Functional morphology and affinities of the hominoid

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Cour. Forsch.-Inst. Senckenberg
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240
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89-111
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6 Figs., 5 Tabs., 2 Pis.
I Frankfurt a. M., 29. 01. 2003
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Functional morphology and affinities of the hominoid
mandible from <;andtr
With 6 figures, 5 tables, 2 plates
•
.. Erksin GOLEC & David R. BEGUN
Abstract
The single primate specimen from \:andlr, a well preserved mandible ofa female and the holotype
of Griphopithecus alpani TEKKAYA, is described and it's functional anatomy and phylogenetic
significance assessed. In molar morphology the specimen is essentially indistinguishable
from the most common primate from Pa~alar. The corpus differs in morphology from that
preserved on a single specimen from Pa~alar, though comparison is complicated by the fact
that the latter specimen is from a male. It also differs morphologically from female specimens
from Fort Ternan, Maboko and Majiwa, all in Kenya, attributed here to Kenyapithecus wickeri
and Griphopithecus africanus. Functional analysis suggests an ability to withstand elevated
occlusal loads, usually associated in primates with an adaptation for hard object feeding. This
is consistent with the morphology of the molars as well. Griphopithecus a/pant from \:andlr
lacks derived characters of late middle and late Miocene hominids, and is probably near the
base ofthe radiation of Eurasian and African hominoids. It conforms closely to the hypothetical
morphotype of the common ancestor ofAsian and Euro-African hominids.
Keywords: middle Miocene Hominoid, robust mandible, thick molar enamel, stem hominid
Zusammenfassung
Das einzige Primaten-FundstUck von \:andlf, die gut erhaltene Mandibel eines Weibchens
und der Holotypus von Griphopithecus a/pani TEKKA YA, wird beschrieben und seine
funktionelle Anatomie und phylogenetische Bedeutung untersucht. In der Morphologie der
Molaren ist das Exemplar im wesentlichen von dem h!\ufigsten Primaten aus P~alar nicht zu
unterscheiden. Das Korpus unterscheidet sich morphologisch von dem einzigen erhaltenen
Exemplar aus Pa~alar. Allerdings wird der Vergleich dadurch erschwert, daB dieses StUck von
einem Mlinnchen stammt. Es fallen auch morphologische Unterschiede zu den weiblichen
Exemplaren aus Fort Ternan, Maboko und Majiwa (aIle Kenya) auf, die hier Kenyapithecus
wickert und Griphopithecus africanus zugeordnet werden. Die Funktionsanalyse zeigt die
Eigenschaft erhOhten Okklusionslasten zu widerstehen. Dies wird bei Primaten iiblicherweise
mit Anpassungen an mechanisch harte Nahrnng in Verbindung gebracht. Dem entspricht die
Morphologie der Molaren. Griphopithecus a/pant aus \:andu fehlen die abgeleiteten Merkmale
der Hominiden des spaten Mittel- und Obermiozans und steht moglicherweise an der Basis
der Radiation eurasischer und afrikanischer Hominoiden. Er entspricht weitgehend dem
hypothetischen Morphotyp des gemeinsamen Vorfahren asiatischer und euro-afrikanischer
Hominiden.
Schliisselworter: Mittelmiozliner Hominoide, robuste Mandibel, dicker Molarenschmelz,
Stammhominide
Authors' addresses: Erksin GOLEC, Oil ve Tarih Cografya Fakiiltesi Sihhiye, Ankara, 06100, Turkey, E-Mail: [email protected];
David R BEGUN, Department ofAnthropology, University of Toronto, Toronto, ON M5S 3G3, Canada, E-Mail: [email protected]·
GOLE~
& BEGUN: Functional morphology and affinities of the hominoid mandible from (:andlf
Introduction
The primate mandible recovered from <;andlr is one of
the most complete and best preserved early middle Mio­
cene hominoid mandible currently known, and has there­
fore received a lot of attention in the past. The specimen
has been described by TEKKAYA (1974), ANDREWS & TEK­
KAYA (1976) and figured by ANDREWS & TEKKAYA (1976)
and WOLPOFF (1980). When combined, these published
descriptions are reasonably comprehensive and will not
be duplicated here. In this paper we review previous in­
terpretations of the <;andlr mandible, supplement previ­
ous descriptions with additional data, add comparisons
to new specimens, and attempt to place the specimen in a
phylogenetic context.
The specimen, MTA 2253, was recently reexamined
by us, and we were graciously granted permission to
clean and mold it. In the process, the glue joint holding
the 2 halves of the mandible together at the symphysis
was dissolved, proving a view of the symphysis in cross
section. After cleaning, the mandible was reassembled,
with a slight offset corrected. We also had the opportu­
nity to CT scan the specimen. Some of these images are
reproduced here. New metric data were also collected to
supplement published measurements of the teeth.
Before discussing previous interpretations of MTA
2253 it is useful to briefly review the taxonomy of
middle Miocene hominoids, focusing on specimens that
share the basic characteristics of robust mandibles and/or
thickly enameled molars. The first such specimens were
described by ABEL (1902), based on two isolated teeth
from a site then in Hungary called Neudorf an der March,
which is now in Slovakia and is called Devinska Nova
Yes. Unfortunately, but predictably, given the common
practice of the time, separate genera were recognized
for each tooth. Griphopithecus suessi is based on the
smallest specimen, a heavily upper molar lacking the
roots and cervical enamel. It has page priority over
Dryopithecus darwini, the type of which is a relatively
large M 3 • REMANE (1921), acting as first reviser of this
material, considered Griphopithecus suessi to be ajunior
subjective synonym of Dryopithecus darwini. He felt
that both genera were synonymous, but that the type
of Griphopithecus suessi, although it has page priority,
was less suitable than the type of Dryopithecus darwini
because the former is a deciduous molar. LEWIS (1934)
transferred D. darwini to Sivapithecus darwini, based on
general similarities to the much larger Siwalik samples
that are mostly related to the shared presence of thick
enamel. Over the years the sample from Devinska Nova
Yes has doubled to four isolated teeth (GLASSER 1931,
STEININGER 1961).
Historically the next sample of middle Miocene
hominoids to be described were the specimens attributed
to Sivapithecus africanus (LE GROS CLARK & LEAKEY
1951). These specimens were first said to come from
Rusinga, with early Miocene sediments, but subsequent
90
analysis confirmed the provenance to be middle Miocene
Maboko (ANDREWS & MOLLESON 1979). Later LEAKEY
(1962) described a new middle Miocene hominoid from
Fort Ternan that he assigned to the nomen Kenyapithecus
wickeri. Most authors place the Maboko and Fort Ter­
nan fossils, and others from localities close to Maboko
(Majiwa, Nyakach and Kaloma) in Kenyapithecus, but
some debate persists on the number of species (PICKFORD
1986, BEGUN 1992, HARRISON 1992, MCCROSSIN & BEN­
EFIT 1993, 1997). New specimens from middle Miocene
deposits at Nachola, in northern central Kenya, origi­
nally tentatively assigned to Kenyapithecus africanus
(IsHTDA et aI., 1984, PICKFORD, 1986) or to a new species
(NAKATSUKASA et aI., 1998) of Kenyapithecus have been
assigned to a new taxon, Nacholopithecus kerioi (IsHTDA
et al. 2000). Specimens from Kipsarimon, in the Tugen
Hills of Western Kenya that had been attributed to Ke­
nyapithecus africanus (WARD & BROWN 1996) are now
considered by these authors to represent yet another new
taxon, Equatorius africanus (WARD et al. 1999). Debate
persists on the legitimacy ofthese newer nomena (BEGUN
2000).
A number of the fossil hominoid specimens from the
Siwaliks are also middle Miocene (Chinji Formation),
but much later in time than the European and African
samples discussed above (KAPPELMAN, et aI., 1991).
These are all currently attributed to Sivapithecus, though
some ofthese specimens may lack some of the diagnostic
characters of that clade (BEGUN & GOLEc,:: (1998). Other
taxa or samples known outside South Asia that have been
synonymized or phyletically linked with Sivapithecus
(Rudapithecus, Bodvapithecus, Ouranopithecus, Grae­
copithecus, Kenyapithecus, and the Buluk, Maboko and
Lufeng hominoids) are now nearly universally attributed
to other genera (Table 1).
TEKKAYA (1974) described MTA 2253 as the type
specimen of a new species, Sivapithecus alpani. Most of
his description concerns the teeth and symphysis. Among
other things, TEKKAYA (1974) noted the small size of the
anterior teeth (based on the preserved alveoli), the verti­
cal symphysis, strongly developed superior and inferior
transverse tori, the broad molars and the presence of
molar cingula. While stressing the overall similarities to
various Siwalk hominoid genera (all currently attributed
to Sivapithecus), he also noted similarities to Plio-Pleis­
tocene hominids, particularly in the development of the
transverse tori, mandibular robusticity and small incisors
(TEKKAYA 1974). ANDREWS & TEKKAYA (1976) pursued
this theme further, noting similarities to specimens in­
terpreted at the time to be more closely related to fossil
humans, usually attributed to the genus Ramapithecus.
