Life in the Slow(er) Lane: Revisiting the Long-Lost Giant Cheetah
For the most part, a cat is a cat is a cat. Large or small, domestic or wild, most are agile ambush predators that subsist almost entirely on meat. But then there’s the cheetah. It’s a cat that hunts like a dog. The felid’s claws are more like cleats than the retractable armaments of its relatives, its nasal cavity is enlarged to house the soft tissues necessary to keep it cool while sprinting, and, as the fastest land mammal, the cat relies on speed to chase down and trip up fleeing antelopes and gazelles. Cheetahs are so different, in fact, that figuring out when they adopted this speedy lifestyle has been clouded by the imagery invoked when we apply the term “cheetah” to their fossil relatives.
Take Miracinonyx, for example. The two species of this svelte fossil cat have often been called “American cheetahs” on the basis of their bones, and even inspired the idea that cheetahs first evolved in the New World rather than the Old. But this idea fell apart. Skeletal and genetic clues have shown that Miracinonyx was more closely related to cougars than cheetahs, and there’s some doubt about whether this cat rocketed over open ground after pronghorn or stalked steep rock walls and caves. The title of “American cheetah” invokes scenes of speed, but, even if the carnivore did so, this cat was a false cheetah.
The modern cheetah’s true fossil relatives started off in Africa about three million years ago and eventually dispersed through Eurasia before leaving only one species behind. But even though they were more closely related to today’s Acinonyx jubatus than other cats, the prehistoric forms didn’t live and hunt just like the living one. In fact, as Sorbonne University paleontologist Denis Geraads recently concluded, the cheetah as we know it today is a relatively recent evolutionary spinoff.
The focus of Geraads’ study was a skull of Acinonyx pardinensis found in France. This species ranged from Spain to Georgia about 2.4 million years ago, and previous paleontologists had concluded that the felid’s skull was already quite similar to that of the modern cheetah. Through using a technique called geometric morphometrics to compare the cat’s skull shape to that of other felids, however, Geraads found that Acinonyx pardinensis was not simply a big version of its living relative. The cat’s skull shape more closely resembled that of a cougar than the more specialized short, deep form of today’s cheetah. In short, the giant cheetah had a skull more like that of other pantherine cats, and the distinctive profile of the modern species evolved much more recently.
Two skulls and a jaw found in Italy bolster Geraads’ argument. Uncovered at a site in Pantalla, Italy and described by Perugia University paleontologist Marco Cherin and coauthors, these Aciononyx pardinensis skulls had some cheetah-like traits – such as a shorter relative length and enlarged nasal openings – but they also retained some traits of their ancestors, such as a high keel on the back of the skull for greater jaw muscle attachments. Acinonyx pardinensis was its own cat, with a skull intermediate in shape between today’s cheetah and its more cougar-like ancestors.
So what does this mean for how the extinct cheetah hunted? On the basis of muscle reconstructions threaded on CT scans of the Pantalla skulls, Cherin and colleagues tentatively suggest that the extinct cheetah had enough biting power to crush neck and skull bones like jaguars and cougars do. (Modern cheetahs, by contrast, often kill prey with a suffocating death grip on the throat.) More than that, Cherin and coauthors point out that Acinonyx pardinensis weighed about 176 pounds – twice as heavy as modern cheetahs – and that the relatively slender proportions of the cat’s postcrania cannot be immediately taken as evidence that it was a fast runner. The skeletons of snow leopards show some striking similarities to those of cheetahs, the researchers note, even though the two cats occupy very different habitats and hunt in very different ways. Despite its relationship to the modern cheetah, Acinonyx pardinensis was more like a typical big cat.
The term “cheetah” isn’t inaccurate for Acinonyx pardinensis. The fossil cat surely belonged to that lineage. But the title has also obscured how different this felid truly was. The exceptional nature of the modern cheetah has masked the unique nature of its fossil relatives. If we can remove that bias and understand fossil species in the context of their own time, we gain more than a richer understanding of the past. We earn a deeper appreciation for the vast changes that made our modern megafauna what they are.
Cherin, M., Iurino, D., Sardella, R., Rook, L. 2014. Acinonyx pardinensis (Carnivora, Felidae) from the Early Pleistocene of Pantalla (Italy): predatory behavior and ecological role of the giant Plio-Pleistocene cheetahAcinonyx pardinensis (Carnivora, Felidae) from the Early Pleistocene of Pantalla (Italy): predatory behavior and ecological role of the giant Plio-Pleistocene cheetah. Quaternary Science Reviews. doi: 10.1016/j.quascirev.2014.01.004
Geraads, D. 2014. How old is the cheetah skull shape? The case of Acinonyx pardinensis (Mammalia, Felidae)How old is the cheetah skull shape? The case of Acinonyx pardinensis (Mammalia, Felidae)How old is the cheetah skull shape? The case of Acinonyx pardinensis (Mammalia, Felidae). Geobios. doi: 10.1016/j.geobios.2013.12.003