The skull was approximately 12 centimeters long, the whole animal not exceeding more than half a meter in length for a weight between 5 and 6 kilograms.

The skull of Proeutatus had some characteristics distinguishing it from the more similar forms, such as Stenotatus and Eutatus ; the premaxilla had an upper tooth, the zygomatic arch was expanded and had a suborbital process ; the mandible was more robust, with an almost vertically ascending branch and a higher coronoid process.

Proeutatus was historically considered to be a member of the group Eutatinae, composed of medium to large armadillos specialized in an herbivorous diet.

More recent researches indicates that it was a basal member of the family Chlamyphoridae, close to the origin of the glyptodonts and the Pampatheres.

The structure of its jaws and teeth indicates that it had an omnivorous diet, with notable specializations for the consumption of vegetal matters.