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Matthew Mihlbachler我建议对北美古近纪有蹄类动物的牙齿微磨损进行研究，以检验哺乳动物的古饮食生态与牙齿形态和气候变化之间的关系。化石记录记录了Lophodon牙齿从更多的牙形牙齿形式反复进化而来的过程。这一趋势被认为与全球变冷、季节性增加以及相关的栖息地变化所导致的饮食从水果类向叶类的转变相对应。牙齿微磨损方法将被用于预测灭绝物种的饮食，重建连续动物群的生态概况，并追踪主要有蹄类世系的早期饮食历史，包括现代的偶蹄目和近足目。牙齿微磨损方法将牙齿形态从进行古饮食推断的任务中解放出来，从而使我们能够独立于形态变化来检查古生态变化，并在更精细的时间尺度上追踪古饮食。索鲁尼亚主要负责开发将要使用的方法，而米尔巴赫勒则在进一步开发这些方法的许多方面发挥了作用。第一年将用于汇编用于磨损分析的牙齿铸模、铸模资料库的管理以及数据的收集和分析。数据分析和成果传播将在第二年完成。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：在古近纪有蹄类和类有蹄类哺乳动物中，放纵的进化对应于从古近纪开始的果食性/杂食性到古近纪结束时以叶为主的广泛转变。如果牙齿微磨损与牙齿分类相矛盾或只是松散地与牙齿分类相关联，这是一个强烈的信号，表明应该更仔细地评估哺乳动物的古饮食生态，不仅从牙齿形态，而且从牙齿使用磨损数据(如微磨损)和其他形态独立的方法，如稳定同位素。假设2：哺乳动物对气候变化的古饮食响应发生在比牙齿宏观进化趋势所暗示的更精细的时间尺度上。Bighorn和Clark？S分叉盆地记录了古新世-始新世界线附近的一个关键时期。这一关键的时间间隔记录了二氧化碳的迅速增加，许多移民分类群的出现，以及几个谱系之间的矮化事件。在这段时间内，高地层分辨率的哺乳动物密集采样为我们提供了一个难得的机会，可以在时间分辨率的尺度上研究哺乳动物进化的关键时期的古生态变化，在这个时间分辨率尺度上，温室效应和许多进化过程(物种形成、灭绝)是已知的。除了更好地了解进化论-生态学-气候动力学，这项提议的其他广泛影响是让一些本科生和医学生接触到科学过程，以促进沿着类似路线进行的进一步研究，并为国家科学基金会资助的网站提供结果，该网站目前正在AMNH开发中。学生们将被雇佣来协助收集这项提案产生的牙科模型，以及Solonious从之前的NSF拨款中收集的现代和中新世哺乳动物的整个模型。这些铸件将被编目，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.