There is a network of caves or burrows under parts of Brazil and other places in South America known about since the 1930s. It wasn't until recently however that geologists and paleontologists took a closer look at these structures and noticed that they were no ordinary caves. Long thought of as tunnels built by humans to escape colonizers, scientists now realize they weren't built by humans at all but by giant ground sloths and giant armadillos!  

In 2010, one geologist, Heinrich Frank, began looking more closely at them and made the connection that these caves were relics of the ice age. He has since documented over 1,500 of these paleoburrows, some with clear claw marks on them. Some of the burrows extend 250 feet and the biggest ones and can span over 12 feet high. Lestodon, was one of the largest giant ground sloths that lived in South America about 30,000 years ago and would have engineered the really big ones. Today with expansion, people have inadvertently built upon them, and because they aren't protected, people are beginning to deface them so this new discovery and new branch of geology has become a race against time.