View source for Biology:Iguanodon

{{Short description|Ornithopod dinosaur genus from Early Cretaceous period}}
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{{Automatic taxobox
| fossil_range = [[Earth:Early Cretaceous|Early Cretaceous]] {{Fossil range|126|122}}
| image = Iguanodon_de_Bernissart_IRSNB_01.JPG
| image_caption = ''I. bernissartensis'' mounted in modern quadrupedal posture, Royal Belgian Institute of Natural Sciences, Brussels
| taxon = Iguanodon
| authority = Mantell, 1825<ref name=GM25/>
| type_species = {{extinct}}'''''Iguanodon bernissartensis'''''
| type_species_authority = Boulenger in Beneden, 1881
| subdivision_ranks = Other species
| subdivision = *†'''''I. anglicus''''' <small>Holl, 1829 (''[[Biology:Nomen dubium|nomen dubium]]'')</small>
*†'''''I. galvensis''''' <small>Verdú ''et al.'', 2015<ref name="Francisco J. Verdú 2015"/></small>
| synonyms = *''Delapparentia turolensis'' <br/><small>Ruiz-Omeñaca, 2011<ref name="omenaca11"/></small>
}}

'''''Iguanodon''''' ({{IPAc-en|ᵻ|ˈ|ɡ|w|ɑː|n|ə|d|ɒ|n}} {{respell|i|GWAH|nə-don}}; meaning '[[Biology:Iguana|iguana]]-[[Biology:Tooth|tooth]]'), named in 1825, is a [[Biology:Genus|genus]] of [[Biology:Iguanodontia|iguanodontia]]n [[Biology:Dinosaur|dinosaur]]. While many species found worldwide have been classified in the genus ''Iguanodon'', dating from the Late Jurassic to [[Earth:Early Cretaceous|Early Cretaceous]], [[Biology:Taxonomy|taxonomic]] revision in the early 21st century has defined ''Iguanodon'' to be based on one well-substantiated species: ''I. bernissartensis'', which lived during the [[Earth:Barremian|Barremian]] to early [[Earth:Aptian|Aptian]] ages of the [[Earth:Early Cretaceous|Early Cretaceous]] in Belgium, {{wipe|Germany}}, {{wipe|England}}, and {{wipe|Spain}}, between about 126 and 122&nbsp;million years ago. ''Iguanodon'' was a large, bulky herbivore, measuring up to {{convert|9|-|11|m|ft}} in length and {{convert|4.5|MT|ST}} in body mass. Distinctive features include large thumb spikes, which were possibly used for defense against [[Earth:Predation|predators]], combined with long prehensile fifth fingers able to forage for food.

The genus was named in 1825 by English [[Geologist|geologist]] Gideon Mantell but discovered by William Harding Bensted, based on fossil specimens found in England and was given the species name ''I. anglicus.'' ''Iguanodon'' was the second type of dinosaur formally named based on fossil specimens, after ''Megalosaurus''. Together with ''Megalosaurus'' and ''[[Biology:Hylaeosaurus|Hylaeosaurus]]'', it was one of the three genera originally used to define [[Biology:Dinosaur|Dinosaur]]ia. The genus ''Iguanodon'' belongs to the larger group [[Biology:Iguanodontia|Iguanodontia]], along with the duck-billed hadrosaurs. The taxonomy of this genus continues to be a topic of study as new species are named or long-standing ones reassigned to other genera. 

In 1878 new, far more complete remains of ''Iguanodon'' were discovered in Belgium and studied by Louis Dollo. These were given the new species ''I. bernissartensis.'' In the early 21st century it became understood that the remains referred to as ''Iguanodon'' in England belonged to four different species (including ''I. bernissartensis'') that were not closely related to each other, which were subsequently split off into ''[[Biology:Mantellisaurus|Mantellisaurus]]'', ''[[Biology:Barilium|Barilium]]'' and ''[[Biology:Hypselospinus|Hypselospinus]].'' It was also found that the originally described [[Biology:Type species|type species]] of ''Iguanodon, I. anglicus'' is now a ''[[Biology:Nomen dubium|nomen dubium]],'' and not valid. Thus the name "''Iguanodon''" became fixed around the well known species based primarily on the Belgian specimens. In 2015, a second valid species, ''I. galvensis'', was named, based on fossils found in the Iberian Peninsula.

