Please answer the following question: List of extinct cetaceans - The list of extinct cetaceans features the extinct genera and species of the order Cetacea. The cetaceans (whales dolphins and porpoises) are descendants of land-living mammals the even-toed ungulates. The earliest cetaceans were still hoofed-mammals. These early cetaceans became gradually better adapted for swimming than for walking on land finally evolving into fully marine cetaceans.This list currently includes only fossil genera and species. Given a choice of categories company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, the text refers to which one?
A:
Animal