The Ice Age movies get one important thing right: Climate changes and ice ages caused profound animal migrations and evolutionary adaptations, although it’s unclear whether any of them were the result of a saber-toothed squirrel burying acorns and splitting a continent. During the Pleistocene epoch, between 2.58 million and 11,700 years ago, or what is colloquially called the most recent “ice age,” North America was home to an impressive array of impressive animals. Giant bears measuring up to 12 feet tall defecated in caves, woolly mammoths trumpeted across the frigid tundra steppes, and ‘American cheetahs’ chased ‘American antelope’ across sprawling grasslands. An artist’s conception of an ‘American cheetah’, weighing about 70 kilograms (150 pounds) and measuring about 2.4 meters (8 feet) from tip to tail, chasing a Saiga antelope, an ice age survivor. (Velizar Simeonovski/UCSC) But a new and exceptionally comprehensive isotopic and DNA analysis revealed that this fleet-footed felid was not actually a cheetah. Turns out it was a sister species to the modern puma (Puma concolor), with a surprising diet to boot. “These cats were remarkably flexible, just like pumas in their current range,” explains Molly Cassatt-Johnstone, a paleogenomist at the University of California, Santa Cruz (UCSC), and lead author of the study. As described in the new paper, published in the journal Current Biology, Miracinonyx trumani was thought to be an endemic American version of the African cheetah (Acinonyx jubatus). This was due to their similar adaptations for running (running), including elegantly slender builds, athletically long limbs, and “greater capacities of the nasal turbinates,” which gave them turbocharger-like noses (the words are related) to increase oxygen intake, with the offset of smaller teeth compared to their kitten relatives. M. trumani skull fragments recovered at great depth from Natural Trap Cave, Wyoming. (Julie Meachen/UCSC) “It’s very difficult to imagine a prehistoric species we’ve never seen without comparing it to something we know,” Cassatt-Johnstone says. “But this approach may limit our understanding of the complexity of ancient animals, their unique evolutionary histories, and their behaviors.” The researchers performed a paleogenomic analysis of four fossil specimens of M. trumani, including one from Wyoming that lived about 23,000 years ago and three from the Yukon (Canadian Arctic) that lived more than 30,000 years ago. An illustration showing a species tree and estimated divergence of felids, with divergence from the cougar lineage about 2.6 million years ago, including DNA comparisons of lions with domestic cats. (Cassatt-Johnstone et al., Current Biology, 2026) “It was cool to see that these cats behaved like totally different predators depending on where they were,” says Cassatt-Johnstone. These Yukon specimens were previously thought to be another species. But by confirming them as M. trumani, separated from their feline cousins further south by a glacial barrier, the researchers expanded this animal’s known range by 20 degrees of latitude with a single scientific stroke. An illustration detailing the geographic distributions of M. trumani, as well as the origin of known samples, including those used in this work. (Cassatt-Johnstone et al., Current Biology, 2026) “This species of carnivore has a huge distribution, from the Arctic to the lower 48 states,” explains paleoecologist Matthew Wooler, director of the Alaska Stable Isotope Facility at the University of Alaska Fairbanks (UAF), where the isotopic analysis was carried out. “They are demonstrating super-specialization at two ends of their range, while feeding on two completely different food sources.” Interestingly, the northern population adapted to their habitat by becoming Pescatarian, according to an analysis of their nitrogen isotopes (heavier or lighter versions of nitrogen that differ in their number of neutrons). The analysis revealed a diet of fish such as salmon, leaving a chemical signature similar to that observed in killer whales and sea lions. He also appears to have adapted his daily biological clock. “We found loss-of-function mutations in certain genes that regulate circadian rhythms,” says Cassatt-Johnstone, “suggesting that they may have adapted to the extreme light cycles of summers and winters at northern latitudes.” A story of two cats. Artist’s conception of how a glacial barrier divided the two American “cheetah” populations, leading to dietary specializations based on their environments. (Julius Csotonyi/UCSC) Mysteries persist, however, including how M. trumani managed to carve out a niche for itself among fish among a large guild of carnivores that included cave lions, scimitar-toothed cats, gray wolves and brown bears, among others. “Miracinonyx persisted for a long time without the signs of inbreeding that we would expect before a collapse,” explains Beth Shapiro, an ecologist and evolutionary biologist at UCSC and lead author of the study. Eventually, M. trumani began to decline as the Pleistocene progressed, a pivotal period of climate change that marked the end of the ice age and closed the curtain on iconic creatures like the woolly mammoth. Related: Saber-toothed cats were a diseased, inbred mess before they went extinct, new research suggests “The decline was slow, not sudden, and that may be what left them unable to adapt when the climate changed,” Shapiro concludes. This research was published in the journal Current Biology. This article was fact-checked by Rachel Garner and edited by Rebecca Dyer. While we take pride in our process, we are human. If you spot an error, please let us know.
