Dreadnoughtus is a genus of titanosaurian sauropod dinosaur containing a single species, Dreadnoughtus schrani. D. schrani is known from two partial skeletons discovered in Upper Cretaceous (Campanian to Maastrichtian; approximately 84–66 Ma) rocks of the Cerro Fortaleza Formation in Santa Cruz Province, Argentina. It is one of the largest terrestrial vertebrates known, 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.