Although not actually reallocating the specimen to Ra­
mapithecus alpani, ANDREWS & TEKKAYA (1976) do place
Sivapithecus alpani in their Ramapithecus group, and
indicate that all the referred material can be assigned to
two species.
ANDREWS & TEKKAYA (1976) emphasize the simi­
Cour. Forsch.-Inst.
Tab. 1: Summary of nomena used in this paper, and their syn­
onyms in this paper.
Griphopithecus alpani
Sivapithecus alpani
Griphopithecus darwini
Ramapithecus sp.
Griphopithecus darwini
Dryopithecus darwini
Sivapithecus dar.vini
Griphopithecus suessi
Austriacopithecus weinfurti
Austriacopithecus abeli
Griphopithecus africanus
Equatorius africanus
Sivapilhecus africanus
Kenyapithecus africanus
Proconsul nyanzae
Sivapithecus sp. I
Dryopithecus sp.
Ramapithecus sp.
Ouranopithecus macedoniensis 2
Dryopithecus macedoniensis
Graecopithecus freybergi
Sivapithecus macedoniensis
Ankarapithecus meleai
Sivapithecus meteai
Graecopithecus meleai
Dryopilhecus sp.
Bodvapilhecus
Rudapilhecus
Kenyapithecus wickeri
Ramapilhecus breviroSlris
Ramapithecus wickeri
Kenyapithecus africanus
Proconsul sp.
,<,
from South Asia has yet to be taxonomically revised, a task well beyond the
of paper. We hmIt our list of synonyms for Sivapithecus to the genus level. Many
other synonyms are summarized in Simons and Pilbeam (1965) and Kelley and Pilbeam
(1986).
<Graecopithecus has pirority over Ouranopithecus, but much debate exist>; over the re­
lationship of these taxa. Until it is resolved, we prefer to use the nomen with the better
"i,j
preserved type and hypodigm.
larities between MTA 2253 and the reconstruction of a
middle Miocene hominoid mandible from Fort Ternan,
Kenya. This composite specimen, originally attributed to
the taxon Kenyapithecus wickeri (LEAKEY 1962) was re­
allocated to Ramapithecus brevirostris by SIMONS (1964),
and later to Ramapithecus wickeri (ANDREWS, 1971). AN­
DREWS & TEKKAYA (1974) note a number of dental simi­
larities between MTA 2253 and the Fort Ternan material,
including the small anterior teeth and the presence of
molar cingula. They emphasize the similarities between
the anterior mandibular areas, which is the best preserved
part of the mandibular material from Fort Ternan (KNM­
FT 45). Both show very short anterior mandibles with
strongly developed transverse tori. The <;andlr specimen
is distinguished from that from Fort Ternan in having a
shorter planum alveolare, more vertical symphysis, and
less strongly developed transverse tori. Based primar­
ily on differences in the symphysis, ANDREWS & TEK­
KAYA (1974) suggest that the <;andlr and Fort Ternan
specimens may belong to different species, possibly
Ramapithecus punjabicus and Ramapithecus wickeri.
2003
The specimen was formally allocated to Ramapithecus
wickeri by SZALAY & DELSON (1979). Stvapithecus alpani
was synonymized with Sivapithecus darwini by ALPAGUT
et al. (1990). In the most recent revision, MTA 2253 is
again recognized as a type specimen, but for the no­
men Griphopithecus alpant, based on similarities to the
sample of Griphopithecus from Devinska Nova Yes and
Pa~alar (ANDREWS et al. 1996).
Many of the similarities among the mandibles dis­
cussed above relate to small size and robusticity. It is
clear today that most if not all ofthe middle and late Mio­
cene hominoid mandibles that resemble MTA 2253 are
female, and cannot be easily distinguished from contem­
porary male specimens except by size. In fact, this point
was made by ANDREWS & TEKKAYA (1974), but without
the recognition that the differences in size were due to
sexual dimorphism and not taxonomy. It has been many
years now since the differences between Ramapithecus
and Sivapithecus were realized to be sexual dimorphism,
leading to the recognition that Ramapithecus is a junior
subjective synonym of Sivapithecus (GREENFIELD 1979,
1980, Al\DREWS & CRO;-.lIN 1982, KAY 1982, PILBEAM
1982). ANDREWS & CRONIN (1982) and PILBEAM (1982)
were the first to recognize the cladistic affinities of
Sivapithecus and Pongo, while other contemporary re­
searchers continued to link Sivapithecus with "hominids"
(GREENFIELD 1979, 1980, KtW 1982). Most researchers
since that time follow ANDREWS & CRONIN (1982) and
Pilbeam (1982) in associating Sivapithecus with the
Pongo clade (WARD & PILBEAM 1983, KELLEY & PILBEAM
1986, ANDREWS & MARTIN 1987a, BROWN & WARD 1988,
SCHWARTZ 1990, 1997, ANDREWS 1992, MCCOLLUM et al.
1997, WARD 1997, BEGUN et al. 1997, although see PIL­
BEAM et al. 1990 and PILBEAM 1996, 1997 for an alterna­
tive view).
Equally common today is the view that non-Siwalik,
middle Miocene, thickly enameled, robust mandibles,
such as the specimens from Fort Ternan and <;andlr, are
not likely to be attributable to Sivapithecus, but represent
more primitive hominoids (ANDREWS & MARTIN 1987a,
ALPAGUT et al. 1990, ANDREWS 1992, MCCROSSIN & BEN­
EFIT 1993, 1997, BEGUN 1994a, BEGUN et al. 1997). ALP­
AGUT et al. (1990) cite preliminary evidence of a phyletic
relationship between Turkish middle Miocene hominoids
(Pa~alar and <;andlr) and Sivapithecus. Based on more
recent discoveries at Pa~alar, ANDREWS et al. (1996)
now believe there is no basis for linking the Pa~alar and
<;andlr hominoids with Sivapithecus-Pongo, which is the
main justification for reviving the nomen Griphopithecus
(BEGUN 1992, MARTIN & ANDREWS, 1993). They cite im­
portant differences in palatal and premaxillary morphol­
ogy, including the retention of a Proconsul-like short
premaxilla and broad incisive canal, and the absence of
diagnostic pongine palatal features as found in Sivapithe­
cus and Pongo (WARD & PILBEAM 1983) and to a lesser
extent in Ankarapithecus (BEGUN AND GULE<; 1998). This
mirrors the conclusion of PICKFORD (1986) regarding the
91
GOLEC & BEGUN: Functional rn,,",",,-."'"'' and affinities ofthe hominoid mandible from
primitive morphology of the palate of Kenyapithecus
from Nachola (now attributed to Nacholapithecus (ISHI­
DA et aL 2000), and is also consistent with the primitive
morphology of postcrania attributed to Kenyapithecus,
Nacholapithecus and Griphopithecus (BEGUN 1992;
WARD & BROWN 1996, Nakatsukasa et al. 1998,2000).
This view is also consistent with a recent reconstruction
ofevolutionary relations among many hominoids (BEGUN
et al. 1997).
To summarize the background information on the af­
finities of the <;andlr mandible, most authorities would
place it in the taxon Griphopithecus a/pant, along with
most of the sample ofhominoids from Pa~alar (ANDREWS
et al. 1996). A second species of the genus is also thought
to be present at Pa~alar (ANDREWS et al. 1996, WARD et al.
1999). Most regard Kenyapithecus, Nacholapithecus and
Griphopithecus as more primitive than most or all other
middle Miocene to recent hominoids, but the relations of
these genera to each other is unclear, because they appear
to share only primitive characters, including a suite of
characters related to heavy mastication (thickly enam­
eled molars, broad, flat molar cusps, a low enamel-den­
tine junction, and short, robust mandibles with heavily
reinforced symphyses).
Materials and Methods
All observations were made on the original specimen,
in the collections of the MTA in Ankara, Turkey. MTA
2253 was cleaned, photographed (Plate 1) and molded
in RTV silicone. High resolution cast.') were made for
comparative analysis. The specimen was compared to
cast.') and original specimens of Miocene to recent hom i­
noids. Data was previously collected on originals of all
Miocene hominoid specimens included in this analysis.
Measurements were made using an electronic dial caliper
with modified jaws for access to small spaces. CT Scans
were prepared at the Hacettepe Hospital Department of
Radiology using a Philips Tomoscan SR 7000 set to 120
KV and 100 MA. All statistical analyses were carried out
using SYSTAT for Windows, version 5. Measurements
appear in Table 2.
Anterior mandible (Plate la, d, e, f, g)
As noted by ANDREWS & TEKKAY A (1974), the planum
alveolare of MTA 2253 is more vertical and shorter than
that of the composite reconstruction from Fort Ternan.
