By The Associated Press

Three genetically engineered wolves that may resemble extinct dire wolves are trotting, sleeping and howling in an undisclosed secure location in the U.S., according to the company that aims to bring back lost species. The wolf pups, which range in age from three to six months old, have long white hair, muscular jaws and already weigh in at around 80 pounds — on track to reach 140 pounds at maturity, researchers at Colossal Biosciences reported Monday.

Dire wolves, which went extinct more than 10,000 years old, are much larger than gray wolves, their closest living relatives today. Independent scientists said this latest effort doesn’t mean dire wolves are coming back to North American grasslands any time soon.

“All you can do now is make something look superficially like something else”— not fully revive extinct species, said Vincent Lynch, a biologist at the University at Buffalo who was not involved in the research.

Colossal scientists learned about specific traits that dire wolves possessed by examining ancient DNA from fossils. The researchers studied a 13,000 year-old dire wolf tooth unearthed in Ohio and a 72,000 yearold skull fragment found in Idaho, both part of natural history museum collections.

Then the scientists took blood cells from a living gray wolf and used CRISPR to genetically modify them in 20 different sites, said Colossal’s chief scientist Beth Shapiro. They transferred that genetic material to an egg cell from a domestic dog. When ready, embryos were transferred to surrogates, also domestic dogs, and 62 days later the genetically engineered pups were born.

Colossal has previously announced similar projects to genetically alter cells from living species to create animals resembling extinct woolly mammoths, dodos and others.