Initially, the bones discovered in the Bluefish Caves and at a mining site in northern Yukon were thought to be from an ice-age puma or cougar. However, DNA analysis from the University of California revealed a different story. The testing was conducted by Molly Cassatt-Johnstone, a lab technician who had recently completed her undergraduate studies. These Yukon bones were among her first samples to work on.
When Cassatt-Johnstone conducted the initial analyses and found that they did not resemble pumas at all, she was surprised. Yukon paleontologist Grant Zazula vividly recalls receiving a message that evening informing him that the supposed cougars were actually cheetahs.
Zazula expressed his amazement at the advancements in ancient DNA analysis, which were once considered futuristic like in Jurassic Park but are now a routine practice for studying genetic material from permafrost-preserved bones in the Yukon.
Cassatt-Johnstone successfully identified a Yukon Miracinonyx, also known as the extinct American cheetah. She is now the primary author of a research paper published in Current Biology, shedding new insights on the ice-age cat’s diet and habitat.
‘A Fascinating Investigation’
Researchers previously believed that the American cheetah, resembling today’s cheetahs with long limbs and a slender physique, evolved to hunt pronghorns across grassy plains. Discovering them in the Arctic tundra puzzled paleontologists.
Cassatt-Johnstone explained that they were initially thought to be specialized predators of American pronghorn antelope in the lower 48 states, but there were no pronghorns in Beringia, the land bridge that once connected Asia and North America.
To unravel how Miracinonyx survived in this region, the study collaborators from Canada and the U.S. employed stable isotope analysis, a technique used in forensics to examine the dietary habits and environmental conditions of ancient organisms.
By analyzing bone fragments from the cheetah’s paw and leg, researchers were able to determine that the Yukon cheetahs predominantly fed on fish, a behavior uncommon among past and present-day felines. This dietary preference is believed to be influenced by the ecosystem and environmental factors.
Yukon Cheetahs and Their Salmon Diet
The revelation that Yukon cheetahs heavily relied on salmon astonished paleontologists like Julie Meachen, an expert in Late Pleistocene mammalian carnivores. The availability of abundant Yukon salmon likely made them an easy catch compared to competing predators like Beringian lions and giant bears.
The study revealed that Miracinonyx was genetically closer to North American pumas than African cheetahs. Researchers also examined the genetic diversity within the cheetah population, indicating consistently low numbers, which could have contributed to their extinction.
Zazula suggests renaming this unique northern population from ‘American Cheetah’ to ‘Yukon Cheetah.’ He emphasizes that every bone found in the Yukon has the potential to unveil a new chapter in the region’s prehistoric biodiversity.