In order to compare these two specimens more directly,
a new reconstruction of the Fort Ternan specimen was
made, based on KNM-FT 45,7,34,40, and 3318 (Plate
2). KNM-FT 46/47 were used to position the posterior
molars relative to the anterior dentition, as in WALKER &
ANDREWS (1973). The Fort Ternan composite is female,
based on the morphology of the KNM-FT 3318 right
canine and the alveolus for the left canine preserved
92
Tab. 2: Measurements of MTA 2253 in millimeters (unless
otherwise indicated).
Symphysis
height
thickness (sagittal)
thickness (actual)
length
sublingual plane
24.75
20.9
16.4
30.1
32"
Corpus (heightlbreadth)
@PJ
@P,
@M,
@M2
@M3
Mental foramen (inf.-sup.)
23.6/15
23.2113.1
23.7/14
21.1/16.6
20.5118.7
8.6/12.9
Dental arcade
bi-I,
bi-I,
bi-canine (mesial)
bi-canine (distal)
bi-PJ
bi-P,
bi-M,
bi-M2
bi-M,
5.25
lOA
11.4
24.1
15.3
18.1
21.5
23.7
29.0
Teeth
P, (m-dlb-I)
P, (max. In/perp. bd)
P,
M,
M,
M;
M J (hydlentd)
molar row length
premolar row length
postcanine length
left
7.919.1
10.4/6.6
6.9/8.6
9.3/8.6
10.319.8
11.9/9.6
7,9/8.5
31.5
14.3
46.1
right
----­
----­
6.8/8.3
9.118.7
10.4/9.9
11.9/9.6
7.9/8.8
31.6
----­
----­
mesiodistal, B-J = buccolingual, max In maximum length, perp.
Bd, = breadth perpendicular to the maxImum length axis, hydlentd talonid breadth be­
tween the hypoconid and entoconid.
Abbreviations: m--d
on KNM-FT 45. MTA 2253 lacks a canine crown. We
are convinced that it is female, given the very small
size of the canine alveoli, the small size the preserved
root of the right canine, and the small size of the canine
jugum (Plate la). KNM-FT 3318, with most of its root
preserved, fits well in the alveolus for the right canine
of MTA 2253. The planum alveolare of the Fort Ternan
composite is in fact noticeably different from that of
MTA 2253. On the Fort Ternan specimen the portion of
the symphysis opposite the p) is preserved to the midline,
but the superior transverse torus is damaged posteriorly.
Based on the preserved portion, it must have projected
posteriorly at least as far as P4 -M 1• This is well posterior
to the extent of the superior transverse torus on MTA
2253, which extends to about the level of the metaconids
of the P4 's. The sublingual plane of the Fort Ternan com­
posite is also much more horizontal than in MTA 2253.
BROWN (1989) reports the angle in KNM-FT 45 to be 20
degrees, while it is 32 degrees in MTA 2253. MCCROSStN
& BENEFIT (1993) report a sublingual angle of38 degrees
in KNM-MB 20573, a juvenile mandible of Griphopithe­
cus africanus from Maboko. The symphysis ofKNM-MJ
5 (Plate 2), attributed here to Griphopithecus africanus
from Majiwa is too damaged to accurately measure. The
Cour. Forsch.-Inst. Senckenberg, 240, 2003
sublingual angle ranges from about 20 to 50 degrees in
Proconsul and averages about 35 degrees in Sivapithecus
(Brown, 1989), so it is not possible to ally MTA 2253
with either group on the basis of this feature. Kenyapithe­
cus wickeri does appear to be distinct from most other
hominoids including Griphopithecus africanus in the
low angle and degree of elongation of its sublingual
plane, contra MCCROSSIN & BENEFIT (1993).
The labial portion of the symphysis and the inci­
sor alveolar portion of the mandible in the Fort Ternan
composite is not preserved. However, it is preserved in
KNM-MB 20573 and KNM-MJ 5, although in the lat­
ter it is seriously damaged. KNM-MJ 5 does preserve a
lateral incisor in situ that does seem to be in close to its
anatomical position. Both of these mandibles preserve
an incisor alveolar portion that is considerably larger
transversely than in MTA 2252. This may also have been
the case for KNM-FT 45, based on the reconstructed
distance between the canines (Plate 2). The distance be­
tween the middle of the mesial canine alveolar margins
in the Fort Ternan reconstruction is between 14 and 15
mm. Although juvenile, the lateral incisor of KNM­
MB 20573 was erupted, so the alveolar portion of the
symphysis must have been close to it's adult size. The
distance between the distal margins of the lateral incisor
alveoli is about 16 mm, judging from McCrossin and
Benefit (1993; Plate 1). KNM-MJ 5 is about 13-14 mm in
the same measurement. In contrast, MTA 2253, which is
dentally closest in size to Fort Ternan, has an internal bi­
canine breadth of 11.4 mm and an external bi-I 2 breadth
of about 10.4 mm. Thus it has a much narrower incisor
region than Kenyapithecus or Griphopithecus africanus.
The lateral incisors known from KNM-MJ 5 and KNM­
MB 20573 are also too large to fit in MTA 2253.
KNM-MB 29573 is described as having a "massive
inferior transverse torus" and a "weak superior trans­
verse" (MCCROSSIN & BENEFIT, 1993), although in cross
section the inferior torus barely extends beyond the level
of the superior torus. KNM-MJ 5 has transverse tori of
roughly equal prominence, and the inferior transverse
torus is strongly developed on KNM-FT 45, as noted
by WALKER & ANDREWS (1974) and ANDREWS & TEKKAYA
(1976). It is not possible to unambiguously reconstruct
the superior transverse torus on KNM-FT 45 because too
much is sheared off posteriorly. It could have been close
in development of the inferior torus, as in many homi­
noids, or it may have been weaker. it is unlikely to have
been stronger, as is the case for the superior transverse
torus in Proconsul generally. in all three African speci­
mens the tori enclose a small, relatively deep genioglos­
sal fossa. In MTA 2253 the symphyseal transverse tori
are of roughly equal prominence, but are on a relatively
deeper symphysis, with the superior transverse torus
more superiorly placed than in Kenyapithecus (Plate 1
d, e, t). The result is a wider separation between the tori,
and thus a much broader genioglossal fossa. The broad
and deep genioglossal fossa is continuous along the lin­
gual aspects of the corpora with well developed intertoral
hollowing, palpable to the level of about the middle of
the M I on both sides.
The basal aspect of the symphysis of MTA 2253 has
broad, shallow, poorly demarcated anterior digastric fos­
sae (Plate Ih). They are similar in development to those
described for KNM-FT 45, and less strongly marked than
on KNM-MJ 5 (BROWN 1989). The anterior digastric fos­
sae are similar to those of GSP 4622 and GSP 13875,
though in these specimens the interdigastric spine is
slightly more strongly developed.
All three African mandibles also have more strongly
proclined labial symphyseal surfaces compared to MTA
2253 and Sivapithecus, confirming the distinction be­
tween the Fort Ternan and <;:andlr specimens noted by
ANDREWS & TEKKAYA (1976). ANDREWS & TEKKAYA (1976)
also note that the Fort Ternan reconstruction has a some­
what longer symphysis, but suggest that the overall pat­
tern is similar to MTA 2253, as evidenced by the position
of the anterolateral angle of the corpus at P3 and the me­
sial position of the canine alveolus. We feel that the dis­
tinctions between the symphyses of Kenyapithecus and
Griphopithecus alpani are more marked. The differences
among these specimens are summarized in Table 3.
Two males of Griphopithecus preserving the anterior
portion of the mandible have been described. G 1313
from Pa~alar is attributed to Griphopithecus alpani
and KNM-TH 28860 to Griphopithecus africanus (or
Equatorius africanus) (ANDREWS et al. 1996, WARD et
al. 1999, BEGUN 2000). No male mandibles have been
described for Kenyapithecus. G 1313 is described as hav­
ing a long, sloping symphysis with a much more strongly
developed inferior transverse torus, probably extending
to the M 2 • As an indication of its great length, the ratio
of symphyseal length to vertical height is 136.5, while
in MTA 2253 it is 121.6. The superior torus extends to
the P4 , as in MTA 2253 (ALPAGUT et al. 1990). The body
of the mandible is also described as tall and gracile, with
a robusticity index of 46.3 at Mp in comparison to 59.1
for MTA2253 (ALPAGUT, 1990; see table 2 of this paper).
While these differences are noteworthy, they are typical
of sexual dimorphism in anterior mandibular morphol­
ogy in many great apes (BROWN, 1989, 1997). In the
absence of other evidence, these differences should not
be interpreted to indicate a taxonomic difference between
G 1313 and MTA 2253. In fact, G 1313 also contains both
left incisors, and they, like the sample of lower inci­
sors from Pa~alar overall, are relatively small. As noted
above, this must have been the case for MTA 2253 as
well, and is a further indication that both may belong to
the same taxon.
