Carpal Anatomy and Primate Relationships

Abstract

A comparative study of skeletonized and wet specimens of a broad sampling of prosimian as well as anthropoid primates provides evidence for the first time of the diversity of morphology and articular relations of the carpals. Phylogenetically, it appears that derived states within Primates support the monophyly of a cheirogaleine-galagine-lorisine clade (marked contact between the os centrale and the hamate), an Old World monkey clade (lack of a hamate process), and a New World monkey clade (medially truncated, but mediolaterally oriented os centrale with a laterally elongate, horizontally oriented, distal extension that is overlapped extensively dorsally by the trapezoid, and broad contact between the lunate and capitate). The latter features provide the first definitive demonstration of New World monkey monophyly on the basis of easily recognized synapomorphy. Fusion of the os centrale and scaphoid seems to occur randomly among primates. This character is thus best interpreted as autapomorphic for the relevant taxa.