For decades, the extinct Ice Age predator known as the American cheetah was assumed to be a close relative of the cheetahs that still run down prey on the plains of Africa, an animal built for speed to chase equally fast prey like pronghorn across open grassland. A new analysis of ancient DNA has overturned that assumption entirely. The animal, formally named Miracinonyx trumani, turns out to be far more closely related to the puma than to any cheetah. Some populations living near the Arctic, the same study found, appear to have survived largely on fish rather than chasing fast-running mammals at all.
A Name Built on a Misleading Resemblance
Miracinonyx trumani earned its common name because its skeleton looked cheetah-like to the paleontologists who first described it, with long limbs and a build suited to running down prey at speed. That resemblance was assumed for decades to reflect a real evolutionary relationship, placing the American animal in the same broad lineage as Africa’s modern cheetahs.
Ancient DNA extracted from fossil specimens tells a different story. According to the study covered by Phys.org, genetic analysis shows the closest living relative of Miracinonyx trumani is the puma, not the cheetah, meaning the two animals arrived at similar cheetah-like body shapes independently rather than through shared ancestry. The puma itself, also known as the mountain lion or cougar, still ranges across large parts of the Americas today, making it possible to compare the extinct species against a close living relative rather than reconstructing its biology from bone alone.
Convergent Evolution, Not a Family Tie
The mismatch between appearance and ancestry is an example of convergent evolution, in which unrelated species evolve similar physical traits because they face similar pressures, rather than because they share a recent common ancestor. A long-legged, deep-chested build suited to chasing fast prey can evolve more than once in unrelated lineages if the environment rewards it each time.
That distinction matters for how the animal is classified and understood, even though it does not change what the fossils themselves look like. A cat that resembles a cheetah because it hunted the way cheetahs hunt, rather than because it descended from cheetah ancestors, tells a different story about how North America’s Ice Age predators evolved relative to their African counterparts. Similar cases of convergent evolution show up throughout the fossil record, including unrelated groups of mammals that independently evolved saber-like teeth or wings, which is part of why relying on skeletal shape alone to determine ancestry has become less trusted as ancient DNA techniques have improved.
Fish-Eating Populations Far to the North
The genetic work was paired with an expanded look at where the species lived and what it ate, using new specimens recovered from Bluefish Caves and Upper Quartz Creek in Canada’s Yukon Territory. Those finds pushed the known range of Miracinonyx trumani roughly 20 degrees of latitude farther north than earlier fossils had shown, into territory near the Arctic Circle.
Populations in that northern range appear to have eaten very differently from their counterparts farther south. While cats living in warmer grasslands in places like Wyoming and Florida behaved as generalist predators of the kind their cheetah-like build would suggest, the Yukon population’s chemical diet signatures point to a diet dominated by anadromous fish, such as salmon, rather than fast-running land mammals. Researchers describe the northern animals as functioning as tertiary consumers in their ecosystem, feeding at a level of the food chain more associated with animals like bears that gather at salmon runs than with a dedicated pursuit predator of open grassland.
A Body Built for Speed, Living Like a Fisher
The finding directly challenges the long-held assumption that Miracinonyx trumani’s cheetah-like proportions meant it specialized in chasing down fast prey such as pronghorn wherever it lived. A population eating mostly fish would have had little use for the kind of high-speed pursuit that its skeleton seems built for, at least in the environment where those specimens were found.
The researchers behind the work note that this kind of dietary flexibility across a wide range is consistent with an adaptable predator rather than a narrow speed specialist, and it raises the question of whether the animal’s build served purposes beyond chasing prey across open ground, particularly in northern environments where terrain and available prey looked very different from the grasslands farther south.
Genetic Traces of Arctic Adaptation
The DNA analysis also turned up loss-of-function mutations in genes tied to circadian rhythm regulation among the northern specimens, a pattern that researchers connect to survival through the extreme seasonal light cycles of the Arctic, where summer brings nearly continuous daylight and winter brings the opposite. Losing strict circadian regulation can be an advantage in an environment where the normal day-night cycle that most animals evolved around barely exists for months at a time.
Coverage from Science News and a release from the University of California, Santa Cruz describe the study as reshaping the picture of Miracinonyx trumani from a single, uniform speed specialist into a species with real regional variation in both range and behavior, closer to how many living carnivores adapt their diet and habits to whatever environment they occupy. The study was published in Current Biology.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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