1Division of Anthropology, American Museum of Natural History, 2Center for the Advanced Study of Hominid Paleobiology, The George Washington University, 3Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 4Paleobiology Department, National Museum of Natural History, Smithsonian Institution, 5Archaeology Department, National Museums of Kenya, 6Anthropology Department, University of Nevada Las Vegas
March 27, 2015 1:30, Grand Ballroom E/F/G
Footprint assemblages preserve unique records of events in specific locations over short periods of time. Interpreting their significance involves a number of challenges, including how to draw statistically robust inferences about behavior based on a small number of individual sites. Recently, our excavations have unearthed hominin prints at several localities. To test the hypothesis that hominins are more abundantly represented among the footprint assemblages than expected based on their scarcity in the skeletodental fossil record, we used a random sampling procedure to identify outcrop areas in the Ileret Tuff Complex (c.9m stratigraphic section between 1.51-1.53Ma) near Ileret, Kenya. We excavated 20 different footprint surfaces (1x1m each) containing identifiable animal prints, documented the taxa represented, and compared their relative abundances to expected frequencies based on systematic sampling of dental and skeletal fossils (“bone walks”) from the same area and stratigraphic interval.
Results show that bovid/suid prints are most abundant, as expected based on skeletodental fossil data. Water bird prints are also well represented, despite being rare among skeletal fossils. Their presence provides compelling evidence, combined with geological data and prints of other animals such as hippopotamids, that these sites were in close proximity to substantial bodies of water. Hominin prints occur significantly more frequently than expected, providing the best to date evidence that they spent disproportionate amounts of time in these near-water habitats. The presence of multiple large hominin prints, putatitvely males, on the same short-lived footprint surfaces further suggests a social dynamic involving male-male tolerance and perhaps cooperation.
Funded by the National Science Foundation (BCS-1128170, -0924476, -1232522; DGE-0801634), Wenner-Gren Foundation, Leakey Foundation, The George Washington University Selective Excellence Initiative and University Facilitating Fund, and the AMNH.