Accelerator 14-C Dating of Individual Species of Small Animals for Reconstructing Paleoclimates 20,000-8000 Yr in N. America

北美晚更新世小型哺乳动物群 在过去的20年里， 两万年 关于这些的主要特征 更新世生物多样性是其物种多样性高， 非模拟社区（不和谐的动物群），以及 物种对区域气候变化的个体反应。 因为不和谐动物群的概念对于 模拟气候变化和生物群落的发展， 这个假设必须用加速器质量来定量检验 光谱（AMS）C测年的个别化石物种， 现在是异地的 目标是用AMS C测定140个化石的年代， 沿着一个环境样带的分层洞穴：霍尔洞穴， 德克萨斯州;阿肯色州的佩卡里洞穴;田纳西州的贝克海崖洞穴。 此外，大约有20对不和谐的化石物种 从单一成分的网站将被添加到数据集。 的 C日期将1）评估不和谐的组合是否是自然的 发生，2）提供物种迁移的年表和3） 将大大改善生物变化的年表 在过去的两万年里。 最终，C年代测定将 提供关于动物群变化背景水平的定量数据- 目前生态学家还无法获得这些数据。

Late Pleistocene small mammal faunas from North America are used extensively as proxies for climate changes during the last 20,000 years. The dominant characteristic regarding these Pleistocene biotas is their high species diversity, the existence of non-analog communities (disharmonious faunas), and the individualistic response of species to regional climate change. Because the concept of disharmonious faunas is critical to modeling climate change and the development of biotic communities, this hypothesis must be tested quantitatively---by accelerator mass spectrometry (AMS) C dating of individual fossil species that are now allopatric. The goal is to AMS C date 140 fossils from three stratified caves along an environmental transect: Hall's Cave, Texas; Peccary Cave, Arkansas; and Baker Bluff Cave, Tennessee. In addition, approximately 20 pairs of disharmonious fossil species from single-component sites will be added to the data set. The C dates will 1) evaluate if disharmonious assemblages are natural occurrences, 2) provide chronologies for species migrations and 3) will improve significantly the chronologies for biotic changes during the past 20,000 years. Ultimately, the C dating will provide quantitative data on background levels of faunal change-- data presently unavailable to ecologists.