DENTAL TOPOGRAPHIC ANALYSIS OF DIETARY ADAPTATIONS IN EARLY EOCENE EUPRIMATES

Application of dental topographic allows quantification of tooth shape revealing morphological adaptations associated with food processing. Comparative analyses of dental dietary morphology in extant primates has been shown to correlate with dietary niche partitioning. In this study, dental topographic analyses are applied to compare the range of dietary overlap and possible divergence in early Eocene Euprimates (Omomyoidea, Adapoidea). Using a high resolution confocal chromatic light profilometer, 3-dimensional models of the mandibular second molars of Cantius, Teilhardina, and Tetonius were generated, and three topographic metrics were analyzed: Dirichlet Normal Energy (DNE); Relief Index (RFI); and Orientation Patch Count Rotated (OPCR). DNE measures curvature across tooth surface, RFI is the ratio between 3-dimensional and 2-dimensional surface areas of the occlusal surface, and OPCR measures relative complexity of the occlusal surface of teeth. From these metrics, the statistical significance of dental dietary variations associated with the physical processing of food sources, was evaluated. After dental topographic analyses were completed we conducted a Kruskal-Wallis test between genera along with a post hoc Mann-Whitney pairwise comparison, to determine any degree of niche space occupation between taxa. Results of this preliminary study indicate (1) dietary divergence between the adapoid Cantius and the omomyoids Teilhardina and Tetonius, and (2) overlap in dietary niche space occupation among the omomyoids Teilhardina and Tetonius. The dental topographic metrics obtained in this study yield results consistent with foliage processing by the adapoid Cantius and fruit processing by the omomyoids Teilhardina and Tetonius without clear metrics associated with faunal processing. The omomyoid results counter expected dietary parameters.The results add to our understanding of the ecological and evolutionary relationships among the primates of the earliest Eocene.