Supporting this view was the greatest comparative anatomist and palaeontologist of the early 19th century. He was Georges Cuvier, Director of the "Muséum national d'histoire naturelle" in Paris. Cuvier had shown that extinction of species had definitely taken place. His catastrophism was an explanation for the regular changes in species seen in the rock strata. He had no real explanation of why later species were different from earlier ones. He rejected the idea of evolution, but did not propose a religious solution.