Evolution of hallucial grasping in the primates

Homology of the adaptive solutions of grasping, like other attributes of the postcranial skeleton, have long been assumed for marsupials, early eutherians, and euprimates. Evidence is presented which contradicts this view. The origin of grasping is documented and discussed in the order Primates, the semiorder Euprimates, the suborders Strepsirhini and Haplorhini, and the semisuborder Anthropoidea. Grasping may have been primitive in the cohort Archonta, but the euprimate grasp appears to be related not only to climbing but to a saltatory, graspleaping, locomotor mode of the common ancestor. The origin of anthropoid modifications involves a reduced emphasis on the pedal grasp. The "prehallux" hypothesis for the explanation of the sesamoid in the entocuneiform-hallucial articulation of anthropoids cannot be corroborated by either topographical, developmental, or functional evidence.