| The upper Busidima Formation (1.6 Ma to < 0.16 Ma), located in the Gona Paleoanthropological Research Project (GPRP) study area, Afar Depression, Ethiopia, has yielded a large collection of Pleistocene vertebrate fossils, archaeological materials, and hominid remains, including a female pelvis attributed to Homo erectus. The significance of the upper Busidima as a rich paleoanthropological site underscores a need for paleoenvironmental data with which to contextualize these materials. This dissertation presents a paleoecological study of three informal stratigraphic units within the upper Busidima Fm. (Boolihinan, Dark Paleosol, and Dahuli) based on taxonomic identification of vertebrate fossils, reconstruction of bovid paleodiets based on mesowear and stable isotope analyses of dentition, and paleovegetation reconstruction via stable isotope analyses of pedogenic carbonates. The faunal and paleovegetation evidence indicate that the lower-most Boolihinan unit (1.7 -- 1.5 Ma) may be characterized as savanna woodland in close proximity to a large, fluvial water source. The landscape changes in the Dark Paleosol unit (1.4 -- 0.9 Ma), as faunal and stable isotope data indicate increased grasslands with a marsh component, evidenced by abundant cane rats (Thryonomys) and reedbucks (Redunca). Paleoecological interpretations of the uppermost Dahuli unit (0.81 - < 0.64 Ma) suggest the return of a relatively more wooded environment to the upper Busidima. The paleoenvironmental variations through time in the upper Busidima are likely due to lateral migrations of the paleo-Awash River through the Awash Valley, rather than the often-cited aridification trend noted at other East African sites. These results caution against projecting regional environmental trends onto all Pleistocene East African fossil localities and suggest that early Homo may have had to negotiate fairly heterogeneous environments well into the mid-Pleistocene. |
