Human fossil record vol. 4

[John Grehan]

I recently had the opportunity to look at volume four of the Human
Fossil Record which looks at the craniodental morphology of early
hominids (Australopithecus, Paranthropus, and Orrorin) by Schwartz and
Tattersall.  

 

If you are wondering why the title does not include Sahelanthropus and
Ardipithecus, the authors note that they had not yet been able to see
the holotype of Sahelanthropus, and that they had not been allowed to
see the specimens of Ardipithecus. The lack of access to holotypes is a
real problem for primate paleontology. If the types are withheld then
the published claims are reduced to the status of metaphysics since
there is not avenue for independent testing.

 

This volume illustrates the problematic status of early hominoid
systematics as it shows how generalized references to groupings such as
'Australopithecus' in systematic studies are meaningless without
specific reference to particular fossil specimens. 

 

Some topical points:

 

P. 467. During the course of this study we have been confronted by an
unexpectedly wide diversity of morphologies - especially dental
morphologies - that makes it necessary ,, in our view, to inquire
whether some accepted components of the hominid fossil record might no
better be viewed as hominoid in a wider sense.

 

P. 467. OH7, the holotype of Homo habilis...this mandibular specimen
possess few if any features apart from thick molar enamel that would
specifically unite it to a monophyletic group that also includes
Australopithecus and Homo. In contrast, in the morphology of its
premolars, especially the P2, it is more comparable to Middle and Late
Miocene hominoids such as Proconsul major and Ouranopithecus
macedoniensis.

 

P. 468. ..sites in Africa...have yielded fossils that have been
classified as Australopithecus, yet present a dental morphology that is
more comparable to what is seen in the clade that also embraces the
living Pongo. The molars in these morphs, for example, display
compressed cusps that are incorporated into continuous cresting systems
that surround broad, shallow basins with heavily crenulated
surfaces-conformations that are not typical of mainstream
Australopithecus.

 

P. 469. From the very clearly reproduced illustration provided [by
Brunet et al for Sahelanthropus] the specimen identified as the right
lower permanent canine of S. tchadensis is of very unusual morphology
not only for a hominoid, but for an anthropoid...It may, indeed, be an
anterior premolar of a carnivore.

 

P. 470. White, Suwa and Asfaw describe this tooth [upper canine] as
slightly less incisiform than homologues of A. afarensis but more
incisiform than any ape counterpart, with occlusally paled termination f
of the mesial and distal apical crests...In fact, this tooth apparently
is a fairly close morphological match not only for the upper canine of
Kanapoi A. anamensis,  but also the upper canine of female orangutans.
Which implies in turn that a canine morphology of this kind is not an
infallible indicator of hominid status.

 

John Grehan

 

 

Dr. John R. Grehan

Director of Science and Collections

Buffalo Museum of Science1020 Humboldt Parkway

Buffalo, NY 14211-1193

email: jgrehan at sciencebuff.org

Phone: (716) 896-5200 ext 372

 

Panbiogeography

http://www.sciencebuff.org/biogeography_and_evolutionary_biology.php

Ghost moth research

http://www.sciencebuff.org/systematics_and_evolution_of_hepialdiae.php

Human evolution and the great apes

http://www.sciencebuff.org/human_origin_and_the_great_apes.php