Further analysis of mandibular molar crown and cusp areas in Pliocene and early Pleistocene hominids


  • Gen Suwa,

    Corresponding author
    1. Department of Anthropology, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113 Japan
    • Department of Anthropology, Faculty of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113 Japan
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  • Bernard A. Wood,

    1. Hominid Paleontology Research Group, Department of Human Anatomy and Cell Biology, The University of Liverpool, Liverpool L69 3BX, United Kingdom
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  • Tim D. White

    1. Laboratory for Human Evolutionary Studies, Department of Anthropology, University of California, Berkeley, California 94720
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Crown and cusp areas of mandibular molars were measured and analyzed on a sample of 249 specimens attributed to Australopithecus afarensis, A. africanus, A. (Paranthropus) robustus, A. (P.) boisei, and early Homo. In addition to intertaxon comparisons, we compared data that had been collected independently by two of the authors using methods that differ slightly in technique of measurement. Interobserver differences were evaluated by the t-test of paired comparisons, method error statistic, percent differences, and principal component analysis. Results suggest that between-technique error of measurement of overall crown area is small. Error estimates for individual cusp area measurements were of larger relative magnitude. However, these were not sufficient to detract from the conclusions derived from comparative analyses. Our results are in general agreement with previous assessments of early hominid dental size. Crown areas of A. africanus, however, exhibit a mosaic pattern, with M1 similar in size to that of A. afarensis and early Homo, and M2 and M3 similar in size to that of A. robustus. Intertaxon comparisons of relative cusp area were undertaken by univariate statistics and principal component analysis. These analyses revealed that while A. (P.) robustus and A. (P.) boisei both possess mandibular molars with cusp proportions significantly different from the ‘non-robust’ taxa, these differences are substantially greater in A. (P.) boisei. © 1994 Wiley-Liss, Inc.