Period: Middle Jurassic
Order, Suborder, Family: Saurischia, Sauropodomorpha, Cetiosauridae
Location: South America (Argentina)
Length: 50 feet (15 meters)
Older than the Late Jurassic dinosaurs of North America, Patagosaurus is one of only two sauropods known from the Middle Jurassic of South America. The other sauropod is Volkheimeria, which is a member of the same family as Patagosaurus. A Patagosaurus skeleton was found in Patagonia, Argentina, in rocks about 15 million years older than those where the North American sauropods were found.
Patagosaurus is known from a nearly complete skeleton, except for the skull. It resembled the English sauropod Cetiosaurus, but its hips and vertebrae were different. Patagosaurus was a medium-size sauropod that weighed about 15 tons. In some ways it resembled the North American sauropod Haplocanthosaurus, but it was somewhat more primitive. Patagosaurus and its relatives may be the direct ancestors of some of the Late Jurassic sauropods. There may have been land connections that allowed the sauropods to travel between South America, western Europe, and Africa. Members of the same family have been found in all these different places.
Patagosaurus ate plants, and its enemies were the theropod dinosaurs. Piatnitzkysaurus, a theropod found at the same time and in the same location as Patagosaurus and Volkheimeria, was as large as Allosaurus and a menace to most plant-eaters.