Anatomy: Riojasaurus was a massive quadrupedal (walked on four legs) herbivore. It was a about 30 to 36 feet (9-11 m) long and was heavily built. It had a long neck, a long tail, a small head, a long, bulky body, and thick, elephant-like legs with claws. The back legs were only slightly larger than the front legs. Its limb bones were solid and thick, but its backbone was hollow. It had spoon-shaped, serrated teeth.

Fossils: Fossils have been found in La Rioja province, Argentina. Fossils include incomplete skeletons from about 20 individuals.

Name: Riojasaurus was named by the paleontologist José F. Bonaparte in 1969 . The type species is R. incertus.