Skip to main content


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 terrestrial 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.

Yarrow Axford uses biological remains preserved in lake sediments, peats, and soils to reconstruct Quaternary environmental changes, including recent climate change and anthropogenic landscape change.  Much of Axford’s paleoecological work utilizes statistical transfer functions based upon modern calibration data to generate quantitative reconstructions of past temperatures and other environmental parameters based upon microfossils preserved in lake sediments -- a powerful method for estimating the rate and significance of past and ongoing changes.  For example, recent work uses insect remains in Greenland, Iceland, Arctic Canada, and Alaska to quantify the rates and magnitudes of naturally driven Holocene climate changes for comparison with 20th century conditions.  In addition to insects, other aquatic invertebrates as well as pollen, diatoms, and plant remains are useful environmental indicators that are commonly preserved in lake sediments and other Quaternary deposits.

An additional line of paleoecological inquiry examines the post-glacial colonization of glaciated landscapes and isolated high-latitude islands (Iceland in the North Atlantic and Adak Island in the North Pacific) by aquatic invertebrates.  Such studies provide insights into how species cope with climate change.


Back to top