Ardipithecus
From Freepedia
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Ardipithecus kadabba |
Ardipithecus is a very early hominid genus (subfamily Homininae). Because it is much like the African apes (genus Pan and genus Gorilla), it is considered by some to be on the chimpanzee rather than human branch, but most consider it a proto-human because of a likeness in teeth with Australopithecus. Ardipithecus lived 4.4 million years ago in the early Pliocene.
Two species have been described, Ardipithecus ramidus and Ardipithecus kadabba. The latter was initially described as a subspecies of A. ramidus, but on the basis of teeth recently discovered in Ethiopia has been raised to species rank. The canine teeth show primitive features that distinguish them from those of more recent hominines. A. kadabba is believed to be the earliest organism yet identified that lies in the human line following its split from the lineage that gave rise to the two modern chimpanzee species.
On the basis of bone sizes, Ardipithecus species are believed to have been about the size of a modern chimpanzee. The toe structure of A. ramidus suggests that the creature walked upright, and this poses problems for current theories of the origins of hominid bipedalism: Ardipithecus is believed to have lived in shady forests rather than on the savannah, where the faster running permitted by bipedalism would have been an advantage.
