The three pups — Romulus, Remus and Khaleesi — were created by modifying 20 genes of the gray wolf, the dire wolf's closest living relative, based on DNA extracted from a dire wolf tooth and skull.

The dire wolf – an extinct animal made famous in the TV series Game of Thrones – has been brought back from extinction after more than 10,000 years, a biotech start-up has announced.

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