What is Australopithecus?
Australopithecus = 'southern ape' a human ancestor. The first bipedal ancestor in human line of evolution was from the genus Australopithecus.
Australopithecus is a genus of human ancestors that spanned from 4.2 to 1.98 million years ago. Species include, Australopithecus afarensis , A. africanus, A, anamensis, A. gahri, and the newest discovery in this genus is A. sediba.
While members of this genus walked upright, they did spend time in trees, as evidenced by long arms and curved fingers (for climbing trees). Their brains were smaller than modern humans and their jaws were more robust. Given the length of time this genus spanned, it is worth examining individual species, as there are significant differences within this genus.
Lucy, of the most famous human ancestors, is a member of Australopithecus afarensis. Seen below, she is also one of the most complete fossil skeletons ever discovered.
Several extinct species of the group are reported from various locations in east and south Africa. The first reported specimen was Taung baby discovered in 1924.
The Smithsonian has an excellent website on human origins that is worth visiting.