The Baringo Basin in the Rift Valley of East Africa has been one of the most productive areas in the world for finding hominoid fossils from the important period of 4-14 million years ago (mya). Reconstructing paleoenvironments for this period is highly relevant to determining whether development of open landscapes should be considered a pivotal driving mechanism during this period in human history. Paleohabitat reconstruction can provide proximate causes for divergence and subsequent radiation of the Hominidae. In particular, Late Miocene and Pliocene sediments exposed along the eastern flanks of the Tugen Hills, west of Lake Baringo, have yielded extensive fossil vertebrate assemblages including 6 of the 11 unequivocal hominoid specimens known from Africa in this time range. These exposures provide a unique opportunity to establish a detailed environmental-ecological context in which change in human fossils over time may be assessed. Preliminary isotopic data and previous analyses of fossil fauna suggest major alteration of the Tugen Hills habitat between 6 mya and 9 mya. This research will provide high resolution stratigraphic, geochemical, and paleontologic data collected from horizons in the 2-12 mya interval which will be used to reconstruct aspects of paleohabitat and paleocommunity and to determine more precisely the timing and nature of environmental change in the Baringo Basin.