Scientific understanding of ''Iguanodon'' has evolved over time as new information has been obtained from [[Biology:Fossil|fossil]]s. The numerous specimens of this genus, including nearly complete skeletons from two well-known [[Biology:Bone bed|bone bed]]s, have allowed researchers to make informed hypotheses regarding many aspects of the living animal, including feeding, movement, and social behaviour. As one of the first scientifically well-known dinosaurs, ''Iguanodon'' has occupied a small but notable place in the public's perception of dinosaurs, its artistic representation changing significantly in response to new interpretations of its remains.

==Discovery and history==

===Gideon Mantell, Sir Richard Owen, and the discovery of dinosaurs===
[[File:Mantell's Iguanodon teeth.jpg|thumb|left|upright|The original ''I. anglicus'' teeth from Mantell's 1825 paper]] 
The discovery of ''Iguanodon'' has long been accompanied by a popular [[Social:Legend|legend]]. The story goes that Gideon Mantell's wife, Mary Ann, discovered the first teeth<ref>{{Cite web|url=https://collections.tepapa.govt.nz/object/212194&coltype=history&regno=gh004839|title= Collections Online – Museum of New Zealand Te Papa Tongarewa|website=collections.tepapa.govt.nz|access-date=20 December 2019}}</ref> of an ''Iguanodon'' in the strata of Tilgate Forest in Whitemans Green, Cuckfield, Sussex, {{wipe|England}}, in 1822 while her husband was visiting a patient. However, there is no evidence that Mantell took his wife with him while seeing patients. Furthermore, he admitted in 1851 that he himself had found the teeth,<ref name=HDS97>{{cite book |last=Sues |first=Hans-Dieter |editor=James Orville Farlow |editor2=M. K. Brett-Surman |title=The Complete Dinosaur |year=1997 |publisher=Indiana University Press |location=Bloomington |isbn=978-0-253-33349-0 |page=[https://archive.org/details/isbn_9780253333490/page/14 14] |chapter=European Dinosaur Hunters |url=https://archive.org/details/isbn_9780253333490/page/14 }}</ref> although he had previously stated in 1827 and 1833 that Mrs. Mantell had indeed found the first of the teeth later named ''Iguanodon''.<ref name="mantell1827">{{Cite book|title=Illustrations of the Geology of Sussex|last=Mantell|first=Gideon|publisher=Lupton Relfe|year=1827|location=London|pages=71–78}}</ref><ref name="mantell1833">{{cite book|title=The Geology of the South East of England|last=Mantell|first=Gideon|publisher=Cambridge University Press|year=1833|chapter=Description of the Organic Remains of the Wealden, and particularly of those of the Strata of Tilgate Forest|pages=232–288}}</ref> Other later authors agree that the story is not certainly false.<ref name=SGL99>{{cite journal |last1=Lucas |first1=Spencer G.|date=December 1999 |title=Book review: Gideon Mantell and the discovery of dinosaurs|journal=PALAIOS |volume=14 |issue=6 |pages=601–602 |issn=0883-1351 |doi=10.2307/3515316 |last2=Dean |first2=Dennis R. |jstor=3515316|bibcode=1999Palai..14..601L}}</ref> It is known from his notebooks that Mantell first acquired large fossil bones from the quarry at Whitemans Green in 1820. Because also theropod teeth were found, thus belonging to carnivores, he at first interpreted these bones, which he tried to combine into a partial skeleton, as those of a giant [[Biology:Crocodile|crocodile]]. In 1821 Mantell mentioned the find of herbivorous teeth and began to consider the possibility that a large herbivorous reptile was present in the strata. However, in his 1822 publication ''Fossils of the South Downs'' he as yet did not dare to suggest a connection between the teeth and his very incomplete skeleton, presuming that his finds presented two large forms, one carnivorous ("an animal of the Lizard Tribe of enormous magnitude"), the other herbivorous.

