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

Reassessing Guenon Craniodental Morphology: closer inspection reveals support for the arboreal and terrestrial clades


1Department of Anthropology, Hunter College of the City University of New York, 2PhD Program in Anthropology, Graduate Center of the City University of New York, 3New York Consortium in Evolutionary Primatology (NYCEP), 4Department of Cell and Neurobiology, University of Southern California

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The guenons (tribe Cercopithecini) are a diverse radiation of arboreal and terrestrial monkeys distributed across sub-Saharan Africa. Traditional morphological estimates of guenon phylogeny have placed the origin of the guenon clade at 1-2 mya and suggested that terrestriality evolved multiple times within the radiation. Recent molecular studies, however, suggest that guenons originated approximately 11.5 mya and that committed terrestriality evolved only once, hypothesizing two major sub-clades, one largely arboreal, and the other terrestrial. This molecular arrangement renders the genus Cercopithecus, currently associated with taxa in both clades, paraphyletic. Considering this lack of congruence between morphological and molecular data, are there any morphological features in guenon anatomy that support the molecular findings? Although guenon postcrania have been examined, there are fewer analyses of craniodental traits. In this study, we analyzed the craniodental morphology of 10 guenon species using measurements collected from calipers and digital photographs. We compared several craniodental features found in the proposed arboreal guenon clade to the corresponding features in the proposed terrestrial clade. After controlling for body size, 11 of 18 characters analyzed were significantly different between the two groups (Mann-Whitney U, p≤0.05). Terrestrial guenons exhibit features such as: wider orbits, broader biorbital widths, and mesiodistally longer M2s. Arboreal guenons exhibit traits including taller mandibular rami and increased basicranial length. Thus, these results demonstrate that there are craniodental characters supporting the molecular groupings. Our findings also highlight the need for reevaluation of guenon morphological systematics and suggest that there is much more to understand about guenon craniodental diversity.

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