The superorder Xenarthra is a group of placental mammals (infraclass Eutheria), existent today only in the Americas and represented by anteaters, tree sloths, and armadillos. The origins of the order can be traced back as far as the Paleogene (about 60 million years ago, shortly after the Mesozoic era). Xenarthrans share several distinctions from those of other placental mammals. The name Xenarthra means "strange joints", and was chosen because their vertebral joints have extra articulations and are unlike those of any other mammals. Also, xenarthrans have the lowest metabolic rates among the therians. Examples : - Giant Anteater - Pink Fairy Armadillo - Pygmy Three-Toed Sloth