禽龙类（Iguanodontia）是群草食性恐龙，生存于中侏㑩纪到晚白垩纪，著名属包括：弯龙、卡洛夫龙、禽龙、豪勇龙、以及鸭嘴龙科...等。禽龙类是第一批发现的恐龙之一。牠们是最著名的恐龙之一，在白垩纪晚期成为多样性、分布广泛的恐龙。不同于早期的鸟脚类恐龙，禽龙类的上颌末端没有牙齿。原始的禽龙类（例如橡树龙）体型小而轻型，可用高速奔跑来逃离掠食动物。禽龙类是相当大的恐龙，有些（例如山东龙身长可达15公尺，重可达10吨以上）体型上接近最大的兽脚类恐龙。

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.