Ardipithecus ramidus

Ardipithecus ramidus is a species of australopithecine from the Afar region of Early Pliocene Ethiopia 4.4 million years ago (Ma). The species A. ramidus is the type species for the genus Ardipithecus. There is an older species in this same genus, Ardipithecus kadabba that was discovered more recently.

A. ramidus, unlike modern hominids, has adaptations for both walking on two legs (bipedality) and life in the trees (arboreality), as it has a divergent big toe and evidence of bipedality. This combination of a big toe that would facilitate climbing suggests that Ardipithecus was not as efficient at bipedality as humans or even Australopithecus (a genus that did not have a divergent big toe), nor as good at arboreality as non-human great apes.