 He established the principle of faunal succession, the idea that each strata of sedimentary rock would contain particular types of fossils, and that these would succeed one another in a predictable way even in widely separated geologic formations.At the same time, Cuvier and Alexandre Brongniart, an instructor at the Paris school of mine engineering, used similar methods in an influential study of the geology of the region around Paris.In 1808, Cuvier identified a fossil found in Maastricht as a giant marine reptile that would later be named "Mosasaurus".