Though most people may know dire wolves from their many scene-stealing appearances in Game of Thrones, they didn’t spring straight from the mind of George R.R. Martin. In fact, scientists have known about the long-extinct creature since the mid-19th century.

Until recently, it was widely believed that the dire wolf (Canis dirus) was essentially a more muscular relative of the gray wolf (Canis lupus), partially because their skeletons look so similar. But a new study published in Nature suggests that the two species share much less than their appearances imply.

It all started when archaeologist Angela Perri, of Durham University in the UK, set off on an expedition across North America to locate dire wolf fossils from museum collections and see if she could extract DNA from them. Her endeavor was successful: As National Geographic reports, Perri and her collaborators were able to sequence genomes from five dire wolf fossils from Idaho, Ohio, Tennessee, and Wyoming. The remains dated from 50,000 years ago to about 13,000 years ago (around the time dire wolves died out).

After comparing the dire wolf sequences to ones from gray wolves and several other canids, the researchers discovered that dire wolves and gray wolves diverged genetically from their common ancestor about 5.7 million years ago. As Scientific American explains, their morphological resemblance seems to be an example of convergent evolution; in other words, they developed similar traits because their lifestyles were similar, not because their DNA was similar.

A dire wolf skeleton on display at the Sternberg Museum of Natural History in Kansas.James St. John, Flickr // CC BY 2.0

Based on these findings, it’s possible that dire wolves spent millions of years evolving in the Americas—far separated from the gray wolves back in Eurasia. In that case, it could’ve been the eventual migration of other species—even humans—that steered dire wolves toward extinction.

“The question now becomes: Is their extinction related to climatic and environmental change, or did humans and potentially other wolves and dogs and [diseases] coming in assist in pushing them out?” Perri told National Geographic.

The study could also impact the dire wolf’s scientific classification. With a weaker genetic link to the Canis genus, it might need to be shifted to its own genus. But even if that happens, there’s a good chance we’ll still call them “dire wolves” in casual conversation—much like we do with koala bears, electric eels, and other animals with misleading monikers.

[h/t Scientific American]