POLLEN DISTRIBUTION AND MORPHOLOGY OF JUGLANDACEAE AND ARECACEAE DURING THE EARLY EOCENE CLIMATIC OPTIMUM

Today plant distributions follow climate closely, thus studying the past distributions of plants can help us to better understand the effect changing climates have on the organisms within them. The purpose of this project was to study changes in the latitudinal distribution of pollen from the walnut (Juglandaceae) and the palm (Arecaceae) families from the late Paleocene cool greenhouse (60- 56 Ma) to the early Eocene Climatic Optimum (53- 49 Ma), the longest and hottest period in the Cenozoic, with global mean temperature >10 °C warmer than today. Juglandaceae, is a presently temperate to montane tropical family, and Arecaceae, a tropical to subtropical family. For this, we studied the morphological features of fossil and modern pollen species from both families using light microscopy, studying selected slides from the USGS Denver Pollen Collection recently deposited at the National Museum of Natural History. We also used published occurrences to evaluate changes in distribution, and mapped and compared the fossil record occurrences of both families with present-day data in both geographic and climatic space. We expect the latitudinal coordinates to increase for both the palm and walnut families as temperature increases. We plan to compare past plant distributions with the climate models for both periods to assess if plant distributions agree with paleoclimate predictions.