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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.
How can you really debate on how a cat ,so similar to the others, acted?
ReplyDeleteWell, often times it is very subtle. But the morphology of an animal's bones can often hint at how that animal behaved in life. The bones of a cheetah look differently then those of, say, a lion. Not only is it because the lion is a larger and more robust animal, but because these two cats behave differently. The cheetah is built for speed and pursuit of prey over open terrain, and its bones can help hint at that. Snow leopards, on the other hand, are built for pursuit over rough and steep terrain, in the high, harsh mountainous areas of the Himalayas, and aspects of its skeleton can help hint at that as well. The mountain lion, commonly what is really considered most closely related to Miracinonyx, is slightly more similar to the snow leopard, although it is also somewhat of a generalist and has adapted to many environments throughout North America. So while it is still only hypothetical, the osteology of Miracinonyx can hint at whether it was North America's version of the cheetah, or something else.
ReplyDeleteCouldnt the different specimens of the Miracinonyx found have acted differently because they were in different climates? Pennsylvania and Texas in today's world are two totally different climates therefore they would behave and act in two totally different ways correct?
ReplyDeleteI think that more research in this topic can certainly explain the answers to the questions pertaining to the Miracinonyx.
If I was a Miracinonyx I would live in the mountains and hunt in the plains. Do you think that the species just died off or do you think that it is possible that because of global cooling that they were able to migrate to warmer climates. Thus branching of into the different species found throughout Asia and Africa today?
ReplyDeleteRachel - Different climates can certainly lead to different behaviors. In that sense, polar bears behave differently then black bears or other warmer cousins. Commonly, however, it can turn out to be the habitat that plays more of a role in how an animal acts. So living in a warm swamp can be far different then living in a tropical mountainous rain forest, even though both are quite hot and humid. And, in general terms, Texas and Pennsylvania are both somewhat temperate climates, even though Texas ends up being quite a bit drier. Also, look below at my response to Jeremy....
ReplyDeleteJeremy - Living in a thicker area, such as the mountains would allow one to more easily protect offspring and hide from other, larger predators. The plains are open, and fast and cunning predators can more easily spot their prey. While the snow leopard (Uncia uncia)is specialized for more mountainous terrain and the cheetah (Acinonyx jubatus)for open terrain like the plains, there are cats that are more generailized. The mountain lion (Puma concolor)is fairly generalized, and is found from the Yukon of Canada to the southern Andes in South America. This means it can survive in a very wide range of habitats, although it prefers forested habitat with some higher rocky areas. There has been some research though, including Barnett (2005, Evolution of the extinct Sabretooths and the American cheetah-like cat) feels that Puma and Miracinonyx evolved from a common ancestor and only looks like the cheetah (with a short skull, etc) due to convergent evolution. This would suggest a similar lifestyle and imply that Miracinonyx was an open plains predator. Still, more work must be done on the rest of the skeleton to see if it really did behave the same way, or just develop a similar looking skull
ReplyDeleteJeremy - as a follow-up, it seems that Miracinonyx would have evolved into Puma, or died off. I don't think it migrated back over to Asia and Europe, there is some old fossils atributed to Acinonyx (aka genus of the cheetah) in Europe already. So, in essence, I would say it is still here in its Puma costume, or has left us forever.
DeleteI would really like to know how this turns out. Isn't it possible that Miracinonyx simply doesn't share any more characteristics to one of the modern examples than another? Is there any evidence that they were fast like today's cheetahs? In my opinion and on what I got from the post, if I had to eliminate one of the possible ancestors, it would be the mountain lion. Mostly because they can adapt very well to many environments and Miracinonyx didn't seem to be able to do so.
DeleteAs a follow up question to Autumn, I was also wondering what led to the disappearance of this species. On Jeremey's post you said it may have evolved ionto the Puma or died off. I am not an expert but it seems to me that ccats are very adaptive, excluding the sabertooth cat and a few others. What would it have taken for a fast, agile creature like this to die out in America? Do we have any evidence of a species that connects the Miracinonyx to the Puma?
DeleteAutumn - While it is possible that is it equally similar to various modern felids, it is possible to tell through things like genetics and which characteristics it shares with either one, which type it is ancestral to. Puma and Acinonyx belong to the same subfamilty, but their are key differences. Little has been done to decide whether they really were that fast, or just superficially look like modern cheetahs. In essence, not enough is known about these cats to determine yet whether they were more specialized or more of a generalist. Some of the only more straightforward clues are that fossils have been found over much of the USA along the east coast down to Florida and west to at least Nevada. So, time and more research may help solve some of these questions
DeleteDan - You are right that cats seem to be a very adaptive group of animals. The biggest problem for them today is not something "natural", its just man his destructive nature. The most probable answer for what could have killed off a species like this is habitat change and prey loss. Both of these could certainly be related as well. If their was prey partitioning during that time in North America, then Miracinonyx may have been specialized for a certain type of prey. This may have been necessary since it lived around much larger predators like giant short-faced bears, dire wolves, and the American lion. While there is some possible morphological evidence and similarities in their anatomy to connect Puma and Miracinonyx, this has not been well investigated yet. I currently am undergoing a study to help shed a bit more light on this though. It appears that their will be more evidence showing similarities between the two, and the similarities between it and the cheetah may be more convergence then evolutionary relationships.
DeleteIt sounds like he was the American cheeta to me, but Im also not a scientist. Cats are very adaptive they seem to be in every corner of every street I have ever lived on. Theres always stray cats running around.The thought of this cat still living in America blows my mind. I just dont see how it acts like a cat that lives in the snow. seems like tyhe cat would have been dealing with a hotter enviorment but i guess the earth was cooler back then.
ReplyDeleteClint Riddle
In some ways various parts of the world would have been cooler. Even so, mountain lions today are found well into Canada, where there is plenty of snow around for a good portion of the year. Rather than thinking that Miracinonyx would have looked like a snow leopard and lived in that same kind of snow-filled environment, think more of a cheetah looking cat living on the steep slopes of the Grand Canyon, scaling walls when needed. Whether it hunted on those slopes or only the plains and steppes above it is not known.
DeleteThe Miracinonyx description fits best with the American Cheetah, in my opinion. But what are other things scientists could compare, besides actual size and how gracile there limbs are, that are similar in these types of cats? I'm sure teeth played a big role in figuring out the species name, but what other types of things could we ultimately compare?
ReplyDeleteTeeth commonly are some of the key pieces of evidence for distinguishing mammals, since they can be so distinct. Skulls and cranial material can also be quite important, although they are commonly quite rare in the fossil record. Post-crania is normally quite conservative throughout groups, and this includes the felids. There are, however, some things that can be determined. Cheetah's have very strong, compact feet since they tend to sprint but don't have to worry about uneven terrain. Mountain lions and snow leopards deal with steep slopes and uneven terrain, and this is shown in their feet and legs, although it may be very very subtle. Other cats, like the margay, have feet and ankles that are incredibly flexible, in fact the margay can turn its hindfeet 180% around so they can walk headfirst DOWN a tree trunk. Aspects of the tail, including its length, may be important, since it deals with balance and helps with running and with uneven terrain. Even so, there will be subtle differences that may help tell differences in behavior, but that work is still to be done.
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