Australopithecus hominid remains. Fossilised skull and humerus (upper arm bone) of an Australopithecus sp. hominid primate encased in rock at the Sterkfontein caves, South Africa. Numerous early hominid remains have been found at these caves, which were declared a World Heritage Site in 2000. These remains are the exposed parts of a complete Australopithecus skeleton thought to be around 4.7 million years old.