Definition
Australopithecus is a genus of gracile bipedal hominins that lived in eastern, southern, and central Africa between roughly 4.2 and 2 million years ago. Recognised species include A. anamensis (oldest), A. afarensis (Lucy's species), A. africanus, A. garhi, A. sediba, A. bahrelghazali, and A. deyiremeda. The genus is widely regarded as containing the ancestral stock from which both Paranthropus and early Homo emerged.
Australopiths combine clearly habitual bipedalism with a small brain (roughly chimp-sized, ~400–500 cc), a projecting face, large molars relative to body size, and arms that retain climbing adaptations. They are the first hominins for which abundant, well-preserved fossils make confident reconstruction possible.
Why it matters
Where it shows up
The richest sites are in East Africa (Hadar, Laetoli, Allia Bay, Omo, Koobi Fora, Middle Awash) and South Africa (Taung, Sterkfontein, Makapansgat, Malapa). Each yields different species and different preservation. The Hadar locality alone has produced hundreds of A. afarensis specimens; Sterkfontein has produced thousands of A. africanus bones and bone fragments.
By around 2.5 mya, the gracile australopith pattern begins giving way to two contrasting descendants: the robust Paranthropus lineage with massive jaws and grinding teeth, and the early Homo lineage with reduced face and expanding brain. Both probably originated within Australopithecus.