Felis (Puma) inexpectata (Cope, 1895) sensu Simpson, 1941
Felis studeri Savage, 1960
Acinonyx studeri (Savage, 1960) sensu Kurtén & Anderson, 1980
Acinonyx inexpectatus (Cope, 1895) sensu Kurtén & Anderson, 1980
M. trumani synonymy
Felis concolor Wilson, 1942
Felis trumani Orr, 1969
Acinonyx trumani (Orr, 1969) sensu Kurtén & Anderson, 1980
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 the ability to act as a specialized pursuit predator.[1][2] The genus was originally known from fragments of skeletons, but nearly complete skeletons have been recovered from
Natural Trap Cave in northern
Wyoming.[3]
The two species commonly identified are M. inexpectatus and M. trumani. Sometimes, a third species, M. studeri, is included, but it is more often listed as a
junior synonym of M. inexpectatus. M. inexpectatus ranged from the
Blancan to
Irvingtonian ages of North America while M. trumani was exclusive to the
Rancholabrean age.[1][4]
Discovery and naming
The first fossils attributed to Miracinonyx were several isolated teeth from
Port Kennedy Bone Cave from
Pennsylvania, dating back to the
Irvingtonian age. 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.[5] However, in 1899 he reclassified the specimens as Uncia inexpectata, considering them closely related to the
snow leopard.[6]
More fossil material was recovered from deposits of similar age in
Maryland and
Arkansas, where in 1941 American paleontologist
George Gaylord Simpson found them all belonging to the same animal, one he considered to be more closely related to the
cougar (Puma concolor), naming the animal as Felis (Puma) inexpectata.[7]
A second species, Felis studeri, was described by D. E. Savage in 1960 based on a more complete material consisting of extensive postcranial and cranial material of the animal.[8] However, a 1976 review of fossil pumas from Kurtén considered F. inexpectata and F. studeri to be the same species, with F. inexpectata having priority. 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.[1]
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.[9] This suggested that the 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 2006 by Johnson et al.,[10] and in 2015 by Dobrynin et al.[11] However, other research by Barnett and Faurby, through examining
mitochondrial DNA and reanalyzing morphology, has suggested reversing the reclassification: the American cheetah developed cheetah-like characteristics through
parallel evolution, but it is most closely related to Puma and not to the modern cheetah of
Africa and
Asia.[1][12][13] Moreover, Faurby notes that no Acinonyx fossils have been found in North America, and no Miracinonyx fossils elsewhere. 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.[14] The veracity of the origin of the modern cheetah is also debated; however, Miracinonyx is believed to have evolved from cougar-like ancestors, regardless of whether in the
Old World or the
New World.[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. trumani.[16]
Below is the phylogeny from Chimento and Dondas (2017) when describing the earliest known fossil record of cougars in
South America. As shown here, they found Miracinonyx to be a sister taxon to Puma (though in their paper they considered the former genus to be an extinct subgenus of the latter).[17]
In 1979 Adams found these animals to be intermediates in size and morphology between cheetahs and cougars and decided to place them in their own genus Miracinonyx. The name is a combination of the
Latinmīrus ('wonderful') and Acinonyx, the cheetah family, itself a combination of the
Greekἀκίνητος (akī́nētos) meaning 'unmoved' or 'motionless' and ὄνυξ (ónyx) meaning 'nail' or 'hoof'.[9]
Description
It is proposed that Miracinonyx is thought to be an instance of
