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

用马齿化石的稳定同位素解释北美晚更新世纬度梯度地球化学研究表明，哺乳动物牙齿化石中保存了碳酸盐组成的原始同位素记录。牙齿化石的碳含量表明了食草动物的植物性饮食，氧含量表明了环境温度。在更新世晚期，马的化石在北美非常广泛，以前的研究表明它主要是食草动物。本研究的目的是分析更新世广泛分布地区的马齿化石的碳氧含量，以确定C3和C4草分布和温度的南北纬梯度变化。将使用整体分析或连续切片技术进行1000个同位素分析。这项研究产生的分析数据将通过建立地理信息系统数据库与其他全球变化参数相结合。末次全冰期（约2万至1.5万年前）的结果将与末次晚冰期（约1.5万至1万年前）的结果进行比较。预测末次全冰期全球纬向气候带相对压缩（C3草多、冷、季节性强）。该研究对重建晚更新世全大陆古气候和古生态具有重要意义。

Late Pleistocene Latitudinal Gradients in North America Interpreted from Stable Isotopes of Fossil Equus TeethBruce J. MacFadden 9909186Geochemical 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.