South America are known from the late Eocene, around 38 million years ago, and they spread to southern North America after the continents became connected around 2.7 million years ago. The best-known genus within the group is Glyptodon.

Glyptodonts were historically considered to constitute the distinct family Glyptodontidae, with their relationships to modern armadillos being contested. In 2016, an analysis of the mitochondrial genome