The enormous burrows dug by ground sloths and giant armadillos were large and apparently well-structured enough to maintain their shape after thousands of years. It also helps that both of the animals went extinct about 10,000 years ago, not too far in the past. But it’s a misconception to think that all the most bizarre animals are already extinct. In fact, there’s plenty of creatures that roam the earth right now that are more wild than anything from prehistoric times. Take the absolutely alien mata mata for example. Photo Credit: Sergiodelgado / Wikimedia Commons | CC BY-SA 3.0