The Iguanodon was an herbivorous dinosaur from the Lower Cretaceous period. It's name means Iguana Tooth. The hands of the Iguanodon were very unusual. Distinctive features included large thumb spikes, which were possibly used for defense against predators, combined with long prehensile fifth fingers able to forage for food. Iguanodon were bulky herbivores that could shift from bipedality to quadrupedality.