In May 1822 he first presented the herbivorous teeth to the Royal Society of London but the members, among them William Buckland, dismissed them as [[Biology:Fish|fish]] teeth or the incisors of a rhinoceros from a [[Earth:Tertiary|Tertiary]] stratum. On 23 June 1823 Charles Lyell showed some to [[Biography:Georges Cuvier|Georges Cuvier]], during a soiree in [[Place:Paris|Paris]], but the famous French naturalist at once dismissed them as those of a rhinoceros. Though the very next day Cuvier retracted, Lyell reported only the dismissal to Mantell, who became rather diffident about the issue. In 1824 Buckland described ''Megalosaurus'' and was on that occasion invited to visit Mantell's collection. Seeing the bones on 6 March he agreed that these were of some giant saurian—though still denying it was a herbivore. Emboldened nevertheless, Mantell again sent some teeth to Cuvier, who answered on 22 June 1824 that he had determined that they were reptilian and quite possibly belonged to a giant herbivore. In a new edition that year of his ''Recherches sur les Ossemens Fossiles'' Cuvier admitted his earlier mistake, leading to an immediate acceptance of Mantell, and his new saurian, in scientific circles. Mantell tried to corroborate his theory further by finding a modern-day parallel among extant reptiles.<ref name = DC00/> In September 1824 he visited the Royal College of Surgeons but at first failed to find comparable teeth. However, assistant-curator Samuel Stutchbury recognised that they resembled those of an [[Biology:Iguana|iguana]] he had recently prepared, albeit twenty times longer.<ref name=DFG97/>
[[File:Mantell's Iguanodon restoration.jpg|thumb|Mantell's "Iguanodon" restoration based on the Maidstone ''Mantellodon'' remains]]
In recognition of the resemblance of the teeth to those of the iguana, Mantell decided to name his new animal ''Iguanodon'' or 'iguana-tooth', from ''iguana'' and the [[Social:Ancient Greek|Greek]] word ὀδών (''odon'', ''odontos'' or 'tooth').<ref name=NM01/> Based on [[Biology:Allometry|isometric scaling]], he estimated that the creature might have been up to {{convert|18|m|abbr=off}} long, more than the {{convert|12|m|adj=mid}} length of ''Megalosaurus''.<ref name=GM25/> His initial idea for a name was ''Iguana-saurus'' ('Iguana lizard'), but his friend William Daniel Conybeare suggested that that name was more applicable to the iguana itself, so a better name would be ''Iguanoides'' ('Iguana-like') or ''Iguanodon''.<ref name=DC00>Cadbury, D. (2000). ''The Dinosaur Hunters''. Fourth Estate:London, 384 p. {{ISBN|1-85702-959-3}}.</ref><ref name=GO97>{{cite web | author = Olshevsky, G | title = Re: Hello and a question about Iguanodon mantelli (long) | url = http://dml.cmnh.org/1997Aug/msg00339.html | access-date = 11 February 2007 |  archive-date = 8 December 2007 | archive-url = https://web.archive.org/web/20071208134851/http://dml.cmnh.org/1997Aug/msg00339.html | url-status = dead }}</ref> He neglected to add a [[Biology:Specific name (zoology)|specific name]] to form a proper [[Biology:Binomial nomenclature|binomial]], but one was supplied in 1829 by Friedrich Holl: ''I. anglicum'', which was later emended to ''I. anglicus''.<ref name = FH29/>
[[File:Maidstone fossil Iguanodon 1840.jpg|thumb|left|Fossil iguanodont remains found in Maidstone in 1834, now classified as ''Mantellisaurus''|alt=]]
Mantell sent a letter detailing his discovery to the local Portsmouth Philosophical Society in December 1824, several weeks after settling on a name for the fossil creature. The letter was read to members of the Society at a meeting on 17 December, and a report was published in the ''Hampshire Telegraph'' the following Monday, 20 December, which announced the name, misspelled as "Iguanadon".<ref name=simpson2015>{{cite journal | last1 = Simpson | first1 = M.I. | year = 2015 | title = Iguanodon is older than you think: the public and private announcements of Gideon Mantell's giant prehistoric herbivorous reptile | journal = Deposits Magazine | volume = 44 | page = 33 }}</ref> Mantell formally published his findings on 10 February 1825, when he presented a paper on the remains to the Royal Society of London.<ref name=GM25>{{cite journal |last=Mantell |first=Gideon A.|year=1825 |title=Notice on the Iguanodon, a newly discovered fossil reptile, from the sandstone of Tilgate forest, in Sussex |journal=Philosophical Transactions of the Royal Society |volume=115 |pages=179–186 |doi=10.1098/rstl.1825.0010 |issn=0261-0523 |jstor=107739|doi-access=free |bibcode=1825RSPT..115..179M }}</ref><ref name=HDS97/>

