Dire wolves Romulus and Remus are now 1-year-old. Born Oct. 1, 2024, they each weigh more than 120 pounds.
A custom-made dire wolf-themed cake from Mishka Luxury Dog Boutique in San Francisco for the male dire wolves' first birthday.
Romulus and Remus, two male dire wolves, snack on their birthday cake. They were born Oct. 1, 2024.

Happy Birthday to the dire wolves.

Romulus and Remus, two male dire wolves born through Colossal Biosciences’ genetic engineering advances, have reached their first birthday.

The Dallas-headquartered biotech company revealed in April 2025 that two separate dire wolf litters had been born: The two male dire wolves were born in October 2024, and a female, Khaleesi (named after the “Game of Thrones” character), was born in January 2025.

“We’ve witnessed their physical, emotional, and social growth – something no one has seen in 12,500 years,” Matt James, Colossal’s chief animal officer who was present for their birth a year ago, told USA TODAY in an email exchange. “Remus is fearless and bold, while Romulus is inquisitive, cautious, and confident.”

For most folks, dire wolves bring to mind the fictional “Game of Thrones” books and HBO series, as well as the Grateful Dead song, “Dire Wolf.”

But dire wolves were actual predators that roamed North America alongside saber-toothed tigers and mastodons for tens of thousands of years before going extinct about 13,000 years ago. Colossal researchers used DNA recovered from a 72,000-year-old dire wolf skull and a 13,000-year-old tooth to create a dire wolf genome.

Researchers then used that genome to make edits in the gray wolf genome to express dire wolf-specific traits. Fertilized eggs were implanted into and born by surrogate dog mothers. While the dire wolves are not 100% matches for their prehistoric ancestors, they are as close as the cutting-edge biotech advances, says Colossal, which first gained attention when it announced plans to bring back the woolly mammoth.

“The dire wolves are thriving – beyond anything we could have imagined,” said Beth Shapiro, the company’s chief science officer, in a statement to USA TODAY. “Over the past year, we’ve learned so much from Romulus, Remus, and Khaleesi. Most importantly, the edits worked as expected and the animals are healthy. You can see it in their size, strength, and their striking white coats. Watching their development has been extraordinary.”

For the birthday celebration, the male dire wolves were recently presented with a cake created by San Francisco luxury dog bakery Mishka, which was made of beef pâté, broth, liver and other organic ingredients.

They also got a special birthday video with a song, “Happy Birthday Dire Wolf,” created by songwriters Stan Bush and Lenny Macaluso (“The Touch,” from “The Transformers: The Movie” and “Never Surrender,” from the movie “Kickboxer”)

Dire wolves’ size: Romulus and Remus at age 1

Romulus is slightly larger than Remus, “hovering right around 120lbs while Remus is just under 115lbs,” James said. “We do not have heights on them as we have not done their annual physical exam yet, but we will be doing so shortly. We expect the boys to end up between 130 and 140 lbs.”

The two male dire wolves were introduced to their sister this summer, and it “has been an amazing socialization opportunity for all three dire wolves,” Colossal CEO and co-founder Ben Lamm said.

“They’ve begun to display hunting instincts and are regularly giving chase to animals within their preserve, even catching a rabbit for the first time a few weeks ago,” Lamm said. “They are developing a more clear social hierarchy with Remus taking the reins as the leader of the pack and Romulus and Khaleesi often waiting for Remus and checking in with him for reassurance and comfort. However, they will often still jostle for feeding opportunities and test Remus’ status as the first to feed.”

What do dire wolves eat?

The male dire wolves eat more than 5 pounds of meat each day. They are fed once daily; their varied diet includes ground meat, stew-sized chunks, and portions of carcasses such as deer, cattle, or whole rabbits, according to Colossal.

Khalessi remains smaller and eats a bit less than Romulus and Remus, who also get to chew on rib and leg bones. They also get about ½ to 1 cup of freeze-dried beef liver, with portions depending on the daily training regimen. The wolves also occasionally hunt small rodents on the 2,000-plus-acre ecological preserve where they live.

At the preserve, which is certified by the American Humane Society and registered with the U.S. Department of Agriculture, a team of 10 full-time animal care staff members helps care for the dire wolves. In addition to natural dens for the wolves, there’s an on-site veterinary clinic and storm shelter.

Within the preserve, the wolves are monitored by live cameras, security staff, and drone tracking to ensure safety and welfare. Colossal also tracks their weight and body condition using a standard canid scoring system to guide dietary needs.

“They surprise the team every day. From their rapid growth and size to their willingness and excitement to accept Khaleesi into the pack,” James said. “Romulus and Remus are siblings, yet they have developed individually unique personalities and even without a typical rearing by a wild wolf mother, their ability to quickly adapt to a wild life including hunting has been one of the happiest developments we have seen.”

Will there be more dire wolves?

Yes. Colossal plans to create a pack of as many as eight dire wolves. “We are working with our internal team and external network of scientific advisors to make plans to grow the pack at the appropriate time,” James said.

Mike Snider is a national trending news reporter for USA TODAY. You can follow him on Threads, Bluesky, X and email him at mikegsnider & @mikegsnider.bsky.social & @mikesnider & msnider@usatoday.com

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This article originally appeared on USA TODAY: Real dire wolves, made famous by 'Game of Thrones,' thriving on first birthday

Reporting by Mike Snider, USA TODAY / USA TODAY

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