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Jocelyn A. Sessa

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Davis Scholar - Postdoctoral Fellow, Paleontology

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Professional Interests

Dr. Sessa’s research focuses on the evolution of shallow marine ecosystems through time. She employs the fossil record as a natural laboratory through which to study how organisms responded to environmental perturbations. Molluscs are the primary focus of her research because they are well preserved and abundant in fossil and modern assemblages. Additionally, the chemistry of mollusc shells records seasonal temperature variations, which she uses to reconstruct past climates. Jocelyn has tracked the response of marine organisms to the Cretaceous-Paleogene mass extinction and to climatic fluctuations, including the Paleocene-Eocene Thermal Maximum, one of the best geological examples of a rapid global warming event. She has recently begun working to reveal the diversity and community structure of mollusc assemblages from the ancient tropics of southern Africa.



  • Sessa, J.A., Callapez, P.M., Dinis, P.A., Hendy, A.J.W. 2013. Paleoenvironmental and paleobiogeographical implications of a Middle Pleistocene mollusc assemblage from the marine terraces of Baía das Pipas, Angola. Journal of Paleontology, v. 87; p. 1016–1040.
  • Sluijs, A., van Roij, L., Harrington, G.J., Schouten, S., Sessa, J.A., Levay, L.J., Reichart, G.J., Slomp, C.P. 2014. Warming, euxinia and sea level rise during the Paleocene-Eocene Thermal Maximum on the Gulf Coastal Plain: implications for ocean oxygenation and nutrient  cycling. Climate of the Past, v. 10, p. 1421-1439.
  • Sessa, J.A., Ivany, L.C., Schlossnagle, T.H.*, Samson, S.D., Schellenberg, S.A. 2012. The fidelity of oxygen and strontium isotope values from shallow shelf settings: Implications for temperature and age reconstructions. Palaeogeography, Palaeoclimatology, Palaeoecology v. 342–343; p. 27–39.
  • Sessa, J.A., Bralower, T.J., Patzkowsky, M.E., Handley, J.C. Ivany, L.C. 2012. Environmental and biological controls on the diversity and ecology of Late Cretaceous through early Paleogene marine ecosystems in the U.S. Gulf Coastal Plain. Paleobiology v. 38; p. 218–239.
  • Sessa, J.A., Patzkowsky, M.E., Bralower, T.J. 2009. Impact of lithification on the diversity, size distribution, and recovery dynamics of marine invertebrate assemblages. Geology, v. 37; p. 115–118.
  • Alroy et al. 2008.  Phanerozoic trends in the global diversity of marine invertebrates, Science, v. 321; p. 97–100.
  • Gibbs, S.J., Bown, P.R., Sessa, J.A., Bralower, T.J., Wilson, P.A. 2006.  Nannoplankton origination and extinction across the PETM, Science, v. 314; p. 1770–1773.

Teaching Experience


  • Teaching Assistant for Geology of National Parks online course; Penn State; 2009, 2008.
  • Teaching Assistant for Geobiology; Penn State; 2005.
  • Teaching Assistant for Earth Futures: Climate Change; Penn State; 2005.
  • Teaching Assistant for Dinosaur Extinctions and Other Controversies; Penn State; 2005, 2004, 2003.
  • Course Instructor for Geology for Architects and Engineers; University of Cincinnati, 2002


  • 2010-2011: Supervisor of SUNY Environmental Science and Forestry sophomore undergraduate Madeline O'Connor’s research project.
  • 2010, Summer: Mentor and supervisor of high school student Philippa Stoddard, currently an undergraduate at Yale.
  • 2009-2010: Mentor and supervisor of SUNY Environmental Science and Forestry senior undergraduate Trevor Schlossnagle.

Exhibition and Outreach

  • 2012, Summer: Supervisor for a Youth Engagement through Science (YES!) 6-week research project for a DC-area high school student at the Smithsonian National Museum of Natural History.  The project involved both specimen and laboratory work and culminated in a student poster presentation.
  • 2011-current: Leader of “behind the scenes” tours of the Paleobiology collections at the Smithsonian National Museum of Natural History to college classes and the general public.
  • 2011, Summer: Supervisor of a YES! research project for two disadvantaged DC-area high school students at the Smithsonian National Museum of Natural History.
  • 2008, Spring: Co-leader for Shake, Rattle, and Rocks, an interactive program for fifth graders at Penn State.
  • 2007, Summer: Project leader for Upward Bound Math and Science Summer Experience at Penn State; I designed and led a 6-week research project for three underrepresented high school students.  My team’s presentation placed first out of 15 groups.

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