, Florida.
Meers M.B. 2003. Crocodylian forelimb musculature and its relevance to Archosauria. Anat Rec, 274A: 891–916.
Oguma H., Murakami G., Takahashi-Iwanaga H., Aoki M., and Ishii S. 2001. Early anchoring collagen fibers at
the bone-tendon interface are conducted by woven bone formation: light microscopic and scanning electron
microscopic observation using a canine model. J. Orthop Res, 19: 873-880.
Russell A.P., and Bauer A.M. 2008. The appendicular locomotor apparatus of Sphenodon and Normal-limbed
Squamates, In Gans C., Gaunt A.S., and Adler K. eds. Biology of the Reptilia volume21, Morphology I: The skull
and appendicular locomotor apparatus of Lepidosauria, 1-465. Society for the study of Amphibians and Reptiles,
Ithaca, New York.
Suzuki D., Murakami G., and Minoura N. 2003. Crocodilian bone–tendon and bone–ligament interfaces. Annals of
Anatomy, 185: 425-433.
139
Fig. 1. The sampling part of the hadrosaur specimens (1991Z01VP02). A. humerus, B. rib, C. phalange II3, D. fibula.
Bar in A and D equals 10cm. Bar in B and C equals 5cm.
140
Fig. 2. The insertion of M. latissimus dorsi. A and B. histological section of Cr. niloticus, C and D. polished section
of Cr. niloticus. E and F. polished section of hadrosaur specimens. A, C, E: under the light microscopy. B, D,
F: under the polarized light microscopy.
141
Fig. 3. The birefringence pattern of hadrosaur specimens. A and B. Insertion of M. flexor digitorum longus. The
birefringence was prominent and oblique striation was observed (arrows). C and D. Non-tendon insertion part
in the humerus. There are no prominent striations. A, C: under the light microscopy. B, D: under the polarized
light microscopy.
142
Relocating the lost 1918 Royal Ontario Museum’s
Gryposaurus incurvimanus quarry, Dinosaur Provincial
Park, Alberta, Canada with comments on Gryposaurus
biostratigraphy
Darren H. Tanke1 and David C. Evans2
1
Royal Tyrrell Museum, Box 7500, Drumheller, Alberta, Canada T0J 0Y0
Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario, Canada M5S 2C6
2
Some of the best dinosaur material (even type specimens) collected long ago from Dinosaur Provincial
Park (DPP) and the Drumheller Valley region in southern Alberta, Canada have little to no locality data,
including ROM (Royal Ontario Museum) material. Concerted relocation of these lost sites and solving other
unidentified ones has been ongoing since 1997, though Loris S. Russell (1904-1998) spearheaded earlier
quarry relocation work in the Drumheller Valley in the mid 1980’s. The simple discovery of some rusty
nails, small pieces of weathered lumber and other historical garbage deep within the badlands of DPP in
2006 resulted in the rediscovery of the long lost type locality for the nearly complete skeleton of ROM 764
Gryposaurus incurvimanus. This famous and nearly complete specimen (fig. 1) has been used in a variety
of multidisciplinary studies.
The site was examined in more detail which lead to the discovery of a wad of old newspaper under a
rock on the surface nearby. The paper, which was in surprisingly good condition, was soaked in water,
cleaned and separated. Study of the historical information contained therein and comparative microfilm
research disclosed it was from The Calgary Daily Herald from 1918. The only museum expedition in DPP
in 1918 was ROM (their first there) and the only dinosaur skeleton they collected was the G. incurvimanus
type. Comparison of photographs of that quarry being excavated to surrounding badlands topography at
the site confirmed both the site and photograph identifications. The old quarry was completely obliterated
by erosion and without the garbage (misidentified as another quarry close by) to provide clues would likely
have never been found.
Recent differential GPS mapping of many DPP dinosaur localities demonstrate distinct “zones” in
which specific dinosaur taxa occur. Confirming and testing these zonation hypotheses can be done either
through the discovery of new specimens and/or relocating the lost quarries of previously excavated ones.
ROM 764 did occur stratigraphically similar to other Gryposaurus specimens, re-enforcing hypotheses
that it occurs only low in section in the Campanian Dinosaur Park Formation. Relocation of lost sites helps
studies of speciation, and stratigraphic zonation through increased database and testing hypotheses.
