By David Grimm

One of North America’s most famous ancient predators—and a favorite of Game of Thrones fans—emerged as mysteriously as it disappeared. Dire wolves, which died out with mammoths and saber-toothed cats at the end of the last ice age, were long thought to be close cousins of gray wolves. Now, the first analysis of dire wolf DNA finds they instead traveled a lonely evolutionary path: They are so different from other wolves, coyotes, and dogs that they don’t belong in the genus that includes these animals. Instead, researchers argue, they need an entirely new scientific classification.

“It’s a fascinating study” that reveals just how distinct dire wolves were, says Robert Dundas, a vertebrate paleontologist and expert on the animals at California State University, Fresno, who was not involved with the work.

Archaeologists know dire wolves lived in North America from about 250,000 to 13,000 years ago. They were about 20% bigger than today’s gray wolves—the size of their skeletons often gives them away—and, like other wolves, they probably traveled in packs, hunting down bison, ancient horses, and perhaps even small mammoths and mastodons. Many followed their prey into the sticky asphalt of what are now Los Angeles’s La Brea Tar Pits, where they were trapped for the ages. Hundreds of dire wolf skulls line the walls of the California museum.

But that’s where most knowledge stops. Because the skeletons of dire wolves are similar to those of gray wolves, the two animals were considered closely related. Scientists have long classified dire wolves as Canis dirus, putting them in the same genus as gray wolves, coyotes, and dogs. But the one thing that could have sealed the deal—dire wolf DNA—had been broken down by the tar of the pits.

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