VEGETATION AND ENVIRONMENT CHANGE ACROSS THE K-PG BOUNDARY IN THE HELL CREEK OF MONTANA
We outline initial results as well as proposed future work using sedimentological and paleobiological methods to decipher and interpret the signal of climate, vegetational restructuring, and floral turnover across the K-Pg boundary. Fieldwork to date has led to the collection of over 1000 leaf macrofossils across the latest Cretaceous and earliest Paleogene. These will be used to reconstruct temperature, environment, and vegetation through leaf physiognomy. Additionally, these data will be used to estimate plant investment (estimated based on leaf mass per area) and floral diversity through this period. We have also collected sediment samples from sections across the Hell Creek and lowest Fort Union Formations to analyze for phytolith and pollen content. Taken together, these lines of evidence will allow us to assess changes in environment and potential correlations between paleofaunal and paleofloral trends across this mass extinction.
Preliminary results indicate a high turnover of plant taxa at the boundary, with declining diversity leading to the K/Pg boundary and approaching pre-extinction levels of diversity by the upper Tullock. Flora remained dominated by angiosperms with a minor component of conifer taxa. Future analyses will aim to quantify diversity, ecology, and structure of these assemblages, and link these sites with the faunal record in the Hell Creek Area. These results will add to our knowledge of how mass extinctions affect ecosystems and the interplay between biotic turnover and environment.