Reconstructing the Local Vegetation and Seasonality of the Lower Eocene Blue Rim Site of Southwestern Wyoming Using Fossil Wood

Premise of research. Permineralized wood along with fossil leaves, reproductive structures, and dispersed pollen and spores are preserved in the uppermost Lower Eocene (∼49.0 Ma) Blue Rim escarpment of the Bridger Formation in southwestern Wyoming. Each component of the flora provides a slightly different view of the diversity and environment, but the wood assemblage provides additional information on the taxonomic composition, forest structure, and local seasonality and climate.Methodology. Fossil wood specimens, including occasional in situ stumps, were collected from Bridger strata exposed at Blue Rim, north of Green River, Wyoming. Thin sections in the three standard orientations were prepared of each specimen and examined by light microscopy. Specific gravity and vulnerability index values were calculated for well-preserved specimens. Tree height was estimated from diameter measurements obtained from 10 specimens.Pivotal results. Seven wood types are recognized in the assemblage, including a single s...