Middle Pleistocene Glacial-Interglacial Transitions and Their Effect on Mammalian Community Reorganization in Colorado

该项目将完成收集并分析一个 中更新世化石哺乳动物群极好序列 豪猪洞，位于科罗拉多落基山脉的高处。 这些化石和其他有关资料将用于：（1）鉴定 高海拔（2900米）哺乳动物群落 通过冰川-间冰期的过渡， 在40到80万年前。 (2)量化，通过 计算机化成像和统计技术， 信号包含在地理分布和空间 形态变异的选定现存物种，也是 存在于化石动物群中。 (3)测试五个假设 气候和哺乳动物群落之间的相互作用。 的 假设是制定特别是为了测试是否变化， 季节性是触发主要社区的重要因素 重组，这是共同进化的基石， 非均衡模型 检验假设将依赖于 将动物群数据与过去的独立预测因素进行比较， 气候，特别是氧和碳同位素曲线（及其 随之而来的影响全球冰量，温度， CO2水平）和模型生成的季节性估计， 其他气候参数。 这项研究对于确定振荡是如何 在特定气候参数下，哺乳动物 在没有人类影响的情况下。 此类信息 目前还没有，不能排除人为影响。 甚至更新世晚期的群落变化-- 对于预测现代可能发生的事情非常有用 几十年到几百年的"保护"生态系统。 额外的意义在于（1）提供一个 在一段时间内发现了异常丰富的动物化石， 一个鲜为人知的地方，这反过来又产生了古生态学， 进化和古气候的见解;（2）精炼和 开发定量技术， 信号来自于脑血管造影范围和形态变化， 哺乳动物物种，目前在许多化石地点的 美国西部

This project will finish collecting and will analyze a superb sequence of middle Pleistocene fossil-mammal faunas from Porcupine Cave, located high in the Colorado Rocky Mountains. The fossils and other relevant data will be used to: (1) Identify how high-elevation (2900 m) mammalian communities were reorganized through glacial-interglacial transitions between - 400,000 and 800,000 years ago. (2) Quantify, through computerized imaging and statistical techniques, the climatic signal contained in the biogeographic distribution and spatial morphologic variation of selected extant species that also are present in the fossil faunas. (3) Test five hypotheses about the interaction between climate and mammalian communities. The hypotheses are formulated especially to test whether changes in seasonality are important in triggering major community reorganizations, which is the cornerstone of the coevolutionary disequilibrium model. Testing the hypotheses will rely on comparing the faunal data with independent predictors of past climate, notably oxygen- and carbon-isotope curves (and their attendant implications for global ice volume, temperature, and CO2 levels) and model-generated estimates of seasonality and other climatic parameters. This research is important in identifying how oscillations in specific climatic parameters provoke changes in mammal communities in the absence of human impact. Such information currently is unavailable -- human influence cannot be ruled out of even late Pleistocene commu n ity changes -- and will be extremely useful in predicting what might happen to modern "protected" ecosystems over tens to hundreds of years. Additional significance lies in (1) providing an exceptionally rich sample of the fossil fauna for a time and place where little is known, which in turn yields paleoecologic, evolutionary, and paleoclimatic insights; and (2) refining and developing quantitative techniques for extracting the climatic signal from biogeographic ranges and morphologic variation of mammal species that are present in numerous fossil sites of the American West.