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


Unmasking the cryptic Cercocebus/Mandrillus clade in the fossil record: a new genus of Plio-Pleistocene African papionin from Ethiopia and Angola

CHRISTOPHER C. GILBERT.

Department of Anthropology, Hunter College of the City University of New York, Department of Anthropology, Graduate Center of the City University of New York, NYCEP, New York Consortium in Evolutionary Primatology

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Since its discovery 30 years ago, researchers have debated the systematic position of Papio quadratirostris, a large papionin cranium found in the Usno Formation of the Omo group, Ethiopia. While some have suggested that P. quadratirostris represents an early member of the genus Theropithecus (specifically a T. brumpti relative), others have argued that its original assignment to Papio was correct and have subsequently assigned a handful of specimens from the Omo Shungura and the Humpata Plateau of Angola to the P. quadratirostris hypodigm. At the time of these arguments, the genus Papio was generally understood to include extant mandrills, drills, and savannah baboons. More recently, however, both genetic and morphological data have instead demonstrated that mandrills and drills are most closely related to Cercocebus mangabeys; a number of features have now been documented differentiating the Cercocebus/Mandrillus group from savannah baboons, geladas and Lophocebus mangabeys.

In this new phylogenetic light, the current study re-examines the P. quadratirostris hypodigm from Ethiopia and Angola. Upon closer inspection, I identified a number of P. quadratirostris craniodental morphologies shared exclusively with the Cercocebus/Mandrillus group. A comprehensive cladistic analysis including fossil and extant African papionins also supports a close relationship to Cercocebus/Mandrillus, broadly, or Mandrillus, more specifically. Because P. quadratirostris is neither closely related to Papio nor Theropithecus, the hypodigm requires a new generic nomen. Along with Procercocebus from Taung, South Africa, this new genus of African papionin represents some of the best evidence of the cryptic Cercocebus/Mandrillus clade in the fossil record.

This study was generously supported by the L.S.B. Leakey Foundation.

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