Sahelanthropus tchadensis is one of the oldest known species in the human family tree. This species lived sometime between 7 and 6 million years ago in West-Central Africa (Chad). Walking upright may have helped this species survive in diverse habitats, including forests and grasslands. Although we have only cranial material fromSahelanthropus, studies so far show this species had a combination of apelike and humanlike features. Apelike features included a small brain (even slightly smaller than a chimpanzee’s), sloping face, very prominent brow ridges, and elongated skull. Humanlike features included small canine teeth, a short middle part of the face, and a spinal cord opening underneath the skull instead of towards the back as seen in non-bipedal apes.
How do we know Sahelanthropus walked upright?
Some of the oldest evidence of a humanlike species moving about in an upright position comes from Sahelanthropus. The large opening (foramen magnum) where the spinal cord exits out of the cranium from the brain is located further forward (on the underside of the cranium) than in apes or any other primate except humans. This feature indicates that the head of Sahelanthropus was held on an upright body, probably associated with walking on two legs.