Late Quaternary chronology and extinction of North American giant short-faced bears (Arctodus simus)

摘要

Eight new AMS radiocarbon dates on giant short-faced bears {Arctodus simus) from the contiguous United States are reported, and previously published dates from across North America are reviewed and discussed. The dates deemed to be most reliable are on purified collagen samples, and these serve as the basis for interpreting the late Pleistocene chronology and extinction of the species. The oldest acceptable radiocarbon date from the lower forty-eight states is 34,080 ± 480 BP from Island Ford Cave, Virginia, and the youngest is the previously reported 9630 ± 60 BP date from Bonner Springs, Kansas. An additional date of 10,921 ± 50 BP on the same Kansas specimen indicates a precision problem in the age of this individual. Regardless of this anomaly, new AMS dates of ～ 10,800-11,000 BP on A. simus confirm that it existed up to the Pleistocene/Holocene transition and may have been one of the last megafaunal species to go extinct in North America. Further, these dates solidify the co-existence of these massive bears with humans of the Clovis cultural complex.