Shocking update on dire wolves brought back from extinction reveal they more than doubled in size

The revived dire wolves are healthy and growing, as Colossal Biosciences has shared an update on the three adorable pups that were brought back from extinction last year.

Animals of this species were known to roam the Americas more than 10,000 years ago before going extinct. After having had a revamp in pop culture thanks to Game of Thrones, which featured a fictionalised version of the ancient dire wolves, they were supposedly brought back from extinction by Dallas-based biotech company Colossal.

Earlier this year, Colossal announced they'd taken ancient DNA from dire wolves, specifically from a 13,000-year-old tooth and a 72,000-year-old skull, and rewritten the genetic code of the common grey wolf. The experiment resulted in 'healthy dire wolf puppies', born using domestic dogs as surrogate mothers.

The images of snow-white wolves Romulus, Remus and their younger sister Khaleesi were then plastered onto the Internet, though experts were quick to point out that these were not, in fact, dire wolves, but 'grey wolves that possess 20 edited genes that are meant to give them dire wolf-like features'.

Romulus and Remus have doubled in size. (YouTube/Colossal Biosciences)

A few months in, the trio of 'new' dire wolves has doubled in size, exhibiting a growth that's 'about 20% larger than a standard grey wolf,' Matt James, Colossal's Chief Animal Officer, said in a video.

"Today, Romulus and Remus, at a little over six months old, weigh a little more than 90 pounds, which is about 20% larger than a standard grey wolf," James said in the update. "So we can really tell that the dire wolf genes are kicking in and we're getting these nice large wolves that are much more representative of what we see in the ancient specimens."

At three months old, Khaleesi is the youngest of the pack remains more petite than her brothers. She currently weighs around 35 pounds, making her 15%-20% larger than a standard grey wolf at that age.

Khaleesi is yet to join Romulus and Remus as the team are looking for 'indicators' that the trio will be compatible.

"Before we make the introduction of bringing Khaleesi into the group with the boys, we're going to be looking for really strong indicators that they are socially compatible," explained James. "We're really excited about that."

Meanwhile, Romulus and Remus have started taking on different roles within their pack-like dynamics.

Paige McNickle, who manages the dire wolves' daily care team, explained that Remus has started acting as the alpha, while Romulus is taking on a more subordinate role.

"Remus really likes to watch things, and he figures stuff out," McNickle said. "He's also a little bit smaller, so sometimes that's interesting to think that the smaller of the two would be the more dominant. But he’s crafty and he’s always watching."

Meanwhile, Romulus is the first to go out when the dire wolves eat and play, an unmistakable 'beta trait', according to McNickle, who said that the pack dynamic could change once Khaleesi joins her brothers.