In 1821 a fossil tooth was discovered by a labourer while quarrying at Cuckfield in Sussex. The tooth came to the attention of Gideon Mantell, the Victorian palaeontologist. Mantell excited by what he believed to be the uniqueness of the find consulted a French comparative anatomist, a certain Baron Cuvier, but Cuvier pronounced it to be merely that of an ancient rhinoceros. Mantell cannot have been entirely convinced by this dismissal because, upon acquiring several more similar remains, he began to search for a living descendant whose teeth might resemble his own growing collection more closely. In his quest he came upon a specimen of iguana from the Galapagos islands. The Galapagos iguana is a herbivorous lizard whose staple diet is seaweed. While its teeth would have been substantially smaller than the petrified equivalents in Mantell’s possession; in every other respect the physical similarities, even down to the patterns of wear, were too similar to be ignored. In 1824 Mantell published these findings in a paper, pronouncing the discovery of a ‘new’ species and naming it Iguanadon, meaning Iguana tooth.

The study of palaeontology in Sussex during the 19th century was fraught with problems. Discoveries were rare and almost invariably incomplete; moreover, not enough was known within this emerging science to provide a framework within which to fit new examples as they came to light. What kind of animal could the teeth have belonged to? From the similar patterns of wear displayed in Mantell’s growing collection, Iguanadon could be established as being a herbivore, but biped or quadruped? Furthermore, of all the other bones that were from time to time dug up, which ones belonged to which? The physical attributes of the tooth collection’s original owners persisted as an enigma for years. Then in 1834 a quarryman in Maidstone found a more complete example of Iguanadon which, while still only partial and scattered, included a similar tooth. Mantell recognised the importance of this find and purchased it. He then set to reconstructing the pieces.

From his knowledge of other ancient and modern skeletons there were few difficulties in the putting together of this strange monster: hip bones, ribs and vertebrae were easily recognisable despite the novelty of the species and a team of technicians and assistants assembled these disparate elements into a semblance of what the creature may have looked like. There was one problem, no one could fathom the placement of a long sharp bone found with the others. Perhaps the earlier meeting with Baron Cuvier had an influence because it was finally decided that this fossil fragment should go on the end of the creatures nose thus giving it a somewhat rhinoceros like appearance.

Illustrations were prepared and the resulting pictures of this exotic beast, when published, stirred the imaginations of the contemporary scientific community. In the great inaugural exhibition of Crystal Palace in London it is recorded that a full sized model of iguanadon was shown, proudly displaying it’s horn.

Several years later in 1878, nineteen more or less complete examples of the dinosaur were exhumed by coal miners in a pit at Benissart in Belgium. In the ensuing excavation organised by Louis Dollo it was discovered that each came with not one but two of the aforementioned pointed bones. In all of the remains their position, when found, corresponded to the places where we might find thumbs on other animals. The illustrations and skeletal reconstructions were subsequently changed.