Sloths, armadillos and anteaters (xenarthrans), as different as they look, are genetically more similar to each other than they are to any other mammals. This suggests that these three very different groups of animals descended from a common ancestor. If this common ancestor lived on an isolated island, we would expect that all of its descendants might live on that same island.
Interestingly, all modern and extinct xenarthrans indeed live(d) on a very large island: the Americas. Based on fossil evidence, we think that the earliest xenarthrans lived in South America and some of them later dispersed North, particularly the extinct ground sloths, glyptodonts and pampatheres.
The only living xenarthran that naturally occurs on the northern continent is the nine-banded armadillo (Dasypus novemcinctus).
This makes sense as an evolutionary biogeographic scenario: xenarthrans originated in South America, diversified into many species, and dispersed to North America. They probably didn’t travel farther than this simply because the Americas are separated from other continents by oceans.
Questions for Creationists
Is it simply a coincidence that sloths, armadillos and anteaters are genetically similar and they all live in the Americas? If all xenarthrans lived on Noah’s Ark and left from it after the floodwaters receded, how did they get over to North and South America? Why did they go to North and South America at all? How did the slow-moving tree sloths make their way across such a vast distance? Given their poor vision, how did the xenarthrans effectively navigate such a tremendous journey?