Period: Late Cretaceous
Order, Suborder, Family: Saurischia, Sauropodomorpha, Titanosauridae
Location: South America (Argentina)
Length: 40 feet (12 meters)
From Salta in Argentina, Saltasaurus was described from several incomplete skeletons, none of which were found with a skull. This medium-size sauropod was dwarfed by its giant relative Antarctosaurus, also from South America. The armor of Saltasaurus consisted of hundreds of small bones about the size of peas, tightly packed in the skin, and a few large oval bony plates. The larger plates were about as broad and thick as a person's palm. This bony protection seems to have covered the back and sides of its body and probably gave it a roughened, bumpy appearance.
Prowling for a meal, a large predator leaping onto the back of a 20-ton sauropod would drive its claws deep into the flesh near the hips. The sudden blow would have harmed most sauropods, bringing them to the ground. But the predator's talons could not break through this sauropod's skin because it was studded with bony plates. An armored sauropod was rare in the world of dinosaurs. Sauropods had lived for more than 70 million years with no defense except their size. Saltasaurus was an unusual dinosaur.
Another Late Cretaceous sauropod from South America, Laplatasaurus, also had bony plates in its skin. Because these two dinosaurs, both in the family Titanosauridae, had armor, it is possible that other members of the family (Antarctosaurus, Hypselosaurus, and Titanosaurus from South America, and Alamosaurus from North America) also had bony plates for protection. This trait would distinguish this family from all other sauropod dinosaurs.
Sauropod dinosaurs were not common in most parts of the world by the end of the Cretaceous Period. This may be because they were competing with more-advanced plant-eating dinosaurs and because predatory dinosaurs kept their numbers down. Some predators had become very large (Tyrannosaurus weighed up to seven tons) and the size of sauropods was not as much protection as when predators were smaller. The armor on the titanosaurids may be what allowed Saltasaurus and other sauropods in this family to survive. Saltasaurus and its relatives were successful in South America, and one member of the family established a population in North America. Alamosaurus in New Mexico and Utah faced the giant predators Albertosaurus and Tyrannosaurus.