Jocelyn A. Sessa

Sessa Large Image


Senior Scientist, Paleontology

Download Curriculum Vitae

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.



  • Paynter, A.N., Metzger, M.J., Sessa, J.A., and Siddall, M.E. (accepted) Evidence of cross-species transmissibility of the cancer-inducing Steamer retrotransposon among ecological cohort bivalve species. Diseases of Aquatic Organisms.
  • Janssen, A.W., Sessa, J.A., and Thomas, E. 2016. Pteropoda (Mollusca, Gastropoda, Thecosomata) from the Paleocene-Eocene Thermal Maximum of the United States Atlantic Coastal Plain. Palaeontologia Electronica, v. 19.3.47A; p. 1-26.
  • Knoll, K., Landman, N. H., Cochran, J. K., MacLeod, K. G., and Sessa, J. A. 2016. Microstructural preservation and the effects of diagenesis on the carbon and oxygen isotope composition of Late Cretaceous aragonitic mollusks from the Gulf Coastal Plain and the Western Interior Seaway. American Journal of Science, v. 316; p. 591–613. An image from this article is the issue’s cover.
  • Sessa, J.A., Larina, E., Knoll, K., Garb, M. Cochran, J.K., Huber, B.T., MacLeod, K.G., Landman, N.H. 2015. Ammonite habitat revealed via isotopic composition and comparisons with co-occurring benthic and planktonic organisms. Proceedings of the National Academy of Sciences, USA, v. 112; p. 15562-15567.
  • 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


  • SCI 670: Earth Evolution and the Earth System; American Museum of Natural History (AMNH) MAT Program; 2016 - Present
  • Practicum Course; American Museum of Natural History (AMNH) MAT Program; 2013 - Present
  • Enrichment classes; AMNH MAT Program; 2013
  • Form and Function of Sharks Teeth class for grades 7 - 12; AMNH MAT Program; 2013 - Present
  • Teaching Assistant; Pennsylvania State University; 2003 - 2009


  • Shaun Mahmood; recent undergraduate and AMNH intern
  • Katja Knoll; Brooklyn College Master's student
  • Madeline O'Connor; State University of New York (SUNY) College of Environmental Science and Forestry (ESY) undergraduate
  • Trevor Schlossnagle; SUNY ESF undergradaute

Exhibition and Outreach

  • Seminar speaker in the Comparative Biology Seminar at the Richard Gilder Graduate School at the AMNH; Spring, 2015.
  • Presenter at the AMNH Student Science Summit, which provides career mentorship to high school students interested in the STEM fields; Spring, 2015.
  • Co-leader of a Paleobiology Database Hackathon, where tools for research, education, & outreach are created; ex. R code, web applications, data analysis tools, and visualizations; Winter, 2015.
  • Supervisor for a Smithsonian National Museum of Natural History Youth Engagement through Science (YES!) high school student; the 6-week research project involved specimen and lab work and culminated in a student poster presentation. Our research was profiled on a local TV news station; Summer, 2012.