Homoplasy and early Homo: An analysis of the evolutionary relationships of H-habilis sensu stricto and H-rudolfensis

Dividing the fossils usually assigned to the taxon Homo habilis sensu lato into two species (as most researchers now accept) necessitates a re-examination of their evolutionary relationships. A cladistic analysis of 48 of the most commonly-used cranial characters from recent studies of Pliocene hominid phylogeny and which distinguish two taxa within H. habilis sensu lato suggests that these fossils have different evolutionary affinities. One taxon, H. habilis sensu stricto, is represented by KNM-ER 1813 and the fossils from Olduvai Gorge, and is most likely a sister group of H. erectus. The other taxon, H. rudolfensis, is represented by KNM-ER 1470, and shares many derived characters with the australopithecines. A close analysis of the developmental basis of these characters suggests that many of the australopithecine similarities of H. rudolfensis are likely to be homologies rather than homoplasies. (C) 1996 Academic Press Limited