Brad Sageman’s research over the years has included work focused on the paleobiologic causes and consequences of perturbations in biogeochemical cycles, and the use of fossils as recorders of change in biogeochemical cycles. A recent collaboration with paleobotanist Jenny McElwain at University College Dublin is expanding earlier work on the marine faunas of the Cenomanian-Turonian (C-T) interval in the Western Interior basin into coeval marginal marine sites in order to sample the terrrestial response to a major perturbation in the global carbon cycle. A graduate student co-advised by Sageman and McElwain, Rich Barclay, has recently completed a reconstruction of pCO2 across the C-T interval using the stomatal index method.
Francesca Smith's research focuses on developing and applying new isotopic proxies for reconstructing vegetation and carbon cycling in terrestrial ecosystems in the geologic past. Her approach to proxy development involves characterizing isotope systems in modern environments, and employing fieldand greenhouse studies of living plants. She is particularly interested in isotopic signatures of individual organic compounds that can be identified by their structure as biomarkers for particular source organisms, such as bacteria, archaea, fungi, algae and vascular plant. Smith’s research focuses on compound-specific isotope measurements of leaf wax lipids as a means of reconstructing carbon isotope discrimination by plants. Specifically, she is examining changes in discrimination due to climatic and plant community changes during the Paleocene-Eocene Thermal Maximum. She has also been a pioneer in the development of carbon isotope ratios of grass microfossils (phytoliths) for reconstructing the proportion of C3 and C4 grasses in grassland ecosystems and has applied this technique to understanding the late Neogene expansion of C4 grasses in the Great Plains.