Geosciences Professor Phoebe Cohen to Present Sigma Xi Lecture at Williams College

Media contact: Noelle Lemoine, executive assistant; tele: 413-597-4277; email: [email protected]

WILLIAMSTOWN, Mass., April 4, 2019—Phoebe Cohen, associate professor of geosciences, will present the Sigma Xi lecture, “Answering Burning Questions by Burning Tiny Fossils: Reconstructing Ancient Ecosystems via Single-Microfossil Carbon Isotopes,” at Williams College. The talk, which is free and open to the public, will be held on Tuesday, April 23, from 4:15 to 5:15 p.m., in Wege Auditorium. A reception will follow in the Science Atrium.

Cohen is a paleontologist who researches how life and environments have co-evolved throughout earth history, with a focus on life before the evolution of animals. She combines a variety of microscopic and microchemical techniques with data from field-based stratigraphy and sedimentology.

“A major research area in paleontology and earth history is understanding the relationship between biological changes such as origination and extinction, and changing amounts of oxygen in the earth’s atmosphere,” Cohen says. “One window into the biological record of the deep time is via organic carbon isotopes, which track the isotope systematics of fixed carbon. However, these measurements are almost always done on bulk samples that represent the entire biological community time averaged into a sedimentary sample, which limits our ability to use these measurements to reconstruct short-term carbon cycle dynamics and to probe the structure of ancient ecosystems.” Recent advances now allow reliable measurement of the carbon isotopic composition of a single organic microfossil, which provides new insight into the relationship between life and oxygen through time.

In her lecture, Cohen will share existing work using this new technique to explore the Late Devonian Mass Extinction event in Upstate New York. She will also discuss her new project utilizing this technique on Proterozoic microfossils from before the evolution of animals.

Cohen earned a B.A. in earth systems science from Cornell University and a Ph.D. in the Department of Earth and Planetary Sciences at Harvard University. She also completed a postdoctoral fellowship at the Massachusetts Institute of Technology. Cohen was awarded the Geological Society of America Subaru Outstanding Woman in Science Award in 2012. Her work has been published in journals including Science Advances, Palaeontology, Palaios, Journal of Paleontology, and Proceedings of the National Academy of Sciences. Cohen’s research is funded by the NASA Astrobiology program, the American Chemical Society Petroleum Research Fund, and the National Science Foundation.


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