Among the other characteristics in common with the modern armadillos, Utaetus possessed a bony connection between the ischium and the sacrum (this structure was constituted by caudal vertebrae known as pseudosacral) and continuous-growth cylindrical teeth similar to chisels, with wear in the occlusal part.

Unlike later armadillos, however, Utaetus still had a varying amount of enamel on the lingual and buccal surfaces of the teeth, and the cervical vertebrae were separated (and not co-ossified).

The skeleton shows that this animal was adapted for digging, as evidenced by the presence of a large acromion on the scapula and a prominent olecranon on the ulna.

The genus Utaetus was first described in 1902 by Florentino Ameghino, based on fossil remains initially thought to date back to the Cretaceous.

In 2021, Claudia Herrera and colleagues named a new species of Utaetus based on several osteoderms that had been unearthed from the Middle Eocene strata of the Upper Lumbrera Formation in Salta Province, Argentina.