Researcher - Paleontologist
Conference : Are fossils witnesses to evolution?
Jean-Sébastien Steyer is paleontologist at the Centre National de la Recherche Scientifique (CNRS) and Museum National d'Histoire Naturelle (MNHN), Paris. He is working on Life before the dinosaurs, with special emphasis on Pangean faunas, and on extinct species reconstruction. Beyond his research articles, he also writes popular books such as "Earth before the dinosaurs" (Indiana Univ Press, 2010) and popular articles about sciences in science-fiction. Between two fieldworks in Africa and Asia, this National Geographic Grantee is also chronicler in the French version of "Scientific American".
Fossils are remains of organisms which have lived on Earth in the past : skeletons, shells, leaves, tree trunks, footprints, trackways, burrows, excrements etc, these organic "time capsules" are of various origins and correspond to natural objects studied by paleontologists. Often fragmentary and mineralized in rocks, these remains present sometimes exceptional preservation cases: this is the case in amber or permafrost. Whatever their preservation state, the fossils allow to better understand the evolution of environments and climates in the course of geological times. But what is the speculative part in the reconstruction work when the fossil is very fragmentary? And what is the advantage of adding fossils in the analyses of species relationships?