A more complete specimen of a similar animal was discovered in a quarry in Maidstone, Kent, in 1834 (lower Lower Greensand 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 [[Biology:Horn (anatomy)|horn]] on the nose.<ref name=GM34>{{cite journal |last= Mantell|first=Gideon A. |year=1834|title= Discovery of the bones of the ''Iguanodon'' in a quarry of Kentish Rag (a limestone belonging to the Lower Greensand Formation) near Maidstone, Kent |journal=Edinburgh New Philosophical Journal |volume=17 |pages=200–201 }}</ref> The discovery of much better specimens in later years revealed that the horn was actually a modified thumb. Still encased in rock, the Maidstone skeleton is currently displayed at the [[Biology:Natural History Museum, London|Natural History Museum]] in [[Place:London|London]]. The borough of Maidstone commemorated this find by adding an ''Iguanodon'' as a supporter to their coat of arms in 1949.<ref name=EC68>{{cite book |last=Colbert |first=Edwin H.|title=Men and Dinosaurs: The Search in Field and Laboratory |url=https://archive.org/details/mendinosaurssear00colb |url-access=registration |year=1968 |publisher=Dutton & Company |location=New York |isbn=978-0-14-021288-4 }}</ref> 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.<ref name=GO97/> The Maidstone specimen, also known as Gideon Mantell's "Mantel-piece", and formally labelled NHMUK 3741<ref name=norman2012>{{cite book |last=Norman |first=David B. |year=2012 |chapter=Iguanodontian taxa (Dinosauria: Ornithischia) from the Lower Cretaceous of England and Belgium |editor-last=Godefroit |editor-first=P. |title=Bernissart Dinosaurs and Early Cretaceous Terrestrial Ecosystems |url=https://archive.org/details/bernissartdinosa00gode |url-access=limited |publisher=Indiana University Press |pages=[https://archive.org/details/bernissartdinosa00gode/page/n191 175]–212 |isbn=978-0-253-35721-2}}</ref><ref name=paul2012 /> was subsequently excluded from ''Iguanodon''. It is classified as ''cf.'' ''Mantellisaurus'' by McDonald (2012);<ref name=McDonald2012>{{cite journal |last=McDonald |first=Andrew T. |year=2012 |title=The status of ''Dollodon'' and other basal iguanodonts (Dinosauria: Ornithischia) from the upper Wealden beds (Lower Cretaceous) of Europe |journal=Cretaceous Research |volume=33 |issue=1 |pages=1–6 |doi=10.1016/j.cretres.2011.03.002}}</ref> as cf. ''Mantellisaurus atherfieldensis'' by Norman (2012);<ref name=norman2012 /> and made the holotype of a separate species ''[[Biology:Mantellodon|Mantellodon carpenteri]]'' by Paul (2012),<ref name=paul2012 /> but this is considered dubious and it is generally considered a specimen of ''Mantellisaurus''<ref name=":0" />
[[File:Mantellodon in Crystal Palace Park.jpg|thumb|Statues in Crystal Palace Park based on the Maidstone specimen of ''"Iguanodon"'', designed by Benjamin Waterhouse Hawkins, after restoration in 2002|alt=]]
At the same time, tension began to build between Mantell and Richard Owen, an ambitious scientist with much better funding and society connections in the turbulent worlds of Reform Act-era British politics and science. Owen, a firm [[Philosophy:Creationism|creationist]], opposed the early versions of [[Biology:Evolution|evolutionary science]] ("[[Biology:Transmutation of species|transmutationism]]") then being debated and used what he would soon coin as dinosaurs as a weapon in this conflict. With the paper describing Dinosauria, he scaled down dinosaurs from lengths of over {{convert|61|m|abbr=off}}, determined that they were not simply giant lizards, and put forward that they were advanced and mammal-like, characteristics given to them by [[Religion:God|God]]; according to the understanding of the time, they could not have been "transmuted" from reptiles to mammal-like creatures.<ref name=HT97>Torrens, Hugh. "Politics and Paleontology". ''The Complete Dinosaur,'' 175–190.</ref><ref name=RS42>{{cite journal|last=Owen |first=R. |year=1842 |title=Report on British Fossil Reptiles: Part II |journal=Report of the British Association for the Advancement of Science for 1841 |volume=1842 |pages=60–204}}</ref>

