POSSIBLE DNA PRESERVATION FROM PLANT FOSSILS IN THE CLAIBORNE FORMATION (MIDDLE EOCENE) OF WEST TENNESSEE

The Claiborne Formation in Tennessee is composed of massive bedded, dark gray to black, organic-rich clay lenses and surrounding sands interpreted as oxbow lakes and fluvial channels of a floodplain-river complex in West Tennessee during the Middle Eocene. The Claiborne is well known for its pristine preservation and diversity of fossil leaves, flowers containing pollen, and associated insects. Individual leaves can be peeled and studied using techniques employed on modern leaves (e.g., stomatal counting, margin analysis, etc.) and pollen is extracted from individual flowers. The preservation of intact and amplifiable DNA from the Eocene Claiborne indicates fossil preservation as a type of Konservat Lagerstätten. As part of a project focusing on the reintroduction/revitalization of living Chestnut in Tennessee, fossilized indigenous Chestnut was sought for comparison. During this search we determined that the preservation state of Claiborne fossil leaves might be favorable for DNA recovery. We have had promising results with standard protocols for DNA extraction which yielded intact DNA. Additional DNA extraction protocols are being tested, to provide DNA that is also suitable for PCR amplification and DNA sequencing. Successful DNA extraction from Claiborne fossil leaves can provide benchmarks for phylogenetic and evolutionary studies between Eocene and living plants, thus allowing a linkage of systematics to a level not generally realized in Eocene deposits. Specifically, DNA analysis should result in the correct taxonomic placement of extinct species within the Claiborne.