The mandible associated with the partial skeleton
KNM-TH 28860 from Kipsarimon, Kenya, is damaged
anteriorly, but has been described by WARD et al. (1999)
as having a strong inferior transverse torus and a pro­
clined sublingual plane, as in G 1313. On the other hand,
the incisors appear to have been relatively large, more in
93
GDLEr,;
&
BEGUN:
Functional
mnrnh,nk.<7v
and affinities of the hominoid mandible from
keeping with the morphology of Griphopithecus africa­
nus from Maboko and Majiwa.
Mandibular corpus
The mandibular corpus of MTA 2253 has been
described as robust and posteriorly mildly divergent
(TEKKAYA 1974; ANDREWS & TEKKAYA 1976). It shallows
noticeably from the symphysis to the region of the pos­
terior molars, as indicated in the measurements provided
in Table 2 (Plate Ib, c). The lateral eminence, which is
opposite M 2, is very strongly developed, and contributes
to the formation of a broad extramolar sulcus. Anterior
to the lateral eminence is a broad, relatively deep fossa
posterior to the mesial root of the P3. The mental foramen
is situated at the antero-inferior corner of this depression.
Both Kenyapithecus and Griphopithecus qfricanus also
share these features whereas they tend to be less strongly
developed on female Sivapithecus.
The oblique line is fairly prominent and descends
from the lateral eminence inferiorly and anteriorly. It
comes very close to the base of the corpus at about the
level of the MI before arching superiorly toward the an­
terior edge of the mental foramen, where is merges with
the P3 mesial root prominence (Plate 1b, c). It is quite
similar in degree of development and position to the
oblique line on asp 16077 (Sivapithecus) and KNM-MJ
5. MTA 2253 lacks the double oblique line or buccinator
line of Proconsul mandibles and KNM-MJ 5 (KELLEY &
PILBEAM, 1986; WARD & BRmvN, 1986; BROWN, 1989).
In superior view the corpus of MTA 2253 thins out
considerably anterior to the M I, as in Sivapithecus, re­
sulting the same pattern of medial vs lateral buttressing
noted by BROWN (1989) for Sivapithecus (Plate la). Lat­
eral buttressing, mainly via the lateral eminence, is stron­
ger than medial buttressing, mainly via the symphyseal
transverse tori, whereas in Proconsul and KNM-MJ 5
medial and lateral buttressing are more equal. Overall the
superior and lateral aspects of the corpus of MTA 2253
are quite sculpted, with strong eminences and fossae, and
strong lateral buttressing. This is most similar to the man­
dibles of Sivapithecus (BROWN, 1989, 1997).
Inferior to the lateral eminence and diverging from the
oblique line is a crest that continues inferiorly to the base
of the corpus, and then curves posteriorly along the infe­
rior edge of the corpus. In inferior view this crest, which
marks the anterior and inferior limits of the attachment of
the masseter muscle, serves to separate the broad, deep
postcanine fossa from a shallower but still well devel­
oped concavity along the surface for the attachment of
the masseter (Plate Ih). This concavity is opposite M3
and ends at a convexity approaching the posterior edge of
the ramus, which is not preserved. Along the base of the
corpus posterior to M3 a small notch marks the anterior
extent of what was a flared gonial angle, most of which is
not preserved (Plate I b, c).
The lingual surface of the corpus of MTA 2253 is
marked by a subtle mylohyoid line and a shallow sub94
mandibular fossa under M 2-M r Posterior to M3 is a very
broad, deep fossa to accommodate a large, thick medial
pterygoid muscle, the posterior and medial edge ofwhich
has left a very well developed crest emanating from the
gonial notch (Plate lb, c). Though damaged, the inferior
border of the corpus near the gonial angle appears to
have been strongly inverted. Again, the morphology of
this aspect of the corpus of MTA 2253 is most similar to
that of asp 16077. In this specimen of Sivapithecus the
contours are exaggerated by the presence of a massive
lingual accessory cusp and associated root that causes
a significant lingual bulge in the region of the M 3. asp
16077 also has a more strongly developed mylohyoid
line than MTA 2253.
In inferior view the corpus of MTA 2253 bulges
strongly posteriorly and laterally compared to most
hominoid mandibles, which are of more uniform thick­
ness anteriorly and posteriorly (Plate Ih). The mandibles
that come closest to the morphology of MTA 2253 are
KNM-MJ 5, asp 16077 and asp 13875.
Prognathism
Short anterior mandibles and mesially displaced
canines were once thought to be related to "hominid"­
like short faces and small canines, but these characters
are clearly associated with sexual dimorphism in Siv­
apithecus. Specimens of Sivapithecus with small canines
or small canine alveoli, which have small roots and
minimally developed jugae tend to have mesially placed
canines (aSp 13875,4622, 9563, YPM 13870, BMNH
15423), while males have laterally positioned canines
(aSp 15000, 9564, YPM 13828, AMNH 19411, AMNH
19412). Early Miocene hominoids tend to lack this dis­
tinction between the sexes, and usually have more later­
ally positioned canines, and this is also the case for Old
World monkeys, while Dryopifhecus (RUD 17), Ourano­
pithecus (RPL 54) and living great apes appear interme­
diate, with less mesially displaced female canines.
While the anterior mandible of MTA 2253 is short,
as in female Sivapithecus, it is in fact much less fore­
shortened in Griphopithecus africanus, despite a similar
placement of the canine. In lateral view female mandibles
of Sivapithecus do not project anteriorly much beyond
the level of the anterior corner of the canine alveoli or the
mesial root of the PJ (aSp 4622, asp 13875). The inter­
nal and external symphyseal inclinations are also similar
in both Sivapifhecus females and MTA 2253. In KNM­
MJ 5 and KNM-MB 20573 the anterior portion of the
mandible does indeed extend further anteriorly beyond
the level of the PJ than in MTA 2253 and Sivapithecus fe­
males. This is probably related to the greater inclination
ofthe symphysis in Griphopithecus africanus, and to the
apparently greater relative size ofthe anterior dentition.
Although the anterior mandibles of Sivapithecus and
MTA 2253 are short, and those of Griphopithecus afi'i­
can us relatively longer, this does not necessarily mean
that the faces in Griphopithecus a/pani and Sivapithecus
Cour. Forsch.-Inst.
were short, while those of Griphopithecus africanus
were long. The teeth of Sivapithecus females are larger
in absolute dimensions than those of MTA 2253, and
the mandibles are consequently noticeably longer. Other
indications suggest that Sivapithecus females may have
been more prognathic than males or females of both spe­
cies of Griphopithecus and Kenyapithecus. In the former,
the lateral eminence occurs opposite M3 or between M2
and M 3. In Griphopithecus and Kenyapithecus, it occurs
opposite M2 • The root ofthe coranoid process arises close
to this point, and it thus positioned more anteriorly in
Griphopithecus and Kenyapithecus than in Sivapithe­
cus females. In relation to the posterior aspects of the
mandible and the insertion of the temporalis muscle,
the mandibles of Griphopithecus and Kenyapithecus are
less anteriorly projecting or prognathic than Sivapithe­
cus females. Possibly related to this is the position of
the mental foramen. Griphopithecus and Kenyapithecus
the mental foramen is anterior to the P4 while in female
Sivapithecus the mental foramen is under P4 or between
P4 and MI (GSP4622, GSP 13875). More ofthe mandible
projects anterior to the mental foramen in Sivapithecus,
suggestive of a more prognathic face. As noted earlier,
the premaxilla of Griphopithecus are short (this region is
not known from Kenyapithecus), suggesting a short, less
prognathic face as well.
A
Cross-sectional Anatomy
CT scans and tracing were made of the corpus of
MTA 2253 (Figure I). The mid-sagittal section of the
symphysis is somewhat different from that published
by TEKKAYA (1974: Figure 5), and reflects, we believe,
a more accurate orientation of the specimen (Figure la).
The sublingual plane is more horizontal than depicted
by TEKKAYA (1974) and the inferior transverse torus
somewhat more projecting. In general though, it is clear
that the symphysis is relatively vertical with strongly
developed but roughly equally prominent superior and
inferior transverse tori. Comparisons to other hominoid
symphyses are depicted in Figure 2.
Coronal sections from P4 to M3 are also included here
(Figure I b-e). The corpus becomes considerably more ro­
bust from P4 to M 3. The relatively deep intertoral sulcus,
a continuation along the lingual surface of the corpus of
the genioglossal fossa, is clear in the coronal section at P4
(Figure Ib), and the well developed fossa of the medial
pterygoid muscle is clear in the section at M3 (Figure Ie).
MTA 2253 shares with Sivapithecus and Griphopithecus
africanus the characteristic thickening ofthe corpus pos­
teriorly and the distinctive triangular shape of the cross
section of the corpus at M3 (Figure 3). Though damaged,
this appears to be less well developed in Kenyapithecus
c
B
2003
D
E
Fig. 1: Mid-sagittal section of the symphysis, and coronal sections of the corpus ofMTA2253. a) symphysis; b) cross section at p.