In 1849, a few years before his death in 1852, Mantell realised that iguanodonts were not heavy, pachyderm-like animals,<ref name=GM51>{{cite book |last=Mantell |first=Gideon A. |title= Petrifications and their teachings: or, a handbook to the gallery of organic remains of the British Museum. |year=1851 |publisher=H. G. Bohn |location=London |oclc= 8415138}}</ref> as Owen was putting forward, but had slender forelimbs. However, since his passing left him unable to participate in the creation of the Crystal Palace dinosaur sculptures, Owen's vision of the dinosaurs became that seen by the public for decades.<ref name=HT97/> With Benjamin Waterhouse Hawkins, he had nearly two dozen lifesize sculptures of various prehistoric animals built out of [[Chemistry:Concrete|concrete]] sculpted over a steel and brick framework; two iguanodonts (based on the Maidstone specimen), one standing and one resting on its belly, were included. Before the sculpture of the standing iguanodont was completed, he held a banquet for twenty inside it.<ref name=MB00>{{cite book |last=Benton |first=Michael S.|title=The Scientific American Book of Dinosaurs| editor=Gregory S. Paul|year=2000 |publisher=St. Martin's Press |location=New York|chapter= brief history of dinosaur paleontology |isbn=978-0-312-26226-6 |pages=10–44}}</ref><ref name=CY96>{{cite journal |last=Yanni |first=Carla |date=September 1996 |title=Divine Display or Secular Science: Defining Nature at the Natural History Museum in London |journal=The Journal of the Society of Architectural Historians |volume=55 |issue=3 |pages=276–299 |doi=10.2307/991149 |jstor=991149 }}</ref><ref name=DBN85>Norman, David B. ''The Illustrated Encyclopedia of Dinosaurs.'' p. 11.</ref>

