Attrition of individual teeth

Although the M3's of Zinjanthropus are not fully erupted, the other teeth are already markedly worn with one or more areas of exposed dentine on every one. Such early wear is characteristic of the Australopithecinae. The degree of wear may be compared with that in South African australopithecine maxillae, of which two specimens of Australopithecus (Sts 52 a and Sts 37) and four specimens of Paranthropus (the Kromdraai specimen, SK 13, SK 52 and SK 49) have the M3's not fully erupted, some being a little more advanced and some at a slightly earlier stage of eruption than Zinjanthropus: in all these maxillae, the amount of attrition is far less than in Zinjanthropus. The degree of attrition in the latter has already levelled the cusps and left numerous areas of dentine exposure (pl. 29). The exposed dentine is black in colour, in contrast with the yellowish-grey enamel. Areas of exposure are thus particularly clearly delimited.

The incisors have a substantial strip of exposed dentine, extending for the full mesiodistal diameter of the teeth, save for the mesial and distal enamel walls (pl. 32). Wear is slightly greater on the right I than on the left, the incisal surface being hollowed on the former, but straight to convex on the latter. The canines show the typically hominid form of wear from the tip (cf. Le Gros Clark, 1950a), which has resulted in a nearly flat occlusal surface with an irregularly biconvex area of dentine exposure, somewhat larger on the right canine than on the left.