A discovery in the Bluefish Caves and a mine site in northern Yukon initially led researchers to believe they had come across remains of an ice-age puma or cougar. However, a DNA analysis conducted by the University of California revealed a surprising truth. The testing was carried out by Molly Cassatt-Johnstone, a lab technician fresh out of her undergraduate studies, who was working on some of her first samples from the Yukon. When the preliminary analyses didn’t match those of pumas, she was taken aback. Paleontologist Grant Zazula vividly recalls the moment he received the unexpected message: “Hey Grant, your cougars aren’t cougars — they’re actually cheetahs.”
Reflecting on the advancements in genetic analysis, Zazula noted that investigating ancient DNA was once considered akin to science fiction, reminiscent of Jurassic Park scenarios. Fast forward to today, genetic analysis on permafrost-preserved bones from the Yukon is now a routine practice. Cassatt-Johnstone’s identification of a Yukon Miracinonyx, also known as the extinct American cheetah, marked a significant milestone. She is now the lead author of a paper published in Current Biology, providing fresh insights into the ice-age cat’s diet and habitat range.
The American cheetah, resembling present-day cheetahs with their long limbs and slender physique, was traditionally thought to have evolved for hunting pronghorns on grassy plains. The discovery of these creatures in the Arctic tundra puzzled paleontologists, as pronghorns were never present in Beringia — the region where Asia and North America once connected. To unravel how Miracinonyx thrived in this environment, researchers, in collaboration with Canadian and U.S. partners, turned to stable isotope analysis. This technique, commonly used in forensics, examines chemical traces to determine the diet, climate, and potential movements of ancient organisms.
By analyzing bone samples from the cheetah’s limbs, researchers like Matthew Wooller, the director of the Alaska Stable Isotope Facility, were able to deduce dietary patterns with remarkable precision. The findings revealed that Yukon cheetahs predominantly fed on fish, a behavior uncommon among historical and contemporary felines. This dietary peculiarity, seen in the context of a complex ecosystem, presented a challenging puzzle for researchers to solve.
The revelation that Yukon cheetahs heavily relied on salmon astonished experts like Julie Meachen, a specialist in Late Pleistocene mammalian carnivores. In a region teeming with formidable predators, the cheetahs’ adaptation to exploit abundant salmon runs was deemed a strategic survival tactic. The study’s comprehensive DNA analysis indicated that Miracinonyx was genetically closer to North American pumas than African cheetahs. Additionally, the research highlighted the low genetic diversity and limited adaptive potential within the cheetah population, factors that might have contributed to their eventual extinction.
Zazula proposed renaming this distinct northern population from ‘American Cheetah’ to ‘Yukon Cheetah’ in light of the discovery. He emphasized that each new bone unearthed in the Yukon has the potential to unveil previously unknown narratives, underscoring the ongoing surprises hidden within the region’s ancient past.