Within this evolutionary framework, we can reasonably assume that feeding-related features observed in extant primates should be, at least in theory, demonstrably the result of natural selection. It is the demonstrable aspect of this important assumption that those concerned with dietary adaptations in the present and in the evolutionary past must confront. In addition to information derived from morphology, it is a truism that scientists studying extant primates have luxury of observing the function of diet-related anatomy via direct observation of a feeding animal, while those scientists evaluating fossil species do so in the absence of such data. Yet both scientits confront a similar challenge, and in evolutionary terms yield comparably synchronic interpretations; the ghost of selection past aunts us all. Hence, our use of the powerful combinations of comparative models, extant species analogs, and correlative evaluations as tools for interpreting changes in form and function over evolutionary time...