Oxygen isotope and paleobotanical estimates of temperature and  18O-latitude gradients over North America during the early Eocene

摘要: Empirical estimates of climate parameters such as mean annual temperature (MAT) are essential to describe both ancient and ground truth model simulations past climates. In terrestrial settings, no single proxy record is able provide detailed temporal yet geographically widespread information, it thus becomes that paleoclimatic information obtained from different proxies be comparable. As an example how compare estimates, illustrate what can learned by doing so, we measured oxygen isotope ratios phosphate in the tooth enamel fossil mammals body scales freshwater fish order estimate which they lived. The samples were collected Paleogene rocks Bighorn, Green River, Powder River basins Wyoming. Earliest Eocene MAT similar for same times areas leaf margin analysis. Furthermore, isotopic data Paleocene Thermal Maximum (PETM), has not yielded floras, indicate a significantly higher 26°C. We also used methods investigate paleoelevation reconstruct geographic patterns over North America early Eocene. Larger Laramide have temperatures lower inferred elevations compared associated volcanic highlands where cooler consistent with substantial elevations. turn, latitudinal gradients warming centered on polar regions played important role during “hothouse”. Lastly, show reconstructed relation between precipitation modern these two variables. Because changed time, correlation should paleo-MAT measurements material.