When the researchers used the DNA to construct a feline family tree, the four “American cheetahs” didn’t end up anywhere near African or Asiatic cheetahs. As cheetah-like as their fossilized remains may have looked, their DNA places them closer to the branch of the American puma, also known as the cougar or mountain lion. It also shows that the two are sister species that shared a common ancestor until about 2.6 million years ago.
That timing coincides with a period of rapid cooling on the continent, during which grasslands expanded rapidly. The cheetah-like features that gave M. trumani its pet name may have helped it survive on these plains by outrunning its prey and the larger predators it would have been wise to avoid. The Yukon bones, which were about 30,000 years old, show this North American feline lived as far north as the Arctic.
“This study is the first published record of Miracinonyx in Canada,” says National Geographic Explorer Julie Meachen, a functional morphologist and paleoecologist at Des Moines University in Iowa and a coauthor of the study. She led the 2014 expedition that found several specimens in Wyoming’s Natural Trap Cave. “It shows this extinct species could survive in various habitats and was eating very different things in different places.”
The team published their findings Friday in the journal Current Biology.
“The major conclusion that Miracinonyx and pumas were sister species seems plausible,” says Stephen O’Brien, a molecular biologist who produced an earlier construction of the felid family tree but was not involved in the recent work. He adds that it is common for genetic evidence from fossils to result in such revisions. “We are regularly correcting evolutionary conclusions that were based on anatomical interpretations.”
The researchers conducted a genetic analysis of four bones from Miracinonyx truman specimens recovered from Wyoming’s Natural Trap Cave and the Arctic Yukon.
Julie Meachen
Ice Fishing
The discovery that M. trumani lived across such a wide region left the researchers wondering what it ate. To find out, they analyzed the relative amounts of different forms of nitrogen and carbon in the fossils, which vary with diet. The results from the Wyoming bones, which were about 20,000 years old, resemble those of other predators of the time that fed on herbivores such assuch as pronghorn, horses, bison, and bighorn sheep. But the fossils from the Yukon revealed markedly different chemical values, suggesting a diet rich in fish such as salmon or trout.
Specializing in fish would have been a way for the slender cat to survive in the harsh Arctic climate while avoiding competition with much larger predators like cave lions.
Cassatt-Johnstone notes an interesting difference between cheetahs and Miracinonyx that would have been helpful in catching fish. “Cheetahs have anatomical adaptations in their forearms and wrists that give them extra stability for when they’re running really fast,” she says. “But that comes at a trade-off, where they have less flexibility and can’t grapple prey the way other big cats do. Miracinonyx did have this ability”
Ross Barnett, an independent researcher who led the 2005 genetic study but was not involved in this work, praised the paper. “To find two populations of the same species with such different diets is really cool,” he says. “That they were found in Arctic biomes is a huge finding.”
(Pumas came back to Patagonia—and met penguins. What happened next surprised scientists.)