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


Feeding biomechanics of OH 5 assessed using finite element analysis

AMANDA L. SMITH1, STEFANO BENAZZI2, GERHARD W. WEBER2, CALLUM F. ROSS3, PAUL C. DECHOW4, IAN R. GROSSE5, MARK A. SPENCER6, BRIAN G. RICHMOND7, QIAN WANG8, BARTH W. WRIGHT9, DENNIS E. SLICE10, CRAIG D. BYRON11 and DAVID S. STRAIT1.

1Department of Anthropology, University at Albany, 2Department of Virtual Anthropology, University of Vienna, 3Department of Organismal Biology and Anatomy, University of Chicago, 4Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M Health Sciences Center,, 5Department of Mechanical Engineering, University of Massachusetts Amherst, 6Department of Anthropology, Institute of Human Origins, Arizona State University, 7Department of Anthropology, Center for the Advanced Study of Hominid Paleobiology, George Washington University, 8Division of Basic Medical Sciences, Mercer University School of Medicine, 9Department of Anatomy, Kansas City University of Medicine and Biosciences, 10Department of Scientific Computing, The Florida State University, 11Department of Biology, Mercer University

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The craniofacial morphology of Paranthropus boisei exhibits a number of highly derived characteristics that have been argued to be functionally related to feeding. These include an anteriorly-placed sagittal crest, a visor-shaped infraorbital region that extends anteriorly and laterally, a zygomatic root that arises anteriorly relative to the tooth row and extremely flared zygomatic arches that twist about their transverse axes. Together, these features are hypothesized to either decrease structural stress, increase the mechanical advantage of the masticatory muscles, or both. This study uses finite element analysis to separately test the hypotheses that the P. boisei cranium is structurally stronger and configured to more efficiently generate bite force than the crania of Pan troglodytes and Australopithecus africanus.

Binary stereolithography files of the external craniofacial surface, the frontal sinus, the left and right maxillary sinuses, the teeth including roots, and trabecular bone of OH5 were obtained from a recent virtual reconstruction of this specimen. Surface files were edited and meshed to produce a finite element model. The model was assigned heterogeneous, orthotropic material properties characteristic of chimpanzee crania, constrained at the TMJs and molar and premolar bite points, and subjected to isometrically scaled muscle forces derived from chimpanzees. Von Mises, maximum principal and minimum principal strains were recorded from various locations across the cranium, as were bite forces and strain energy. The results were compared to those from comparable finite element analyses of crania of Pan troglodytes and Australopithecus africanus. Preliminary findings from these comparisons are broadly consistent with the functional hypotheses.

This project was funded by grants from the National Science Foundation Physical Anthropology HOMINID program (NSF BCS 0725219, 0725183, 0725147, 0725141, 0725136, 0725126, 0725122, 0725078) and the EU FP6 Marie Curie Actions MRTN-CT-2005-019564 “EVAN”.

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