The subject will be treated in its biological aspects, because the relations of palaeontology to historical and stratigraphic geology are more appropriately considered under the article Geology.
Observing for himself (1794-1800) the stratigraphic value of fossils, he began to distinguish the great Mesozoic formations of England (1801).
Cuvier (1769-1832) is famous as the founder of vertebrate palaeontology, and with Alexandre Brongniart (1770-1847) as the author of the first exact contribution to stratigraphic geology.
He proposed the term " mutations " for the minute progressive changes of single characters in definite directions as observed in successive stratigraphic levels.
More recent analysis has shown, however, that certain modifications observed within the same stratigraphic level are really grades of mutations which show divergences comparable to those found in successive levels.