By WILL DUNHAM Reuters
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WASHINGTON — The dire wolf was one of the most formidable predators in the Americas during the last Ice Age, possessing a body more stout and a skull more robust than those of modern wolves. The species went extinct along with many others as the Ice Age ended.

Roughly 13,000 years later, a U.S. company has taken a step aimed at bringing the dire wolf back from oblivion — aside from the TV versions in the popular “Game of Thrones” fantasy series. Dallas-based Colossal Biosciences has announced the birth of three genetically engineered wolf pups — all with striking white fur — created with the help of ancient DNA obtained from fossilized remains of dire wolves.

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The company is calling them dire wolves and is referring to this as the world’s first successfully “de-extincted” animal. The same approach can be used to resurrect other extinct species for which ancient DNA is available, according to the company.

Outside experts are more cautious, describing the pups as genetically modified gray wolves because the process used to create them involved editing the genes of that species to add dire wolf traits. The gray wolf is the closest living relative of the dire wolf.

There are two male pups, named Romulus and Remus after Rome’s legendary founders who were suckled by a she-wolf, and one female, named Khaleesi in honor of a “Game of Thrones” character.

All three are large for their age compared to gray wolves, according to Beth Shapiro, Colossal’s chief science officer. Romulus and Remus, both six months old, are around 80 pounds (36 kg) while Khaleesi, at two months old, is around 25 pounds (11 kg).

Dire wolves were as much as 25% bigger than gray wolves, with a slightly wider head and a stronger jaw, the company said.

Company scientists extracted ancient DNA from two dire wolf fossils — a tooth from Sheridan Pit, Ohio, approximately 13,000 years old, and an inner ear bone from American Falls, Idaho, roughly 72,000 years old.

Twenty genes of gray wolves were edited with this DNA to include dire wolf traits in gray wolf cells. Through cloning, embryos were created from the edited gray wolf cells, and these were implanted in surrogate domesticated dog mothers. Three different dogs gave birth to the pups.

“We define de-extinction success as bringing back the functional ecological traits that made dire wolves unique contributors to their ecosystem, and our dire wolves are an example of that,” Shapiro said.