1Anthropology, University of Florida, 2Anthropology, The Ohio State University
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Enamel thickness in primates is hypothesized to be the selective product of several distinct constraints on feeding. Durophagy and lifetime dietary wear are known to be associated with thickened enamel caps, while folivory—or consumption of tough, sheet-like materials—is hypothesized to be associated with both thinner enamel and more heterogeneous thickness. The presumed thinner and more heterogeneous thickness of folivore enamel has been proposed as a mechanism for producing shearing crests, whereby thinner sections of enamel are worn more quickly, exposing the underlying dentine. Junctions between remaining enamel and exposed dentine form sharp blade-like edges which are functionally analogous to ungulate lophs. Indeed, folivorous primates are known to exhibit wear patterns that enhance the lengths of enamel dentine junctions (EDJs) on occlusal surfaces.
To determine whether heterogeneity in enamel thickness characterizes the teeth of folivorous primates, we collected enamel thickness data from unworn molars of three sympatric cercopithecids for which diets are known: durophagous mangabeys (Cercocebus atys) and two folivorous colobines (Colobus polykomos and Procolobus badius). Results indicate that colobines have thinner enamel overall (p = 0.008); however, coefficient of variation measures reveal the three taxa do not differ in the variability of enamel thickness within crowns (p = 0.976).
Based on our data we argue that heterogeneous enamel thickness is not necessarily associated with folivory in primates—and is therefore an unlikely mechanism for lengthening occlusal EDJ. We suggest that additional factors, such as enamel microstructure, and disparate occlusal surface usage are important in exposing enamel-dentine interfaces.
Supported by NSF BCS-0922429 and 0921770.