Sahelanthropus tchadensis

Sahelanthropus tchadensis is the type species of the extinct hominid genus Sahelanthropus, dated to about 7 million years ago in the Late Miocene. It was announced in 2002 on the strength of a partial cranium nicknamed Toumai, found in the Djurab Desert of northern Chad, and the remains of six to nine adults have since been recovered from a single area of under one square kilometre. Its place on the family tree is uncertain: it was first described as a possible early hominin ancestral to both humans and chimpanzees, but later interpretations treat it as an early member of the gorilla tribe or a stem hominid outside the hominins. Whether it walked upright is also debated, with a 2020 description of a femur concluding it was not bipedal and a 2022 study arguing that the limb bones show obligate bipedalism.