'Unusual primate' Ardi's skull reveals links to human lineage

A new breakthrough has allowed scientists to expand the catalogue of anatomical similarities linking humans, Australopithecus, and Ardipithecus on the tree of life.

"Ardi" was an unusual primate. Though it possessed a tiny brain and a grasping big toe used for clambering in the trees, it had small, humanlike canine teeth and an upper pelvis modified for bipedal walking on the ground.

New research led by ASU paleoanthropologist William Kimbel confirms Ardi's close evolutionary relationship to humans.

Kimbel and his collaborators turned to the underside (or base) of a beautifully preserved partial cranium of Ardi. Their study revealed a pattern of similarity that links Ardi to Australopithecus and modern humans and but not to apes.

Kimbel said that given the very tiny size of the Ardi skull, the similarity of its cranial base to a human's is astonishing.

The research has been published online in Proceedings of the National Academy of Science.