(note the development of the intertoral sulcus); c) at M 1; d) at M 2; e) at Mr
A
B
c
D
E
F
Fig. 2: Some fossil hominoid symphyses in mid-sagittal sectional MTA 2253; b) GSP 1373/5; c) GSP 16077; d) GSP 4622; e)
KNM-RU 7290; 1) RPL 54. B-D are Sivapithecus. E is Proconsul. F is Ouranopithecus. All sections from Brown (1989) except
MTA 2253, from this analysis.
95
GOLEc,: & BEGUN: Functional morphology and affinities of the hominoid mandible from <;:andlr
wickeri. The coronal section at M3 also reveals the strong
lingual inclination of the M3 relative to the Mr A number
of Sivapithecus specimens show this morphology, which
appears to be more strongly developed in the smaller, ro­
bust mandibles (YPM 13814, YPM 13806, GSP 16077,
GSP 4622) (Figure 3). The same condition may have
been present on KNM-MJ 5, though the damage to the
corpus makes a definitive assessment difficult.
Subocclusal morphology
CT scans ofMTA 2253 also reveal details of the sub­
occlusal morphology of the specimen (Figure 4). The
roots of the P4 in MTA 2253 are longer than those of
the M" and their long axes converge (Figure 4). This is
A
B
c
D
E
F
QUo
UU()
Uou
UU(J O{)U UU(J
Fig. 3: Coronal sections of the same specimens from Figure 2.
a) MTA 2253; b) GSP 13873/5; c) GSP 16077; d) GSP 4622;
e) KNM-RU 7290; f) RPL 54 (M2' M3 not available) Taxa and
sources are in Figure 2.
96
similar to Kenyapithecus and Griphopithecus africanus,
while in Sivapithecus the roots of the P4 are the same
length or shorter than those of the M J and they diverge
or remain parallel (BROWN 1989: Figure 5.37). Also in
contrast to most Sivapithecus, MTA 2253 has relatively
short, thick molar roots. The distal root of M J is roughly
the same length as those of the more posterior molars,
while the mesial root is shorter. This is most like the
condition in Gorilla reported by BROWN (1989). In most
Sivapithecus the M J roots are both shorter than those of
the posterior molars (BROWN 1989). The exceptions for
the most part are the smaller, more robust mandibles,
which appear to have root proportions close to that of
MTA 2253. Even among these robust specimens, most
have M J mesial and distal roots of close to the same
length, though YPM 13828 shares with MTA 2253 and
Gorilla a shorter M J mesial root (BROWN 1989: Figure
5.37). The mesial root ofM J has a slight distal inclination
to its long axis, whereas roots of the premolars are more
vertical. It is more typical, according to BROWN (1989)
for the transition from vertical to distal inclination to oc­
cur at the distal root ofM J in hominoids, though a few of
the fossil specimens she depicts have M] root angulations
similar to MTA 2253, including YPM 13814, a small, ro­
bust specimen, and KNM-MJ 5. Pulp chambers are very
difficult to discern but appear overall to be cynodont, as
in Sivapithecus generally (BROWN, 1989).
A damaged portion of the right corpus has now been
cleaned of adhering matrix, and reveals characteristics
of the subocclusal morphology that are not visible on
the CT scans (Figure 1c). A cross section of the inferior
alveolar canal is visible just inferior to the distal root of
the M3. The canal disappears deep to some dense cancel­
lous bone, and then re-emerges more inferiorly under the
mesial root of the Mr From this point the medial and
superior portions of the canal continue antero-inferiorly
across the M2. Damage has obliterated the canal between
the mesial root of the M2 and below P4 -M J , where a cross
section of the canal can be seen at the interface between
the alveolar process and the base of the mandible, cours­
ing towards the mental foramen.
Most of the alveolar process appears more or less in­
tact minus the sheared off lateral eminence. The cortical
bone of the base of the mandible is relatively thick, espe­
cially laterally. The base ofthe alveolar process, exposed
in the roof of the damaged mandibular base, deepens
anteriorly to accommodate the longer roots of the pre­
molars and canines. At about the level of the distal root
of the P4' approximately two thirds down the corpus, the
alveolar process merges into a thickened beam of cortical
bone inferior of the metal foramen and continuous with
the inferior transverse torus. The cortical bone ofthe base
ofthe mandible posterior to this point is also much thick­
er that the cortex of the walls of the mandibular corpus.
A similar pattern of basal cortical thickening continuous
with the inferior transverse torus, and hollowing inferior
to a robust alveolar process characterizes KNM-FT 45.
Cour. Forsch.-Inst.
a
240,2003
b
Fig. 4: Longitudinal section through the left corpus ofMTA 2253. a) CT scan; b) tracing.
Dentition
The dentition of MTA 2253 has been described in
detail in TEKKAYA (1974), with some additions by AN­
DREWS & TEKKAYA (1976). They noted the small size of
the anterior teeth (deduced from the alveoli), the narrow,
elongated P3 with a small metaconid, the broad P4 and
molars, the latter with flat cusps, and the traces of cingu­
la, developed most strongly on the M3. As noted above,
the wear pattern and cusp morphology of the dentition of
MTA 2253 are consistent with thickly enameled molars.
The hypoconulid of the right M3 is fractured distobu­
cally, exposing the underlying dentine and an enamel
cross section that is very thick at close to the cusp apex
(Figure la).
Tekkaya (1974) suggested that the P4 of MTA 2253
had four cusps and a low trigonid cristid, but this is not
the ease. The teeth are heavily worn and both have dam­
aged protoconids. These teeth in fact have high trigonids
relative to their talonids, and a strongly developed lateral
protocristid extending uninterrupted between the meta­
conid and the protoconid (Figure I a, b). It is also worth
noting that the M 1 is much smaller than the M,. The M
is the longest tooth, and it is strongly tapered (Figure la)~
The teeth of MTA 2253 are extremely similar to those
of the Devinsk Nova Yes lower molars (two M/s), and
also to the specimens from Pa~alar. The premolars are
strikingly similar to those ofKNM-FT 45. Molars are not
well known from Fort Ternan. Lower posteanine teeth
from Maboko, Majiwa and Kaloma are also quite similar
to those of MTA 2253, and share many of the features
noted above. However, the specimens from Maboko and
Kipsarimon tend to be more erenulated and have more
distinct cusps separated by deeper grooves on the occlu­
sal surface and by notches buccally. The talonid basins
are also broad and deep, which appears to be related to
the less rounded morphology of the occlusal surfaces of
the trigonid cusps surrounding the basin. The distal fovea
are also larger and deeper than on MTA 2253. The com­
parisons ofMTA 2253 to other robust Miocene hominoid
mandibles are summarized in Table 3.
Tab. 3: Summary of the morphological differences among Griphopithecus Kenyapithecus and female Sivapithecus rnand'bl
1 es.
Caracter
Griphopithecus alpani
Griphopithecus africanus
Kenyapithecus wickeri
Sivapithecus sp.
I. Planum alveolare
2. Inferior transverse torus
3. Interora! comparison
4. Sublingual plane
5. Labial symphysis
6. Incisor alveolus length
7. Genioglossal fossa
8. Interoral hollowing
9. Symphyseal depth
10. Corpus depth change
11. LAteral eminence
12. Mental formen
13. Mylohyoid line
14. Anterior mandible
shorter (mesial P4)
mid-P4
sub-equal
38 degrees
vertical
short (10.4)
broader
developed
deep
deep anteriorly
shorter
mid- P4
sub-equal
32 degrees
proclined
long (13-16)
smaller
indistinct
deep
deep anteriorly
@M,
distal p]
subtle
short
longer (P4-M,)
mid-M,
inferior> superior
20 degrees
proclincd
long (14-15)
smaller
indistinct
shallow
more constant
shorter
mid-P 4
sub-equal
mean 35 degrees
vertical
long
broader
developed
deep
more constant
@M,
P/P4-M ,
stronger
short
@Mz
distal P,
subtle
short
@Mz
distal P 1
subtle
long
97
GDLE<;: & BEGUN: Functional morphology and affinities of the hominoid mandible from <;andlf
Fortsetzung Tab. 3:
Caracter
Griphopithecus a/pani
Griphopithecus africanus
Kenyapithecus wickeri
Sivapithecus sp.
