Sauropods

Sauropoda ( /sɔːˈrɒpɵdə/), or the sauropods (/ˈsɔrəpɒd/), are an infraorder of saurischian ("lizard-hipped") dinosaurs. They had long necks, long tails, small heads (in comparison to the rest of their body), and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Brachiosaurus, Diplodocus, and Apatosaurus (which, under current classification, is a senior synonym of Brontosaurus). Sauropods first appeared in the late Triassic Period, where they somewhat resembled the closely related (and possibly ancestral) group Prosauropoda. By the Late Jurassic (150 million years ago), sauropods had become widespread (especially the diplodocids and brachiosaurids). By the Late Cretaceous, those groups had mainly been replaced by the titanosaurs, which had a near-global distribution. However, as with all other non-avian dinosaurs, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilised remains of sauropods have been found on every continent, including Antarctica.