Iguanodon was the first plant-eating dinosaur ever discovered, and the second dinosaur to be named. A sharp spike on its thumb provided a useful defensive weapon against predators. It occupied Europe during the Early Cretaceous, 125 million years ago.
The history of Iguanodon goes back almost 200 years. The first fossilremains of Iguanodon were collected in the 1820s from the gravels ofTilgate Forest in southern England. The fossils consisted of largeteeth, similar is shape to those of a modern iguana, but muchlarger. These fossils were amongst the first dinosaur remains everfound. However, at that time nobody knew what a dinosaur was! So,these mysterious giant teeth shed the first light onto an ancientprehistoric world.
The teeth, along with some other isolated bones, were given thename Iguanodon in 1926. The name means 'iguana tooth'. It wasthought to be a giant reptile but, since this was before the word'dinosaur' was even invented, the early paleontologists had adifficult task reconstructing Iguanodon from its fragmentary fossils. It was originallythought to be a lumbering four-legged monster, similar to aniguana, with a horn on its nose. Later discoveries of completearticulated skeletons led to it being regarded as a biped with aposture more like a kangaroo, and the horn on its nose wascorrectly identified as a thumb spike. Today, Iguanodon is thought to have walked on four legs most of thetime - the early 19th century palaeontologists were right aboutthat after all!
Fossil trackways of Iguanodon show that it was a social animal that lived inherds. This is because there is safety in numbers. It used itshorny beak and leaf-shaped teeth to chomp through vegetation. Mostof its claws are blunt and hoof-like, but a sharp spike on itsthumb provided a defensive weapon to protect itself from predatorydinosaurs.
Iguanodon was the first plant-eating dinosaur to be named,early in the history of dinosaur palaeontology, and so dozens oflater dinosaur species were also allocated to the genus Iguanodon. However, modern studies have shown that theseformer Iguanodon species are actually distinct dinosaurs. Forexample, one of the best known of these species ('Iguanodon' atherfieldensis) was given the new name Mantellisaurus in 2007. Today, there are only two validspecies of Iguanodon: I. bernissartensis from northern Europe, and I. galvensis from Spain. Iguanodon occupied Europe during the Early Cretaceous, 125million years ago, and is one of the best known of alldinosaurs.