Iguanodon was a large herbivore that could walk on 4 legs or upright on its 2 hind legs. Iguanodon means Iguana tooth. The original fossils were discovered by Gideon Mantell. At the time there was much debate as to whether this creature was like a lizard or more like or mammal. The replicas of Iguanodon have changed many times as scientists make further discoveries about Iguanodon.