Exactly how many extinct animals are there in the world?

The exact number of extinct animals in the world is difficult to determine, as new discoveries are constantly being made and there is no definitive record of all extinct species. However, estimates range from several hundred thousand to several million species. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species currently lists 913 extinct species, but this is just a fraction of the total number of extinctions that have occurred throughout Earth's history. Many extinct species are not known to science and have never been formally described or named, making it impossible to provide a precise count.