Even though its name means “stiff lizard“, they were also called “armored dinosaurs“. It lived in humid regions where it fed on low vegetation (ferns, grasses, etc.).
Its stocky silhouette allows it to face predators. The back, sides, neck, and tail are covered with a thick armor with many flat bony plates interlocked with each other and spines. At the end of the tail was a bony mass formed by the fusion of osteoderms, vertebrae and tendon. This mass could break bones. Bony outgrowths at the level of the orbits allow the head to be protected. The bones of its head were fused with other bones of the skeleton, allowing for better resistance.
Only the ventral side does not have a defense system. That is why it appears it would lie down on the ground during attacks to be completely safe.