American Cheetah is an extinct genus of two feline species that were endemic to North America. Their existence only came to be known from their skeleton samples. Species belonging to genus Miracinonyx were larger compared to modern Cheetah found in Africa. In fact, their size was similar to a cougar.

Species

The two species identified with genus Miracinonyx are Miracinonyx inexpectatus and Miracinonyx trumani. Some researchers also add a third species Miracinonyx studeri to this list.

Miracinonyx trumani – Their skull and tooth morphology was more similar to the modern day Cheetah. They were primarily found in parts of Western America. It is assumed that they fed on hoofed plains’ animals like the pronghorn.

Miracinonyx inexpectatus – Miracinonyx inexpectatus was quite alike to the cougar than it was to Miracinonyx trumani. Its proportionalities were between that of the Cougar and Miracinonyx trumani. They had retractable claws. Since they had a bit lighter built, it was believed that they were more swift runners than the cougars. They were also more skillful in climbing than Miracinonyx trumani.

Relation with Modern-day Cheetah

With shortened faces as well as nasal cavities spread out for increased oxygen capacity, the appearance of species belonging to genus Miracinonyx were similar to modern day Cheetah. They also had legs properly proportioned for swift running. These resemblances may not all be inherited from one common ancestor. Instead, it is a result of either convergent or parallel evolution.

Taxonomy and Evolution

Research works into this genus came with different results. Earlier it was believed that the American Cheetah was an early Cougar representative. In 1970, it was reclassified as the closest relative of present-day Cheetah. This theory suggests that Cheetah’s ancestors drew apart from the Puma origin in the Americas and came back to the ancient world.

Another research re-analyzing morphology and studying mitochondrial DNA has asked for a reversal of its reclassification. It said that the American cheetah acquired cheetah-like characteristics with convergent evolution. However, this genus is most closely related to Puma. Therefore, the hypothesized American origin of the modern day Cheetah is ambiguous. Scientists believe that the present day Cheetah have originated from a Cougar-like animal from the New World or the Old World.

It is believed that Miracinonyx trumani and Cougar have developed independently from a Cougar-like animal around three million years ago. However, it is not clear where Miracinonyx inexpectatus fits properly. Some believe that this species was a more like an archaic version of Miracinonyx trumani.

Reasons for extinction

Their extinction causes are not exactly known, but there are some hypotheses like climate change, shortage of food and human pressure that are believed to have triggered their extinction. American Cheetah went extinct at the end of the last ice age – the same time when American lions, mammoths and horses died off.

Interesting Facts

• A new discovery suggests that they used to inhabit Arizona’s Grand Canyon region.
• It is believed that the reason why pronghorns evolved to run fast (60 miles per hour being top speed) because Miracinonyx was their predator. This extreme speed also helped then to outrun other predators in their native range – like wolves and cougars.