The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


Revisiting Pliocene hominid phylogeny: a postcranial perspective

YOHANNES HAILE-SELASSIE1,2,3 and BRUCE M. LATIMER2,3.

1Physical Anthropology, Cleveland Museum of Natural History, 2Anthropology, Anatomy, and Cognitive Sciences, Case Western Reserve University, 3Center for Human Origins, Institute for the Science of Origins, Case Western Reserve University

Thursday 9:00-9:15, Grand Ballroom II Add to calendar

Several Pliocene hominid phylogenetic hypotheses have been proposed focusing exclusively on craniodental morphology. Postcranial specimens are historically rare and are considered less informative in reconstructing the natural history of early hominids. This narrow view has resulted in our overlooking subtle, yet important evidence from the existing hominid postcranial materials. Some researchers have argued that craniodental data are inconsistent with molecular data, and hence unreliable for reconstructing phylogenetic relationships among early hominid taxa. The disparity between the two datasets is likely an indication of substantial homoplasy in craniodental features.

A recently discovered hominid partial foot from the Woranso-Mille, Central Afar, Ethiopia, clearly indicates that additional evidence from the postcranial skeleton bears directly on early hominid taxonomy, phylogenetic relationships, and locomotor adaptations. Pliocene-Pleistocene hominids are generally assumed to have been uniformly obligate terrestrial bipeds. However, preliminary analysis of the partial foot from Woranso-Mille clearly shows that there was a hominid species in the middle Pliocene of eastern Africa with a locomotor adaptation substantially different from the contemporaneous Australopithecus afarensis. Elements of the Woranso-Mille partial foot, which include complete first and second metatarsals, are morphologically similar to pedal elements recovered from Member 2 at Sterkfontein, South Africa. Although the phylogenetic implications of these morphological similarities, to the exclusion of Australopithecus afarensis, require further investigation with additional fossils, the new discoveries from Woranso-Mille indicate that earlier impressions that in eastern Africa, post-Australopithecus anamensis locomotor adaptations were essentially invariable need to be re-examined.

This research was supported by the National Science Foundation (BCS-0542037).

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