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

Trabecular bone structure in the forelimb and hindlimb of quadrupedal primates and carnivores


Department of Anthropology, Pennsylvania State University

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Primate quadrupeds differ from most other mammals in having higher peak reaction forces on the hindlimb compared to the forelimb. Recent analyses indicate that primates in general have more robust trabecular architecture in the femur than in the humerus, independent of locomotor behavioral differences. These results support locomotor analyses indicating hindlimb dominance in primates, perhaps to allow the development of greater forelimb manipulatory abilities. Differential limb usage in non-primate quadrupedal species often reflect the opposite pattern of forelimb and hindlimb loading. The goal of this study is to explore the adaptive response of trabecular architecture in two contrasting loading environments, represented by primates and carnivorans. High-resolution computed tomography scan data were collected for the proximal femur and humerus of 20 individuals from three carnivoran species, and 30 individuals from four primate species. Bone volume fraction, anisotropy, trabecular thickness, spacing and number were quantified in multiple volumes of interest within the articular region of each specimen. Despite significant differences in the kinematics of locomotion among the taxa analyzed, all species exhibit the same pattern of forelimb to hindlimb trabecular bone structural organization. Bone volume fraction is significantly higher in the femoral head than in the humeral head in all taxa, independent of locomotor behavior or taxonomic group. Humeral head trabecular bone is significantly more isotropic. These results suggest that individual measures of trabecular bone do not appear to reflect locomotor behavioral differences, and potentially indicate a canalization of femoral and humeral trabecular bone architecture across quadrupedal mammals.

Grant Sponsors: NSF BCS-0617097

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