Late Pleistocene Latitudinal Gradients in North America Interpreted From Stable Isotopes of Fossil Equus Teeth

University Of Florida, Gainesville FL

Investigators

Abstract

Late Pleistocene Latitudinal Gradients in North America Interpreted from Stable Isotopes of Fossil Equus Teeth Bruce J. MacFadden 9909186 Geochemical studies have shown that the original isotopic record of carbonate composition is preserved in fossil mammal teeth. The carbon content of fossil teeth indicates the plant diet of herbivores and the oxygen indicates ambient temperature. During the late Pleistocene, the fossil horse Equus was very widespread throughout North America, and previous studies have shown that it was predominantly a grazer. The goal of this study is to analyze the carbon and oxygen content of fossil Equus teeth from widespread localities during the Pleistocene to determine changes in N-S latitudinal gradients of C3 and C4 grass distribution and temperature. One-thousand isotopic analyses will be conducted using either bulk analysis or serial sectioning techniques. The analytical data produced from this study will be integrated with other global change parameters through the establishment of a GIS (Geographic Information Systems) database. Results from the last Full Glacial (ca. 20,000 to 15,000 years ago) will be compared to those of the last Late Glacial (ca. 15,000 to 10,000). It is predicted that global latitudinal climatic belts were relatively compressed (i.e., more C3 grasses, colder, and more seasonality) during the last Full Glacial. This study will have broad ramifications with regard to reconstruction continental-wide paleoclimates and paleoecology during the late Pleistocene.