143
Fig. 1. ROM 764 Gryposaurus incurvimanus, collected in 1918 by the Royal Ontario Museum in today’s Dinosaur
Provincial Park, Alberta.
144
Osteopathy in Hadrosauridae from Alberta, Canada
Darren H. Tanke1 and Bruce M. Rothschild2
1
Senior Technician II, Royal Tyrrell Museum, Box 7500, Drumheller, Alberta, Canada T0J 0Y0
Biodiversity Institute, University of Kansas and Department of Medicine, Northeastern Ohio Universities College of
Medicine, Lawrence, Kansas, USA 66045
2
The Late Cretaceous rocks of Alberta record a diverse array of well-preserved examples of hadrosaur
paleopathology. Pathologies are found on isolated bones and nearly complete skeletons. In sheer numbers
of specimens, and quality of preservation for research (i.e., gross inspection, histology, X-ray, MRI and CT
scanning) they represent the best known examples of dinosaur osteopathy globally. Well over 85% of the
dinosaur pathology specimens in the Royal Tyrrell Museum (TMP) derive from this family, though much
of the sample still awaits quantification and fuller study. Some of the first dinosaur bones illustrated from
the province (in 1902) are hadrosaur jaws in which the pathology originally went unrecognized. Healing
fractures predominate in the sample.
Curiously, nearly all the fractures are well- but not completely healed- suggesting the afflicted animal
survived for an extended period of time, but only later succumbed to predation, disease and/or other
conditions.
Pathology of the teeth is rare and skull pathology, seldom recognized. Several examples of dentaries
with healing fractures and/or massive infection have been observed. Deformed teeth are known but are rare
and appear to be developmental in origin, perhaps related to damage to the tooth bud.
Dorsal vertebrae and rib osteopathy consist of fused neural spines (type specimen of Parasaurolophus)
which were erroneously ascribed to an attachment point for a flap of skin attached to the back of the
elongate crest. Wedge-shaped “hemivertebrae” are observed in an embryonic Hypacrosaurus. This usually
produces a lateral bending of the vertebral column, referred to as scoliosis. Another hadrosaur specimen
revealed an additional source of scoliosis- one side of an otherwise normal centrum experienced excessive
unilateral growth, tilting the neural arch strongly to one side. Rib fractures with well-aligned healing are
known from various sites and occur in animals of all ages (hatchlings excepted), but predominate in adults.
Forelimb injuries, while rare, are of a serious nature. A spectacular example involves an unspeciated
left humerus (fig. 1). The bone was broken transversely or obliquely in a dorso-ventral plane, the two
pieces becoming separated and rotated slightly, then healed misaligned with infection resulting in a large
subperiosteal abscess. Barnum Brown of the American Museum and collector of the specimen was quoted
that it was the “…. sickest fossil bone I have ever seen”. The specimen is so modified that it is nearly
unrecognizable as a humerus, only the distal articular end retains normal morphology. An adult radius and
ulna were broken mid-shaft. Subsequent healing thoroughly fused the two bones together. Metacarpal and
manal phalanx osteopathy occurrences in TMP collections and in the field are low despite a large sample
size; most are infectious in origin. This low occurrence is unexpected given the heavy mass of the animals
and the frequent quadrupedal gait now ascribed to them.
The most impressive example of hadrosaur osteopathy in TMP collections is an unspeciated
lambeosaurine with bilateral fracture of the proximal ischia with extensive healing, but without infection.
It is remarkable this individual survived such a pelvic fracture, especially so near to the acetabulum.
Pathology of the major hind limb bones is rare, as they were likely incompatible with survival. An isolated
adult tibia with massive osteomyelitis is known. Despite a large sample size of metatarsals and pedal
phalanges, traumatic or infectious osteopathy is infrequent.
“Divots” in articular surfaces (osteochondrosis) is well known, mostly restricted to pedal phalanges; the
proximal articular surfaces of D. IV, Ph. 2-4 are most commonly affected. These occur as subcircular to
elongate oval-shaped and smooth-bottomed depressions with occurrences independent of ontogenetic stage.
Stress fractures in manal or pedal phalanges are presently unrecognized.
Caudal vertebrae represent the most common osteopathy, with so many specimens now known that a
demonstrable pattern of types and distribution of injuries is well understood. Generally only adult-sized
145
animals are affected. Proximal caudals regularly show fractured, with healed neural spines usually close to
the tip. The pathology consists of a single fracture (sometimes two) with the tip usually healed, but angled
laterally.
