1. Geobiology Program, Department of Anthropology, George Washington University, Washington, DC 20052; Geophysical Laboratory, Carnegie Institute of Washington, Washington DC 20008
2. Geophysical Laboratory, Carnegie Institute of Washington, Washington, DC 2008
3. Center for Geochronological Research, Institute of Arctic and Alpine Research and Department of Geological Sciences, University of Colorado, Boulder, CO 80309
4. Center for Geochronological Research, Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309; Department of Geosciences, University of Arizona, Tucson, AZ 85721
5. Department of Anthropology, Southern Methodist University, Dallas, TX 75275