COMPARISON OF THREE MICROVERTEBRATE ASSEMBLAGES IN THE UPPER HELL CREEK FORMATION IN EASTERN MONTANA

The Upper Hell Creek Formation in Montana has been of interest to geoscientists due to the vertebrate fossils it preserves. Many of these fossils provide information about the history of the region due to their depositional conditions, stratigraphic location, and preservation qualities. The faunal composition of the Maastrichtian stage, which is located right below the Cretaceous/Paleogene (K/Pg) boundary, is of interest in this study, which sampled three microsites from the upper Hell Creek Formation in eastern Montana to collect fossil material just below the boundary. The microvertebrate assemblages contain numerous species of turtles, crocodiles, fish, and even mammals, and were found alongside the infamous macrovertebrates of the time, the dinosaurs. Stratigraphic field measurements indicate that the elevations of the microsites occur at different depths below the K/Pg boundary, suggesting slight variations in the fossil assemblages at each site. Thus, an in-depth understanding of the organisms that lived during the latest Cretaceous time provides useful information for interpreting the region's paleoenvironment and paleoecology.