Miocene Continental Paleoclimate and Fossil Horse Evolution:Trace Element and Stable Isotope Geochemistry of Enamel- Phosphate

我们建议探索将中新世中期 通过建立系统学， 微量元素和同位素在骨骼和牙齿中的保存 北美化石马的磷酸盐。 我们将测试 牙釉质磷酸盐提供了有关变化的定量信息 在古环境（温度、水文）、古食物（放牧与放牧）、古环境（温度、水文）、古环境（温度、水文）中， 浏览）和进化（马的中新世中期辐射），或 如果骨和牙齿磷酸盐在成牙学上是不透明。 这 初步的工作可以催化解开中新世的新途径 大陆古气候变化是全球气候变化的重要时期 缺乏定量古地球化学的气候恶化 Continental Records的相关信息 化石马特别适合研究，因为它们 在地理上分布广泛， 始新世至晚更新世，并有现代类似物。 马 经历了爆炸性的适应性辐射， 中新世中期（16-12 Ma）的转变可能是对 古气候变化和萨凡纳的扩张。 这 气候变化是从古海洋学数据推断;饮食 转移，从牙齿的功能形态的研究。 我们希望 以确定古饮食变化是否在化学物质中很明显 如果大陆的古气候记录 在大小、方向和时间上证实了海洋记录; 如果古气候变化与 古环境和演化变化。 在这个初步的 风险，我们将探讨成岩作用的影响， 种内变异，并表征化石的del 18 Opo 4 伯奇采石场的马牙和骨头，是世界上最富有的， 保存最完好的中新世中期（-12Ma）马动物群。 岩作用 将通过微量元素、SEM和XRD分析进行评估， 搪瓷磷酸盐和现代马相比。 如果成岩作用 被证明是微不足道的，del 18 Opo 4牙釉质在现代和 化石牙齿将确定重建 大陆古气候记录

We propose to explore the potential for linking mid-Miocene paleoclimate and horse evolution by establishing the systematics of trace elemental and isotopic preservation in the bone and tooth phosphate of North American fossil horses. We will test whether enamel phosphate provides quantitative information about changes in paleoenvironment (temperature, hydrology), paleodiet (graze vs. browse), and evolution (the mid-Miocene radiation of horses), or if bone and tooth phosphate is diagenetically opaque. This preliminary work could catalyze new avenues for unraveling Miocene continental paleoclimate changes, an important period of global climatic deterioration with scant quantitative paleogeochemical information from continental records. Fossil horses are particularly suitable for study because they are geographically widespread and common in fossil assemblages from the Eocene to late Pleistocene and have modern analogues. Horses underwent an explosive adaptive radiation and presumed dietary shift in the middle Miocene (16-12 Ma) perhaps responding to paleoclimatic changes and the spread of savannah grasslands. This climatic shift is inferred from paleoceanographic data; the dietary shift, from studies of the functional morphology of teeth. We wish to determine if a paleodietary shift is evident in the chemistry of the fossil teeth; if the continental paleoclimate record corroborates the marine record in magnitude, direction, and timing; and if paleoclimatic change occurred concurrently with paleoenvironmental and evolutionary changes. In this preliminary venture, we will explore the effects of diagenesis, inter- and intraspecific variations, and characterize the del 18Opo4 of fossil horse teeth and bones from the Burge Quarry, one of the richest and best-preserved middle Miocene (-12 Ma) horse faunas. Diagenesis will be evaluated with trace element, SEM, and XRD analyses of enamel phosphate and compared to modern horses. If diagenesis proves to be negligible, del 18Opo4 of tooth-enamel in modern and fossil teeth will establish the suitability of reconstructing the continental paleoclimate record.