The dinosaur’s long neck, bulging body and long tail stretched about 120 feet long, with the living animal estimated to weigh in at more than 70 tons. What was heralded as the largest dinosaur of all in 2014 has wound up in a neck-and-neck tie with several other dinosaurian giants such as Argentinosaurus. The shrinkage comes as part of a long history of supersized dinosaurs that have been downsized after their initial discovery. Although many dinosaurs lived large—the famous T. rex was 40 feet long and weighed nine tons—all of the very largest dinosaurs belonged to a group called sauropods. Part of the problem is that many of the largest dinosaur skeletons are incomplete.