A PHYLOGENETIC APPROACH TO PALEOCLIMATE RECONSTRUCTION

Taxonomic calibration, a widely-used method of paleoclimate reconstruction, uses the multivariate relationship between climate and the taxonomic composition of modern biotic communities to estimate climatic conditions experienced by fossil assemblages. Traditionally, the use of species as the unit of comparison has restricted this technique to Holocene fossil assemblages. More recently, higher taxa such as genera and families have been shown to provide comparable results to species-level analyses, and have extended the reach of taxonomic calibration to much older time periods. Unfortunately, in all cases, the use of taxonomic ranks introduces bias due to the treatment of closely-related taxa as independent observations and discards information at present at deeper evolutionary nodes. In this study, we explore the use of community phylogenetic methods for paleoclimate reconstruction by using a large database of modern forest inventories to estimate paleotemperature for several fossil assemblages, including the late-Eocene Florissant fossil flora.