15. Postcanine fossa
16. Buccinator line
17. Corporal buttressing
18. Posterior tickening
19. P4-M, roots length
20. P4 roots orientation
21. Molar roots
22. M, root proportions
23. M, mesial root angulation
24. P4 breadth
25. Molar shape
26.M,-M 2
27. Molar cingulum
28. Molar cusps
29. Molar occlusal surfaces
30. P4 talonid
31. Incisor size
32. incisor implantation
prominent
absent
lateral> medial
pronounced
longer
convergent
short, thick
short mesial
distal
broad
broad
small
moderate
less distinct
simple
low
small
vertical
prominent
present
lateral = medial
pronounced
longer
convergent
short, thick
equal
distal
broad
broad
small
moderate
more distinct
more crenulated
low
large?
more horizontal
prominent
absent
lateral = medial
weaker
longer
convergent
longer, slender
equal
distal
intermediate
broad
small?
reduced?
less distinct?
simple
low
large
more horizontal?
shallower
absent
lateral = medial
pronounced
same/shorter
parallel/divergent
longer, slender
equal
usually vertical
long
long
larger
absent
less distinct
simple
high
large
vertical
Morphometric analysis
While it is most useful in a phylogenetic analysis to
consider individual character states (see below), some
patterns of overall morphological similarity may emerge
only from a multivariate approach. In order to examine
general rather than specific patterns of similarity among
the specimens discussed above, metric data were used to
perform a cluster analysis and a principle components
analysis, the latter primarily to detect the specific sources
of variance in the sample that may be most responsible
for the cluster analysis results.
A cluster analysis was run using a normalized Euclid­
ean distance metric and single linkage. Nine variables
reflecting mandibular robusticity, dental shape, and rela­
tive dental/mandibular size were included in the analy­
sis (Table 4). The results are given in Figure 5. <;andlr
clusters most closely with Sivapithecus (GSP 16077)
and then KNM-MJ 5 and another Sivapithecus specimen
(YPM 13814). GSP 16077 and YPM 13814 are from the
Chinji Formation, and are among the oldest specimens
attributed to Sivapithecus. They are thus closer in age to
Griphopithecus than most of the sample of Sivapithecus,
though still about 2.5-4.0 MA younger than these taxa
(BEGUN, et al. this volume, BROWN 1989, KApPELMAN
1990, RAzA et al. 1983). This could be interpreted to indi­
cate that the oldest Sivapithecus more closely resembles
Griphopithecus than later Sivapithecus, but the signal
is mixed. Other Chinji Sivapithecus, such as D198 and
D118/119 cluster more distantly, while D197/GSI 18040,
one of the youngest Sivapithecus, is the next closest spec­
imen to the group that includes MTA 2253. Nevertheless,
two of the four Chinji Sivapithecus mandibles do cluster
with Griphopithecus, and both species of Griphopithecus
also cluster with each other, suggesting that there may be
a real signal present in these data.
Tab. 4: Shape indices fOf MTA 2253, Griphopithecus africanus (KNM-MJ 5) and 11 mandibles of Sivapithecus.
Specimens
M,shape
M3 shape
M3 taper
M,I
mandible
M/
mandible
robust@M,
robust@M3
M,iM3
!l. robusticity
<;andir
KMN-MJ 5
aSID1181119
aSI D 198104
YPM 13814
asp 16077
asp 9564
asp 4622
asp 13566
asp 15000
AMNH 19413
YPM 13806
aSI D 1971180
105.100
113.330
116.830
104.880
106.730
107.830
116.000
127.890
118.640
110.850
108.870
115.630
107.140
123.960
127.710
117.930
108.400
107.410
126.320
134.780
125.710
138.980
112.600
110.240
124.720
123.080
109.090
106.410
108.160
111.970
108.000
120.000
100.000
111.700
103.510
110.440
115.460
104.710
104.000
59.040
61.220
68.240
72.350
63.030
64.610
62.500
70.270
69.410
60.850
65.960
56.140
67.310
51.340
47.980
53.000
64.850
52.680
53.270
48.320
51.220
61.780
52.050
61.650
37.808
61.910
78.670
84.970
67.270
51.520
72.690
76.720
50.250
56.490
66.930
67.300
62.460
68.400
75.640
91.220
96.110
81.000
65.160
97.620
92.240
59.500
72.700
72.080
76.730
66.030
92.310
85.370
88.360
104.340
89.950
85.300
92.150
86.870
101.580
99.800
85.370
101.580
94.150
107.870
100.960
88.770
84.970
74.000
84.160
80.490
83.180
86.890
72.200
89.010
86.890
91.260
71.250
99.050
98
Cour. Forsch.-Inst. Senckenberg, 240, 2003
GSP 13566
GSP 9564
-----------,J
GSP 4622
D 1181119
GSP 15000
AMNH 19413
D 198
D 197/GSI 18040
MJ 5 <::ANDIR GSP 16077 YPM 13814 YPM 13806
I
I
Fig. 5: Results of a cluster analysis (Euclidean distance, single linkage) of hominoid mandibles, using ratio data from table 5.
See text for discussion.
A number of principle component analyses were run
on the same data to discover more about the variables
that are contributing most to the pattern of overall simi­
larity detected by the cluster analysis. Two of these are
reproduced in Figure 6. The specimens of Sivapithecus
are labeled by areas corresponding to different time
periods (BROWN 1989). <;andlr groups closely with the
same two Chinji specimens that clustered with MTA
2253, while KNM-Ml 5 is more distant, particularly
along factor 1. Loadings for factor 1 are primarily high
mandibular robusticity at M3, a high ratio of mandibular
breadth at M2 compared to M3 (reflecting the position
of the lateral eminence), and small or narrow molars
relative to mandibular breadth. Factor 2 loadings are
mainly high robusticity at M2 and M3 and a broad M2
relative to length (Figure 6a). The younger specimen of
Sivapithecus Dl97/GSI 18040 again falls fairly close to
MTA 2253. KNM-Ml 5 may separate from MTA 2253
in this analysis mainly due to the effects of molar size,
which may in tum be related to the much smaller size of
KNM-MJ 5 compared to MTA 2253. In Figure 6b, Ke­
nyapithecus falls closest to Griphopithecus along factors
2 and 3. The main Factor 3 loading is high mandibular
breadth ratio at M2 compared to M3, which suggests that
it is indeed relative molar size that distinguishes KNM­
MJ 5 from MTA 2253 along factor 2.
Results and Discussion
Functional interpretations
The robust mandible, thick enamel, and low rounded
molar cusps of MTA 2253 are part of a classic suite of
characters routinely associated with powerful mastication
(HYLANDER 1979, 1985, 1988, KAy 1981). Some more
detailed aspects of mandibular and dental morphology
may provide additional insights into the nature of Griph­
opithecus dietary adaptations. Damage to the lateral side
of the right corpus reveals a thickened cortex at the base
of the mandible below the P4 that appears to continue to
about the level of the M J in the CT images. The thick
cortex of the base of the mandible is continuous with the
inferior transverse torus and the base of the symphysis,
which is the most massive part of the symphysis. The
thickened anterior halves of the bases of each corpus are
probably structurally related to the basal symphysis and
serve to stiffen the mandible and reinforce the symphysis
against both wishboning and bending due to twisting of
the corpora along their long axes (HYLANDER 1988). The
relatively strongly developed superior transverse torus
is also a response to wishboning, the bending moments
of which derive from laterally placed muscle resultant
forces in the molar region (HYLANDER 1985, 1988). Addi­
tionally, high muscle resultant forces are indicated in the
molar region of the corpus by its substantial thickness,
related both to the presence of a pronounced lateral emi­
nence and thickened cortical bone, especially buccally.
Transversely thick corpora are an effective response to
wishboning and torsional stress caused by twisting along
the long axis of the corpus, which results from eversion
of the corpus due to the lateral placement of resultant
muscle vectors (HYLANDER et al. 1987).
The posterior mandible is very shallow, which while
reducing torsional and transverse bending stress (wish­
boning), would not be an effective response to parasagit­
99
GOLE<;: &
BEGUN:
Functional morphology and affinities of the hominoid mandible from <;:andlr
tal bending. However, the corpus does increase in depth
anteriorly. This is only partly related to the length of the
roots of the canine and P3. Most of the increase in vertical
depth anteriorly can be related to the strong thickening
of the base of the corpus from M1 anteriorly to the sym­
physis. The thickened bone of the base of the corpus con­
tributes directly to increasing the depth of the symphysis,
another structural response to symphyseal bending due
to corporal twisting (HYLANDER 1988). It is possible that
the increase in mandibular depth anteriorly is entirely
related to reinforcing the symphysis, but it would also
have served to reduce parasagittal bending moments in
the anterior corpus, since the increase in depth is not
confined to the symphysis, but continues to the MI. Hy­
LANDER (1979) suggests that parasagittal bending is most
significant on the balancing side corpus. The fact that this
response to parasagittal bending is confined to the anteri­
or mandible, if it is not simply a side effect of increasing
the depth of the symphysis, may indicate strong parasag­
ittal bending stresses in the anterior mandible. The fact
that the increased depth is relatively anterior is probably
related to the relatively anterior position of the resultant
muscle forces given the anterior placement of the lateral
eminence and the root of the ramus on MTA 2253. It
could reflect powerful incisal biting (HYLANDER 1979),
though this seems unlikely given the probable small size
of the incisors of MTA 2253. HYLANDER (1979) also sug­
gests that increased mandibular depth may be a response
to prevent fatigue failure, which he further suggests may
be more critical for primates that spend more time chew­
ing, such as folivores. MTA 2253 does not have a denti­
tion suggestive of folivory (SMITH 1999), but it may have
consumed relatively low quality hard or tough foods
requiring both powerful and frequent mastication.
