Tag: Jocelyn A. Sessa

Jocelyn Sessa is a paleobiologist and faculty instructor at the American Museum of Natural History in New York City. Her research melds fossil and modern data to elucidate the response of mollusks to environmental stresses, such as climatic shifts and mass extinction events, across both space and time. Mollusks are the primary focus of her research because they are well preserved and abundant in fossil and modern assemblages (and quite beautiful!). Additionally, the chemistry of mollusk shells records seasonal temperature variations, which she uses to reconstruct past climates. Jocelyn has tracked the response of mollusks to the Cretaceous-Paleogene mass extinction, to the Paleocene-Eocene Thermal Maximum, one of the best geological examples of a rapid global warming event, and to the evolution of oceanographic parameters in the Pleistocene.

Contact Details:

Dr. Jocelyn A. Sessa, Division of Paleontology and Division of Education, American Museum of Natural History, New York, New York, USA.

Fossil Focus: Ammonoids

Fossil Focus
by Kenneth De Baets1, René Hoffmann2, Jocelyn A. Sessa3 and Christian Klug4. Introduction: Ammonoids (Ammonoidea) are an extinct group of marine invertebrates with an external shell. They were cephalopods, and hence closely related to modern cuttlefish, squid, octopuses and the pearly nautilus. In a non-scientific context, they are commonly called ammonites, but that term really includes only Jurassic and Cretaceous forms in its stricter scientific sense. The Ammonoidea as a whole lived from the Early Devonian to the earliest Palaeogene period, covering a timespan of about 350 million years. Normally, only their shells, also called conchs, or their internal moulds are found in the fossil record. Conchs from adult ammonoids range from about 5 millimetres to 2 metres in diameter. Due to