Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, and Ouranosaurus. Iguanodonts were one of the first groups of dinosaurs to be found. They are among the best known of the dinosaurs, and include the "duck-billed" hadrosaurs. Iguanodontians were fairly large animals, and some (such as Shantungosaurus, which measured up to 50 ft (15 m) in length and weighed up to 8 tons) approached the largest carnivorous dinosaurs in size.
Iguanodontia is often listed as an infraorder within a suborder Ornithopoda, though Benton (2004) lists Ornithopoda as an infraorder and does not rank Iguanodontia. Traditionally, iguanodonts were grouped into the superfamily Iguanodontoidea and family Iguanodontidae. However, phylogenetic studies show that the traditional "iguanodontids" are a paraphyletic grade leadig up to the hadrosaurs (duck-billed dinosaurs). Groups like Iguanodontoidea are still used as unranked clades in the scientific literature, though many traditional "iguanodontids" are now included in the superfamily Hadrosauroidea.
Iguanodontia |--Tenontosaurus `--+--Rhabdodontidae | |-?Mochlodon | |--Rhabdodon | `--Zalmoxes |-?Muttaburrasaurus `--Euiguanodontia |--Anabisetia |--Gasparinisaura `--Dryomorpha |--Dryosauridae | |--Dryosaurus | `--Valdosaurus `--Ankylopollexia |-?Bihariosaurus |-?Talenkauen |--Camptosauridae | |--Cumnoria | |--Callovosaurus | |--Draconyx | `--Camptosaurus `--Iguanodontoidea |--Lurdusaurus |--Lanzhousaurus `--Hadrosauriformes |--Iguanodon `--Hadrosauroidea