Diet and Incisor Surface Curvature in Cercopithecids
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Date
2012-06
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The Ohio State University
Abstract
Understanding the relationship between tooth morphology and feeding ecology in extant taxa provides for more reliable interpretations of the primate fossil record. Recent studies by Deane (2005, 2008, 2009) suggest that frugivorous species, especially hard-object feeders, have incisors of relatively greater labial and mesio-distal curvature than folivorous species. The present study builds on the work of Deane and that of Schubert et al. (2010) to further test the relationship between diet and incisor surface curvature in an expanded sample of African cercopithecids.
Maxillary central and lateral right incisors of adults were measured in a sample representing ten cercopithecid genera and eleven species for which dietary information was available. Each taxon was assigned to one of three diet categories. Points were recorded at one-millimeter intervals along the surface using a measuring microscope. Polynomials were then fit to the data and the first derivative of the line tangent to the curve at each point was determined. Logistic regression analysis on the first derivatives was used to test the ability of incisor curvature to predict diet type.
Results indicate that, based on incisor curvature, individuals could be correctly assigned to their respective diet categories more than 73% of the time when two groups were compared at a time. However, when the mean slopes of the lines tangent to the curve were compared there appeared to be little difference among the three groups, indicating there may be no discernable difference in incisor curvature among the categories used. More data on food material properties as well as on the mechanics of incising different food types are necessary to test associations between curvature and diet and to determine the functional significance of incisor curvature. Only then can we know if this element of incisor shape can be used to infer diet in fossil taxa.
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Keywords
Primates, Teeth, Diet