In the Bluefish Caves and a mine site in northern Yukon, bones initially believed to be from an ice-age puma or cougar were subjected to DNA analysis by the University of California. The testing, conducted by Molly Cassatt-Johnstone, a lab technician fresh from completing her undergraduate studies, revealed surprising results. Contrary to expectations, the Yukon bones did not match the characteristics of pumas.
Yukon paleontologist Grant Zazula vividly recalls the moment he received the unexpected revelation that the presumed cougars were, in fact, cheetahs. This breakthrough, once considered akin to science fiction due to the complexities of ancient DNA analysis, has now become a routine practice in studying permafrost-preserved bones from the Yukon.
Cassatt-Johnstone’s identification of the Yukon Miracinonyx, known as the extinct American cheetah, marked a significant milestone. This discovery led to her authorship of a paper in Current Biology, shedding new insights on the ice-age cat’s dietary habits and habitat range.
Researchers were initially puzzled by the presence of American cheetahs in the Arctic tundra, as they were believed to have evolved to hunt pronghorns in grassy plains. The absence of pronghorns in Beringia, the land connecting Asia and North America, raised questions about how the Miracinonyx species thrived in this region.
To unravel this mystery, researchers, in collaboration with Canadian and U.S. counterparts, employed stable isotope analysis. This method, commonly used in forensics, provides chemical clues about ancient diets and environmental conditions. The study revealed that Yukon cheetahs predominantly fed on fish, a behavior uncommon among historical and contemporary felines.
The study’s findings challenged previous assumptions about the American cheetah’s diet and habitat preferences, particularly in comparison to specimens found in Wyoming. The unique adaptation of Yukon cheetahs to capitalize on the abundant salmon runs in the region showcased their ability to thrive alongside larger predators like Beringian lions and giant bears.
Genetic analysis further revealed that Miracinonyx was genetically closer to North American pumas than African cheetahs. The study also highlighted the low genetic diversity and limited adaptive potential within the cheetah population, which may have contributed to their eventual extinction.
Grant Zazula suggested renaming this distinct northern population from ‘American Cheetah’ to ‘Yukon Cheetah,’ emphasizing the significance of ongoing paleontological discoveries in the region. The study underscores the importance of even the smallest bone fragments in uncovering new insights into prehistoric ecosystems and species dynamics.