Hominid fossils show their age By Dr David Whitehouse BBC News Online science editor Australopithecus fossils from caves in South Africa may have been buried about 4 million years ago, as much as 1 million years earlier than previously thought. Australopithecus is an important hominid - human ancestor - that demonstrates the transition from ape-like features to human ones. Its kind were first discovered in East Africa and lived about four million years ago. Researchers used a technique that measured the decay of radioactive isotopes formed when the fossil was on the surface, but which declined when it was buried....