Found in 2001 at Toros-Menalla in the Djurab Desert of Chad, this skull was named Sahelanthropus tchadensis by its discoverers and nicknamed "Toumaï" — "hope of life" in the local Goran language. It dates to roughly 7–6 million years ago and sits squarely within the window when the human and chimpanzee lineages are thought to have separated.

Its significance is contested. The position of the foramen magnum — the opening at the base of the skull through which the spinal cord exits — sits well forward, suggesting upright posture. The brain, however, was only 320–380 cm³, similar to a chimpanzee's. The dental and facial architecture nonetheless places Toumaï at the base of the hominin family tree rather than among apes.

Some palaeoanthropologists argue Sahelanthropus may not be our direct ancestor but a contemporary cousin; others doubt it is a hominin at all. The debate runs on: a 2020s re-analysis of an associated femur cast doubt on bipedalism, while another team argued the same evidence supports it. Toumaï's value is less as an answer than as a question made tangible: in which corner of Africa, and as what kind of creature, did our lineage begin to part ways with the chimpanzee line?