English: Size comparison showing several of the big ornithopod dinosaurs. Several giant length estimates have been proposed for different taxa, with varying degrees of accuracy. This diagram uses more rigorous estimates to avoid inaccuracy. The seven shown taxa are:

• Shantungosaurus giganteus (red) A large Chinese taxon measuring 15 meters long and weighing 13 tonnes. Zhuchengosaurus maximus and Huaxiaosaurus aigahtens are now considered to be larger specimens of this species.^[1] References: Skeletal^[2] Restoring of Fossils^[1]
• Magnapaulia laticaudus (yellow) Long considered to be a giant species of Lambeosaurus, this Mexican hadrosaur was about 12.5 meters long (no more recent mass estimate to my knowledge).^[3] References: Skeletal^[3]
• Edmontosaurus annectens (brown) This common American and Canadian hadrosaurid was generally around 9 meters long and 3.2 tonnes in mass, although some specimens could be considerably larger (up to 13 meters). Anatosaurus is synonymous with this genus, and the giant Anatotitan copei with this species, the latter likely represents the fully mature ontogenetic stage of this species.^[1][4][5][6] References: Skeletal^[1] Skull^[6]
• Saurolophus angustirostris (blue) This large Mongolian species is related to the more famous (although smaller) North American S. osborni. S. angustirostris could reach lengths of 13 meters and weights of 11 tonnes, and yet rarely receives the same attention as some of the other taxa shown here, despite being known from a nearly complete skeleton and ontogenetic series.^[1][7] References: Skeletal^[8][1] Skull^[7]
• Hypsibema missouriensis (orange) This poorly known dinosaur with taxonomic issues was nevertheless chosen to be Missouri's state fossil. It was approximately 10 meters long.^[9] References: Skeletal^[10]
• Charonosaurus jiayinensis (violet) Another Chinese species, Charonosaurus was similar to the famous Parasaurolophus. Charonosaurus was the larger of the two, growing up to 10 meters and 5 tonnes.^[1] References: Skeletal^[11]
• Iguanodon bernissartensis (green) The only Brittish taxon here, and the only non-hadrosaurid, Iguanodon was, on average, 8 meters long and 3.2 tonnes in mass. However, it did get bigger than this.^[1][5] References: Skeletal^[12]

References