Morphological variation in adult chimpanzees (Pan troglodytes verus) of the Tai National Park, Cote D'Ivoire

Twenty five adult chimpanzee skeletons (Pan troglodytes verus) of known age and sex (15 females, 10 males) from a long-term study site in Tai National Park, Cote d'Ivoire present new data on variation. These skeletons provide a rare opportunity to measure the cranium and postcranium from the same individuals. We compare measurements and indices of the Tai sample with those of relatively complete Pan troglodytes schwein-furthii skeletons from Gombe National Park, Tanzania. Measurements of Pan paniscus are included as an outside comparison. The Tai and Gombe samples are analyzed by sex; combined sex samples are compared between the two groups, and the two sexes to each other. Tai females and males do not differ in most long bone lengths or in pelvic dimensions, but do differ significantly in cranial capacity, facial measurements, clavicle length, scapular breadth, and femur length. Gombe females and males differ significantly in some facial measurements and in scapular breadth. In combined sex samples, Tai individuals have lower cranial capacity, longer palate and mandible, and greater dimensions in the trunk and limb lengths. Tai females account for most of the variation; males differ from each other only in greater length of humerus and femur. The Tai skeletons provide new data for assessing individual variation and sexual dimorphism within and between populations and species. The combination of cranial and postcranial data provides a clearer picture of chimpanzee intraspecific and interspecific variation than can be gained from either data set alone.