Intermediately located caudals have healing fractures near the neural spine tips. Pseudoarthrosis above
and below the pre- and postzygapophyses are also noted. Intermediately located caudal centra sometimes
have deep cracks on one or both (typically) endplates (fig. 2); CT scans show similarly aligned disruptive
trabecular bone, suggesting the centrum was split in two (or more) pieces as a burst fracture and then
healed back together.
Distal caudal vertebrae exhibit fusion of up to four (but usually two) adjoining centra. These centra
often demonstrate a swollen condition, anteriorly-placed neural arch (suggesting post-traumatic posterior
elongation of the centrum), cracking phenomenon (as per intermediate caudal centra), pointed notochordal
projections centrally placed on the endplates, abnormal “diseased” bone texture, longitudinal keel
on ventral midline, and other malformations. These vertebrae are sometimes fused together at angles
indicating the tail healed with the tip kinked up or off to one side. Some specimens suggest extreme distal
tail infection and amputations or sloughing. Some ossified tendons appear to show fracture repair as well.
Increasingly over the past decade, dinosaur behavior has been interpreted from pathological conditions,
especially when repeated patterns of osteopathy are observed. Most of the injuries in hadrosaurs appear
to be developmental, benign, or simply the minor “bumps and knocks” of day to day life. However there
are some clues. Torso and forearm trauma appears to be related to serious falls, an apparently common
occurrence in extant animals. The rarity of hind limb injuries indicates wounding in this area was likely
fatal. The proximal caudal neural spine injuries are curious. Early interpretations suggested mating trauma,
but more recent suggestions of tendon tension and compression causing fractures cannot be confirmed, as
neural spines further down the tail (where tendons are absent) also show these injuries. The intermediate
and especially distal caudals appear to have suffered crush fractures, possibly the result of having the tail
stepped on by a conspecific. Hadrosaurs were herding animals, so such accidents appear to have been a
regular occurrence in crowded situations when an unwary prone individual rested its’ tail on the ground
while others moved about close by.
There is an Edmontosaurus on display at the Denver Museum of Natural History with a tail injured
in life. A Tyrannosaurus bite with the victim escaping has been implicated. The middle of five injured
neural spines is missing, presumed to have been sheared off and lost during the attack, leaving the others
fractured and healing in a twisted condition. While tyrannosaurids no doubt attacked live hadrosaurs, we
do not think this is the case in this particular example. The middle neural spine, with its distal expansion
at the trauma site, appears to form a pseudoarthrosis which can only develop if the distal segment is still
present post-trauma. The distal segment is missing now possibly via disuse atrophy, taphonomy, or other
causes. If the Denver Edmontosaurus truly represents a tyrannosaurid bite, then hundreds of similar
specimens in TMP collections and those regularly observed in the Albertan badlands (and Montana,
Wyoming and east Asia) record similar “failed” attacks. None of these specimens show healing tyrannosaur
tooth strike trauma (as now well known in tyrannosaur on tyrannosaur healing bite specimens) nor do
any of these specimens preserve embedded tyrannosaur teeth. Support for this perspective of tyrannosaur
predation on hadrosaurs awaits discovery of the smoking gun. Alternative hypotheses for these common
hadrosaur caudal injuries are conspecifics trampling or perhaps use of the tail as an offensive/defensive
weapon as seen in extant lizards and crocodilians.
Caution is urged regarding the interpretation of dinosaur osteopathy as representing failed predation
encounters. Such encounters were few in the lifespan of a given individual. Rather, the individual
continually interacted with its environment, and, in terrestrial herding animals, others of its own kind. In
these situations, the chances for wounding are greatly increased, either through falls and intraspecific
contact- be it accidental or deliberate. Predation attempts today often completely fail, with the prey
escaping without injury. Successful capture of the prey (with or without accompanying bone trauma)
nearly always results in the death of the victim. Very few individuals today escape a predator’s bite with
bone trauma and live long enough to heal or partially heal their wounds. We are often reminded how very
few animals (or parts thereof) enter the fossil record. Therefore true tyrannosaur bites on hadrosaurs with
146
healing should be extremely rare. Yet the Late Cretaceous deposits of Alberta are replete with hadrosaur
caudal osteopathy identical to those seen on the Denver Edmontosaurus. Do all these specimens (and others
seen elsewhere) represent failed tyrannosaur attacks or do they represent something more benign and easily
explained? We think the latter.
