Friday, March 8, 2019 at 12:20pm
Curator of Fossil Plants, Smithsonian National Museum of Natural History
I am a biologist interested in evolution and ecology. I study fossils because they provide a long-term record of evolutionary, ecological and environmental change. If properly interpreted that record can say much about process as well as history. I use fossil plants to reconstruct past climates and local environments, and I also study the composition and diversity of floras through time as they respond to changing conditions. My research has focused on the Cretaceous and early Cenozoic - a period of globally warm climate when flowering plants were emerging as the dominant form of terrestrial life. My research is based largely on field work and collections made by me or under my direction. I collect data on the morphology and taxonomy of fossil and analyze them through statistical characterization of trends in morphology, composition or diversity of floras, and comparison of floral change with indicators of environmental change. I also make climatic interpretations based on fossil plants for comparison with paleoclimatic estimates derived from computer simulations.
I have a long-running project examining climatic and floral change across the Paleocene/Eocene boundary, a time of global climatic warming. The project has been directed at quantifying temperature and precipitation change and also change in floral composition and diversity over about 5 million years spanning the boundary. Much of my field work has been in western North America because there are abundant fossils, the stratigraphic and temporal context of the fossils has been established (by me and many others), and study of these areas is interdisciplinary. I have also worked on this project in Pakistan and Argentina.
In a second long-term project I am studying the abundance and diversity of angiosperms in the Late Cretaceous. Angiosperms are the youngest major group of terrestrial organisms, which raises the question: how did they achieve such high diversity and abundance over a relatively brief geological interval (~100 - 60 million years ago)? I have been examining exceptionally preserved, in situ, fossil floras from the Cretaceous in order to establish the relative contribution of angiosperms to vegetational biomass and overall plant diversity in different types of environments. I am using these data to understand the ecological dimensions of this major evolutionary radiation.
I am also a member of a large team of paleobotanists who are adding data (mostly from the literature) on fossil plant assemblages to a web-accessible database maintained at the National Center for Ecological Analysis and Synthesis. In the long run this database will allow us to better quantify changes in the diversity and composition of terrestrial floras across the whole history of life on land. By comparing results compiled from the literature with more detailed studies like the ones I am doing in the Cretaceous and Cenozoic, I hope we will also reach a better understanding of the biases and limitations of the published fossil record.