In a new paper in the Journal of Human Evolution, researchers from Chaffey College, New York University, and California State University San Bernardino find the distinctive forelimb morphology of the African knuckle-walking apes in the forelimb of the roughly 7-million-year-old Sahelanthropus tchadensis. Only chimpanzees and gorillas exhibit robust and forward-curving ulna shafts, which are thought to serve as an adaptation to knuckle-walking. This bone in all other primates is straight or curves backward and contrasts with humans and other fossil hominins (bipeds).
Click here for original story, Once thought to be a biped, Sahelanthropus is instead the earliest known knuckle-walking ape, says study
Source: Phys.org