 Iguanodon ( / <unk> / i @-@ <unk> @-@ <unk> @-@ don ; meaning " iguana @-@ tooth " ) is a genus of ornithopod dinosaur that existed roughly halfway between the first of the swift bipedal <unk> of the mid @-@ Jurassic and the duck @-@ billed dinosaurs of the late Cretaceous . While many species have been classified in the genus Iguanodon , dating from the late Jurassic Period to the late Cretaceous Period of Asia , Europe , and North America , research in the first decade of the 21st century suggests that there is only one well @-@ <unk> species : I. bernissartensis , which lived from the late Barremian to the earliest <unk> ages ( Early Cretaceous ) in Belgium and possibly elsewhere in Europe , between about 126 and 125 million years ago . Iguanodon were large , bulky herbivores . <unk> features include large thumb spikes , which were possibly used for defense against predators , combined with long prehensile fifth fingers able to forage for food . 
