It is already a questionable idea to return the long-extinct dire wolf—a creature 25 percent bigger than the modern gray wolf, whose enormous teeth once slew horses and bison across the primordial American plains—to the modern world.

A genetically modified wolf juvenile, one of three successfully bred by reconstructing a genome from the ancient DNA of fossils from dire wolves that had been extinct for over 12,500 years by Colossal Biosciences,

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

Three genetically engineered wolves that may resemble extinct dire wolves are living in an undisclosed secure location in the U.S., according to researchers at Colossal Biosciences.

Dire wolves, made famous by “Game of Thrones,” went extinct some 13,000 years ago. Now, researchers have bred gray-wolf pups that carry genes of their ancient cousins.

The dire wolf is a relative of the now-common grey wolf, with clear differences apparent between the two species' skeletons. Based on the sequence of two new dire wolf genomes, the researchers at Colossal conclude that dire wolves formed a distinct branch within the canids over 2.

Unlike most fantasy creatures, dire wolves actually existed once upon a time. They patrolled North America hunting giant ground sloths, bison, and other megafauna until about the end of the last ice age.