Riojasaurus ('LA RIOJA LIZARD') had a small head, long neck and tall, massive body, and four elephant-like limbs. This bus-length melanorosaurid prosauropod may have been the largest and heaviest of all land animals before the evolution of the sauropods. in fact, it matched the smaller sauropods in size and weight, and resembled them in build.

Deep hollows made the vertebrae of this huge dinosaur lighter, but its limb bones were massive and solid in order to support the vast body. Riojasaurus had relatively longer hands and feet than a sauropod, and more of its digits were tipped with claws.

It was once believed that enormous melanorosaurld prosauropods like Riojasaurus were carnivores and not herbivores. This misconception arose largely because sharp, pointed teeth were found mixed up with headless melanorosaurld remains. Scientists now think that the old, worn teeth had fallen from the mouths of carnivorous dinosaurs feeding on the prosauropods' corpses.

Riojasaurus really had leaf-shaped teeth that were designed for shredding plant fibres, not for slicing through flesh. Riojasaurus, with its elevated back and long neck, was one of the first land animals capable of browsing on vegetation growing high above the ground. Another benefit of Riojasaurus's enormous size was the protection afforded by sheer bulk against attack from early, large, flesh-eating dinosaurs, or from predatory, carnivorous rauisuchid reptiles.

Location: Argentina

Diet: Tree leaves

Size: Length 10m

      Weight 1 tonne

Classification:

Family Melanorosauridae

Infraorder Prosauropoda

Suborder Sauropodomorpha

Order Saurischia

Time (million years ago): 219