A new study led by researchers at the University of California, Santa Cruz, has challenged long-held beliefs about Miracinonyx trumani, an extinct predator once thought to be a close relative of the modern cheetah. By examining nuclear DNA and stable isotopes from fossils found as far north as the Yukon, scientists discovered that this species was not a true cheetah but a relative of the puma, or mountain lion. It had adapted to survive in Arctic environments by specializing in eating fish, such as salmon. Published in Current Biology, the research shows that M. trumani's range extended much farther north than previously believed—20 degrees of latitude further—suggesting it lived in both temperate and Arctic regions. In southern areas like Wyoming and Florida, it likely behaved like a generalist predator, hunting in grasslands, while its northern counterparts adapted to the unique challenges of Arctic life. The study found that M. trumani was a close relative of the modern puma, diverging from that lineage about 2.6 million years ago. Its sleek, cheetah-like body was once thought to indicate a close evolutionary relationship with cheetahs, but the research shows this was an example of convergent evolution—where unrelated species develop similar traits due to similar environmental pressures. The study also identified genetic changes in M. trumani that may have helped it adapt to the extreme light conditions of the Arctic, such as long summer days and prolonged winter darkness. These changes involved genes that regulate circadian rhythms, the body’s internal clock. By sequencing the complete genomes of M. trumani fossils from the Yukon, which date back 23,000 to 31,000 years, researchers uncovered genetic clues about how this species survived in harsh environments during the Late Pleistocene. The fossils were found in the Tr'ondëk Hwëch'in and Vuntut Gwitchin Traditional Territories, highlighting the importance of Indigenous knowledge and collaboration in such research. Another intriguing finding was that M. trumani, along with all other felids studied, lacked a functional gene responsible for detecting sour tastes. This is the first time such a sensory adaptation has been recorded in cats, possibly linked to their specialized diets. The study underscores the risks of naming extinct species based solely on their physical appearance. The term "American cheetah" is misleading, as it suggests a close evolutionary link and similar hunting behavior to true cheetahs, which the genetic data do not support. The research also found that M. trumani populations in Wyoming and the Yukon had low genetic diversity, but unlike pumas, they did not show signs of inbreeding or sudden population crashes. Instead, they experienced a slow decline over thousands of years, which may explain their rarity in the fossil record and their eventual extinction.