SK 48, Paranthropus robustus (cast)

Discovered in the debris pile at a cave site commercially mined for calcite, this skull represented until recently the best preserved skull of any member of this species. SK 48 is the cranium of an adult robust australopith. Most of the skull (minus the lower jaw) is preserved and is relatively undistorted by the fossilization process, although some damage did occur when the specimen was dynamited out of the limestone deposits by miners. Preserved in the cranium were the right canine tooth and first premolar and all three left molars, indicating the individual was an adult at death.

The flat face, caused by the anterior (frontward) position of the cheekbones, and the extremely large molars and premolars are typical traits of robust australopithecines. These traits are linked to the development of a chewing complex designed to process tough, fibrous foods. The anterior position of the cheekbones created more space for large chewing muscles to pass behind the zygomatic arch. The large molars and premolars provided large surfaces for grinding tough foods.

The fossil was originally described by Robert Broom of the Transvaal Museum of South Africa. He inferred that the individual was a female based on the presence of a very small sagittal crest.