Anthropology, George Washington University
Saturday All day, Plaza Level
A central goal of paleoanthropology is to understand patterns of human evolution, including the timing of appearance of key adaptations, as well as speciation and extinction events. These patterns are often correlated to physical phenomena including regional tectonics or global climatic change. Here I assess the robusticity of known patterns in hominin species turnover during the late Pliocene and early Pleistocene with data from the Omo-Turkana Basin of Ethiopia and Kenya. The data derive from the Omo-Turkana databases, compiled by the author in collaboration with many colleagues, and include records of 245 hominins from the Shungura Formation, 17 records from the Usno Formation, 211 records from the Koobi Fora Formation, 58 records from the Nachukui Formation, and 50 records from the Kanapoi Formation. In the context of the vertebrate fossil record from this region (about 64,000 records of mostly fossil mammals), we can place confidence intervals on the first and last appearance of key hominin species: Australopithecus anamensis, Kenyanthropus platyops, Paranthropus aethiopicus, Paranthopus boisei, Homo rudolfensis, Homo habilis, and Homo ergaster. The low abundance of hominin species in the context of the vertebrate fossil record from this region indicates that first and last appearances of these species remain poorly constrained. This conclusion suggests that as new research continues to improve the hominin fossil record, we should expect significant revisions to presently known patterns of hominin turnover.