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


Mandibular molar elongation distinguishes Mabokopithecus from other nyanzapithecine genera

RUTGER J.W. JANSMA1, BRENDA R. BENEFIT2 and MONTE L. MCCROSSIN2.

1Department of Anthropology, University of Minnesota, 2Department of Anthropology, New Mexico State University

Thursday 9:45-10:00, Ballroom C Add to calendar

The taxonomy of the nyanzapithecines has been challenged by the discovery of two mandibles at Maboko Island, Kenya. The M3 hypoconulid of one mandible is like that of Mabokopithecus clarki while the other is identical to Nyanzapithecus pickfordi. The mandibles also differ in the height of the genial pit, the angle of the symphyseal planum, and the degree to which the lateral incisors are caniniform, as well as subtle differences in the degree to which P4 and molar cusps are flared. The sample of isolated maxillary and mandibular teeth is highly variable, however, and difficult to sort into two discrete morphs. Consequently, determining whether two distinct genera or species occur at the site has been difficult.

In this study we examine mandibular molar crown shape variation in a large sample of Miocene and extant hominoids. We find both Mabokopithecus clarki and “Nyanzapithecuspickfordi M1s to differ from other nyanzapithecines. Given their distinctive degree of first mandibular molar elongation, we suggest it is an important character uniting the two Maboko nyanzapithecine morphs into a single genus, Mabokopithecus, and distinguishing them from other nyanzapithecines. The two Mabokopithecus species share a restricted temporal and spatial distribution at Maboko, body size, and indications of folivory, including relative proportions of scratches and pits on their molar teeth. Among living primates bamboo lemur species with similarly specialized diets coexist in spatially restricted areas and may provide a model for understanding nyanzapithecine species diversity at Maboko. A nyanzapithecine ancestry of Oreopithecus is further corroborated by this analysis.

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