Fig. 1. Severely pathologic right humerus (TMP1998.011.0001, a cast of AMNH 5207) in external view with
transverse fracture of shaft, poor healing and massive infection, compared to TMP 1992.053.0021, a normal
left humerus (reversed here) of same size for comparison. Scale bar = 10 cm.
Fig. 2. TMP 1992.036.0602, a partial mid-caudal vertebra in posterior view (left) and anterior view (right), showing
transverse crack across the endplates. A pseudoarthrosis (with two small subcircular openings) near the base
of the neural spine is also visible in the left image. Such openings are occasionally misdiagnosed as theropod
tooth punctures. Scale bar = 5 cm.
147
First hadrosaur trackway from the Upper Cretaceous
(late Campanian) Oldman Formation, southeastern
Alberta
François Therrien1, Darla K. Zelenitsky2, Kohei Tanaka2, and Wendy J. Sloboda3
1
Royal Tyrrell Museum, Drumheller, AB T0J 0Y0
Department of Geoscience, University of Calgary, Calgary, AB T2N 1N4
3
Warner, AB T0K 2L0
2
Dinosaur tracks have been reported from the St. Mary River, Dinosaur Park, and Horseshoe Canyon
formations, but are unknown from other Upper Cretaceous deposits of southern Alberta. Here we report
on the discovery of the first dinosaur trackway from the Upper Cretaceous (late Campanian) Oldman
Formation. The trackway, exposed in the Milk River Natural Area of southeastern Alberta, occurs in the
upper member of the Oldman Formation, approximately 25 m above the top of the Comrey Sandstone. The
trackway appears as a series of one isolated and seven consecutive tracks preserved as brown carbonate
concretions protruding above a drab green, structureless mudstone. Three tracks are sufficiently wellpreserved to allow for their identification as hadrosaur tridactyl pedal tracks, whereas the others are heavily
weathered and broken, rendering them indistinguishable from other nearby concretions. The tracks are
robust with blunt digit termination, are slightly longer than wide (l/w = 1.07; length = 58 cm and width = 54
cm), and have a maximum thickness of 17.5 cm. They show a total divarication of digits II-IV of 63o, and
an interdigital angle of digits II-III (22o) smaller than that of digits III-IV (41o). The posterior portion of the
track is asymmetrically bilobed. The trackway is narrow and can be traced to the south over a distance
of 12 m. The distance between tracks varies along the trackway, beginning with a pace length of 136 cm,
increasing to 160 cm in the middle, and to 264 cm at the end. The trackway is inferred to have been formed
by a large hadrosaur, approximately 3.3 m high at the hip. The animal significantly increased its walking
speed in the area of the trackway, from an estimated 3.7 km/h (SL/h ~0.82) to 4.9 km/h (SL/h ~ 0.97),
before accelerating to 11.6 km/h (SL/h ~1.64) at the end of the trackway.
148
PHYLOGENETIC AND BIOGEOGRAPHIC IMPORTANCE OF AN
EARLY LATE CRETACEOUS (CENOMANIAN - CAMPANIAN) DERIVED
HADROSAUROID (ORNITHOPODA) NEWLY DESCRIBED FROM
MONGOLIA
Khishigjav Tsogtbaatar1, David B. Weishampel, and Mahito Watabe2
1
Mongolian Paleontological Center, Mongolian Academy of Science, Ulaanbaatar, Mongolia
Center for Paleobiological Research, Hayashibara Biochemical Laboratory, Inc., Okayama, Japan
2
The ornithopods (derived hadrosauroids) have been less studied among Mongolian dinosaurs. However,
there have been frequent discoveries of the hadrosauroids from the Bayn Shire Suite (early late Cretaceous),
in contrast to the abundance of derived hadrosaurine Saurolophus of the Nemegt Suite (Maastrichtian)
(Rozhdestvenskii, 1957). By our studies, the evolution of ornithopod dinosaurs in Mongolia had been
very poorly understood (but, for iguanodont, Norman, 1996 and 1998; for hadrosaurids, Maryanska and
Osmolska, 1981a and b). Mongolia and Japan Joint Expedition have found many articulated, associated,
and isolated skeletons and bones of the derived hadrosauroids from the Baynshire Suite (Cenomanian –
Santonian: Hicks et al., 1999) and Djadokhta Formation (Campanian) in southeastern and central Gobi
desert (Suzuki and Watabe, 2000).
