With a little more excavation, the unusual find turned out to be something much more recent: a nearly complete, metre-long shell of a beast that trundled around South America over 10,000 years ago!
While they’re superficially similar to their relatives, the armadillos, in having body armour made of bone, the glyptodonts had solid, rounded domes for shells rather than the more flexible bands of their cousins. More than that, many glyptodonts had caps of bone over their skulls to help protect them from jaguars, sabre-toothed cats and other predators of their time. Some species, such as Doedicurus, took defence to the extreme with mace-like tail clubs.
These strange mammals evolved in South America over 18 million years ago, back when the continent was an island separated from other landmasses. This isolation led to the evolution of not just the glyptodonts, but also other oddities, like giant sloths, terror birds and more.
By about seven million years ago, though, South America became connected to North America by the Panama land bridge. The glyptodonts maintained their stronghold to the south, but they were also one of the few groups to find success in North America.