Miracinonyx
| American cheetah | |
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| File:Miracinonyx trumani.jpg | |
| Miracinonyx trumani | |
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| Genus: | Miracinonyx
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Miracinonyx (American cheetahs) is an extinct genus of the family Felidae, endemic to North America during the Pleistocene epoch (1.8 mya—11,000 years ago), existing for approximately 1.8 million years.[1]
There were at least two species of feline morphologically similar to the modern cheetah. Living from three million to ten or twenty thousand years ago in North America, these cats are known only from fragments of skeletons. The two species commonly identified are 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 may not be inherited from a common ancestor, but result from either parallel or convergent evolution.
Taxonomy and evolution
Research into the American cheetah has been contradictory. It was originally believed to be an early cougar representative, before being reclassified in the 1970s as a close relative of the cheetah.[2] This suggested that ancestors of the cheetah diverged from the Puma lineage in the Americas and migrated back to the Old World, a claim repeated as recently as Johnson et al. (2006).[3] Other research by Barnett, however, examining mitochondrial DNA and re-analyzing morphology, has suggested reversing the reclassification: the American cheetah developed cheetah-like characteristics through convergent evolution, but it is most closely related to Puma and not to the modern cheetah of Africa and Asia.[4] The supposed American origin of the modern cheetah is thus equivocal; however, it is believed to have evolved from cougar-like ancestors, whether in the Old or New World.
The cougar and M. trumani are believed to have split from a cougar-like ancestor around three million years ago;[4] where M. inexpectatus fits in is unclear, although it likely is a more primitive version of M. trumani.[5]
Miracinonyx trumani
M. trumani was the most similar to true cheetahs in morphology. Living on the prairies and plains of western America, it was likely a predator of hoofed plains animals such as the pronghorn. In fact, predation by Miracinonyx is thought to be the reason that pronghorns evolved to run so swiftly, their 60 mph top speed being much more than needed to outrun extant American predators such as cougars and gray wolves.[6]
The similarity between M. trumani and the cheetah is an example of parallel evolution.[citation needed] As grasslands became more common in both Africa-Eurasia and North America, cougar-like cat species from both continents evolved to catch the new fleet-footed herbivores.[citation needed] The claws of M. trumani had even become only partially retractable, to be used for better grip at high speeds.[citation needed]
Miracinonyx inexpectatus
M. inexpectatus was more[vague] similar to the cougar, its proportions between that of the cougar and M. trumani. It had fully retractable claws,[citation needed] and although it was likely[vague] faster than the cougar due to its slim build, it is also thought[by whom?] to have been more adept at climbing than M. trumani.
References
- ^ PaleoBiology Database: Miracinonyx, basic info
- ^ Adams, Daniel B. (14 September 1979). "The Cheetah: Native American" (abstract). Science. 205 (4411): 1155–1158. doi:10.1126/science.205.4411.1155. PMID 17735054. Retrieved 2007-06-04.
- ^ Johnson, W.E., Eizirik, E., Pecon-Slattery, J., Murphy, W.J., Antunes, A., Teeling, E. & O'Brien, S.J. (6 January 2006). "The Late Miocene radiation of modern Felidae: A genetic assessment" (abstract). Science. 311 (5757): 73–77. doi:10.1126/science.1122277. PMID 16400146. Retrieved 2007-06-04.
{{cite journal}}: More than one of|number=and|issue=specified (help)CS1 maint: multiple names: authors list (link) - ^ a b Barnett, Ross (9 August 2005). "Evolution of the extinct Sabretooths and the American cheetah-like cat". Current Biology. 15 (15): R589–R590. doi:10.1016/j.cub.2005.07.052. PMID 16085477. Retrieved 2007-06-04.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Haaramo, Mikko (2005-11-15). "Mikko's Phylogeny Archive - Felidae: Felinae – small cats". Retrieved 2007-02-20.
- ^ Byers, John (1998). American Pronghorn: Social Adaptations and the Ghosts of Predators Past. Chicago University Press. p. 318. ISBN 978-0-226-08699-6.