The extinction of at least 33 genera of large mammals ca 11,000 yr B.P. in the New World provides an excellent opportunity to study the dynamics of continental scale extinctions. Similar magnitude extinctions occurred throughout the Cenozoic and help define biostratigraphic Land Mammal Ages. Because the extinctions occurred within the range of radiocarbon dating, the Late Pleistocene events can be dated with the precision and accuracy needed to address ecological issues. By using accelerator mass spectrometry 14C dating of individual fossils, it is possible to date species to < +80 years at 11,000 yr B.P. The proposed research will be the 14C dating of ~80-100 large mammal fossils representing at least 15 North American genera that have undergone major changes in geographic distribution. The dating will help establish 1) If extinctions occurred significantly after 10,800 yr B.P., 2) If genera went extinct over several millennia, or en masse over a few hundred years and 3) If Late Pleistocene biotic changes were at the level of individual species or entire animal communities. This research will be a major beginning for providing time control in the multidisciplinary FAUNMAP project, a synthesis of geographic ranges for Late Pleistocene and Holocene vertebrate faunas in North America.
