SGER: Dietary Paleoecology of Early Cenozoic Ungulates of North America

北美早新生代有蹄类动物的饮食古生态学（英语：Dietary ecology of North America） （matthew mihlbachli）提出对北美古近系有蹄类动物牙齿微磨损的研究，以验证有关哺乳动物古饮食生态与牙齿形态和气候变化之间关系的假说。化石记录证明了齿形动物的牙齿从更多的齿形动物进化而来。这一趋势被认为与全球变冷、季节性增加和相关栖息地变化所必需的从果食到叶食的饮食转变相对应。牙齿微磨损方法将用于预测灭绝物种的饮食，重建连续动物群的生态概况，并追踪主要有蹄类谱系的早期饮食历史，包括现代目偶蹄目和腕足目。牙齿微磨损方法将牙齿形态学从推断古饮食的任务中解放出来，从而使我们能够独立于形态学变化来研究古生态变化，并在更精细的时间尺度上追踪古饮食。Solounias主要负责开发将要使用的方法，而Mihlbachler则在进一步开发这些方法的许多方面发挥了作用。第一年将用于编制牙齿模型，用于使用磨损分析，管理铸件库，以及收集和分析数据。数据分析和结果散发将在第二年完成。这个项目将解决两个我们认为对哺乳动物进化饮食古生态学至关重要的基本假设：假设1：古近纪有蹄类和类有蹄类哺乳动物的齿形进化对应于古近纪开始时从果食/杂食到古近纪末期以叶食为主的广泛转变。如果牙齿微磨损与牙齿分类相矛盾，或者只是松散地联系在一起，这是一个强烈的信号，表明哺乳动物古饮食生态学应该更仔细地进行评估，不仅要从牙齿形态学中获取证据，还要从牙齿使用磨损数据（如微磨损）和其他形态学独立的方法（如稳定同位素）中获取证据。假设2：哺乳动物对气候变化的古饮食反应发生在比牙齿宏观进化趋势所暗示的时间尺度更精细的时间尺度上。大角兽和克拉克？福克盆地记录了古新世-始新世边界附近的一个关键时期。这个关键的时间间隔记录了二氧化碳的快速增加，许多移民分类群的出现，以及几个谱系中的侏儒事件。在这段时间内，以高地层分辨率密集采样的哺乳动物为我们提供了一个难得的机会，在已知的温室变暖过程和许多进化过程（物种形成、灭绝）起作用的时间分辨率尺度上，研究哺乳动物进化的关键时期的古生态变化。除了更好地理解进化-生态-气候动力学之外，该提案的其他广泛影响是使许多本科生和医科学生接触到科学过程，以促进类似路线的进一步研究，并为美国国家科学基金会资助的网站提供结果，该网站目前正在美国国立卫生研究院开发中。学生们将被雇佣来协助收集牙科模型，这一建议产生的，以及由Solonious从先前的NSF资助中收集的现代和中新世哺乳动物的整个模型集合。这些模型将被编目并提供给那些希望在哺乳动物古生态学中进行类似研究的人。

Dietary Paleoecology of Early Cenozoic Ungulates of North AmericaMatthew MihlbachlerI propose the study the dental microwear of Paleogene ungulates of North America to test hypotheses relating the paleodietary ecology of mammals to dental morphology and climate change. The fossil record documents the repeated evolution of lophodont dentitions from more bunodont forms. This trend is thought to correspond to a dietary shift from frugivory to folivory necessitated by global cooling, increasing seasonality, and associated habitat changes. The dental microwear methodology will be used to predict the diets of extinct species, to reconstruct the ecological profiles of successive faunas, and to trace the early dietary histories of major ungulate lineages, including the modern orders Artiodactyla and Perissodactyla. The dental microwear methodology liberates dental morphology from the task of making paleodietary inferences, thus allowing us to examine paleoecological change independent of morphological change and to track paleodiets at finer temporal scales. Solounias is largely responsible for developing the methods that will be used, while Mihlbachler has taken a role in further developing many aspects of these methods. The first year will be spent compiling casts of teeth for use wear analysis, curation of the cast library, and collection and analysis of data. Data analysis and dissemination of results will be completed in year two. This project will address two basic hypotheses that we believe are critical to mammalian evolutionary dietary paleoecology: Hypothesis 1: The evolution of lophodonty among Paleogene ungulates and ungulate-like mammals corresponds to a widespread shift from frugivory/omnivory in the beginning of the Paleogene to predominantly folivory by the close of the Paleogene. If dental microwear contradicts or is only loosely associated with dental classifications, it is a strong signal that mammalian paleodietary ecology should be more carefully evaluated, drawing evidence not just from dental morphology, but from dental use wear data (such as microwear) and other morphologically independent methods such as stable isotopes.Hypothesis 2: Mammalian paleodietary responses to climate changes occurred on time scales that are much finer than that which is suggested by trends in dental macroevolution. The Bighorn and Clark?s Fork Basins document a critical time period near the Paleocene-Eocene boundary. This critical time interval documents a rapid increase in CO2, the appearance of many immigrant taxa, and dwarfing events among several lineages. The dense sampling of mammals with high stratigraphic resolution through this interval afford us a rare opportunity to study paleoecological change during a critical interval in mammalian evolution at a scale of temporal resolution in which greenhouse warming processes and many evolutionary processes (speciation, extinction) are known to operate. In addition to developing a better understanding of evolution-ecology-climate dynamics, other broad impacts of this proposal are to expose a number of undergraduates and medical students to the scientific process to facilitate further research along similar lines and to provide results for an NSF funded website that is currently under development at the AMNH. Students will be hired to assist with the dental cast collection resulting from this proposal, and the entire collection of casts on modern and Miocene mammals collected by Solonious from prior NSF grants. These casts will be cataloged and made available to those who wish to conduct similar research in mammalian paleoecology.