72 - Using Topographic Measurements to Detect Sexual and Dietary Signal in the Cercopithecoid Honing Premolar

Poster Board Number: 72
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Abstract Body : The cercopithecoid P3 has a unique morphology that is specialized for honing the enlarged upper canines; this ‘honing premolar’ forms a functional module with the canines that has played a key role in anthropoid evolution. P3 exhibits extreme sexual dimorphism in correlation with canine size, with males generally possessing extremely elongate ‘honing facets’ on P3 to accommodate enormous maxillary canines. The selective pressures related to dietary ecology influencing the evolution of the P3 have not been thoroughly investigated; this study addresses this gap in our knowledge using dental topographic measures Orientation Patch Count Rotated and dental relief (OPCR , RFI). The sample includes unworn premolars from 48 specimens representing 15 extant species of cercopithecines and colobines. Dentition were scanned to create three-dimensional meshes, which were processed in Geomagic prior to taking measurements in R using the molaR package. ANOVAs were utilized to test for topographic differences between sexes and two dietary groups: folivores and frugivores.
Relief indices differed significantly between males and females; this is likely related to sexually dimorphic premolar elongation. Significant topographic differences were also measured between males of different dietary ecologies, with folivores possessing higher median OPCR values compared to frugivores. Relationships are less clear among females. These results indicate that folivorous cercopithecoids have evolved a more molarized honing premolar in response to stronger dietary pressures (stemming from the need to masticate tough vegetation) and/or a reduced pressure toward evolving canine weaponry compared to frugivorous taxa, which tend to be more aggressive.