Australopithecus africanus skull, STS 5 "Mrs Ples" (5 million years), with lower jaw.
The Australopithecus africanus Skull STS 5 "Mrs Ples" was discovered in 1947 by R. Broom and J. Robinson in Sterkfontein, Transvaal, South Africa. The discovery of this nearly complete cranium of a mature specimen led to a much more positive reception of South African australopithecines as hominids. Twenty years earlier, Raymond Dart had labelled a skull found at Taung "Australopithecus africanus." The dentition of that skull indicated that it was a juvenile, which led to much criticism and broad dismissal of Dart's contention that the skull was a hominid. Instead, critics considered it an ape. However, the discovery of STS 5 two decades later provided support for Dart's earlier claim.
Like other early hominids, STS 5 had an ape-sized brain. The STS 5 cranial capacity is about 485cm3. Compared to Australopithecus afarensis, it has a more rounded skull, a less projecting face, absence of cranial crests, and smaller front teeth. However, the front teeth are larger than in robust australopithecines. The cheek teeth are larger than in Australopithecus afarensis but smaller than in the robust australopithecines. Originally thought by Broom to be a middle-aged female, STS 5 is now considered by most to be a male.