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Dreadnoughtus, a genus of large sauropod dinosaurs, the largest land animal that ever lived. It had a total length of roughly 26 metres (about 85 feet) and an estimated mass of 59 metric tons (about 65 tons). Dreadnoughtus is known from rock deposits of southern Patagonia, Argentina, that date to about 77 million years ago, during the Late Cretaceous Period (roughly 100 million to 66 million years ago). Dreadnoughtus is known only by one species, D. schrani, and is classified as a titanosaur, a group that includes Argentinosaurus, Saltasaurus, and other similar gargantuan dinosaurs.
Dreadnoughtus is known from two fossils, which were described in 2014. The larger of the two contained 115 bones, which represented roughly 70 percent of the dinosaur’s skeleton behind its head. The recovery of such a complete skeleton along with parts of Dreadnoughtus’s head and teeth allowed scientists to estimate the dinosaur’s size and make inferences about its lifestyle. Dreadnoughtus was a herbivore that stood 9 metres (30 feet) tall and likely used its 11-metre (37-foot) neck to reach leaves high up on trees in addition to other vegetation near the ground, reducing the dinosaur’s need to walk much. The paleontologists who discovered Dreadnoughtus also speculated that it may have used its long muscular tail to fend off potential predators.