South America's three-banded armadillo can. Even if Texas armadillos could roll up, their shells are no protection against large dogs. Nor could they have protected them from the grizzly bears, wolves, and jaguars that once inhabited Texas. Rather, they seem to function similar to a cowboy's chaps. When pursued by a large predator, an armadillo can run through thick brush spiked with thorns.
Armadillo shells are most useless on Texas highways.
Unfortunately, they are frequently found dead on roadsides and have often been depicted in print and movies lying on their backs with a Lone Star Beer bottle between their front legs. Most armadillo deaths can be considered suicide. If they stayed put, they'd be killed only if run over by a vehicle's wheels. But armadillos have a curious jump reflex. When startled by a car, they jump up, slamming into the car's underside.