PALEOBOTANICAL RECONSTRUCTIONS OF THE CLIMATE AND ECOLOGY OF THE CANADIAN HIGH ARCTIC DURING THE EARLY PALEOGENE

The early Paleogene was characterized by multiple hyperthermal events, such as the Paleocene Eocene Thermal Maximum (PETM) and the Eocene Thermal Maximum 2 (ETM2), which caused marked increases in temperature that can be recognized in the fossil record by changes in flora and fauna. The Arctic is of significant interest during these hyperthermal events because warming and other climate changes were likely most pronounced in polar regions. We reconstruct climatic and ecological changes of the Arctic during the early Paleogene before and after the PETM using fossil leaves collected by the late L.J. Hickey from Ellesmere and Axel Heiberg Islands in the Canadian High Arctic. We photographed the entire Hickey Arctic collection housed at the Yale Peabody Museum and digitally measured a variety of morphological characteristics, such as blade area and perimeter, petiole width, and margin state, from all leaves that were at least 25% complete. We then reconstructed mean annual temperature (MAT) and mean annual precipitation (MAP) using the leaf physiognomic methods Digital Leaf Physiognomy (DLP), Leaf Margin Analysis (LMA), and Leaf Area Analysis (LAA), as well as reconstructed leaf mass per area (M_a) to estimate leaf lifespan. Preliminary results indicate that the climate of the Paleocene and Eocene was warm and relatively wet and that the floras were temperate forests with predominately deciduous taxa. Future work will assess differences between Paleocene and Eocene climate and floral community ecology. The results of this work help provide a better understanding of high latitude ecosystems. This in turn can help provide important insights into the climate of polar regions during warm times in Earth history which has important implications the future given the current global climatic warming trends.