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| The Carnivores of Rancho La Brea. From left to right. The dire wolf (Canis dirus), the sabre-toothed cat (Smilodon fatalis), the short-faced bear (Arctodus simus), the cheetah-like cat (Miracinonyx sp.), and the American lion (Panthera atrox). Modified from Turner, A., and Anton, M., The Big Cats and Their Fossil Relatives. Columbia University Press: New York, 1997. |
Miracinonyx, commonly called the American cheetah by some, has been found various places throughout North America. Cope (1895) named Uncia inexpectata from some isolated teeth from a cave in Pennsylvania. A second species was named "Felis" studeri from Texas by Savage (1960). Both these would eventually be referred to the genus Miracinonyx (aka American cheetah). Both these taxa were alive pre-Rancholabrean (>240,000 ybp), and Kurten (1976) synonymized both felids with the idea that there was only one Miracinonyx species before the Rancholabrean. Not long after the erection of studeri, Orr (1969) named "F." trumani baed on a skull from a cave in Nevada.
Adams (1979) grouped these taxa together within Acinonyx, the genus of the modern cheetah, due to morphological similarities. He went a step further, however, and grouped them in the subgenus Miracinonyx. The taxonomy of these cats was in a state of flux for awhile, with numerous workers considering the only valid genera to be A. studeri and A. trumani. Van Valkenburgh et al. (1990), however, reported on a remarkable specimen from Hamilton Cave in West Virginia, and concluded that, while A. trumani was valid, it was A. inexpectatus that was the second valid species, with A. studeri as its junior subjective synonym.They also elevated Miracinonyx to the generic level. Van Valkenburgh et al. (1990) were also keen to call them American "cheetah-like cats" rather than American "cheetahs".
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Osteological reconstruction of Miracinonyx inexpectatus based on material from Hamilton Cave, West Virginia. Scale = approximately 240 cm (from Van Valkenburgh et al., 1990). |
Miracinonyx inexpectatus is the species that first came to be viewed as the "American cheetah". In many ways, the cranial and post-cranial morphology were quite reminiscent of cheetahs today. They have been also, however, commonly compared to Puma, and many researchers have debated which they are more closely related to. While M. inexpectatus had longer and somewhat gracile limbs, M. trumani was, in comparison, a smaller and relatively more robust cat.
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Phylogenetic relationships of the Miracinonyx-Acinonyx lineage based on 27 morphological characters with Leopardus pardalis as the outgroup (from Christiansen and Mazak (2009)). |
Miracinonyx has been considered more of a plains species, commonly using Acinonyx (cheetah) as a modern analogue. This is true for both species, even though M. trumani is less similar to Acinonyx than M. inexpectatus, and seems to be more similar morphologically to Puma. This was discussed not long ago by J.P. Hodnett. Hodnett, in an upcoming study, discusses remains of M. trumani from caves in the Grand Canyon of Arizona. Rather than living in a plains habitat, it seemed to be living in a more mountainous terrain with lots of elevation change.
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| Adult Snow Leopard (Uncia uncia) |
Hodnett took it a step further though, and compared Miracinonyx trumani to the ultimate modern felid adventurer, Uncia uncia, or the snow leopard. He felt that, in order to be agile and a top predator in the Grand Canyon, that M. trumani would have been behaving similar to the snow leopard.
So, Miracinonyx similar to the snow leopard? It seems like a bit too extreme. Puma behaves, in some ways, similar to Uncia, although in many ways the former is more of a habitat generalist, doing well in a wide variety of habitats throughout North America. Acinonyx, on the other hand, is specialized for open habitat, and Uncia tends to stick to mountainous areas.
With that being said, is Miracinonyx still the American cheetah? Is it the "American Puma"/ancient ancestor of the modern Puma? Or could it be the American snow leopard? While I would lean towards it being more of a generalist like the puma, it could also turn out that M. inexpectatus behaved like the cheetah, while M. trumani behaved like the mountain lion, so one answer will not suffice. Presumably, time and further research will tell us the answer.
References:
Adams, D.B. 1979. The cheetah: native American. Science 205:1155-1158.
Christiansen, P. and Mazák, J.H. 2009. A primitive Late Pliocene cheetah, and evolution of the cheetah lineage. Proceedings of the National Academy of Sciences 106(2):512-515.
Cope, E.D. 1895. The fossil vertebrates from the fissure at Port Kennedy Cave, Pennsylvania. Proceedings, Academy of Natural Sciences, Philadelphia 1895:446-451.
Hodnett, J-P., White, R.S., Carpenter, M., and Mead, J.I. in prep. Miracinonyx trumani (Carnivora: Felidae) from the Rancholabrean of the Grand Canyon, Arizona and its implications on the ecology of the “American cheetah”.
Kurtén, B. 1976. Fossil puma (Mammalia: Felidae) in North America. Netherlands Journal of Zoology 26:502-534.
Orr, P.C. 1969. Felis trumani a new radiocarbon dated cat skull from Crypt Cave, Nevada. Bulletin of the Santa Barbara Museum of Natural History Department of Geology 2:1-8.
Savage, D.E. 1960. A survey of various late Cenozoic vertebrate faunas of the panhandle of Texas. Part III, Felidae. University of California Publications in Geological Sciences 36:317-343.
Turner, A. and Anton, M. 1997. The Big Cats and Their Fossil Relatives. Columbia University Press, New York. 234 pp.
Van Valkenburgh, B. Grady, F. and Kurtén, B. 1990. The Plio-Pleistocene cheetah-like cat Miracinonyx inexpectatus of North America. Journal of Vertebrate Paleontology 10(4):434-454.
