Dinosaur Evolutionary Dynamics and Habitat Bottlenecks

约翰霍普金斯大学最近对蒙大拿州西北部圣玛丽河和柳溪组的恐龙动物群进行了研究，提供了有关上游沿海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产生晚白垩世动物群的地区是不存在的。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沿海平原栖息地的动物组成以及海洋入侵(即栖息地瓶颈)及其释放造成的陆地环境严重减少的影响至关重要。考虑到这些目标，野外工作将致力于收集标本，绘制地点图，并详细说明圣玛丽河和柳树溪遗址的地层。实验室研究将侧重于对圣玛丽河动物群的古生态和进化解释，这是关键了解这些栖息地瓶颈所必需的。这项工作包括1)使用基于里程碑的形态计量学分析圣玛丽河动物个体发育阶段和演化的新方法，2)圣玛丽河动物摄食和运动对颌骨和牙齿运动学以及四肢运动学和横断面几何的新分析，(3)从圣玛丽河类群的演化动力学角度对这些数据进行了解释，并通过熊掌海的回归解释了陆地生境的开放。这项研究将填补我们对恐龙和其他脊椎动物历史(白垩纪结束时的埃德蒙顿陆地哺乳动物时代)至关重要的晚白垩世生态系统的一个重要组成部分(上海岸平原环境中的生命)的认识上的一个重大空白。通过这样做，它将有助于我们理解重大环境危机，如广泛的越轨和退化与大型脊椎动物的进化动态之间的关系。

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.