Armadillos, sloths and anteaters evolved in the Americas and belong to the same “superorder.” Originally classified in the order Edentata with the pangolins and aardvarks from Africa, DNA studies and anatomical comparisons now suggest that these three icons of the topics are actually a biological innovation that can be traced back 59 million years ago to the South American Paleocene. While armadillos, sloths and anteaters share the generally toothless anatomy of their African counterparts, the distinguishing feature of these mostly South and Central American mammals is the structure of their vertebral joints. Now considered members of the Superorder Xenarthra, which means “strange joints,” these animals have a characteristically low metabolism. Furthermore, all male Xenarthran's possess internal testes which reside between the bladder and rectum.