The Principal Investigators will test hypotheses concerning the Eocene global warm period and its effects on high-latitude terrestrial ecosystems by reconstructing paleoclimate and -ecology from d18O(PO4), d18O(CO3), and d13C values of biogenic phosphate in vertebrate tooth enamel from Early-Middle Eocene localities on Ellesmere Island, Canada (~79degrees N). Specifically, they will test the hypothesis that Eocene vertebrates inhabiting the High Arctic preferred temperatures and habitats similar to their living analogs and are therefore accurate paleoclimate and paleoecologic proxies. By comparison to published sea surface temperatures (SSTs), the Principal Investigators will test the hypothesis that quantitative climate changes in northern high-latitude terrestrial environments correlate to those determined for high-latitude open marine environments. The project will provide quantification of latitudinal gradients by determining d18O values of multiple vertebrate taxa (e.g., alligators, brontotheres, and tapirs) that co-occur in mid- and high-latitude North America. Quantitative climate estimates for Early - Middle Eocene localities on Ellesmere Island should also provide data critical to understanding the onset of the Cenozoic cooling trend, purported to have begun with during early Middle Eocene time. Comparison of the Eocene mammals, particularly the large herbivores, from Ellesmere Island with living relatives and analogues, combined with d13C analysis of the biogenic phosphate in their teeth, should provide insight into their habitat preferences (i.e., open habitat vs. closed canopy). Additionally, comparison of d13C values from the same genera coexisting at both mid- and high-latitudes (e.g., Coryphodon and the brontotheres Eotitanops and Palaeosyops) may illuminate important paleoecological differences that would otherwise not be evident in their morphology. Extensive paleontological field work in Eocene strata of the Eureka Sound Group on Ellesmere Island by the Principal Investigators provides paleoclimatic and paleoenvironmental estimates that are inferred from the fossil plants and animals, in addition to numerous specimens on which to conduct isotope analyses Broader Impacts: This project will result in the first comprehensive, quantitative paleoclimate data set from northern high-latitude terrestrial environments for the most significant global warming event in the last 65 million years (the Early Eocene), which is critical to understanding the impacts of future global warming on Earth's biota. The research will provide important high-latitude terrestrial data points for paleoclimate modelers concerned with Eocene climatic variability and latitudinal temperature gradients. This study will be the first to infer paleoecology of a high Arctic terrestrial vertebrate community on the basis of coupled carbon and oxygen isotope analyses (in conjunction with comparisons to mid-latitude taxa and modern analogs). The project will engage students, the general public (including the Inuit community), and scientists in a multidisciplinary, collaborative research alliance, and foster international and intercultural discourse. Results of the research will be broadly disseminated to scientific and lay audiences.
