Orrorin

Orrorin tugenensis is an extinct species of hominid that is closely related to humans. The name was given by the discoverers who found Orrorin fossils near the village of Tugen, Kenya, and dated them to approximately 6 million years ago. The fossils found thus far come from at least five individuals, and include a femur suggesting that Orrorin walked upright; a thick right humerus, suggestive of tree-climbing skills but not brachiation; and teeth that suggest a diet much like that of modern humans. The full molars and small canines suggest that Orrorin ate mostly fruit and vegetables, with occasional meat. Orrorin was about the size of a modern chimpanzee.

The team that found these fossils was led by Martin Pickford. Pickford claims that Orrorin is clearly a hominid; based on this, he dates the split between hominids and other African great apes to at least 7 million years ago. This date is markedly different from those derived using the molecular clock approach.

Other fossils found in these rocks show that Orrorin lived in a wooded environment, not the savanna assumed by many theories of human evolution and, in particular, the origins of bipedalism.

If Orrorin proves to be a human ancestor, Australopithecus afarensis (including "Lucy") would be on a side branch of the hominid family tree: Orrorin is both earlier, by 1.5 million years, and more similar to us than A. afarensis. There is, however, significant controversy over this point, and other researchers assert that Pickford et al. gloss over a number of uncertainties.

External links: http://www.esi-topics.com/fbp/comments/december-01-Martin-Pickford.html http://cogweb.ucla.edu/EP/Orrorin.html