Bones discovered in the Bluefish Caves and a mining site in northern Yukon were initially believed to be from an ice-age puma or cougar. However, DNA testing conducted by the University of California revealed a different story. The analysis was carried out by Molly Cassatt-Johnstone, a lab technician who had recently completed her undergraduate studies. The Yukon bones were among her first samples to work on, and the results surprised her as they did not match those of pumas.
Yukon paleontologist Grant Zazula vividly recalls his astonishment upon receiving the message that the supposed cougars were actually cheetahs. Zazula noted the significant advancements in analyzing ancient DNA, which was once considered a realm of science fiction akin to Jurassic Park but has now become a routine practice in studying permafrost-preserved bones from the Yukon.
Cassatt-Johnstone made history by identifying the first Yukon Miracinonyx, also known as the extinct American cheetah. She is now the lead author of a paper published in Current Biology that provides fresh insights into the ice-age cat’s dietary habits and habitat. Researchers had long assumed that the American cheetah, resembling modern cheetahs with their elongated limbs and slender physique, would have evolved to pursue pronghorns across grassy plains. The unexpected discovery of these creatures in the Arctic tundra puzzled paleontologists.
The study delved into the survival of Miracinonyx in Beringia, the region where Asia and North America once connected, encompassing present-day Russia’s easternmost territory, Alaska, and the Yukon. Stable isotope analysis, a method used in forensics to trace the diets and environmental conditions of ancient organisms, was employed by the researchers. The analysis of bone fragments from the cheetah’s limbs revealed a peculiar diet preference for fish, a behavior uncommon among past and present feline species.
The revelation that Yukon cheetahs primarily fed on salmon was a significant finding, challenging previous assumptions about their dietary habits. The study also highlighted the genetic proximity of Miracinonyx to North American pumas rather than African cheetahs, indicating low genetic diversity within the population, which may have contributed to their eventual extinction.
Paleontologist Julie Meachen, an expert in Late Pleistocene mammalian carnivores, expressed surprise at the distinct behavior of Yukon cheetahs compared to those in midcontinental North America. The abundance of fish in the Yukon likely provided an easy food source for the smaller cheetahs, allowing them to thrive in competition with larger predators such as Beringian lions and bears.
Zazula proposed renaming this unique northern population from ‘American Cheetah’ to ‘Yukon Cheetah’ to reflect their specialized adaptation to the region’s environment. The discovery underscores the ongoing potential for new revelations in paleontology, emphasizing the importance of every bone in unraveling the mysteries of the past.