Riojasaurus
- Pronunciation: REE-o-ha-SAWR-us
- Translation: Rioja Lizard
- Order: Saurischia
- Suborder: Sauropodomorpha
- Infraorder: Prosauropoda
- Family: Melanorosauridae
- Height: 16 feet (4.9 meters)
- Weight: Period
- Length: 36 feet (11 meters)
- Description: Herbivore, Quadrupedal
- Notes: Found in La Rioja Province, Argentina, Riojasaurus' bodyand legs were massive.