===Bernissart mine discoveries and Dollo's new reconstruction===

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|footer = Four ''I. bernissartensis'' fossils drawn as they were found in 1882
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The largest find of ''Iguanodon'' remains to that date occurred on 28 February 1878 in a coal mine at Bernissart in Belgium, at a depth of {{convert|322|m|abbr=on}},<ref name=DBN85b/> when two mineworkers, Jules Créteur and Alphonse Blanchard, accidentally hit on a skeleton that they initially took for [[Biology:Petrified wood|petrified wood]]. With the encouragement of Alphonse Briart, supervisor of mines at nearby Morlanwelz, Louis de Pauw on 15 May 1878 started to excavate the skeletons and in 1882 Louis Dollo reconstructed them. At least 38 ''Iguanodon'' individuals were uncovered,<ref name=DBN04/> most of which were adults.<ref name=DBN87>{{cite journal|last=Norman |first=David B. |date=March 1987 |title=A mass-accumulation of vertebrates from the Lower Cretaceous of Nehden (Sauerland), West Germany |journal=Proceedings of the Royal Society of London. Series B, Biological Sciences |volume=230 |issue=1259 |pages=215–255 |doi=10.1098/rspb.1987.0017|pmid=2884670 |bibcode=1987RSPSB.230..215N |s2cid=22329180 }}</ref> In 1882, the holotype specimen of ''I. bernissartensis'' became one of the first ever dinosaur skeletons mounted for display. It was put together in a chapel at the Palace of Charles of Lorraine using a series of adjustable ropes attached to scaffolding so that a lifelike pose could be achieved during the mounting process.<ref name=norman2012/> This specimen, along with several others, first opened for public viewing in an inner courtyard of the palace in July 1883. In 1891 they were moved to the Royal Museum of Natural History, where they are still on display; nine are displayed as standing mounts, and nineteen more are still in the Museum's basement.<ref name=DBN85b/> The exhibit makes an impressive display in the Royal Belgian Institute of Natural Sciences, in Brussels. A replica of one of these is on display at the Oxford University Museum of Natural History and at the Sedgwick Museum in Cambridge. Most of the remains were referred to a new species, ''I. bernissartensis'',<ref>I.e. "from Bernissart".</ref> a larger and much more robust animal than the English remains had yet revealed. One specimen, IRSNB 1551, was at first referred to the nebulous, gracile ''I. mantelli'', but is currently referred to ''[[Biology:Mantellisaurus|Mantellisaurus atherfieldensis]]''. The skeletons were some of the first complete dinosaur skeletons known. Found with the dinosaur skeletons were the remains of plants, fish, and other reptiles,<ref name=DBN85b/> including the crocodyliform ''[[Biology:Bernissartia|Bernissartia]]''.<ref name=palmer99>Palmer, D. ed. (1999). ''The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals''. London: Marshall Editions. p. 100 {{ISBN|1-84028-152-9}}.</ref>
[[File:Bernissart Iguanodon mounted skeleton.jpg|thumb|upright|Photograph of a Bernissart ''Iguanodon'' skeleton being mounted in outdated kangaroo-like pose]]
The science of conserving fossil remains was in its infancy, and new techniques had to be improvised to deal with what soon became known as "[[Chemistry:Pyrite|pyrite]] disease". Crystalline pyrite in the bones was being oxidized to [[Chemistry:Iron(II) sulfate|iron sulphate]], accompanied by an increase in volume that caused the remains to crack and crumble. When in the ground, the bones were isolated by anoxic moist clay that prevented this from happening, but when removed into the drier open air, the natural chemical conversion began to occur. To limit this effect, De Pauw immediately, in the mine-gallery, re-covered the dug-out fossils with wet clay, sealing them with paper and plaster reinforced by iron rings, forming in total about six hundred transportable blocks with a combined weight of a hundred and thirty tons. In Brussels after opening the plaster he impregnated the bones with boiling gelatine mixed with oil of cloves as a [[Chemistry:Preservative|preservative]]. Removing most of the visible pyrite he then hardened them with hide glue, finishing with a final layer of [[Chemistry:Tin foil|tin foil]]. Damage was repaired with papier-mâché.<ref>De Pauw, L.F., 1902, ''Notes sur les fouilles du charbonnage de Bernissart, Découverte, solidification et montage des Iguanodons'', Imprim. photo-litho, JH. & P. Jumpertz, 150 av.d'Auderghem. 25 pp</ref> This treatment had the unintended effect of sealing in moisture and extending the period of damage. In 1932 museum director Victor van Straelen decided that the specimens had to be completely restored again to safeguard their preservation. From December 1935 to August 1936 the staff at the museum in Brussels treated the problem with a combination of [[Chemistry:Ethanol|alcohol]], [[Chemistry:Arsenic|arsenic]], and 390 kilograms of [[Chemistry:Shellac|shellac]]. This combination was intended to simultaneously penetrate the fossils (with alcohol), prevent the development of mold (with arsenic), and harden them (with shellac). The fossils entered a third round of conservation from 2003 until May 2007, when the shellac, hide glue and gelatine were removed and impregnated with [[Chemistry:Polyvinyl acetate|polyvinyl acetate]] and [[Chemistry:Cyanoacrylate|cyanoacrylate]] and [[Chemistry:Epoxy|epoxy]] glues.<ref>Pascal Godefroit & Thierry Leduc, 2008, "La conservation des ossements fossiles : le cas des Iguanodons de Bernissart", ''Conservation, Exposition, Restauration d'Objets d'Art'' '''2''' (2008)</ref> Modern treatments of this problem typically involve either monitoring the humidity of fossil storage, or, for fresh specimens, preparing a special coating of [[Chemistry:Polyethylene glycol|polyethylene glycol]] that is then heated in a vacuum pump, so that moisture is immediately removed and pore spaces are infiltrated with polyethylene glycol to seal and strengthen the fossil.<ref name=DBN85b/>

Dollo's specimens allowed him to show that Owen's prehistoric pachyderms were not correct for ''Iguanodon''. He instead modelled the skeletal mounts after the [[Biology:Cassowary|cassowary]] and [[Biology:Wallaby|wallaby]], and put the spike that had been on the nose firmly on the thumb.<ref name=LD82>{{cite journal |last=Dollo |first=Louis|year=1882 |title=Première note sur les dinosauriens de Bernissart |journal=Bulletin du Musée Royal d'Histoire Naturelle de Belgique |volume=1 |pages=161–180 |language=fr}}</ref><ref name=LD83>{{cite journal |last=Dollo |first=Louis|year=1883 |title=Note sur les restes de dinosauriens recontrés dans le Crétacé Supérieur de la Belgique |journal=Bulletin du Musée Royal d'Histoire Naturelle de Belgique |volume=2 |pages=205–221 |language=fr}}</ref> His reconstruction would prevail for a long period of time, but would later be discounted.<ref name=DBN85b/>

