PALYNOLOGICAL ANALYSES OF THE HELL CREEK FORMATION, MONTANA

The Hell Creek Formation in Garfield County, Montana straddles the Cretaceous-Paleogene (K-Pg) boundary, when mass extinctions affected dinosaurs and several other organisms. During a 2008 excavation expedition by researchers from Washington University in St. Louis, St. Louis Community College – Meramec, and St. Louis Science Center to recover fossil bones of the dinosaur Triceratops, the sedimentary sequence was sampled for palynological study. Twenty-six samples have been analyzed for their dispersed organic matter components (palynofacies) and palynomorphs. Palynofacies results indicate that comminuted and degraded phytoclasts are the dominant components, suggesting that the sediments were deposited in a continental paleoenvironment. The samples are palynomorph-rich, are mostly pollen grains, and support the palynofacies interpretation. The common pollen are mostly Late Cretaceous and include several species of Aquilapollenites and Orbiculatus, Striatellipollis striatellus, Wodehousia spinata, and Tricolpites microreticulatus. The paleobotanical affinities of the palynomorphs as well as integration of palynological data with other techniques (sedimentology, vertebrate paleontology, etc.) will be used to further constrain the continental depositional paleoenvironment.