Search the Collections
Stephen Chester

Stephen Chester

My general research interests include functional morphology, mammalian phylogeny, and early primate evolution. My primary goal in paleontological research is to improve our understanding of how morphological features functioned in the past, and what role they played in the interaction between mammals and the selective demands of their environments. I gather morphological and functional data by comparing the skeletal anatomy of fossil mammals with similar extant forms, and use these data to reconstruct behaviors such as locomotory habits.

I study fossil mammals from the Late Cretaceous to the early Eocene with particular focus on two events that are very significant in mammalian and early primate evolution. The first is the K-T mass extinction event 65.5 million years ago, which eliminated the non-avian dinosaurs, and represents the beginning of a major radiation of Paleocene mammals including plesiadapiform primates. The second is the Paleocene-Eocene Thermal Maximum 55.8 million years ago, which was a major global warming event that marks the appearance of several modern orders of mammals including euprimates (primates of modern aspect), and is important for understanding the effects of global warming on mammalian evolution. I am currently co-leading annual Yale Peabody Museum expeditions focused on mammalian faunal composition across the K-T boundary in the Hell Creek and Fort Union formations of Montana with Eric Sargis and Tyler Lyson. I am also continuing to help conduct summer fieldwork with Jonathan Bloch in the southern Bighorn Basin, Wyoming, which focuses on mammalian response to climate change during the earliest Eocene.

Other collaborative projects include the analysis of Mesozoic mammal postcrania from the Kyzylkum Desert, Uzbekistan, with Eric Sargis, Fred Szalay, David Archibald, and Alexander Averianov. My dissertation research is focused on the origin and earliest evolutionary history of primates, with emphasis on the systematics and paleobiology of micromomyid plesiadapiforms.

For more information, please visit my website: