Patterns of allometry in the pelvis of higher primates

Abstract

Patterns of allometric variation are compared between the pelves of six primate taxa, Pongidae, Hylobatidae, Cercopithecinae, Colobinae, Atelinae and Cebinae, using a sample of 488 specimens. The study focuses on four variables, ischium length, pubis length, lower iliac height and sagittal diameter, that were shown to be especially important in producing discrimination in a previous canonical analysis of these specimens. Ischium length, a major discriminator between colobine and cercopithecine monkeys is found to have similar coefficients of allometry in these two groups. The difference between them is more a function of position on a graph (a combination of slope and intercept) rather than allometry. The differences between these groups is shown to be significant at 95% confidence even in the smaller size range where the lines converge somewhat. Sagittal pelvic diameter was analysed in terms of two of its components—lower iliac height and pubis length. Analysis of these variables is more difficult than that of ischium length because several biomechanical factors are effected by their variation. Hypotheses are suggested about the relative significance of these factors and the specific field data required to test them are indicated.