(pronounced ig-WAHN-oh-don) Iguanodon was a plant-eating dinosaur with thumb spikes. It was about 33 feet (10 m) long and lived during the early Cretaceous period, roughly 130 million to 110 million years ago. The type species is I. anglicum. Iguanodon was named by Holl in 1829.
Iguanodon (meaning "Iguana tooth") is the name given to a genus of ornithopod dinosaur, which lived roughly halfway between the early hypsilophodontids and their ultimate culmination in the duck-billed dinosaurs. Most of its species lived between 140 to 120 million years ago, in the Valanginian to Barremian ages of the Early Cretaceous Period, although one dubious species is from the Late Jurassic. Iguanodon's most distinctive feature was a large 'thumb spike', possibly used for defense against predators.