Drimolen: a new hominid-bearing site in Gauteng, South Africa.

The co-occurrence of Paranthropus robustus and early Homo in South Africa has so far been firmly documented only at the site of Swartkrans. Our analysis of a sample of 79 early hominid fossil specimens from the newly discovered cave site of Drimolen confirms that Paranthropus [Australopithecus] robustus was contemporaneous with early Homo in South Africa during the Plio-Pleistocene. In addition, analysis of the large number of robust australopithecine dental remains from Drimolen demonstrates the considerable variability in this taxon. The sub-sample of deciduous P. robustus teeth from Drimolen encompasses a wide range of the metrical and morphological variation observed in the robust australopithecine samples from Swartkrans and Kromdraai. This finding supports the idea of a single, variable species of robust australopithecine in South Africa during the Plio-Pleistocene. At the same time, it weakens the hypothesis of the existence of two separate robust australopithecine species (namely, P. robustus from the site of Kromdraai and P. crassidens from Swartkrans) in South Africa, as first proposed by Broom6 and later supported by others.