Cranio-Mandibular Biometrics and Skull Maturation of Macaca sylvanus L., 1758

We report on the biometrics of cranial and dental features in 42 Macaca sylvanus specimens from various museums across Europe. Age classes were determined following dental criteria. Standard biometric landmarks were used to take 17 measurements on the cranium and five on the mandible. The permanent cheek dentition (except the C1/C1–P3/P3 complex) was also recorded with four measurements for each molar tooth (three for the P4/P4). Skull measurements show strong sexual dimorphism for characters tied to the mandibular and muzzle/facial portions. The unusual molar dimorphism of M. sylvanus is rather an unexpected result, as well as the significant difference, between M. sylvanus and other macaques, in the respective narrowing of the molar distal loph. Finally, a multivariate comparison for absolute shape difference, into the whole M. sylvanus longitudinal sample, suggests that in the males the full maturation of skull shape is delayed longer than what would be expected, in spite also of the most restrictive dental criteria used here for the subadult/adult discrimination. By clustering results, indeed, major phenetic differences seem to persist between most of male crania which are far advanced in their latest dentition steps and the “fully developed adults”. Outcomes of final growth such as observed in M. sylvanus suggest that polymorphic maturational patterns may seriously mislead the assessment for a true adult skull shape.