Morphometric analysis of platyrrhine femora with taxonomic implications and notes on two fossil forms

Postcranial elements have been relatively neglected in primate evolutionary studies, especially for platyrrhine primates. We have analyzed 38 variables of the femur in 92 specimens of fossil and extant platyrrhines to determine patterns of shape affinity for comparison with other, more traditional information. Callitrichids¹ and advanced cebids were separated along a morphological continuum bridged by the more generalized cebids (Cebus, Callicebus, Saimiri, Aotus). Callitrichids were very closely interrelated and included Callimico as an integral member. Pithecines (Pithecia, Chiropotes and Cacajao) and atelines (Ateles, Brachyteles, Lagothrix plus Alouatta) form two clusters with considerably greater intra-group variability, inferentially related to the great adaptive radiation and changes undergone by these groups. Two fossil specimens, Homunculus and Cebupithecia, are significantly divergent from all extant ceboids but are nearest callitrichids, lying at the extreme callitrichid pole as that grade is contrasted with cebids.