Its back was armoured, and it is placed in the Thyreophora with the other armoured dinosaurs. It was one of the earliest members of this group, and the most basal (primitive) form so far known. Its closest relatives may have been "Emausaurus" and "Scelidosaurus". These, and the larger armoured dinosaurs "Ankylosaurus", "Stegosaurus" and "Huayangosaurus", were all quadrupedal. The lightly built bipedal "Scutellosaurus" is similar in form to the ancestral dinosaurs, which were bipedal.