Final answer:
Georges Cuvier was a leading advocate of the theory of catastrophism, which proposed that natural disasters were responsible for extinction and the subsequent creation or repopulation of new animals. Although catastrophism is no longer accepted, Cuvier's idea of extinction remains influential in evolutionary thinking.
Step-by-step explanation:
Georges Cuvier was indeed a leading advocate of the theory of catastrophism. According to Cuvier, natural disasters such as floods and earthquakes were responsible for killing all the animals alive in certain places at certain times. He believed that either new animals were created or the areas were repopulated by animals from neighboring areas. Although catastrophism is no longer considered a viable theory, Cuvier's idea of extinction continues to be an important aspect of evolutionary thinking today.