Final answer:
Australopithecus boisei is an East African version of the South African Australopithecus africanus, with A. boisei being a robust species characterized by larger jaws and a 'mohawk' of bone on the skull, while A. africanus is a gracile species with a slender build.
Step-by-step explanation:
Australopithecus boisei is an East African version of the South African Australopithecus africanus. Both species are part of a group known as australopiths. While A. africanus lived roughly between two and three million years ago and had a brain size of about 500 cubic centimeters, which is slightly less than one-third that of modern human brains, the robust species including A. boisei continued to exist for a little longer. A. boisei is characterized by a mohawk of bone on the top of the skull, larger jaws, and greater attachments for chewing muscles, indicative of its robust nature. A. africanus, which had a slender build and was bipedal with robust arm bones, is considered a gracile form of austral pith, unlike the hyper-robust A. boisei.