The lateral eminence is a thickened region of cortical
bone that not only serves to increase the transverse diam­
eter of the corpus in response to bending and twisting,
but also serves to anchor the ramus onto the corpus to
counter the effects of multiple loading modes generated
by the powerful muscles of mastication. The dense and
complex network of cancellous bone of the alveolar pro­
cess, along with the other structures and materials of the
alveolar process (large, thickly enameled molars, short,
thick roots) served to absorb and dissipate the substantial
bite forces generated by these powerful muscles. This
is not to say that the alveolar process and the base of
the mandible have separate and unrelated functions. As
noted by DAEGLING et al. (1992), in normal, healthy jaws
with crowns, roots, alveoli and periodontium in good
condition these structures all contribute to the structural
integrity of the mandible, and serve to reduce torsional
loads in the corpus. However, as also noted by these au­
thors, elevated bite forces or occlusal loads will also raise
shear strain in the alveolar process of a healthy mandible
(DAEGLING et al. 1992).
KING et al. (1999) conclude that Griphopithecus was
a Pongo-like frugivore, mostly consuming relatively
100
soft fruits and occasionally ingesting harder fruits and
nuts. This is on the basis of microwear on molars from
Pa~alar. SMITH (1999) reaches a similar conclusion for
both the Pa~alar and <;:andlr molars based on her analysis
of cusp proportions, although KING et al. (1999) place
more emphasis on hard objects and SMITH (1999) on soft
fruit. A possible explanation for this minor discrepancy
may come from the circumstances of deposit and the
paleoecology of Pa~alar. ANDREWS (1990) concluded that
the environment represented at Pa~a1ar was forested but
seasonal, with a marked dry season and nearby patches
of grass. QUADE, et al. (1995) concluded on the basis of
stable isotopes that Griphopithecus from Pa~alar was
exploiting resources from both open and closed envi­
ronments. ANDREWS & ERSOY (1990) concluded that the
assemblage of hominoids from Pa~alar was probably
deposited very rapidly over a very short time. However,
more recently ANDREWS (1995) concluded that the fossils
from Pa~alar probably accumulated over as much as 200
years elsewhere before being redeposited in a very rapid
event, possibly no more than a few hours duration, at the
locality. It may be that there is a bias that favored the
sampling of hominoids at Pa~alar during the pronounced
dry season. Since microwear signals are relatively
ephemeral on occlusal surfaces, the importance of hard
object feeding may be over-emphasized due to seasonal
differences in food availability. On the other hand, if the
sample was attritional, as suggested more recently by
ANDREWS (1995), a seasonal bias may be less likely than
in the case of an catastrophic accumulation, though still
possible.
Griphopithecus molars have more steeply inclined
cusp occlusal surfaces lingually than buccally, both at
Pa~alar and <;:andlr. Though we have not measured the
angles, the relatively unworn mesial cusps ofthe M3 from
<;:andlr and of a number of molars from Pa~alar have this
morphology clearly apparent from visual inspection.
This configuration is most like the inclination of cusp oc­
clusal surfaces in Pan, and less like that in Homo, Pongo,
or Gorilla, according to SPEARS & CROMPTON (1996). In
their model of the effects of occlusal surface inclinations
on stresses that are applied to food particles SPEARS &
CROMPTON (1996) concluded that the configuration in
Pan was in a sense the best of both worlds, combining the
ability to apply both high tension and shear stress, given
their relatively flat buccal cusps and their relatively in­
clined lingual cusps. If the mechanics of Griphopithecus
occlusal surfaces is similar to that of Pan, then according
to the analysis of SPEARS & CROMPTON (1996) it should
have been relatively efficient at processing foods that
require high tensile stress to induce failure (hard foods)
and foods that require high shear stress (leaves or fibrous
fruits). However, as noted above, the M3 of MTA 2253
is strongly inclined lingually, which is another way of
saying that it has a marked Curve of Monson. As SPEARS
& CROMPTON (1996) note, the Curve of Monson could
significantly affect the inclination of the cusp occlusal
I
Cour. Forsch.-Inst.
surfaces. The effect would be to reduce the inclination
of the lingual cusps relative to the maxillary cusps com­
pared to their inclination relative to the cervical line, the
measurement used by Spears and Crompton (1996). This
may mean that the shear stress capabilities of the teeth of
Griphopithecus are somewhat exaggerated in this type of
analysis. Overall, the combined evidence of the dentition
suggests a varied diet, perhaps with the ability to exploit
certain key, more difficult to process food items during
periods of scarcity.
Despite the somewhat ambiguous signal from the
teeth, it is likely that the MTA 2253 mandible in life
was subjected to high levels of stress directly related to
elevated bite forces required for food processing. This
conclusion is based on the combination of indications
of powerful muscles of mastication, relatively large oc­
clusal surfaces, thickly enameled molars, and robust and
structurally reinforced mandibular corpora and symphy­
sis. This suite of characters is most commonly associated
with "hard object feeding" (KAy 1981), although it is
certainly possible that hard objects represented a critical
but not extremely common component of the diet. Griph­
opithecus probably needed the ability to consume foods
requiring very high, possibly sustained and frequent bite
forces. These can range from hard, or brittle foods, such
as nuts with brittle cortices, to tough foods with resistant
coverings requiring very high occlusal loads to induce
structural failure. The mandible and teeth of MTA 2253
are inconsistent morphologically and functionally with
soft fruit frugivory or folivory of the type that typifies
the African apes, or probably even the "hard object feed­
ing" of the type seen in orang-utans. The closest modem
analogue may be the hard object feeding of Cebus apella
(Kay, 1981). However, differences in cusp proportions
and microwear however suggest that Griphopithecus did
not have a very close analogue among living primates.
Systematic interpretations
It has been noted elsewhere that attempts to recon­
struct hominoid phylogeny based exclusively on man­
dibular evidence is a risky business (BEGUN 1994b).
Mandibles and teeth are highly responsive to dietary
adaptations, and they seem to concentrate homoplasy
more than most other primate skeletal elements. That the
primate mandible is a magnet for homoplasy is evident
in the numerous suggestions of parallelism in primate
jaws and teeth, ranging from hominoids to prosimians
(lOLLY 1970, BEECHER 1983, RAVOSA 1991, SKELTON &
McHENRY 1992, TURNER & WOOD 1993, BEGUN 1994a,
b, 1995, 2001, LIEBERMAN et al. 1996, BEGUN & KORDOS
1997, STRAIT et al. 1997). In the absence of other primate
fossils from <;andlr it is tempting to carry out a phyloge­
netic analysis on this mandible alone. In our view a cla­
distic analysis based exclusively on characters preserved
on this specimen would result in a character tree of very
unclear relationship to the true phylogenetic tree of the
~prl('l<,pnhpro-
2003
Hominoidea. However, we do feel that it is possible to
make some basic conclusions about the phylogenetic po­
sition of Griphopithecus, based on a number of lines of
evidence. It is clear from the preceding analysis and from
previous work that MTA 2253 is morphologically closest
to the sample of hominoids from Pa~alar (MARTIN AND
ANDREWS 1993; ANDREWS et al. 1996). It is also reason­
ably well established that the sample from Pa~alar retains
a number of primitive characters, particularly of the pal­
ate, and the same is true of cranial and postcranial fos­
sils of Griphopithecus africanus (MARTIN AND ANDREWS
1993, ANDREWS et al. 1996, PICKFORD 1986, BEGUN 1992,
2001, WARD & BROWN 1996, NAKATSUKASA et al. 1998,
WARD et al. 1999). Candlr is also roughly the same age
as the localities from which these other samples come,
and is geographically close to Pa~alar. MTA 2253, while
sharing mandibular characters with such diverse taxa as
Australopithecus, Sivapithecus, Ouranopithecus, and
Gigantopithecus, also retains primitive morphology seen
in Proconsul. These attributes include broad molars and
premolars, presence of molar cingula, small M, relative
to M 2 , large, tapered M 3 , and an anterior placement of the
lateral eminence. Overall this evidence supports sugges­
tions that Griphopithecus and Kenyapithecus are succes­
sive sister clades to either all subsequent hominoids, or to
great apes and humans, with Kenyapithecus being derived
relative to Griphopithecus (Al\DREWS 1992,ANDREWS et al.
1996, BEGUN 1994a, 2001, BEGUN et al. 1997, WARD et al.
