A discovery in the Bluefish Caves and a mine site in northern Yukon initially led researchers to believe they had unearthed bones of an ice-age puma or cougar. However, DNA analysis conducted by the University of California revealed a surprising truth. The testing, carried out by Molly Cassatt-Johnstone, a lab technician fresh out of her undergraduate studies, yielded unexpected results. The Yukon bones she examined did not resemble pumas at all, leading to the revelation that they were, in fact, cheetahs.
Grant Zazula, a Yukon paleontologist, vividly recalls his astonishment upon receiving the message that the supposed cougars were, in reality, cheetahs. He reflects on the significant advancements in genetic analysis over the past 25 years, emphasizing how studying ancient DNA was once considered akin to science fiction but has now become a routine practice, especially with permafrost-preserved bones from the Yukon.
Cassatt-Johnstone’s groundbreaking identification of a Yukon Miracinonyx, also known as the extinct American cheetah, marked a pivotal moment. Her research, now published in Current Biology, provides fresh insights into the ice-age cat’s diet and habitat range.
The American cheetah, presumed to have evolved to hunt pronghorns in grassy plains, posed a mystery when discovered in the Arctic tundra. Researchers were perplexed by their presence in a region devoid of pronghorns, such as Beringia, the land connecting Asia and North America. To unravel this enigma, a collaborative team from Canada and the U.S. employed stable isotope analysis, a technique used in forensic investigations to trace dietary patterns and environmental conditions.
The study revealed that Yukon cheetahs had a peculiar diet primarily consisting of fish, a behavior uncommon among historical and contemporary felines. This unexpected finding sheds light on the intricate ecosystem dynamics and evolutionary adaptations of these ancient predators. The researchers, led by Matthew Wooller from the University of Alaska Fairbanks, meticulously analyzed bone samples to uncover the cheetahs’ dietary preferences, likening the process to solving a complex puzzle.
The revelation that Yukon cheetahs heavily relied on salmon astonished experts like Julie Meachen, a paleontologist specializing in Late Pleistocene mammalian carnivores. In a region teeming with formidable predators, the abundance of fish likely provided an easy food source for the relatively smaller cheetahs, contrasting their behavior with that of their counterparts in midcontinental North America.
Further genetic analysis indicated that Miracinonyx was more closely related to North American pumas than African cheetahs, with a limited gene pool suggesting a small population size. This reduced genetic diversity may have contributed to their eventual extinction, according to Cassatt-Johnstone. Zazula proposes renaming this distinctive northern population from ‘American Cheetah’ to ‘Yukon Cheetah,’ underscoring the ongoing revelations and mysteries unearthed by paleontologists in the region.