Excavations at the quarry were stopped in 1881, although it was not exhausted of fossils, as recent drilling operations have shown.<ref name=AR03>{{cite journal |last=de Ricqlès |first=A.|year=2003 |title=Bernissart's ''Iguanodon'': the case for "fresh" versus "old" dinosaur bone |journal=Journal of Vertebrate Paleontology |volume=23 |issue=Supplement to Number 3 |pages=1–124 |issn=0272-4634| doi = 10.1080/02724634.2003.10010538|s2cid=220410105}} Abstracts of Papers, Sixty-Third Annual Meeting.</ref> During [[Social:World War I|World War I]], when the town was occupied by [[Place:German Empire|German forces]], preparations were made to reopen the mine for palaeontology, and Otto Jaekel was sent from [[Place:Berlin|Berlin]] to supervise. Just as the first fossiliferous layer was about to be uncovered, however, the German army surrendered and had to withdraw. Further attempts to reopen the mine were hindered by financial problems and were stopped altogether in 1921 when the mine flooded.<ref name=DBN85b/><ref name=cordier17>Cordier, S (2017). ''De botten van de Borinage. De iguanodons van Bernissart van 125 miljoen voor Christus tot vandaag''. Antwerpen: Vrijdag {{ISBN|9789460014871}}. {{page needed|date=December 2021}}</ref>

===Turn of the century and the Dinosaur Renaissance===
[[File:Iguanodon Skelett 2.jpg|thumb|upright|''I. bernissartensis'' skeletal mount in modern bipedal pose, Übersee-Museum Bremen]]
Research on ''Iguanodon'' decreased during the early part of the 20th century as World Wars and the [[Finance:Great Depression|Great Depression]] enveloped Europe. A new species that would become the subject of much study and taxonomic controversy, ''I. atherfieldensis'', was named in 1925 by R. W. Hooley, for a specimen collected at Atherfield Point on the Isle of Wight.<ref name=RWH25>{{cite journal |last=Hooley |first=R. W. |year=1925|title=On the skeleton of ''Iguanodon atherfieldensis'' sp. nov., from the Wealden Shales of Atherfield (Isle of Wight) |journal=Quarterly Journal of the Geological Society of London |volume=81 |issue=2 |pages=1–61 |issn=0370-291X |doi=10.1144/GSL.JGS.1925.081.01-04.02|s2cid=129181645 }}</ref>

''Iguanodon'' was not part of the initial work of the dinosaur renaissance that began with the description of ''Deinonychus'' in 1969, but it was not neglected for long. David B. Weishampel's work on ornithopod feeding mechanisms provided a better understanding of how it fed,<ref name=DBW84>{{cite book |last=Weishampel |first=David B. |title=Evolution of Jaw Mechanisms in Ornithopod Dinosaurs |chapter=Introduction |year=1984|journal=Advances in Anatomy, Embryology, and Cell Biology |volume=87 |pages=1–109 |series=''Advances in Anatomy, Embryology, and Cell Biology'', 87|location=Berlin; New York|publisher=Springer-Verlag |pmid=6464809|isbn=978-0-387-13114-6 |doi=10.1007/978-3-642-69533-9_1 }}</ref> and David B. Norman's work on numerous aspects of the genus has made it one of the best-known dinosaurs.<ref name=DBN04/><ref name=DBN85b/><ref name=DBN80/><ref name=DBN86>{{cite journal |last=Norman |first=David B. |title=On the anatomy of ''Iguanodon atherfieldensis'' (Ornithischia: Ornithopoda) |journal=Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre |year=1986 |volume=56 |pages=281–372 |issn=0374-6291}}</ref> In addition, a further find of numerous disarticulated ''Iguanodon'' bones in Nehden, Nordrhein-Westphalen, {{wipe|Germany}}, has provided evidence for gregariousness<!--not quite the same thing, but it'll have to do--> in this genus, as the animals in this [[Area|areally restricted]] find appear to have been killed by [[Earth:Flash flood|flash flood]]s. At least 15 individuals, from {{convert|2|to|8|m}} long, have been found here, most of the individuals belong to the related ''[[Biology:Mantellisaurus|Mantellisaurus]]'' (described as ''I. atherfieldensis'', at that time believed to be another species of ''Iguanodon'').<ref name=DBN87/><ref name=GSP08>{{cite journal |last=Paul |first=Gregory S. |year=2008 |title=A revised taxonomy of the iguanodont dinosaur genera and species |journal=Cretaceous Research |volume=29 |issue=2 |pages=192–216 |doi=10.1016/j.cretres.2007.04.009|bibcode=2008CrRes..29..192P |url=http://doc.rero.ch/record/16134/files/PAL_E2902.pdf }}</ref> but some are of ''I. bernissartensis.''