The Baynshire hadrosauroid discovered from the Baynshire Suite (fluvial) in localities Bayshin Tsav
and Khoorai Tsav is characterized by primitive skull structures and small adult (Tsogtbaatar, 2006). There
is another form with large size in the specimens from the suite in localities Baynshire and Khongil Tsav
(eastern Gobi desert) (Watabe and Suzuki, 2000a). It is hard to detect clear morphological (taxonomical)
difference between these smaller (Bayshin Tsav and Khoorai Tsav) and larger forms (Baynshire and
Khongil Tsav). The infant individuals were also found from the same quarry where the large form was
found in the locality Bayn Shire (Watabe and Suzuki, 2000b).
The Baynshire hadrosauroid is positioned as a sister group of a clade: (the Djadokhta form +
(Telmatosaurus + Hadrosauridae)), as a plesion (Figure 1). The cladistic analyses on the taxa are based on
character matrix by Horner et al. (2004). The Baynshire form is more derived than Eolambia, having no
phylogenetic relationships with other Asian more derived hadrosaurids in China and even Mongolia (genus
Saurolophus).
The new taxon from the Djadokhta Formation in Alag Teg locality with large size is placed as a sister
group of the clade: (Telmatosaurus + Hadrosauridae) in the same cladogram with the Baynshire taxon
(Figure 1). The morphological difference between the Baynshire form and this Djadokhta one is very
small. Both of the Bayshin Tsav and Alag Teg taxa have no development of horn or crest on their skull, as
plesiomorphic condition. There is no expansion of nasal part. The beds in Alag Teg yielded the skeleton
are of fluvial origin. The adult and infant skeletons of the hadrosauroid have been also found from eolian
sandstone bed in Tugrikin Shire (Barbold and Perle, 1983), located about 5km south of Alag Teg. This case,
together with the Baynshire case, provides important data on ontogeny of derived hadrosauroid.
Phylogenetic tree including those two Mongolian derived hadrosauroids indicates several new results.
The ornithopod member of the early late Cretaceous Baynshire vertebrate fauna is represented by
the smaller derived hadrosauroid that had no direct phylogenetic relationships with Mongolian early
Cretaceous iguanodons. The derived hadrosauroid of the Baynshire age is survived to the Djadokhta age
(Campanian). The form had been extinct by the Nemegt age when derived hadrosaurids: Saurolophus and
Barsboldia are widely distributed in Mongolia.
There is no direct ancestor – descendant relationships between Campanian (Djadokhta) derived
hadrosauroid and Maastrichtian (Nemegt) derived hadrosaurids in Mongolia. This suggests that these
derived hadrosaurids of Maastrichtian immigrated from other area to Mongolia. The derived hadrosauroids
of preceding vertebrate ages did not leave direct descendant to the later age. The immigration event of
derived hadrosaurid to Mongolia will be used as FAD of hadrosaurid in the Upper Cretaceous fluvial and
eolian sections with limited source for physical dating (Figure 2).
149
References
Barbold, R. and Perle, A. 1983. On taphonomy of a joint burial of juvenile dinosaurs and some aspect of their ecology.
Sovmestnaya Sovetsko-Mongol’skaya Ekspeditsiya Trudy, 24: 121-125.
Hicks, J. F., Brinkman, D. L., Nichols, D. J. and Watabe, M. 1999. Paleomagnetic and palynologic analyses of Albian
to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh, eastern Gobi Desert, Mongolia. Cretaceous
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152
Quantifying Forelimb Posture in Hadrosaurs: A
Morphometric Approach
Collin S. VanBuren and Matthew F. Bonnan
Western Illinois University, Macomb, IL, USA
It is well-accepted that the ancestor to all dinosaurs was a small, bipedal archosaur. However, a number
of dinosaur clades adopted a secondarily quadrupedal posture, which has led to debate about the posture of
their forelimbs. It has been suggested that dinosaurs, unlike their sprawling reptilian relatives, had an erect
forelimb posture, similar to modern mammals. While previous studies have indicated significant trends
in dinosaur posture, quantifying forelimb posture has remained relatively unexplored. The shape of the
radius affects forelimb posture in modern mammals and sauropsids. Therefore, we tested the hypothesis
that hadrosaur radius morphology should not be significantly different from mammals if their forelimbs
were held erect. Over 380 radii from mammals, sauropsids, and dinosaurs were examined, photographed,
and measured from four museum collections to quantify radial morphology. Linear dimensions, radial head
photographs, and long axis photographs were captured for each radius specimen and traditional and shape
analysis software tested these variables for significant differences among the taxa. Our results indicate that
hadrosaur radial morphology did not significantly differ from mammals or sauropsids.
