Department of Anthropology, Tulane University
Saturday All day, Plaza Level
In a series of influential papers, Collard and Wood have argued that two fossil hominin paleospecies, Homo habilis and H. rudolfensis, should be removed from the genus Homo due to their failure to meet two main criteria: 1) lack of consensus in the cladistic assignation of these two species as sister taxa to later Homo to the exclusion of any australopith species, and 2) failure of these two paleospecies to exhibit morphological characters indicative of a shared "adaptive zone" with H. sapiens. Here postcranial examples of these "adaptive zone" characters are re-examined in light of recent paleontological data. Specifically, relative lower limb length, humero-femoral proportions, relative forearm length, relative pelvic breadth, and body size (as reflected in estimated body mass and a stature proxy) are examined among the australopiths and Homo. It is found that only for body size is Homo readily distinguished from the australopith taxa; for all other postcranial characters there are either insufficient data or considerable morphological overlap between the australopiths and Homo. These data are indicative of a pattern of mosaic postcranial evolution associated with the emergence of the genus Homo, and also suggest that the emergence of H. erectus/ergaster was not as marked a morphological shift as has been previously maintained.
Support from NSF (#SBR9321339), the L.S.B. Leakey Foundation, the University of the Witwatersrand, and Tulane University.