The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Ecomorphology of the bovid astragalus: body size, function, phylogeny, and paleoenvironmental reconstruction


Department of Anthropology, University of Texas at Austin

Friday 1, Park Concourse Add to calendar

Many antelopes (bovids) are habitat specialists, making them valuable for paleoenvironmental reconstruction. Astragali are frequently the most abundant postcranial skeletal element in fossil collections. Thus, bovid astragali offer a robust statistical sample for inferring past habitats, provided astragalar morphology reflects habitat preference. Bovids are known to differ in degree of cursoriality due to habitat-dependent strategies of predator avoidance.

Previous work on the ecomorphology of the bovid astragalus relied heavily on raw measurements with little or no functional justification. Indeed, a recent study (Klein et al. , 2010. Journal of Archaeological Science 37:389–401) suggests that prior work on astragalar ecomorphology merely captured body size differences between habitat groups. The functional links between bovid astragalar morphology and habitat are poorly understood.

In this study, I test two functional hypotheses relating astragalar morphology to habitat preference. Highly cursorial bovids living in structurally open habitats are hypothesized to have (1) greater parasagittal range of motion at the ankle and (2) more pronounced “spline-and-groove” morphologies promoting lateral joint stability compared with less cursorial bovids occupying structurally closed habitats.

I laser-scanned 100 bovid astragali from 35 different extant species across the habitat spectrum. I collected a dataset of 10 measurements with predicted functional relevance, corrected them for body size using a geometric mean of all measurements and used Phylogenetic Generalized Least Squares (PGLS) to control for phylogeny. Results demonstrate significant morphological differences between habitat groups consistent with functional hypotheses. This study validates the use of the bovid astragalus as a habitat predictor.

This work was supported by a NSF Graduate Research Fellowship.

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