Collection of hominid fossil remains belonging to the australopithecine group found at the Swartkrans site near Johannesburg, South Africa. The remains here include leg and arm bones, (right) a mandible (foreground), vertebrae and a cranium sitting on top of a leopard's jaw bone (left). The australopithecines are the oldest known group of hominids, dating from 3.7 to 1.6 million years ago. There are four species, of which Australopithecus africanus represents the gracile, lightly built type and A. robustus, the robust or heavily built type. Swartkrans' remains are thought to be of the robust australopithecine type, which became extinct.