The American cheetahs (genus Miracinonyx) were at least two species of feline, morphologically similar to the modern cheetah, but which probably evolved their adaptations for swift running independently. Living from three million to ten or twenty thousand years ago in North America, these cats are known only from fragments of skeletons. They are not of the genus Acinonyx, to which the modern cheetah and its closest ancestors belong, and may be more closely related to species of Puma.
Two species have been identified: Miracinonyx inexpectatus and M. trumani. Sometimes a third species, M. studeri, is added to the list, but it is more often listed as a junior synonym of M. trumani. Both species are similar to the modern cheetah, with faces shortened and nasal cavities expanded for increased oxygen capacity, and legs proportioned for swift running. However, these similarities are parallel rather than inherited from a common ancestor.
