Miracinonyx (colloquially known as the "American cheetah") is an extinct genus of felids belonging to the subfamily Felinae that was endemic to North America from the Pleistocene epoch (about 2.5 million to 16,000 years ago) and morphologically similar to the modern cheetah (Acinonyx jubatus), although its apparent similar ecological niches have been considered questionable due to anatomical morphologies of the former that would have limited its ability to act as a specialized pursuit predator.

The American paleontologist Edward Drinker Cope originally considered these to be related to the spotted hyena, and described the material as Crocuta inexpectata in 1895.

The other valid species (then as Felis trumani) was described in 1969 by Orr based on a complete skull from the Late Pleistocene found in Crypt Cave, Nevada.

However, O'Brien et al. (2016) posit that the supposed homoplasy between the genera is controversial, as it is asserted that is not necessarily any conclusive anatomical or genetic basis for dismissing a homologous relationship between Acinonyx and Miracinonyx.

[15] The cougar and M. trumani are believed to have split from a cougar-like ancestor around three million years ago;[12] where M. inexpectatus fits in is unclear, although it is probably a more primitive version of M.

smaller cats ) Adams (1979) found these animals to be intermediates in size and morphology between cheetahs and cougars and decided to place them in their own genus Miracinonyx.

M. trumani also had a brain similar to a cougar's, albeit with cheetah-like adaptations in the auditory and visual cortexes, and therefore was not as cognitively prepared for the predatory behavior of true cheetahs.

Moreover, it had underdeveloped paranasal sinuses which prevents the brain from overheating in Acinonyx during high-speed chases, though this may reflect the colder temperatures of Pleistocene North America compared to Africa and Iran.

As a result, artiodactyls and perissodactyls generally evolved with hypsodont dentition for eating C4 grasses and distally longer limbs for easier movement within open environments.

In comparison, true pursuit predators didn't even exist until the Plio-Pleistocene, a more recent development of carnivorans compared to the ungulates that already were built for speed some 20 million years before.

[1][29] M. trumani, exclusive to the Rancholabrean age, was more cursorial and Cheetah-like then M. inexpectatus,[4][15] but unlike cheetahs, both species retained fully retractable claws.