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

*PRESENTATION WITHDRAWN* Isotopic evidence of hominoid paleoenvironments and diets from Napak and Moroto, Uganda


1Department of Anthropology, Emory University, 2Department of Anthropology, University of Michigan, 3Museum of Paleontology, Universtiy of Michigan

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Early Miocene sediments exposed along the flanks of the extinct Moroto (>20.6 Ma) and Napak (~20 Ma) volcanoes in Uganda have yielded extensive fossil assemblages that document the early stages of a transition from archaic to more modern East African faunal communities. Included in this transition is the earliest recorded diversification of the hominoid clade, as exemplified by the taxa Morotopithecus and Proconsul, for whom locomotor and dietary distinctions have been inferred. As part of ongoing research to establish the environmental factors associated with these evolutionary events, and to further elucidate adaptive strategies, we are developing an isotopic template of fossil herbivore dietary guilds to constrain aspects of paleovegetation and paleoclimate. Bulk isotopic analyses of enamel C and O from 130 specimens of variable herbivore taxa (including suiforms, pecorans, rhinoceros, proboscideans, primates, and anthracotheres) from multiple sites reveal dietary variability partitioned spatially and temporally in the sequences. Despite the fact that the paleohabitats were dominated by C3 vegetation, isotopic signatures of fossil taxa reveal diverse and complex foraging patterns suggesting habitat heterogeneity. Overall, the C isotopic dietary signatures of enamel range from -6‰ to -14‰ , less depleted than values characterizing modern fauna in closed canopy forests, indicating relatively open forest ecosystems at some sites. Bulk isotopic analyses of fossil enamel from Morotopithecus and Proconsul, evaluated in the context of modern hominoid isotopic signatures, indicate variable foraging strategies in more open forest habitats than is typical of extant apes.

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