While our results showed conclusive results for ceratopsians and sauropodomorphs, we suggest
that radius morphology is not a good proxy for hadrosaur forelimb posture. It has been suggested that
hadrosaurs adopted their quadrupedal stance later in life, which, if true, could explain why comparing their
radii to those of life-long quadrupeds yields inconclusive results. Hadrosaurs are a highly derived group
of dinosaurs, and a variety of morphological adaptations for quadrupedality could be affecting their radial
morphology as examined here. Our results ultimately suggest that other quantitative studies should be
performed on hadrosaur forelimb morphology to better understand forelimb posture in this group.
153
A History of Scientific Works on Hadrosaurs and How Are
We to Understand Their Phylogeny
David B. Weishampel
Center for Functional Anatomy and Evolution, Johns Hopkins University, Baltimore, Maryland 21205, U.S.A.
The history of scientific work on hadrosaurid dinosaurs and their close relatives is characterized by
an exponential increase since it began in 1825. I review some of this increasingly abundant literature,
characterizing it in terms of papers that focus on initial descriptions and general taxonomy, functional
morphology and biomechanics, phylogenetics and evolutionary patterns, biostratigraphy and taphonomy,
biogeography, paleoecology, soft-tissue reconstruction, growth, and extinction. These topics are traced
through the history of hadrosaur publication in a way that documents changing emphases in research
programmes through time.
In addition, I hope to discuss problems with current phylogenetic analyses of hadrosaurids and their
close relatives. Specifically, I will also explore some of the repercussions of the introduction of new taxa
and its effect on the stability of tree topologies.
154
List of Contributors
Ashworth, A. ................................................................................................................................. 60
Azuma, Y. ..................................................................................................................................... 131
Bailleul, A.M. ................................................................................................................................. 11
Barrett, P.M. .................................................................................................................................. 71
Bates, K. ................................................................................................................................... 71
Bell, P.R. ..................................................................................................................................... 12, 13
Bergmann, U. ................................................................................................................................ 91
Bolotsky, Y. ................................................................................................................................... 59
Bonnan, M.F. .............................................................................................................................. 153
Brink, K.S. ...................................................................................................................................... 14
Brinkman, D.B. ....................................................................................................................... 16, 127
Brown, C.M. .................................................................................................................................. 68
Buckley, L.G. ................................................................................................................................... 97
Buckley, M. ..................................................................................................................................... 91
Burns, M.E. ..................................................................................................................................... 13
Campione, N.E. ................................................................................................................ 21, 68, 105
Canudo, J.L. .................................................................................................................................. 33
Clemens, M.E. ............................................................................................................................. 127
Clayton, K.E. .................................................................................................................................. 23
Coria, R.A. .................................................................................................................................... 28
Cruzado-Caballero, P. .................................................................................................................. 33
Currie, P.J. ........................................................................................................................... 12, 13, 48
Cuthbertson, R. ............................................................................................................................. 87
Dalla Vecchia, F.M. ....................................................................................................................... 38
Dodson, P. ...................................................................................................................................... 62
Eberth, D.A. ............................................................................................................................ 45, 127
Erickson, G.M. ................................................................................................................................47
Evans, D.C. ......................................................................................14, 21, 45, 48, 68, 105, 127, 143
Fanti, F. ........................................................................................................................................... 13
Farke, A.A. .............................................................................................................................. 50,65
Freedman, E.A. ............................................................................................................................ 53
Fricke, H.C. .................................................................................................................................... 55
Fry, J. ............................................................................................................................................ 135
Gaete, R. ...................................................................................................................................... 38
Galobart, A. .................................................................................................................................. 38
Gates, T.A. ................................................................................................................................... 56
Getty, M.A. ......................................................................................................................... 23, 56, 58
Godefroit, P. .......................................................................................................................... 59, 70
Golovneva, L. .............................................................................................................................. 59
Gould, B. ....................................................................................................................................... 60
Guenther, M. .................................................................................................................................. 61
Hedrick, B.P. ................................................................................................................................... 62
Henderson, D.M. ......................................................................................................................... 64
Hernández-Rivera, R. ........................................................................................................... 124, 129
Herrero, L. .................................................................................................................................... 65
Horner, J.R. .................................................................................................................. 11, 14, 48, 66
Irmis, R.B. ..................................................................................................................................... 23
Ikegami , N. ................................................................................................................................... 67
Jinnah, Z. ......................................................................................................................................56
155
Larson, D.W. ................................................................................................................................. 68
Lauters, P. .................................................................................................................................. 70,59
