Dryomorpha

Iguanodontia Temporal range: Middle Jurassic–Late Cretaceous, 163–66 Ma PreЄ Є O S D C P T J K Pg N
Heads of different iguanodontians
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Order:	†Ornithischia
Suborder:	†Ornithopoda
Clade:	†Iguanodontia Dollo, 1888
Subgroups
†Tenontosaurus †Rhabdodontidae †Elasmaria †Anabisetia †Gasparinisaura †Macrogryphosaurus †Morrosaurus †Notohypsilophodon †Talenkauen †Trinisaura †Dryomorpha †Dryosauroidea †Ankylopollexia

Iguanodontia is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Tenontosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodontians were one of the first groups of dinosaurs to be found. They are among the best known of the dinosaurs, and were among the most diverse and widespread herbivorous dinosaur groups of the Cretaceous period. Derived iguanodontians (such as Muttaburrasaurus and many ankylopollexians) were generally large animals, and some (such as Shantungosaurus, which measured up to 50 ft (15 m) in length and weighed up to 8 tons) equaled 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, iguanodontians were grouped into the superfamily Iguanodontoidea and family Iguanodontidae. However, phylogenetic studies show that the traditional "iguanodontids" are a paraphyletic grade leading up to the hadrosaurs (duck-billed dinosaurs). Groups like Iguanodontoidea are sometimes still used as unranked clades in the scientific literature, though many traditional "iguanodontids" are now included in the more inclusive group Hadrosauroidea. Iguanodontia is usually defined as the most inclusive group containing Parasaurolophus walkeri but not Hypsilophodon foxii or Thescelosaurus neglectus, or other combinations of species that would ultimately result in the same group in most modern analyses. The group was first defined as a clade in 2008 by Paul Sereno.