 A more complete specimen of similar animal was discovered in a quarry in Maidstone , Kent , in 1834 ( lower Lower <unk> Formation ) , which Mantell soon acquired . He was led to identify it as an Iguanodon based on its distinctive teeth . The Maidstone slab was utilized in the first skeletal reconstructions and artistic renderings of Iguanodon , but due to its incompleteness , Mantell made some mistakes , the most famous of which was the placement of what he thought was a horn on the nose . The discovery of much better specimens in later years revealed that the horn was actually a modified thumb . Still <unk> in rock , the Maidstone skeleton is currently displayed at the Natural History Museum in London . The borough of Maidstone commemorated this find by adding an Iguanodon as a supporter to their coat of arms in 1949 . This specimen has become linked with the name I. mantelli , a species named in 1832 by Christian Erich Hermann von Meyer in place of I. anglicus , but it actually comes from a different formation than the original I. mantelli / I. anglicus material . The Maidstone specimen , also known as Gideon Mantell 's " <unk> @-@ piece " , and formally labelled <unk> <unk> was subsequently excluded from Iguanodon . It is classified as cf . Mantellisaurus by McDonald ( 2012 ) ; as cf . Mantellisaurus atherfieldensis by Norman ( 2012 ) ; and made the holotype of a separate species Mantellodon <unk> by Paul ( 2012 ) . 
