FURTHER ANALYSIS OF MANDIBULAR MOLAR CROWN AND CUSP AREAS IN PLIOCENEAND EARLY PLEISTOCENE HOMINIDS

Crown and cusp areas of mandibular molars were measured and analyzed o n a sample of 249 specimens attributed to Australopithecus afarensis, A. africanus, A. (Paranthropus) robustus, A. (P.) boisei, and early Ho mo. In addition to intertaxon comparisons, we compared data that had b een collected independently by two of the authors using methods that d iffer slightly in technique of measurement. Interobserver differences were evaluated by the t-test of paired comparisons, method error stati stic, percent differences, and principal component analysis. Results s uggest that between-technique error of measurement of overall crown ar ea is small. Error estimates for individual cusp area measurements wer e of larger relative magnitude. However, these were not sufficient to detract from the conclusions derived from comparative analyses. Our re sults are in general agreement with previous assessments of early homi nid dental size. Crown areas of A. africanus, however, exhibit a mosai c pattern, with M1 similar in size to that of A. afarensis and early H omo, and M2 and M3 similar in size to that of A. robustus. Intertaxon comparisons of relative cusp area were undertaken by univariate statis tics and principal component analysis. These analyses revealed that wh ile A. (P.) robustus and A. (P.) boisei both possess mandibular molars with cusp proportions significantly different from the 'non-robust' t axa, these differences are substantially greater in A. (P.) boisei. (C ) 1994 Wiley-Liss, Inc.