129-67 An Early Eocene Florule from Hatchetigbee Bluff, Southwestern Alabama, USA and Its Paleoclimate Interpretation

Abstract:

The Early Eocene experienced among the warmest temperatures in the Cenozoic, producing tropical and subtropical conditions globally. The Hatchetigbee Formation at Hatchetigbee Bluff, Alabama preserves Venericardia hatcheplata fossils used to reconstruct a mean annual temperature of 27°C. In 2019, fossil leaves were also discovered, which can serve as an additional line of paleoclimate evidence. The Hatchetigbee Bluff flora consists of about 200 specimens of about 20 morphotypes. Morphotypes were described and assigned species based on published descriptions of Eocene flora. Angiosperms dominate the flora, with families including Fabaceae (legumes), Juglandaceae (walnut family), Moraceae (fig family), Celastraceae (bittersweet family), Sapindaceae (soapnut family), Sapotaceae. These are consistent with tropical to subtropical climates. Several species and two families (Juglandaceae and Fabaceae) were shared with the roughly coeval Red Hot Truck Stop locality of Mississippi. The sediment in which leaf fossils were preserved is poorly consolidated and friable, yielding many fragmentary specimens, which complicates leaf physiognomy-based paleoclimate reconstruction. To develop the most accurate reconstruction, we apply three techniques together: the Climate Leaf Analysis Multivariate Program (CLAMP), Leaf Margin Analysis (LMA), and Digital Leaf Physiognomy (DiLP). This analysis provides additional context to temperature estimates based on marine bivalves.

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