Iguanodon
Name: Iguanodon (Iguana tooth).
Phonetic: Ig-wah-no-don.
Named By: Gideon Mantell - 1825.
Synonyms: Delapparentia turolensis.
Classification: Chordata, Reptilia, Dinosauria, Ornithischia, Ornithopoda.
Species: I. bernissartensis (neotype) I. galvensis.
Diet: Herbivore.
Size: Specimens seem to average around the 10 meter long mark, but some individuals are possibly as large as 13 meters long.
Known locations: Initially associated with Western Europe, attributed remains are now known in Africa, Asia and North America.
Time period: Kimmeridgian of the Jurassic through to the Barremian/Aptian of the Cretaceous. Some specimens from some parts of the world suggest as late as the Cenomanian of the Cretaceous.
Fossil representation: Many specimens resulting in reconstruction of complete examples.
Discovery and Early Reconstruction of Iguanodon.
Iguanodon has a firm place within dinosaur history books, not just because of the large expanse of fossil material attributed to it, but because it was the second dinosaur to ever be identified and named. The first dinosaur was actually Megalosaurus which was named a year earlier, and back then the term dinosaur didn't even exist.
The exact discovery of Iguanodon has become something of a popular story, but with successive retelling some of the details have become a little blurred. The main area of this is just who discovered the first Iguanodon teeth, one Gideon Mantell, or his wife Mary Ann. Gideon Mantell was a practising obstetrician and the popular version of this story is that his wife Mary Ann discovered the first teeth in a quarry in Whiteman's Green, Sussex while he was visiting a patient in 1822. However a statement by Gideon Mantell himself in 1851 stated that it was he who had found the original teeth. Mantell's notes dating back to 1820 also show that he had discovered other material as well as different teeth from what we would call today a carnivorous theropod. There is also a mention of the discovery of teeth that seem to have belonged to a herbivore. This is why who discovered the Iguanodon teeth varies depending upon who is telling the story.
Initially the teeth were a secondary concern for Mantell as he was more concerned about the reconstruction of the bones and theropod teeth. Back then the idea of animals like dinosaurs had not yet been conceived and so bones like these were usually taken as being part of an animal similar to those alive at the time. In this case Mantell thought that he was dealing with a crocodile because of the shape of the carnivorous teeth. The herbivore teeth were however considered by Mantell to belong to a different but possibly equally massive reptile.
In 1822 the herbivore teeth were submitted to the Geological Society of London, but the response was not positive as the members declared the teeth to belong to either a rhinoceros or possibly a fish. Interestingly one of these members was William Buckland, who under two years later would actually go on to name the first dinosaur, Megalosaurus. Just over a year after this in 1823, Charles Lyell showed some of the teeth to Georges Cuvier, A French naturalist who used techniques of comparative anatomy to identify fossil animals. One of Cuvier’s most famous successes was that he was the first person to correctly identify the pterosaur Pterodactylus as a flying reptile. Initially Cuvier had the same conclusion as the Geological society in that the teeth were of a rhinoceros, but the next day he actually doubted that interpretation. Unfortunately Lyell's communication to Mantell only contained Cuvier's initial opinion of the teeth, something that resulted in Mantell putting the teeth to one side.
William Buckland's 1824 description of Megalosaurus sent shock waves throughout the scientific community and caused many to start thinking about the kinds of animals that once lived and how they could be different. Buckland himself visited Mantell soon after to look at his collection of bones and realised immediately that Mantell had a creature that appeared to be similar to Megalosaurus. The idea of giant 'lizards' like Megalosaurus being carnivores was still fresh in the head however, and Buckland still insisted that what Mantell had was a carnivore and not a herbivore.
At least encouraged by Buckland's identification of the bones, Mantell sent the herbivore teeth to Cuvier so that he may have a second opportunity to examine them. Cuvier remembered his doubts after initially declaring the teeth to be those of a rhinoceros, and this time his interpretation was very different. Cuvier replied and confirmed to Mantell that the teeth were reptilian, and could be those of a herbivore. On top of this Cuvier printed a public retraction of his first interpretation and confirmed that he now believed the teeth to be reptilian, not mammalian. Georges Cuvier was a highly respected scientist in natural history circles and when he spoke, others stopped and listened.
With the weight of Cuvier's reputation behind him, Mantell now found himself widely accepted and began to piece together the extinct animal, specifically searching for a living reptile that had similar teeth. Mantell's answer was supplied by Samuel Stutchbury, assistant-curator of the Royal College of Surgeons. Stuctchbury had recently worked on an iguana and saw a close match with the teeth. Now that Mantell had a close match he began his reconstruction. The obvious thing to him, and probably most others of the time, was to scale the size of the iguana tooth to the fossil tooth to see how many times larger the fossil was. Mantell then measured the body of the iguana and then multiplied this by how many times the fossil tooth was larger than an iguana tooth. The result of this was a colossal eighteen meters long, even bigger than Megalosaurus. Needless to say that this was a gross overestimate, and while versions of this technique are still used today, they are strictly restricted to animals that are known to have at least the same body shape.
The similarity of the fossil to the iguana teeth was the inspiration for the name, although Mantell's first choice was actually Iguanasaurus which translates to 'iguana lizard'. However as Mantell's friend William Daniel Conybeare pointed out the iguana is a lizard, and the name might course confusion between the animals. He then suggested Iguanoides which means 'iguana like' and Iguanodon, which means 'iguana tooth'. As you have probably already gathered, Mantell chose Iguanodon.
