The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)


Late Pliocene to Late Pleistocene paleoenvironments in southwestern Kenya from carbon isotopes in herbivore tooth enamel

SCOTT A. BLUMENTHAL1,2, THOMAS W. PLUMMER1,2,3, THURE E. CERLING4, PETER W. DITCHFIELD5, LAURA C. BISHOP6, J. TYLER FAITH7, CHRISTIAN A. TRYON8, DANIEL J. PEPPE9, EMILY J. BEVERLY9 and RICHARD POTTS10.

1Department of Anthropology, The Graduate Center, City University of New York (CUNY), 2New York Consortium in Evolutionary Primatology (NYCEP), 3Department of Anthropology, Queens College, CUNY, 4Department of Geology and Geophysics, University of Utah, 5School of Archaeology, University of Oxford, 6Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, 7School of Social Science, University of Queensland, 8Department of Anthropology, Harvard University, 9Department of Geology, Baylor University, 10Human Origins Program, Smithsonian Institution, National Museum of Natural History

March 27, 2015 2:30, Grand Ballroom E/F/G Add to calendar

While a number of hypotheses have been proposed directly linking hominin evolution with environmental change, the breadth of available terrestrial environments across eastern Africa over the past 3 million years remains poorly understood. We use stable carbon isotopes in herbivore tooth enamel from fossil- and artifact-bearing deposits in the Lake Victoria region, southwestern Kenya to reconstruct paleoenvironmental conditions from the Late Pliocene to Late Pleistocene. We sampled 386 fossil teeth from seven time intervals, including material from the Late Pliocene Rawi Formation, the Early-to-Middle Pleistocene Kanjera Formation, the late Early Pleistocene Kasibos Formation, and the Late Pleistocene exposures at Karungu. Fossils sampled include all major large mammalian herbivore taxa. The distribution of enamel carbon isotope values from each time interval includes a peak at or greater than -1‰, indicating that most herbivores had a C4-dominated diet. Isotope values from Kanjera North Bed 5 have an additional, lower peak at -3‰ that indicates many herbivores also had a mixed C3/C4 diet. All time intervals except Rawi include 1-5 individuals with C3-dominated diets, but none consuming closed-canopy forest vegetation. Our results demonstrate that from the Late Pliocene through the Pleistocene herbivores in southwestern Kenya primarily relied on C4 resources, which indicates that paleoenvironments in this region were characterized by an abundance of grass during periods of fossil mammal preservation. These findings indicate that the spectrum of habitats available to hominins in eastern Africa included those associated with the savanna biome at multiple time intervals over the last 3 million years.

This research was funded by the National Science Foundation (BCS-1260535,BCS-1327047, BCS-1013108), The Leakey Foundation, and The Wenner-Gren Foundation, and the National Geographic Society (9284-13 and 9349-13).