Variability and evolutionary trends in tooth size of Gigantopithecus blacki

The measurements of Gigantopithecus blacki teeth from Liucheng are summarized and comparative statistics are calculated. Compared to the variability of tooth size in living nonhuman primates, emphasizing Pongo because of close ecological and genetic relationships, the hypothesis of a single species for Liucheng specimens is acceptable. The Liucheng sample pattern of variability in tooth size, as well as the South African robust australopithecines, differs from living nonhuman primates in the same way; the first molar is not the least variable of the molars, and the molars are relatively variable compared with the other teeth. Sexual dimorphism may be responsible for this pattern in both cases. Later G. blacki cheek teeth are significantly larger than early G. blacki. From early G. blacki to later, the expansion ratio in tooth breadth is more than in tooth length. The pattern of expansion is like that seen in South African australopithecines. Both G. blacki and South African robust Australopithecus seem to show continued adaptation to more powerful and efficient chewing. The diet of G. blacki is not known, and its reconstruction depends on estimates of body size that differ greatly.