Iguanodon is an iguanodontid ornithopod dinosaur from the Early Cretaceous of the United Kingdom, Belgium, and Spain. It was named in 1825 by Gideon Mantell. It was one of the first non-avian dinosaurs known to science (alongside Megalosaurus), and, like its theropod counterpart, it was a wastebasket taxon.
Iguanodon resembled a large, reptilian cow. It had a bulky body, long forelimbs ending in hoof-like fingers, and a large head with a small beak in front of its mouth; perhaps the most defining trait of Iguanodon was its spike-like thumb. Its body would have been covered in scaly skin.
Iguanodon was an herbivore, feeding on leaves, horsetails, cycads, and conifers. Its round beak was used to strip leaves off branches, while the many teeth in the back of its mouth would grind together, processing the leaves.
The way how Iguanodon should be constructed was under debate for a long time, with people reconstructing it as an herbivorous dragon with a nose horn, a bipedal, tail dragging, kangaroo-like reptile, and a quadrupedal, partially digitigrade (walking on its digits) ornithischian with hands facing forward and flat on the ground; today, the most accepted reconstruction is a quadrupedal, completely digitigrade ornithischian. A debate that still goes on about the ornithopod is its thumb-spike; many people say that it was used as defense against predators, while others say it was used for breaking into nuts and fruits, or possibly even intraspecific combat (fighting against a member of its own species). Due to massive bone beds containing multiple individuals, it is now commonly assumed that Iguanodon was a social animal that lived in massive herds; however, a possible explanation for the bone beds is that they were all killed by a flash flood. Finally, it was once thought that the ornithopod had a long tongue that can stretch at its will; however, an examination of the tongue bones showed that the tongue was no more flexible than those of many other ornithopods, and would have only been used for moving food around the mouth while the dinosaur grinded it up with its teeth.
In popular culture
Iguanodon was one of the 1st Mesozoic animals discovered, so it was featured in Crystal Palace Park (a pleasure ground in London) as a large, horned, herbivorous dragon, alongside Megalosaurus (also depicted as a dragon), Pterodactylus, Mosasaurus (depicted as a large, iguana-like squamate), Plesiosaurus, and Ichthyosaurus. Even then, it has still managed to be extremely popular, appearing in major pieces of media such as the Lost World novel, the 1998 adaptation of Journey to the Center of the Earth, Walking with Dinosaurs, and Disney's Dinosaur.