American cheetahs
| American cheetahs | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
American cheetah ( Miracinonyx ) illustration |
||||||||||||
| Temporal occurrence | ||||||||||||
| late Pliocene to late Pleistocene | ||||||||||||
| 1.8 million years to 11,000 years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Miracinonyx | ||||||||||||
| Adams , 1979 |
The American cheetah ( Miracinonyx ) are an extinct genus of the family of cats (Felidae) that from the late Pliocene to the late Pleistocene ( Upper Pleistocene ) from 1,800,000 to 11,000 years before our era endemic in North America lived. There were at least two species of this genus that were morphologically similar to today's cheetah . They are only known through skeletal fragments.
Taxonomy and Evolution
The American cheetahs were initially regarded as the early representatives of the puma , but were reclassified as close relatives of the cheetah in the 1970s . This theory assumes that the ancestors of the cheetah evolved from the puma line on the American continent (the New World ) and migrated back to the Old World (especially Asia and Africa) via the Bering Bridge .
Other research, such as that of Ross Barnett, which included studying the mitochondrial DNA of the bone finds and a new analysis of the morphology, see the American cheetahs as immediate relatives of the puma , who developed cheetah-like traits through convergent evolution . According to this analysis, the puma and the American cheetah are the sister group of the jaguarundis , a rather small cat-like South American species. Only this group of three is the sister group of the Old World cheetah. The presumed American origin of the cheetahs would then be obsolete, because the American cheetah line would only have separated from the puma line in the New World (about 3 million years ago), whereas these separated clearly before (more than 6 million years ago) and separated from the old world cheetah line even outside America.
The exact classification of the second species Miracinonyx inexpectatus has not been finally clarified, although it is probably a more primitive species than Miracinonyx trumani .
Two species of the American cheetah have been described so far: Miracinonyx trumani and Miracynonix inexpectatus . A third species, Miracinonyx studeri , is sometimes also mentioned, but this is considered a younger synonym for Miracynonix trumani . Both species were very similar to today's cheetah, with shortened, round skulls and enlarged nasal passages for a greater breathing flow as well as extremely long limbs and a long tail specially proportioned for fast running . Compared to other cats , the dentition is said to have been much smaller and relatively weak. Still, the similarities were not inherited through a direct common ancestor, but were the result of either parallel or convergent evolution.
Through genetic and immunological studies have determined that today's cheetahs probably all descended from a very small core group (→ genetic bottleneck ), who lived about 10,000 years ago. It was then that the American cheetah became extinct, and the common cheetah in Africa and Asia apparently only narrowly escaped that fate. However, it spread again in the savannas of Africa and Asia and was therefore able to survive until our time. This study is highly regarded in specialist circles and is now used as a classic example in population genetics .
The exact reasons that led or could have led to the extinction of the American cheetah have not yet been conclusively clarified, despite all research. Some experts suspect, in addition to the genetic bottleneck mentioned, other influences such as the onset of climate changes and increased food competition. This is supported by the fact that around 10,000 years before our era, during the Quaternary extinction wave , several other large animal species of America became extinct, such as the American lion .
Miracinonyx trumani
Miracinonyx trumani was morphologically most similar to the real cheetah. He lived in the plains and the vast plains of western North America and chased likely ungulates of the Great Plains , such as the still living pronghorn . There is reason to assume that its maximum achievable speed was only slightly inferior to that of today's cheetahs and should have been at least around 100 km / h.
The re-enactment of the pronghorns by the Miracinonyx trumani was generally regarded as an example of a coevolution in the predator-prey relationship ( Red-Queen hypothesis ), since its maximum speed of 86 km / h is far higher than necessary for the American who is still alive today Escape predators like the puma and the wolf . The oldest evidence of Miracinonyx , however, comes from the end of the Pliocene . However, since the earliest representatives of the fork-horned bearers from the early Miocene around 20 million years ago are to be regarded as extremely fast runners for anatomical reasons, this view lacks a scientific basis, according to many scientists.
The similarity between Miracinonyx trumani and the cheetah is an example of parallel evolution . As vast grasslands became more common in both North America and Africa during the Pleistocene , puma-like species of cats evolved into fast runners on both continents to hunt the newly emerging fast herbivores . The claws of Miracinonyx trumani developed in such a way that - as with the cheetah - they were only partially retractable in order to increase the grip on the ground when running fast.
Miracinonyx inexpectatus
Miracinonix inexpectatus was more like the puma than the cheetah. It had fully retractable claws and was likely able to run faster than the puma due to its slim build. It might still be able to climb and its habitat was less on the prairie than in more wooded regions. Due to the somewhat cooler habitat, it could have had a longer coat.
Individual evidence
- ↑ PaleoBiology Database: Miracinonyx , basic info
- ^ Daniel B. Adams: The Cheetah: Native American . (abstract) In: Science . 205, No. 4411, September 14, 1979, pp. 1155-1158. doi : 10.1126 / science.205.4411.1155 . PMID 17735054 . Retrieved June 4, 2007.
- ↑ Johnson, WE, Eizirik, E., Pecon-Slattery, J., Murphy, WJ, Antunes, A., Teeling, E. & O'Brien, SJ: The Late Miocene radiation of modern Felidae: A genetic assessment . (abstract) In: Science . 311, No. 5757, Jan 6, 2006, pp. 73-77. doi : 10.1126 / science.1122277 . PMID 16400146 . Retrieved June 4, 2007.
- ^ A b Ross Barnett, Ian Barnes, Matthew J. Phillips1, Larry D. Martin, C. Richard Harington, Jennifer A. Leonard, and Alan Cooper: Evolution of the extinct Sabretooths and the American cheetah-like cat . In: Current Biology . 15, No. 15, August 9, 2005, pp. R589-R590. doi : 10.1016 / j.cub.2005.07.052 . Retrieved June 4, 2007.
- ↑ Haaramo, Mikko: Mikko's Phylogeny Archive - Felidae: Felinae - small cats . November 15, 2005. Archived from the original on March 27, 2007. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved February 20, 2007.
- ↑ M. Menotti-Raymond, SJ O'Brien: Dating the genetic bottleneck of the African cheetah . In: Proceedings of the National Academy of Sciences . 1993; 90 (8): 3172-3176
- ↑ Model calculation of the genetic drift
- ^ John Byers: American Pronghorn: Social Adaptations and the Ghosts of Predators Past . Chicago University Press, 1998, ISBN 978-0226086996 , p. 318.
- ↑ James R. Heffelfinger, Bart W. O'Gara, Christine M. Janis, and Randall Babb: A bestiary of ancestral Antilocaprids. Proceedings of the 20th Biennial Pronghorn Workshop 20, 2004, pp. 87-111
