Morphometric analysis of craniofacial growth in Cebus apella.

The present study was undertaken to provide a quantitative description of craniofacial growth in Cebus apella in three dimensions. Landmarks from a cross-sectional sample of sexed and dentally aged crania were collected using a 3Space digitizer. Two methods of three-dimensional form analysis, euclidian distance matrix analysis (EDMA) and finite-element scaling analysis (FESA), were used to investigate growth changes in the cranium. Male and female growth was examined by comparing the youngest male mean form to all other age/sex specific mean forms. In addition, form differences between the sexes were studied by comparing male and female mean forms at each age. The cranium was divided into four regions for analysis: muzzle, upper face, neurocranium, and basicranium. Growth changes within each region were examined. In the muzzle and neurocranium, most growth occurs along the anteroposterior axis. Growth around pterion and the lower orbital rim is prominent within the upper face. The basicranium shows a surprisingly large amount of form change with growth. This form change is due to the mediolateral expansion of the basioccipital, and to the posterior migration and inferior rotation of basion. Males and females have similar growth patterns, but males tend to be larger than females in nearly all dimensions at every developmental age except the youngest. Evidence suggests that craniofacial sexual dimorphism is primarily due to males growing faster than females for approximately the same amount of time.