Levitt, C.G. .................................................................................................................................... 56
Loewen, M.A. .............................................................................................................................. 23
Lucas, S.G. ................................................................................................................................... 135
Lund, E.K. ...................................................................................................................................... 23
Lyson, T. ........................................................................................................................................ 91
Maidment, S.C.R. ........................................................................................................................... 71
Main, D.J. ..................................................................................................................................... 81
Mallon, J.C. ................................................................................................................................... 87
Manning, P. L. ........................................................................................................................ 62, 91
Margetts, L. ................................................................................................................................. 62
McCarthy, S. ................................................................................................................................. 61
McCrea, R.T. .................................................................................................................................. 97
McDonald, A.T. ...................................................................................................................... 62, 101
McGarrity, C.T. .............................................................................................................................. 105
Moreno-Azanza, M. ...................................................................................................................... 33
Morschhauser, E. .......................................................................................................................... 62
Nabavizadeh, A. ........................................................................................................................... 108
Nellermoe, R. ................................................................................................................................ 60
Nicholls, W.J. ............................................................................................................................... 23
Norell, M.A. .................................................................................................................................. 47
Norman, D.B. ................................................................................................................................ 113
Noto, C.R. ...................................................................................................................................... 81
Ohashi, T. .............................................................................................................................. 116, 137
Oms, O. ......................................................................................................................................... 38
Persons, W.S., IV ......................................................................................................................... 117
Prieto-Márquez, A. .............................................................................................................. 38, 122
Ramírez-Velasco, A.A. .......................................................................................................... 124, 129
Riera, V. ......................................................................................................................................... 38
Rothschild, B.M. ......................................................................................................................... 145
Ruiz-Omeñaca, J. I. ....................................................................................................................... 33
Russell, R. .................................................................................................................................... 132
Ryan, M.J. ............................................................................................................................. 68, 127
Scotese, C.R. ................................................................................................................................ 81
Sellers, W.I.S. ........................................................................................................................... 91, 62
Sellés, A.G. ................................................................................................................................... 38
Servín-Pichardo, R. ..................................................................................................................... 129
Shibata, M. .................................................................................................................................. 131
Sissons, R.L. ................................................................................................................................... 13
Sloboda, W.J. .............................................................................................................................. 148
Spakowski, S. .............................................................................................................................. 132
Stevens, K.A. ................................................................................................................................ 62
Strilisky, B. ................................................................................................................................... 132
Sullivan, R.M. ............................................................................................................................. 135
Suzuki, D. ..................................................................................................................................... 137
Tanaka, K. .................................................................................................................................... 148
Tanke, D.H. .......................................................................................................................... 143, 148
Therrien, F. ............................................................................................................................. 143, 145
Tirabasso, A. ................................................................................................................................. 87
Tomida, Y. ....................................................................................................................................... 67
156
Tsogtbaatar, K. ............................................................................................................................. 149
VanBuren, C.S. ........................................................................................................................... 153
van Dongen, B.E. ........................................................................................................................... 91
Vercauteren, M. ............................................................................................................................ 70
Vila, B. ............................................................................................................................................ 38
Wagner, J.R. ................................................................................................................................ 122
Watabe, M. .................................................................................................................................. 149
Webb, S. ........................................................................................................................................ 91
Weishampel, D.B. ................................................................................................................... 81, 149
Witmer, L.M. ................................................................................................................................. 48
Wogelius, R.A. ............................................................................................................................... 91
Woodward, H.N. ........................................................................................................................... 66
Wosik, M. ...................................................................................................................................... 61
Wu Wenhao ................................................................................................................................... 59
Zelenitsky, D.K. ....................................................................................................................... 14, 148
157
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