The Iguanodon's horn

"Ever since mysterious bones were found in 1822, scientists and artists have tried to figure out what the creature they came from looked like. But it seems that every time they've made up their minds, someone makes a new discovery, and they have to start all over. That's only fair, though--after all, it's how knowledge advances! . . . traces the process of defining--and redefining--the dinosaur called Iguanodon"--Provided by publisher.