Predicting euarchontan body mass: A comparison of tarsal and dental variables.

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Multiple meaningful ecological characterizations of a species revolve around body mass. Because body mass cannot be directly measured in extinct taxa, reliable body mass predictors are needed. Many published body mass prediction equations rely on dental dimensions, but certain skeletal dimensions may have a more direct and consistent relationship with body mass. We seek to evaluate the reliability of prediction equations for inferring euarchontan body mass based on measurements of the articular facet areas of the astragalus and calcaneus.Surface areas of five astragalar facets (n = 217 specimens) and two calcaneal facets (n = 163) were measured. Separate ordinary least squares and multiple regression equations are presented for different levels of taxonomic inclusivity, and the reliability of each equation is evaluated with the coefficient of determination, standard error of the estimate, mean prediction error, and the prediction sum of squares statistic. We compare prediction errors to published prediction equations that utilize dental and/or tarsal measures. Finally, we examine the effects of taxonomically specific regressions and apply our equations to a diverse set of non-primates.Our results reveal that predictions based on facet areas are more reliable than most linear dental or tarsal predictors. Multivariate approaches are often better than univariate methods, but require more information (making them less useful for fragmentary fossils). While some taxonomically specific regressions improve predictive ability, this is not true for all primate groups.Among individual facets, the ectal and fibular facets of the astragalus and the calcaneal cuboid facet are the best body mass predictors. Since these facets have primarily concave curvature and scale with positive allometry relative to body mass, it appears that candidate skeletal proxies for body mass can be identified based on their curvature and scaling coefficients.





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Yapuncich, Gabriel S, Justin T Gladman and Doug M Boyer (2015). Predicting euarchontan body mass: A comparison of tarsal and dental variables. American journal of physical anthropology, 157(3). pp. 472–506. 10.1002/ajpa.22735 Retrieved from

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Gabriel Yapuncich

Assistant Professor of the Practice of Medical Education

I hail from the great mountain states of Montana (the state of my birth) and Wyoming (the state of my childhood). I have a bachelor's degree in English literature from the University of Wisconsin and a bachelor's degree in the evolutionary biology from Columbia University. I completed my PhD in evolutionary anthropology at Duke University in March 2017, working with Dr. Doug M. Boyer. I have taught gross and microanatomy to Duke University School of Medicine students since 2018. In 2021, I joined the DUSOM MD program as an Assistant Professor of the Practice of Medical Education and Director of Accreditation and Continuous Quality Improvement.


Douglas Martin Boyer

Associate Professor of Evolutionary Anthropology

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