Colossal Biosciences says it used novel gene-editing technology to alter gray wolf DNA to breed the animals. Dire wolves recently featured prominently in the HBO series Game of Thrones.

Colossal, the company looking to bring back the woolly mammoth from extinction has born three dire wolves, an animal extinct for 13,000 years.

The dire wolf was one of the most formidable predators in the Americas during the last Ice Age, possessing a body more stout and a skull more robust than those of modern wolves. The species went extinct along with many others as the Ice Age ended.