A MORPHOTYPE CATALOG OF THE FOSSIL LEAVES FROM THE MID EOCENE DAWSON PIT LOCALITY (CLAIBORNE FORMATION, TN)

The Eocene Claiborne Formation in western Tennessee is famous for clay deposits rich in plant fossils remains with exceptional preservation, but paleoecology and paleoclimate studies using these fossils are lacking. Here, we describe the diversity of plant megafossils from the Dawson clay pit locality, compare the fossil leaves with those known from other localities in the Claiborne, and use univariate approaches to reconstruct paleoclimate using leaf architecture. We recognize 30 plant morphotypes from a collection over 150 specimens, and the known families include Anemiceae, Arecaceae, Fabaceae, Fagaceae, Lauraceae, Malvaceae, Myrtaceae, Rhamnaceae, Salicaceae and Ulmaceae. Only two morphotypes are shared with the nearby but younger Power’s clay pit. We estimated Mean Annual Temperature (MAT) for both the Dawson and the Powers clay pit floras using leaf margin analysis, and we estimated Mean Annual Precipitation (MAP) using leaf area analysis. The paleoclimate estimates for the two floras are statistically indistinguishable despite the dramatic difference in species composition (MAT: ~22C and MAP: ~119cm/year). The Dawson and Powers clay pit leaf floras most likely grew under seasonal subtropical conditions.