Science18th-19th century (c. 1796-1812)Francehigh confidence

Georges Cuvier showed that the life of the past was not necessarily the same as that of the present.

Notes on verification

Multiple independent, high-quality sources (Britannica, UC Berkeley, NPS, Linda Hall Library) corroborate that Cuvier established extinction as a real phenomenon and demonstrated past life differed from present life, primarily via comparative anatomy of fossil vertebrates.

Sources