CRANIAL GROWTH AND GROWTH DIMORPHISM IN ATELES-GEOFFROYI

With the exception of the work of Schultz (1960), cranial growth in At eles is not well documented. This paper describes the results of a det ailed quantitative study of cranial ontogeny in male and female Ateles geoffroyi. Using Euclidean Distance Matrix Analysis (EDMA), local are as of form change due to growth within spider monkey crania are identi fied. We found substantial change local to the zygomatic region in the face, identified mediolaterally directed changes in the palate, detec ted relatively larger amounts of change local to the anterior neurocra nium compared to the posterior neurocranium, and demonstrate a greater amount of basicranial growth along a mediolateral axis than previousl y reported. Cranial sexual dimorphism is also examined. A. geoffroyi i s noted for being monomorphic, and we found a general similarity betwe en male and female cranial forms at all developmental ages. However, d ifferences in overall cranial size between the sexes were found in the oldest subadult age group but not between male and female adults. Thi s difference suggests that A. geoffroyi females attain their adult cra nial form slightly before males and implies a pattern of earlier onset of female maturity relative to males. (C) 1993 Wiley-Liss, Inc.