Dreadnoughtus is a genus of giant titanosaurian sauropod dinosaur which contains a single species, Dreadnoughtus schrani. D. schrani is known from two partial skeletons discovered in Upper Cretaceous (Campanian-Maastrichtian; 84–66 Ma) rocks of the Cerro Fortaleza Formation in Santa Cruz Province, Argentina. It is one of the largest of all known terrestrial vertebrates, possessing the greatest mass of any land animal that can be calculated with reasonable certainty. D. schrani is known from a more complete skeleton than any other gigantic titanosaurian.