Glyptodon (Greek for "grooved or carved tooth") was a relative of the armadillo that lived during the Pleistocene Epoch. It is named for its globe-shaped teeth. Flatter than a Volkswagen Beetle, but about the same general size and weight, the glyptodon (or glyptodont) is believed to have been a herbivore, grazing on grasses and other plants found near rivers and small bodies of water. A large and heavy mammal, it could probably only have moved one or two miles per hour.

Glyptodons were covered by a protective shell composed of more than 1,000 inch-thick bony plates, called osteoderms or scutes. Each species of glyptodont had its own unique osteoderm pattern and shell type. With this protection, they were armored like turtles, but unlike most turtles, could not withdraw their heads, so they developed a bony cap on the top of their skull. Even the tail of Glyptodon had a ring of bones for protection. The nasal passage was reduced with heavy muscle attachments for some unknown purpose. Some have speculated that the muscle attachments were for a proboscis, or trunk, much like that of a tapir or elephant. However, most animals with a trunk have nasal bones receding back on the skull, and glyptodons do not have this feature. The lower jaws were very deep and helped support massive chewing muscles to help chew the coarse fibrous plants that can be found along river and lake banks.

Glyptodons are part of the placental group of mammals known as Xenarthra. This order of mammals includes anteaters, tree sloths, extinct ground sloths, and armadillos.

Predators of the glyptodon could have included the sabre-toothed tiger, although this predator would likely have struggled to turn the 1 to 2-ton animal over to reach its unprotected belly.

Glyptodons originated in South America and first appeared in the American Southwest after North and South America connected at the Isthmus of Panama, about 2.5 million years ago. They became extinct about 10,000 years ago.