Among the interesting features about the armadillo is it is not a species which is native to North America, and the absence of predators for the armadillo has enabled the species to flourish on the continent. The animals originated in South America, and their original habitat was in the warm and moist forests that covered the area for so long. But, it was a dramatic shift in the continent that eventually allowed the armadillos to make the move north, and they've been growing their inhabitants ever since.
There are lots of species of armadillo that originated in South America, but the one which has become most common is the Nine-Banded Armadillo, which is currently the armadillo with the biggest range. The woodlands of South America was the habitat for these animals for many thousand years, and their defensive armor which served them so well in that area, is still a very important part of their survival now.
The continents of North and South America were entirely separate continents before both were connected when the Isthmus of Panama was increased through volcanic action, developing a land connection between the two continents which had developed separately. When you believe the armadillo resembles a creature from another era, the chief reason is that it really is a monster from another age.
The Great American Interchange: Even though the climbing of the Isthmus was approximately fifteen million years back, it was about three million years ago the exchange of species actually begun to occur, and it's thought that around that time the armadillos first found their way into Central and on to North America. The tough carapace that had evolved in South America was too resilient, and there were very few natural predators in North America that could come over the armadillo from the food chain, allowing it great liberty to expand its range.
Armadillos In North America Now: Because armadillos don't have much fat reserves, they don't deal well with harsh winters, which has meant that the northern states rarely tend to see substantial populations of the species. But they have a huge population in the Southern states, and survive as far north as Ohio and New Jersey, giving them a massive range within america.