2013-09-092013-09-092005MUNIZ, Izaura da Conceição Magalhães. Desenvolvimento do dimorfismo sexual nos macacos-de-cheiro (Saimiri VOIGT, 1831). 2005. 117 f. Dissertação (Mestrado) - Universidade Federal do Pará, Museu Paraense Emílio Goeldi, Belém, 2005. Programa de Pós-Graduação em Zoologia.https://repositorio.ufpa.br/handle/2011/4223The squirrel monkeys Saimiri Voigt, 1831 are arboreal and agile primates with a relatively small body as compared to other New World primates. The species are distributed in the Amazon and part of Central America. Several investigations were contucted in order to stablish the taxonomic groups in Saimiri. However, the results of these investigations showed an amount of divergences as to the classification, taxon validity as well as the taxonomic status. In this genus, there are sexual differences with regard to the pattern of coloration of skin, size and form of canine teeth and in the annual spermatogenic cycle in males that characterises the fatted condition due to the deposition of subcutaneuos fat. During this period, the males present an increase in weight ranging from 15 to 20%. The present study aimed to analyse the sexual dimorfism in Saimiri sciureus, comparing the results with other five species of the genus Saimiri (S. cassiquiarensis, S. juruanus, S. ustus, S. boliviensis e S. vanzolinii). A total of 610 specimens were analysed from the collections of the Museu Paraense Emílio Goeldi (MPEG), Museu Nacional, Universidade Federal do Rio de Janeiro (MNRJ) and Museu de Zoologia da Universidade de São Paulo (MZUSP). The age classes were determined according to the morphology of the dental arch described on the basis of the eruptive sequence of deciduous and permanent teeth. Data on chromatic characteristics were collected to analyse the preauricular patch of females in relation to the process of dental eruption, cranial morphology to verify the sexual and age differentiation. In addition, twenty one cranial measurements were perfomed using the Student t-test. There were no differences in the coloration of the skin among the sexual classes up to the adult age in any sexes. There were no differences in the coloration of the skin among the age classes in males. The blackish preauricular patch is an exclusive trait of adult females, however it is not related to ontogeny. The beginning of the sexual dichromatism of the skin is not associated with the rising of dimorfism in cranial morphology, specially of teeth. Macroscopic sexual differences such as size and morphology of cranium, morphology of face, bizygomatic distance and morphology of jaw could be observed from the subadult age. The findings indicated that the sexual dimorfism for the species analysed is better observed in the variables related to the mastigatory apparatus. Moreover, sexual differences in the mophology of cranial bones could be clearly identified among subadult individuals of any taxon. The males were bigger than females from the subadult age onwards and the most conspicuous characteristic of the sexual dimorfism is the cranium length. The species differ from each other because they presented an exclusive or a group of morphometric variables demonstrating the sexual dimorfism.porAcesso AbertoMamíferosPrimataSaimiri sciureusMacaco-de-cheiroCaracterísticas sexuaisAmazônia brasileiraDissertaçãoCNPQ::CIENCIAS BIOLOGICAS::ZOOLOGIA::ZOOLOGIA APLICADA