By the Upper Jurassic (150 million years ago), sauropods had become widespread (especially the diplodocids and brachiosaurids). By the Upper Cretaceous, those groups had mainly been replaced by the titanosaurs, which had a near-global distribution. They were larger relatives of the brachiopods. 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.