The long genetic isolation is significant in another way.
Larisa DeSantis, a paleontologist at Vanderbilt University, who was not involved in the research, said it “is consistent with the idea of a North American origin of dire wolves.”
They were here at least 250,000 years ago, and they were still around, although nearing the end of their existence, when the first humans were arriving in the Americas, perhaps 15,000 years ago.
“They were not this ginormous mythical creature, but an animal that most likely interacted with humans,” Dr. Perri said.
In the search for fossils that could provide ancient dire wolf DNA, Dr. Perri joined forces with a number of other researchers around the world, including Kieren Mitchell, an evolutionary biologist at the University of Adelaide; Alice Mouton, a geneticist at the University of Los Angeles; and Sandra Álvarez-Carretero, a genomics doctoral student at Queen Mary University of London.
They combed museums to find 46 bone samples that might have usable DNA. Five did. “We got really lucky,” Dr. Perri said. “And we found a lot of things we didn’t really expect.”
The findings were surprising because dire wolf skeletons are similar to gray wolf skeletons, and because DNA was not available. Xiaoming Wang, a paleontologist at the Los Angeles County Natural History Museum, who published a review of the fossil evidence in 2009 that placed the dire wolf squarely in the genus Canis, called the new paper a “milestone,” adding that “morphology is not foolproof.”
As to why the dire wolf went extinct and wolves survived, the authors speculated that its long genetic isolation and lack of interbreeding with other species may have made it less able to adapt to the disappearance of its main prey species. More promiscuous species like gray wolves and coyotes were acquiring potentially useful genes from other species.