parallel evolution with the cheetah of the Acinonyx genus, but recent studies suggest that it was not specialized in chasing like the cheetah was since it retained retractable claws that would have crippled its ability to run fast. Instead, it was more closely related to the cougar, and at least M. trumani might have employed a hunting behavior that has no modern analogues, suggesting that it running fast like the cheetah is a common misconception. Additionally, the injuries that led to the death of a sub-adult Miracinonyx according to a 2022 research article by John-Paul Michael Hodnett et al suggest that Miracinonyx felids regularly engaged in fighting similar to the extant puma and most other cats and unlike the cheetah, where instances of cheetah individuals fighting each other are rare, further bringing doubts of convergence.[2][4][18]Miracinonyx species were larger than a modern cheetah and similar in size to a modern
North American cougar. The body mass was typically around 70 kg (150 lb), with a head-and-body length of 170 cm (67 in), tail length around 92 cm (36 in), and shoulder height of 85 cm (33 in).[19] Large specimens could have weighed more than 95 kg (209 lb).[20]Miracinonyx most likely preyed on
mountain goats (Oreamnus americanus),
horses (Equus sp.) and especially
pronghorns (Antilocapra americana), which still exhibit morphological adaptations to outrun Miracinonyx.[21][22][23][24]
Behavior
Fossils from Arizona show that American cheetahs were territorial animals, with evidence of pathologies being found on some of the bones.[25][26][27]
M. inexpectatus, ranging from the
Blancan to
Irvingtonian ages, and was more similar to the cougar in build than M. trumani.[4][15] Fossil remains of M. inexpectatus found in
Hamilton Cave in
West Virginia show that this creature lived with and competed with other large cats like
jaguars (Panthera onca) and the saber-toothed cat (Smilodon sp.).[1][28]
M. trumani, exclusive to the
Rancholabrean age, was more cursorial and
Cheetah-like then M. inexpectatus,[4][15] however unlike cheetahs both species retained fully retractable claws.[2]
^Cope, Edward D. (1895). "The fossil vertebrata from the fissure at Port Kennedy, Pa". Proceedings of the Academy of Natural Sciences of Philadelphia. 47: 446–450.
JSTOR4061990.
^Cope, Edward D. (1899). "Vertebrate remains from Port Kennedy bone deposit". Journal of the Academy of Natural Sciences of Philadelphia. 11 (2).
^Savage, Donald E. (1960). "A Survey of Various Late Cenozoic Vertebrate Faunas of the Panhandle of Texas: Felidae". University of California Press. {{
cite journal}}: Cite journal requires |journal= (
help)
^Chimento, N.R.; Dondas, A. (2017). "First record of Puma concolor (Mammalia, Felidae) in the Early-Middle Pleistocene of South America". Journal of Mammalian Evolution. 25 (3): 381–389.
doi:
10.1007/s10914-017-9385-x.
S2CID16249074.
^Caro, T.M. (1994). Cheetahs of the Serengeti Plains: Group Living in an Asocial Species. Chicago: University of Chicago Press. p. 500.
ISBN978-0-226-09433-5.
^The microtine rodents of the Cheetah Room fauna, Hamilton Cave, West Virginia, and the spontaneous origin of Synaptomys (Report). 1988.
doi:10.3133/b1853.
^editor., Baskin, Jon A., editor. Czaplewski, Nicholas J., editor. Lucas, Spencer G., editor. McDonald, H. Gregory (Hugh Gregory), 1951- editor. Mead, Jim I., editor. White, Richard S. Jr., editor. Lichtig, Asher J. (2022). Late Cenozoic vertebrates from the American Southwest: a tribute to Arthur H. Harris. New Mexico Museum of Natural History and Science.
OCLC1350541559. {{
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abcSanders, A.E. (2002). "Additions to the Pleistocene Mammal Faunas of South Carolina, North Carolina, and Georgia". Transactions of the American Philosophical Society. 92 (5): i.
doi:
10.2307/4144916.
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^Scott, M.; Gary, S. (1987). Late Pliocene (Late Blancan) vertebrates from the St. Petersburg Times site, Pinellas County, Florida, with a brief review of Florida Blancan faunas. Florida Paleontological Society.
OCLC182860777.
^Simpson, G.G. (1929). Pleistocene mammalian fauna of the Seminole Field, Pinellas County, Florida. American Museum of Natural History.
OCLC729432.