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.
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.
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.