The biotech company looking to achieve a Jurassic Park-like resurrection of the woolly mammoth has issued an update on the three genetically-modified “dire wolves” produced by their research, reporting that the animals are doing well as they mature into adulthood, and like the dire wolves they’re meant to emulate are already one-fifth larger than the gray wolves their DNA is based on.

First revealed in an April 2025 press release, the now-nine month-old pups, named Romulus and Remus after the legendary twin brothers that founded the city of Rome, already weigh “a little more than 90 pounds (41 kilograms), which is about 20 percent larger than a standard gray wolf,” according to Colossal Biosciences Chief Animal Officer, Matt James, speaking in a recent video.

Romulus and Remus will soon be attending their first annual medical exam, allowing the research team an “opportunity to take blood” samples and “use CT imaging to get really advanced ideas of what’s happening within their skeleton and their musculature,” James continued.

The pair have graduated to “eating pretty much their adult diet even though they are not adults,” reports Paige McNickle, Colossal’s Manager of Animal Husbandry, “and they are eating high quality dog kibble and ground meat, which is human grade.”

“Sometimes we’ll switch it out with some chunk meat, which is a soft tissue meat,” McNickle continued. “They also get some organ meats,” along with “access to bones.

“They really like rib bones and knucklebones.”

“As of right now, the roles in the pack are in flux because they’re growing up and they’re still youngsters,” McNickle says of the brother’s relationship, with Remus currently taking on the alpha role, who “really likes to watch things and figure stuff out.”

The brothers have a little sister, Khaleesi, named after the title of the fictional character Daenerys Targaryen from Game of Thrones, who, having been born on January 30 2025, is already 35 pounds (16 kilograms). She is expected to alter the dynamic of the pack when she is introduced to her brothers “as soon as she’s big enough to do so safely,” McNickle stated.

It is widely accepted by paleogeneticists that Romulus, Remus and Khaleesi are not true dire wolves (Aenocyon dirus): because there isn’t enough surviving dire wolf DNA to clone the animal properly, Colossal was forced to resort to modifying the genes of existing wolves to emulate their extinct cousins. While in the movie Jurassic Park amphibian DNA was used to fill the gaps in the missing code for the story’s dinosaurs, such creatures wouldn’t be faithful clones, but instead wind up being hybrids of both donor animals.

“To truly de-extinct something, you would have to clone it,” explained Nic Rawlence, an associate professor with the University of Otago’s Palaeogenetics Lab. “The problem is we can’t clone extinct animals because the DNA is not well enough preserved.”

After studying genetic samples harvested from a 13,000-year-old tooth and a 72,000-year-old ear bone from dire wolf fossils, Colossal’s researchers modified 14 key genes in modern gray wolf (Canis lupus) endothelial progenitor cells (EPC) so that they would express 20 traits known to be unique to dire wolves, meaning that “no ancient dire wolf DNA was actually spliced into the gray wolf’s genome,” according to an April 7 Time Magazine article.

While this experiment in recreating a long-extinct species may seem superfluous, the experience gained in producing the three modified pups can be applied to the conservation of species that are either recently extinct or on the brink of extinction, specifically those that have had their entire genomes preserved before they disappeared, allowing researchers to recreate the creatures seemingly from scratch.

One such candidate is the northern white rhinoceros (Ceratotherium simum cottoni): the last male died in 2018, leaving only two females as the sole representatives of their species—a pairing that is, understandably, unable to reproduce through natural breeding. However, there is hope that an embryo can be produced from preserved genetic material, giving these nearly-extinct rhinos—and other species facing the same fate—a second chance.