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


Cranial shape variation in extant and fossil Papio and its implications for the evolution of the Kinda baboon

STEPHEN R. FROST.

Department of Anthropology, University of Oregon

Thursday Afternoon, 301D Add to calendar

To evaluate cranial variation in Kinda baboons relative to that of the genus Papio, forty-five three dimensional landmarks were digitized on 527 extant and fossil specimens of Papio, representing both sexes. Bilateral asymmetry was mitigated by superimposing each specimen with its mirror image and taking their average, which also replaced missing bilateral landmarks with their contralateral counterpart where present. These were analyzed using generalized Procrustes analysis, Procrustes distances, principal components analysis, multivariate regression, and partial least squares analysis. Results were visualized using Landmark editor software by warping an exemplar surface.

Static allometry and sexual dimorphism together accounted for nearly half of the total variance. Adjusting for these two factors, extant baboons fall into two major geographic clusters: northern (anubis, hamadryas, and Guinea) and southern (chacma, yellow, and Kinda), and within the latter Kinda baboons are most similar to yellows. In fact, this relationship holds even when the relatively small fossil forms P. h. angusticeps and P. izodi are included. The geographic locations of specimens accounted for the majority (64%) of variance after size and sex adjustment, with differences among the various Papio forms in turn representing a small component of the residual variation. Taking this clinal pattern into account, significant differences in cranial shape remain between all extant forms of Papio except between P. h. kindae and P. h. cynocephalus. This overall pattern of relationships for the Kinda baboon is broadly consistent molecular studies and suggests a significant amount of gene flow among baboon populations.

This research was supported by the Wenner-Gren and Leakey Foundations, as well as the University of Oregon.

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