Allometric Scaling of Deciduous and Permanent Molars in Catarrhine Primates

抄録

The allometric relationship between the second deciduous molar (dm2), the first permanent molar (M1), and body weight was investigated in catarrhine primates, including fossil hominid taxa. In this study, tooth and body weight measurements were compared in 14 species of hominoids and 11 species of cercopithecids. In all species, the mesiodistal and buccolingual crown diameters of dm2 were smaller than those of M1. The tooth crown area (mesiodistal crown diameter multiplied by buccolingual crown diameter) was used as the measure of tooth size. Allometric coefficients were computed as the slope of rectilinear functions of the logarithmically transformed data. Allometric scaling of tooth crown area to body weight showed isometry (the slopes ranged from 0.593 to 0.700). The allometric coefficients were slightly larger in M1 than in dm2, and were larger in the mandible than in the maxilla, but these differences were not significant. Both hominoids and cercopithecids were close to the regression line in both dm2 and M1, but Australopithecus species were peculiar that they have large permanent and deciduous molars in comparison to body weight, with A. boisei having the largest molars. These results indicated that the tooth crown size of dm2 scales to body weight in the same pattern as in the M1. The allometric scaling of the tooth crown area of dm2 to that of M1 showed negative allometry in both the maxilla and mandible, but these slopes were nearly 1.000 (0.932 in the maxilla and 0.954 in the mandible). Both hominoids and cercopithecids lay close to the regression line, indicating that the size of dm2 is closely related to that of M1.