Any member of a clade of extinct hominins that contains the earliest known species in the human ancestral lineage. Sparse fossil evidence, mostly from East Africa, indicates a combination of apelike and humanlike features. The oldest known remains belong to Sahelanthropus tchadensis and date from between 7 and 6 million years ago (mya). They reveal a small brain and prominent brow ridge, similar to apes, but small canine teeth and an opening for the spinal cord beneath the skull, indicating that the head was held upright on the body and hence bipedal locomotion. Fossilized thigh bones from another ardipithecine species, Orrorin tugenensis, also suggest bipedalism; these date from 6.2 to 5.8 mya. The genus Ardipithecus contains two species: Ar. kadabba, from about 5.8 to 5.2 mya, and Ar. ramidus, about 4.4 mya. A partial female skeleton of the latter has adaptations for tree climbing, namely an opposable big toe, as well as a pelvis suggestive of bipedalism. It is estimated to have stood about 120 cm tall.