Anatomical similarities between grey wolves and dire wolves had suggested they could be related in a manner similar to humans and Neanderthals, but co-lead author Kieren Mitchell said a more accurate comparison would be distant cousins, like humans and chimps.

"Dire wolves are sometimes portrayed as mythical creatures, giant wolves prowling bleak frozen landscapes, but reality turns out to be even more interesting," Dr Mitchell said.

"While ancient humans and Neanderthals appear to have interbred, as do modern grey wolves and coyotes, our genetic data provided no evidence that dire wolves interbred with any living canine species.

"All our data point to the dire wolf being the last surviving member of an ancient lineage distinct from all living canines."

It's the first time ancient DNA has been obtained from dire wolves.

Analysis suggests that unlike many canid species who were thought to have migrated repeatedly between North America and Eurasia, dire wolves evolved solely in North America for millions of years.

The researchers suggest that their evolutionary differences meant they were ill equipped to adapt to changing conditions at the end of the ice age.

Known scientifically as Canis dirus, meaning 'fearsome dog', the dire wolf preyed on large mammals like bison and was common across North America until about 13,000 years ago, after which they became extinct.

"When we first started this study we thought that dire wolves were just beefed up grey wolves, so we were surprised to learn how extremely genetically different they were, so much so that they likely could not have interbred," senior author Laurent Frantz said.

"Hybridisation across Canis species is thought to be very common, this must mean that dire wolves were isolated in North America for a very long time to become so genetically distinct."

The research was led by the University of Adelaide, Durham University in the UK, Ludwig Maximilian University in Germany, and the University of California.

Australian Associated Press