Colossal Biosciences says the revived dire wolves are healthy and growing.
The company shared an update on the three pups that were brought back from extinction last year.
These animals once roamed the Americas more than 10,000 years ago before vanishing.
After a pop culture resurgence driven by Game of Thrones, Dallas-based biotech firm Colossal announced it had recreated dire-wolf-like animals.
Earlier this year, Colossal said scientists extracted ancient DNA from a 13,000-year-old tooth and a 72,000-year-old skull.
They rewrote the genetic code of the common grey wolf and used domestic dogs as surrogate mothers.
The experiment produced what the team described as “healthy dire wolf puppies.”
Images of the snow-white animals — Romulus, Remus and their younger sister Khaleesi — spread across the internet.
Experts quickly noted these are not original dire wolves but rather “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)
After a few months, the trio has grown rapidly.
The team says growth is “about 20% larger than a standard grey wolf.”
Matt James, Colossal’s Chief Animal Officer, gave specifics on weight and age.
“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.
He added the dire wolf genes appear to be expressing expected traits.
At three months old, Khaleesi remains smaller than her brothers.
She currently weighs roughly 35 pounds, about 15%-20% larger than a typical grey wolf of that age.
The team is waiting for social cues before introducing Khaleesi to the older pair.
“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,” James explained. “We’re really excited about that.”
The brothers have already developed distinct roles within their pack-like group.
Paige McNickle, who leads the dire wolves’ daily care team, described the emerging hierarchy.
“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.”
McNickle said Romulus tends to take a subordinate position.
“Romulus is the first to go out when the dire wolves eat and play, an unmistakable ‘beta trait’,” she said.
She added the dynamic might shift once Khaleesi joins them.