Gideon Mantell

Gideon Algernon Mantell MRCS FRS (Lewes, 3 February 1790 – London, 10 November 1852) was an English obstetrician, geologist and palaeontologist.
Mantell's work on the structure and life of "Iguanodon" began the scientific study of dinosaurs. In 1822 he was responsible for the discovery (and the eventual identification) of the first fossil teeth, and later much of the skeleton, of "Iguanodon".
Mantell's work on the Cretaceous of southern England was also important. His phrase the "Age of Reptiles" was significant. He recognised that reptiles were the dominant life-form in what we now call the Jurassic and Cretaceous periods.
Mantell did two things which were most important. He showed that the teeth of "Iguanodon" meant it must be a herbivore, and its shorter front legs meant it could be bipedal (walk on two legs). This was denied by Richard Owen, who did a good deal to hide Mantell's achievements. The discovery of this fossil is known to be the first evidence of a prehistoric reptilian dinosaur, dating back roughly 130 million years ago.
At the end of Mantell's life he suffered terribly from damage to his spine caused by an accident. He took an overdose of opium, which caused his death. It is not known whether he did this deliberately; he took opium to dull the pain.
Works by Mantell.
Sixty-seven books and memoirs appear in Agassiz and Strickland's "Bibliographia Zoologiæ", and forty-eight scientific papers in the Royal Society's Catalogue.