Definition
Sahelanthropus tchadensis is a late-Miocene ape known from a nearly complete cranium (nicknamed Toumai) and several jaw fragments recovered in the Djurab desert of Chad, dated by biostratigraphy to roughly 7 million years ago. Discovered by Michel Brunet's team and described in 2002, it is the oldest fossil proposed as a hominin, sitting very close in time to the chimp-human split.
The classification rests primarily on cranial features: a foramen magnum positioned more forward than in chimpanzees (suggesting upright posture), a small canine without a honing facet against the lower premolar, and a face that is short and broadly humanlike. Below-the-neck remains are minimal, so bipedalism cannot be directly demonstrated.
Why it matters
Where it shows up
The Toumai cranium is the type specimen and centerpiece of every published reconstruction. The associated jaw fragments and isolated teeth flesh out the dental anatomy. A reported femur from the same locality, described in 2022, has been used to argue for habitual bipedalism but its taxonomic attribution to Sahelanthropus is debated.
The fossils sit in a sedimentary context that records a mixed habitat — gallery forest along a river, with open woodland and grassland nearby — consistent with mosaic environments where bipedalism might have been advantageous.