These Massive Tunnels Were Dug by a Giant Sloth That Lived 10,000 Years Ago in South America

A giant mammal that lived 10,000 years ago in Brazil dug gigantic tunnels called “palaeoburrows”. And digging those tunnels required claws. Huge ones.

What could have left those giant claw marks? Image credit: Heinrich Frank
But what could those giant creatures be? That was exactly the question geology professor Heinrich Frank asked himself while crawling through a mysterious tunnel uncovered at a construction site in Novo Hamburgo, Brazil.

Since it was unlike any geological formation he’d ever seen, Frank speculated that the tunnel must have been dug out by a living thing.

“There’s no geological process in the world that produces long tunnels with a circular or elliptical cross-section, which branch and rise and fall, with claw marks on the walls,” Frank told Discover.

Whatever the enormous creature was, it left huge claw marks across the walls and ceiling of this tunnel and others of similar size found in the area. At that point, the professor slowly backed out and told the construction workers he’d be back in a few weeks.

Frank, who works as a professor at the Federal University of Rio Grande do Sul, kept his promise. He ended up naming the mysterious tunnels and identifying the animal most likely to have done the excavations, not only of the tunnels in Novo Hamburgo but also thousands of others in Brazil.