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


Detailed measurements of primate calcanei from 3D models allow for reliable body mass estimation

JUSTIN T. GLADMAN1,2 and DOUG M. BOYER1,2,3.

1Department of Anthropology, The Graduate Center, City University of New York, 2NYCEP, New York Consortium in Evolutionary Primatology, 3Department of Anthropology and Archaeology, Brooklyn College, City University of New York

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Determining body mass is a fundamental step in understanding the paleobiology of fossil primates. Tooth size is the most commonly available proxy for body mass in fossil taxa. Certain tarsal bones are also abundant in the fossil record. Unlike teeth, postcranial articular surfaces of weight-bearing joints transmit forces that scale proportionally to body mass, therefore offering great promise for accurately predicting body mass. This study is the first to examine the calcaneus using surface area and volumetric measurements derived from 3D surface scans. A diverse set of calcanei was represented in this study, ranging from the smallest extant primate, Microcebus, to the largest, Gorilla, and including highly derived forms such as the specialized leaper Tarsius, and the slow climber Nycticebus. Linear regressions were created using four measurements of the calcaneus: total volume and surface area, surface area of the cuboid facet and surface area of the posterior calcaneal facet against average species body masses from the literature . Results showed that facet areas had the best correlations with body mass (r2>.97). Facet areas scale with positive allometry to body mass, indicating proportionally larger facets in larger taxa. Calcaneal volume and total surface area scale with slopes suggesting geometric isometry, but were less correlated (r2>.93), suggesting variation due to other factors (e.g., function and/or phylogeny). Body masses were estimated for several fossil platyrrhines, catarrhines and subfossil strepsirrhines and were found to be comparable to published estimates from dental and postcranial data sets.

This work was supported by the New York Consortium in Evolutionary Primatology, NSF DGE 0333415 (NYCEP IGERT) and NSF BCS 1125507 to DMB.

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