The Amphicoelias (“doubly hollow”) was a herbivorous sauropod dinosaur that included what may be the largest dinosaur ever discovered—A. fragillimus from the Late Jurassic period. The evidence—a single fossil bone—was uncovered in the 1870s. If the description is true, it may have been the longest known dinosaur vertebrae, measuring 131 to 196 feet (40 to 60 meters) in length, with the animal weighing in at 135 tons (122 metric tons); thus rivaling the blue whale, the heaviest animal ever known. However, because the only fossil remains were lost at some point after being studied, the evidence survives only in drawings and field notes.