1. Yale Institute for Biospheric Studies, Yale University, New Haven, CT 06520-8118 USA; Department of Anthropology, Yale University, New Haven, CT 06520-8277 USA; Department of Paleobiology, National Museum of Natural History, Smithsonian Institution,
2. Division of Vertebrate Paleontology, Peabody Museum of Natural History, Yale University, New Haven, CT 06520-8118 USA