genus of extinct giant mammals (mammal) related to modern armadillos (armadillo) found as fossils in deposits in North and South America dating from the Pliocene (Pliocene Epoch) and Pleistocene epochs (Pleistocene Epoch) (5.3 million to 11,800 years ago). Glyptodon and its close relatives, the glyptodonts, were encased from head to tail in thick, protective armour resembling in shape the shell of a turtle but composed of bony plates much like the covering of an armadillo. The body shell alone was as long as 1.5 metres (5 feet). The tail, also clad in armour, could serve as a lethal club; indeed, in some relatives of Glyptodon, the tip of the tail was a knob of bone that was sometimes spiked. Glyptodonts ate almost anything—plants, carrion, or insects.