1Anatomy, Kansas City University of Medicine and Biosciences, 2Anthropology, University of Massachusetts, 3Biology, University of Massachusetts, 4Mechanical and Industrial Engineering, University of Massachusetts
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Recent stable carbon isotope and finite element analyses of the craniofacial biomechanics of the subfossil lemurs Hadropithecus and Archaeolemur have revealed differences suggestive of tough food feeding in Hadropithecus and a broader diet including some large hard foods in Archaeolemur. In this study we further investigate the feeding propensities of Archaeolemur by comparing its craniofacial biomechanics with that of the destructive feeding Sapajus apella and sclerocarpic Cacajao calvus. Finite element models of all species were created from CT scans of the crania of single individuals. Five different bite point load cases were compared, including biting at the upper incisors, upper canine, P3, and M2. The fifth case involved a Cacajao specific pattern of loading with constraints on the buccal edge of the lateral incisor and lingual edge of the canine loaded to mimic the exploitation of pyxidia of the family Lecythidaceae. In every bite case Cacajao exceeded both S. apella and Archaeolemur in biting effieciency (muscle force/bite force). In turn, Sapajus exceeded Archcaeolemur in every case and more closely approximated Cacajao in efficiency. Maps of von Mises stress also revealed a markedly more diffuse pattern of stress for all load cases in Archaeolemur, which is hypothesized to be a consequence of the open post-orbit. The fact that Archaeolemur more closely approximates Sapajus in bite efficiency suggests a relatively generalized form of destructive and hard food feeding in this subfossil lemur. These findings are further discussed in light of preliminary observations of the craniofacial biomechanics of the wood gouging Daubentonia madagascariensis.
This project was funded by a grant from NSF (DBI-0743460), and KCUMB Department of Research