CONICET | Buscador de Institutos y Recursos Humanos

ABSTRACT. Pattern of skull development and sexual dimorphism were studied in Cebus apella and Alouatta caraya using univariate, bivariate, and multivariate statistics. In both species, sexual dimorphism develops because the common growth trajectory in males extends and because of differences in growth rates between sexes. The expectation that the ontogenetic bases of adult dimorphism vary interspecifically is well substantiated by the present study. A. caraya exhibits transitional dimorphism in its subadult stage, although the condylo-basal length, zygomatic breadth, and rostrum length are strongly dimorphic in the final adult stage, being greater in males. Most cranial measurements in C. apella exhibit significant dimorphism in the adult stage,being strongly influenced by a faster rate of growth in males. Sexual dimorphism is alsoevidenced through sex differences in growth rates in several cranial measurements. These results also indicate that different ontogenetic mechanisms are acting in C. apella and A. caraya and reveal differences in the way through which neotropical primates attain adult sexual dimorphism.