SK 46 preserves the left half of the braincase and the nearly complete palate of Paranthropus robustus. The cheek teeth are nearly perfectly preserved; although the incisors and one canine tooth have been lost, their alveoli (the bony pits that hold the tooth roots) remain. Because these alveoli are still preserved, paleoanthropologists are able to reconstruct the size of the cheek teeth (molars and premolars) relative to the incisors and canines. This information can give clues about the dietary habits of this early human species. The large size of the cheek teeth relative to the front teeth suggests that Paranthropus robustus had a diet dominated by coarse vegetable matter. The large teeth provided a large occlusal area (the area where the upper and lower teeth contact each other during chewing). Think about a cow, or a horse, both of which eat large amounts of grass and other coarse plant foods. These animals have large cheek teeth and large chewing surfaces. By this kind of analogy and by direct study of microscopic wear on the tooth surfaces, scientists have determined that the large cheek teeth of robust australopiths were used for grinding tough, fibrous foods.

The preserved portion of the cranium has other features typical of P. robustus, including large zygomatic arches and a prominent sagittal crest. These features are associated with large chewing muscles used in grinding tough foods.

Image of SK 46, skull, side view
SK 46
Exhibit item
Site: 
Swartkrans, Republic of South Africa
Date of discovery: 
1936
Discovered by: 
local quarryman
Age: 
Between 1.8 and 1.5 million years old