2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 5
Presentation Time: 9:20 AM


LEVIN, Naomi, Dept. of Geology & Geophysics, Univ of Utah, 135 S. 1460 East Rm 719, Salt Lake City, UT 84112, QUADE, Jay, Department of Geosciences, Univ of Arizona, Tucson, AZ 85721, SIMPSON, Scott, Dept. of Anatomy, Case Western Reserve Univ, School of medicine, Euclid Ave, Cleveland, OH 44106 and SEMAW, Sileshi, CRAFT Stone Age Institute, Indiana Univ, 1392 W. Dittemore Road, Gosport, IN 47433-9531, nlevin@mines.utah.edu

The western margin area of the Gona Paleoanthropolgical Research Project in Afar, Ethiopia, is composed of both fluvial and lacustrine sediments, and contains abundant fossils, including those of Ardipithecus ramidus. We use the carbon and oxygen isotopic composition of paleosol carbonates, fossil teeth and aragonitic shell from these sediments to characterize early Pliocene (4.3-4.5 Ma) environments at Gona. δ13C values of paleosol carbonates and tooth enamel indicate environments with a mix of C3 and C4 vegetation wherein the majority of large mammals had C4-dominated diets. δ18O values of paleosol carbonates, fossil teeth and aragonitic shell are too low to have formed under the present climate conditions at Gona and likely indicate more rainfall and different circulation patterns in the early Pliocene.