\999). Both appear to share only primitive characters with
each other, while each can be distinguished from the other
by characters of the mandible (see above). Thus, while
we feel the evidence is strong that they represent differ­
ent genera, placing Griphopithecus and Kenyapithecus in
the same clade in the absence of shared derived characters
would make that clade paraphyletic, and is thus inadvis­
able. For this reason, until more is known ofthese taxa we
prefer to assign both genera and the species they contain to
Hominoidea family indeterminate (Table 5).
The hominoid mandible from Candlr is one of the
best preserved jaw specimens of a middle Miocene
hominoid. It is one of a number of specimens ranging in
age between about 17 and 14 MA that show evidence of
more modem hominoid morphology (thickly enameled,
low cusped molars, low dentine penetrance, robust man­
dibles, reduced cingula) while retaining primitive char­
acters of early Miocene hominoids (primitive postcrania,
continued presence of cingula on many molars, small M,
relative to M2 , broad molars and premolars, large, tapered
M 3, anteriorly placed lateral eminence). Griphopithecus
a/pani lacks a number of characters that have been re­
lated to a specialized sclerocarp feeding adaptation in
Griphopithecus aji-icanus and Afropithecus and possibly
Kenyapithecus as well (MCCROSSIN & BENEFIT 1997,
LEAKEY & WALKER 1997). It may be that this morphology
is convergent in these hominoids, as it is between these
taxa and living pithecines, but it could also be primitive
for the clade that includes Griphopithecus, and lost in G.
101
GOLE<;: & BEGUN:
Functional morphology and affinities of the hominoid mandible from Candrr
Tab. 5: Taxonomy of middle Miocene to recent Hominoidea
Vienna Basin (Devinska Nova Ves), Turkey (Candlr and
Pa~alar), and Kenya (Maboko, Majiwa, Kaloma, Nacho­
Hominoidea
la, Kipsarimon) (HEIZMANN & BEGUN 2001). Some of the
Hylobatidae
hominoids
from Kenya become more specialized in their
Hylobates
Hominidae
anterior dentition, possibly in relation to changing eco­
Ponginae
logical conditions, and may have become more terrestrial
Sivapithecus
as well, although the evidence for this is very ambiguous
Pango
Ankarapithecus
(NAKATS{]KASA et al. 1998,2000). None of these samples
Homininae
or taxa share any specific affinity to specific clades of
Dryopithecus
more advanced hominoids (hominids). Out of this array
Ouranopithecus
Gorilla
of hominoids, but most likely from the Eurasian contin­
Pan
gent, later middle and late Miocene hominoids evolve
Ardipithecus
(BEGUN et al. 1997, 2000, 2001, STEWART & DISOTELL
Praeanthropus I
Australopithecus'
1998). Some slim evidence suggests a possible link
Homo
between
pongines and Griphopithecus. BEGUN & GOLE<;:
Paranthropus
(1998) have suggested that Ankarapithecus is the sister
Hominidae indeterminate
Lufengpithecus
clade of the clade that includes Sivapithecus and Pongo.
Gigantopifhecus
Ankarapithecus
lacks some of the derived characters
Gen. et sp. nov. 3
of this clade, and Chinji Sivapithecus may lack some
Hominoidea indeterminate
Oreapithecus
of these characters as well (BEGUN AND GULE<;: 1998).
Kenyapithecus
Ankarapithecus
may share with Griphopithecus small
Griphapithecus
lower incisors, though the symphyses ofthe males of An­
Samburupithecus
karapithecus (MTA 2124) and Griphopithecus (G1313)
lPraeorUhropus includes the hypodigm of Australopithecus a/arensis (Strait, et a1., 1997) and possibly also Paroustralopithecus aethiopicus. are morphologically different (BEGUN AND GULE<;: 1998).
zAuslralopithecu'i, including samples usually attributed to A. anamensis, A, bahrelgha::ali, and A. africanu:; is in our opinion paraphyletic. We believe that Austra{opilhecuJ a/ricanus Beyond this, there is no good evidence to exclude Griph­
is the only specics of the genus Australoplthecus, and that the other taxa represent 1 or opithecus or a Griphopithecus-like taxon from the ances­
more different genera. '>The diversity of Chinese fossil hominoid" from localities other than Lufeng tKalyuan, try of all subsequent hominids or hominoids.
Yuanmou, Shihuiba) probably belong to at least one nev., genus. Intense and rigorous renewed excavations at Candlf
have unfortunately failed to yield any new primate mate­
rial, though a tremendous amount of information on the
alpani. The morphology related to sclerocarp feeding is
locality has been amassed (chapters in this volume).
well preserved in the anterior dentition, maxilla and man­
There are therefore no new fossil data from Candlr with
dibles of Afropithecus (LEAKEY & WALKER 1997), while it
which to test these hypotheses. However, much new and
is somewhat more ambiguous in Kenyapithecus and Gri­
little or unpublished fossil material exists from Pa~alar
phopithecus africanus. Of the three mandibular symphy­
and East Africa. Detailed anatomical descriptions and
ses, one is juvenile and two are seriously damaged. Even
rigorous phylogenetic hypothesis testing based on these
if one or both of Kenyapithecus and Griphopithecus afri­
data should allow other researchers to test some of the
canus were sclerocarp feeders, their incisors and canines
hypotheses presented here.
are less robust than in Afropithecus, and it also lacks the
short crowned, massive canines and flared premolars of
Afropithecus, suggesting that the sclerocarp adaptations
Acknowledgements
of Afropithecus may have been acquired independently.
The oldest known thickly enameled, low dentine
DRB is grateful to Erksin
for her invitation to
topography hominoid fossil is the M3 fragment from
participate in the analysis of the Candlr mandible. We
Engelsweis, dated to between 16 and 17 MA (HEIZMAN"N
are grateful to the staff of the Maden Tetkik ve Arama
1992, HEIZMAN"N et al. 1996, HEIZMANN & BEGUN 2001,
Enstitilsil for granting access to the specimens and for
permission to restore it. Special thanks go to Sevim
ANDREWS et al. 1996, BEGUN 2001). It is impossible to say
ifthis individual had adaptations ofthe anterior mandible
YILDIRIM and her staff in the Natural History Museum,
and dentition similar to those seen in Afropithecus and
and to the General Director of the MTA at the time,
possibly Kenyapithecus and Griphopithecus africanus.
Ziya G6ZLER. Thanks also to Ger\,:ek SARA<;:, Mustafa
One scenario to explain the geographic and temporal
KARABIYIKOGLU, and Engin UNA y for their hospitality and
distribution ofthese middle Miocene hominoids is as fol­
collegiality. This work benefited from discussions about
mandibles with Bobbie BROWN and Matt RAVOSA, and by
lows. A descendant of Afropithecus and/or Heliopithecus
(ANDREWS & MARTIN 1987b) dispersed into Eurasia after
discussions and comparisons to Sivapithecus specimens
about 17 MA, with a first occurrence datum at Engels­
made possible by Jay
Steve WARD, and David
weis at about 16.5 MA (HEIZMANN 1992, HEIZMAN"N & BE­
PILBEAM. This manuscript was improved by the valuable
comments of Denis GERAADS and 2 anonymous review­
GUN 2001.). Following the Langhian regression about 15­
15.5 MA, thickly enameled hominoids disperse into the
ers. We both acknowledge the financial support of the
102
COUTo
2
~I
• GandIr
./
C~---
Hari/·
0 .Chinji
•
Majiwa
•
•
\
-1
•
Hari •
........... Khaur........
•
0
Majiwa
•
Khaur•
•
Har~
Hari
Chinji
.
•
2003
.<;andlr
Khaur
Chinji
Forsch.-Inst.
·C~·
..
•
illJI
-I
Hari
• Khaur
Khaur
~
-2
-2
-I
0
-2
2
-2
-I
0
2
Fig. 6: Principle component analysis of hominoid mandibles. Data from Table 5. See text for discussion. a) Factors I (robusticityat
M) and a posterior lateral eminence) and 2 (robusticity at Me and M3 and a broad M2 ; b) Factors 1 and 3 (mandibular breadth ratio
at M2 compared to M). See text for discussion.
Natural Sciences and Engineering Research Council of
Canada, the Ministry of Culture of Turkey, and the Alex­
ander von Humboldt Stiftung.
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GOLEi;'
&
BEGUN:
Functional ""',mt,,,I,,,,,, and affinities of the hominoid mandible from
Plate 1 MTA 2253. a) Occlusal; b) left buccal; c) right buccal; d) left lingual; e) right lingual; f) internal symphysis;
g) anterior; h) inferior. Scale equals 1 cm.
108
Plate I
Cour. Forsch.-Inst. Senckenberg, 240, 2003
b
a
c
d
9
h
& BEGUN: Functional
~_h~I~~.
and affinities of the hominoid mandible from
Plate 2
Casts, from left to right, ofMTA2253, KNM-MJ 5, and the Fort Ternan composite reconstruction used in this analysis.
Scale is in ems.
110
COllr. Forsch.-Inst. Senckenberg. 240. 2003
Pl ate 2