The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Dental morphology and dietary adaptation in Homunculus patagonicus


Evolutionary Anthropology, Duke University

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Homunculus patagonicus, from the Miocene of Patagonia, is part of the southernmost limit of the platyrrhine radiation. While paleoecological reconstructions of Miocene Patagonia suggest a warmer environment than is present today, there would have been significant seasonality, perhaps requiring dietary flexibility throughout the year. To better understand the dental adaptations of Homunculus, our study uses three-dimensional geometric morphometrics to examine molar morphology. The maxillary and mandibular first and second molars of a sample of platyrrhine primates (n>250) were laser scanned to create three-dimensional models. Twenty-three x,y,z coordinate landmarks were applied to each tooth to outline major morphological features such as crests, cusp tips, and basins. Principal components analysis (PCA) was then performed on generalized Procrustes analysis - aligned landmarks. For lower molars, PC1 was largely driven by cusp and crown height and was found to successfully differentiate primates of different dietary categories using discriminant function analysis (DFA). PCA of upper molar landmarks was less successful at differentiating primates by diet, and PC1 was largely driven by relative cusp position rather than cusp and crown height. Additionally, there appears to be more of a phylogenetic component to the morphology of the upper molars. Homunculus showed a moderate degree of dental relief on the lower molars – in the range of Aotus or Callicebus amongst the modern taxa. For upper molar morphology, it also fell within the range of these species. DFA classifies Homunculus with the frugivorous primates, but it falls within the range of the less committed frugivores Aotus and Callicebus.

This study was partially funded by: NSF DDIG # 40761-0001 (SBC) and NSF 0851272 (RFK).

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