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.
