Despite the fact that he refused to believe in evolution, naturalist and palaeontologist Georges Cuvier (1769-1832) contributed to Charles Darwin's theory of evolution, particularly in terms of natural selection, by establishing that certain species had gone extinct over time. However, Cuvier did not believe extinction confirmed evolution. He contended that all species were created at once and that some had died off during natural catastrophes.
According to "PBS Evolution Library," extinction was a foreign concept to naturalists in Cuvier's time. When scientists of the era found fossils, they postulated that they represented unusual versions of existing species, or that the type of creature preserved in fossil form still existed in remote parts of the world.
Cuvier, however, was able to convince a number of scientists that extinction was real. According to "PBS Evolution Library," he did this in part by demonstrating that different strata of rock in what was known as the Paris basin contained its own unique fossilized mammals.
According to the website About Darwin, Cuvier was not able to explain why there were no fossil versions of modern mammal species. In fact, Cuvier argued strongly against the evolutionary theories put forth at the time by Geoffroy Saint-Hilaire and Jean-Baptiste de Lamarck.