Feeding adaptations in New World primates: an evolutionary perspective: introduction.

Research conducted over the past decade has dramatically increased our knowledge of the evolutionary biology, behavior, and ecology of New World primates. Extensive field data have been collected for species from virtually all of the 16 extant genera. During this same period, the discovery of a large number of platyrrhine fossils from the Oligocene of Argentina and Bolivia, and the Miocene of Colombia, has led to a major reevaluation of the evolution and systematics of this primate group (Fleagle and Rosenberger, 1990). These specimens provide a more complete sequence from which to identify phylogenetic relationships between fossil and living forms. There is now serious doubt concerning the simple and longstanding dichotomy of New World primates into “clawed and “nonclawed taxa, and researchers have constructed a new framework for assessing the adaptive trends which characterize this important primate radiation. The papers presented in this issue of the American Journal of Physical Anthropology were originally presented on April 7, 1989, at the 58th Annual Meeting of the American Association of Physical Anthropologists in San Diego, California. The purpose of the symposium was to examine in detail the evolution of feeding adapations in each of the four subfamilies of living New World primates-Callitrichinae, Cebinae, Pitheciinae, and Atelinae. Within each paper, special attention is given to relationships between body size, diet, dental morphology, locomotor anatomy, and foraging behavior. Comparisons are made between extinct and extant taxa, as well as interspecific comparisons within subfamilies. These provide a basis for understanding the origin and function of dietary adaptations in Platyrrhini. The lead paper by Ford and Davis outlines the major issues and lines of evidence that have been used to construct the phylogenetic history of New World primates. Beginning with the argument that the traditional CallitrichidaeICebidae classification can no longer be supported, these authors review several recently proposed schemes of platyrrhine systematics. Although these schemes are in general agreement regarding the taxonomic grouping within the Callitrichinae (the marmosets and tamarins; termed Callitrichidae by some authors), and the close evolutionary relationship between the Atelinae and the saki-uakari group, the positions ofdotus, Callicebus, Saimiri, and Cebus continue to be debated. Ford and Davis also address a series of questions regarding the influence of body size (weight) on Neotropical primate foraging strategies. These authors argue that the evolutionary history of many platyrrhine lineages has been characterized by major increases andor decreases in body size. Comparisons of feeding adaptations in extant species, therefore, must consider “patterns of body size change through time,” and whether particular taxa have attained similar size through common or independent evolutionary pathways. Ford and Davis provide four alternative cladograms to account for the direction and magnitude of body weight changes in living New World monkeys and use these reconstructions to identify significant dietary, behavioral, locomotor, and ecological issues in