VANISHED WITH THE SABERTOOTHS: THE AMERICAN CHEETAHS

The extinction of the sabertooths at the end of the American Pleistocene is one of those lingering mysteries of paleontology, but if science manages to solve it one day, it will also have to explain the disappearance of many other large carnivores, some of them utterly unsabertooth-like.
Among those predators that vanished with the last Ice Age, there is one that makes old theories about sabertooth extinction crumble: the “American cheetah”, Miracinonyx trumani.
It has often been argued that modern cats, being swift and agile, left the powerful but slow sabertooths behind in the evolutionary race. But in North America, one of the fleetest felines ever to exist went extinct broadly at the same time as the sabertooths did.
Whatever the cause of the American cheetah’s extinction, it seems that if it could come back today, it would still find one of its favorite prey around, concretely the pronghorn. Often called the American antelope, this ruminant is no true antelope, and it belongs in a family of ts own, the Antilocapridae, which has only one living species but had a considerable diversity until the end of the Pleistocene. It has been suggested that the amazing speeds that this ungulate can attain (up to 85 km/h) are an adaptation to escape from a predator that no longer exists, and the American cheetah certainly fits that description.
Many years ago I prepared a reconstruction of Miracinonyx trumani for National Geographic Magazine, an assignment that took me to the university of Kansas in Lawrence, where paleontologist Larry Martin showed me the amazing collection of cheetah fossils from the site of Natural Trap Cave (Wyoming).
My observations and measurements of that material allowed me to create an accurate reconstruction of the skeleton of M. trumani, which emerged as a cheetah-like animal indeed.

Here is a sketch of the skeleton of Miracinonyx trumani, based on my study of the fossils from Natural Trap Cave
esqueleto m trumani 1 baja

Here is an early sketch that showed the running american cheetah in side view
boceto m trumani 1 baja

In this later sketch I depicted the animal in the same pose but in a slightly more frontal view.
boceto m trumani 2 baja

The scene had to depict the moment when the cat is hooking the hind leg of the pronghorn with its dewclaw.
boceto escena m trumani 3 baja

In this later sketch I changed the pronghorn in the scene from the extant Antilocapra to the extinct Stockoceros. I also changed the environment to fit with the surroundings of a fossil site where both cheetah and pronghorn were recorded.
boceto escena m trumani 2 baja

And here is the final version that appeared in the June 1997 issue of NG Magazine:
OLYMPUS DIGITAL CAMERA

I gave the extinct cat a hypothetical coat color pattern that is not especially cheetah-like, trying to reflect the concept that it was not a true cheetah. Fossil and genetic evidence suggests that, while pumas, Old World cheetahs and American cheetahs are closely related and have a common ancestor not shared with other cats, Miracinonyx developed its adaptations for speed independently from the Old World Acinonyx. If this is true, and it seems to be, then this would be a very remarkable example of convergent evolution.

Posted on 01/10/2014, in Uncategorized. Bookmark the permalink. 7 Comments.

  1. Richard White

    Stockoceros was not recovered from Natural Trap Cave, and the American Cheetah is unknown from the two sites which have large concentrations of Stockoceros, Papago Springs Cave in Arizona, and San Josecito Cave in Mexico.

    • You are right, Richard, and that is the reason why my first sketch showed a modern pronghorn. But then the editors at NGS thought that it would be more visually striking if we showed an extinct pronghorn species in the scene, and that is why I depicted Stockoceros and changed the scenery to reflect the kind of environments found in areas of Nebraska, where the distributions of both animals have some degree of overlap.

  2. Convergent evolution is so fascinating. This would be a beautiful example of it! What a neat reconstruction. I haven’t seen this one before so it’s like a new piece of art to me.
    The thing about the pronghorns is fascinating. Whatever drove the American cheetah to extinction, it certainly was not the pronghorns being wiped out first. Maybe for a while the landscape became more brushy and less conducive to running. We see sad things happening to cheetahs due to human activity in parts of Africa that causes the brush to replace grassland, with cheetahs going blind in at least one eye due to being struck by briars while running, etc.😦

    Speaking of convergent evolution, I’ve heard it said that the nimravid Dinaelurus was more gracile and cheetah-like than other nimravids, but everything in the literature that I can find on Dinaelurus only references a single skull that was found. A few book chapters mention that they were “gracile” but even combing their references I haven’t found the source for that claim yet, other than the observation from that skull that they perhaps had an enlarged nasal passageway rather like a cheetah. Cannot find whether even a single leg bone been found. If it has been confirmed that Dinaelurus really was also built quite a cursorial predator, it would be a very interesting example of yet another way nimravids may have filled many of the niches that true felids do today.

    • Yes, the degree of convergence is really striking. My observations on the fossils from Natural Trap Cave revealed M. trumani as amazingly cheetah-like, not only in terms of measurements but of morphology as well. Concerning its extinction, it was part of a large event, which led to the extinction of 2 kinds of sabertooth cats plus the American lion, the dire wolf and the short-faced bear in North America alone, so maybe we don´t need to look for something very specific to the cheetah. As a matter of fact, the Old World cheetah was also on the verge of extinction at that time, and it went throught such a population bottleneck that living cheetahs have a strikingly low genetic diversity. The late Pleistocene was indeed a time of crises.
      And yes, the lack of postcranial fossils of Dinaelurus is so frustrating. Personally I would be surprised that the animal had very long limbs, because all known nimravids have shortish legs. Even in animals like Dinictis, whose limb bones are relatively gracile, the distal segments (metapodials) are so short relative to the proximal ones that the animal would not be a true runner. But only the discovery of new fossils will tell!

  3. Do you have any thoughts on whether Miracinonyx would have preyed on the Dwarf Pronghorn Capromeryx?

    • Phillip, I think that in terms of its size and structure Capromeryx was indeed a suitable prey for Miracinonyx trumani. I am not sure whether the two species shared the same landscapes in Pleistocene North America, but if they did I am sure the dwarf pronghorn would be in Miracinonyx’s menu.

  4. Beautiful art. Love to go back there and see. does the pronghorn of today fall prey to any carnivore, maybe the young when they are vulnerable lying on the grassland not yet able to fly.

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