In order for a fossil to form, the body must be buried quickly before weather conditions and scavengers have a chance to scatter or otherwise destroy the bone.
Iguanodon was probably a herding animal, as evidenced by bonebed discoveries in Belgium. In these bonebeds, dozens of Iguanodon fossils were found together, suggesting that they congregated during their lives
This website is about the Cretaceous Period. It talks about the dinosaurs (land and marine) that lived there, the climate, and how the Cretaceous Period ended. Overall, this is a good and informative website, even though it's Wikipedia.