Glyptodonts: Giant South American Armadillos

Glyptodonts are curious creatures of the ancient world. These mammalian relatives of armadillos, anteaters, and sloths lived during the Pleistocene Epoch of the Cenozoic and originated in South America. The majority of glyptodont finds have been in Argentina, and the name glyptodont means "carved tooth." After the land bridge between North and South America formed at the Isthmus of Panama, glyptodonts were able to successfully migrate north into the American Southwest where they continued to thrive before becoming extinct around 10,000 years ago.

Glyptodonts resemble modern-day armadillos, but are much larger. Around eight feet long, these giant herbivores could weigh as much as a small car. Much of that weight came from the bony shell that formed a domelike structure over the glyptodont's back, providing it with nearly complete protection from predators. The shell of interlocking segments of bone had tiny holes through which hairs and sweat glands could pass in order to regulate the animal's body temperature. Similar to the ankylosaurs of the Mesozoic Era, once glyptodonts reached adulthood, they faced little if any threat at all from neighboring predators. The only vulnerable area on a glyptodont was the soft underbelly, which would be hard to expose unless the predator was capable of knocking over a creature weighing more than a ton. The head of the glyptodont could not withdraw back into its shell as in reptilian turtles, but the head itself sported a bony plate that would be impossible to bite through. For icing on the cake, certain species of glyptodonts also sported a bony tail, sometimes terminating in a club that could be swung with bone-shattering force against attackers.

It is likely that glyptodonts foraged on the wide grasslands of South America during the cyclical ice ages in the Pleistocene. They had specialized teeth for grinding up tough vegetation like grasses and scrub plants. Because of the enormous weight it had to carry about on its back, glyptodonts had small legs to prevent buckling. The front legs had five clawed toes which could have aided in digging up plants and roots, while the back legs had hoof-like toes to help support the animal. The combination of these small legs and titanic weight meant that the glyptodonts could not have been very fleet-footed, perhaps only moving at one or two miles per hour. Running fast was a moot point for this mammal though, given its already extensive and adequate defensive measures.

Glyptodonts could have gone extinct due to the increasingly chilly worldwide temperatures, as well as the encroachment of humans from Asia into the Americas. Although this plant eater was well-suited to drive off most predators, it was no match for the spears and cooperative hunting tactics that invaded its homeland.