Dinosaur Evolutionary Dynamics and Habitat Bottlenecks

约翰霍普金斯大学最近在蒙大拿西北部的圣玛丽河和柳溪地层进行的研究，提供了有关上海岸平原环境中恐龙动物群的重要信息，这些信息在大多数其他已经发现晚白垩纪动物群的地区是无法获得的。这些新数据对于它们对大型陆生脊椎动物的灭绝和物种形成的影响这一更大的问题至关重要。进一步的实地和实验室工作对于更好地了解这一上海岸平原栖息地的动物组成以及海洋海侵（即栖息地瓶颈）导致陆地环境严重减少及其释放的影响至关重要。考虑到这些目标，实地工作将致力于收集标本，绘制地点和详细介绍圣玛丽河和柳溪遗址的地层。实验室研究将集中在对圣玛丽河动物群的古生态学和进化解释上，这是对这些栖息地瓶颈的批判性理解所必需的。这项工作包括1)使用基于地标的形态计量学分析圣玛丽河类群的个体发生阶段和进化的新方法，2)对圣玛丽河动物的摄食和运动进行了新的分析，包括下颌和牙齿的运动学，以及四肢的运动学和横截面几何，3)通过熊掌海的回归，从圣玛丽河类群到陆地栖息地开放的进化动态来解释这些数据。这项研究将填补我们对晚白垩纪生态系统（上海岸平原环境中的生命）的重要组成部分的知识空白，这一时期对恐龙和其他脊椎动物的历史至关重要（白垩纪末期的埃德蒙顿陆地哺乳动物时代）。在这样做的过程中，它将有助于我们理解主要的环境危机，如广泛的越界和回归，是如何与大型脊椎动物的进化动力学联系起来的。

Recent research by The Johns Hopkins University in the St. Mary River and Willow Creek formation of northwestern Montana has contributed important information about dinosaur faunas from upper coastal plain environments not otherwise available from most other regions that have yielded Late Cretaceous faunas. These new data are critical to the larger issues of their effects on extinction and speciation of large-bodied terrestrial vertebrates. Further field and laboratory work is essential for a better understanding of the faunal components of this upper coastal plain habitat and the effects of severe reduction in terrestrial environments through marine transgressions (i.e. habitat bottlenecks) and their release. With these goals in mind, the field work will be devoted to collecting specimens, mapping localities and detailing the stratigraphy of the St. Mary River and Willow Creek sites. Laboratory research will focus on the paleoecologic and evolutionary interpretation of the St. Mary River fauna necessary for a critical understanding of these habitat bottlenecks. This work includes 1) new approaches to the analysis of ontogenetic stages and evolution of St. Mary River taxa using landmark-based morphometrics, 2) new analyses of the feeding and locomotion of the St. Mary River animals on the kinematics of the jaws and teeth, and the kinematics and cross- sectional geometry of the limbs, and 3) interpretation of these data in terms of the evolutionary dynamics of St. Mary River taxa to the opening of terrestrial habitats through the regression of the Bearpaw Sea. This study will fill a significant void in our knowledge of an important component of Late Cretaceous ecosystems (life in upper coastal plain environments) at a time critical to the history of dinosaurs and other vertebrates (the Edmontonian Land Mammal Age at the close of the Cretaceous). In doing so, it will contribute to our understanding of how major environmental crises such as extensive transgressions and regressions relate to the evolutionary dynamics of large-bodied vertebrates.