One major revision to ''Iguanodon'' brought by the Renaissance would be another re-thinking of how to reconstruct the animal. A major flaw with Dollo's reconstruction was the bend he introduced into the [[Biology:Tail|tail]]. This organ was more or less straight, as shown by the skeletons he was excavating, and the presence of ossified tendons. In fact, to get the bend in the tail for a more wallaby or [[Biology:Kangaroo|kangaroo]]-like posture, the tail would have had to be broken. With its correct, straight tail and back, the animal would have walked with its body held horizontal to the ground, arms in place to support the body if needed.

===21st century research and the splitting of the genus===
[[File:Iguanodon-Pink Iggy-MIWG5126.jpg|thumb|left|''I. bernissartensis'' from the Isle of Wight, Dinosaur Isle Museum]] 
In the 21st century, ''Iguanodon'' material has been used in the search for dinosaur [[Physics:Biomolecule|biomolecule]]s. In research by Graham Embery ''et al.,'' ''Iguanodon'' bones were processed to look for remnant [[Biology:Protein|protein]]s. In this research, identifiable remains of typical bone proteins, such as phosphoproteins and proteoglycans, were found in a [[Biology:Rib|rib]].<ref name=GEetal03>{{cite journal |last1=Embery |first1=Graham |last2=Milner |first2=Angela C. |last3=Waddington |first3=Rachel J. |last4=Hall |first4=Rachel C. |last5=Langley |first5=Martin S. |last6=Milan |first6=Anna M. |title=Identification of proteinaceous material in the bone of the dinosaur ''Iguanodon'' |journal=Connective Tissue Research |year=2003 |issue=Suppl. 1 |pages=41–46 |pmid=12952172 |doi=10.1080/03008200390152070 |volume=44|s2cid=2249126 }}</ref> In 2007, [[Biography:Gregory S. Paul|Gregory S. Paul]] split ''I. atherfieldensis'' into a new, separate genus, ''[[Biology:Mantellisaurus|Mantellisaurus]]'' which has been generally accepted.<ref>{{Cite book|last=Paul|first=Gregory S.|url=http://dx.doi.org/10.2307/j.ctt1zxz1md.9|title=Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs|publisher=Indiana University Press|year=2007|isbn=978-0-253-02795-5|editor-last=Carpenter|editor-first=Kenneth|pages=69–78|chapter=Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England|doi=10.2307/j.ctt1zxz1md.9|access-date=14 June 2021}}</ref> In 2009 fragmentary iguanodontid material was described from upper Barremian Paris Basin deposits in Auxerre, Burgundy. While not definitively diagnosable to the genus/species level, the specimen shares "obvious morphological and dimensional affinities" with ''I. bernissartensis.''<ref>{{Cite journal|last=Knoll|first=Fabien|date=November 2009|title=A large iguanodont from the Upper Barremian of the Paris Basin|journal=Geobios|language=en|volume=42|issue=6|pages=755–764|doi=10.1016/j.geobios.2009.06.002|bibcode=2009Geobi..42..755K }}</ref>

In 2010, David Norman split the [[Earth:Valanginian|Valanginian]] species ''I. dawsoni'' and ''I. fittoni'' into ''[[Biology:Barilium|Barilium]]'' and ''[[Biology:Hypselospinus|Hypselospinus]]'' respectively.<ref name="DBN10" /> After Norman 2010, over half a dozen new genera were named off English "''Iguanodon"'' material. Carpenter and Ishida in 2010 named ''Proplanicoxa, Torilion'' and ''Sellacoxa'' while Gregory S. Paul in 2012 named ''Darwinsaurus'', ''Huxleysaurus'' and ''Mantellodon'' and Macdonald et al. in 2012 named ''Kukufeldia''. These species named after Norman 2010 are not considered valid and are considered various [[Biology:Synonym (taxonomy)|junior synonyms]] of ''Mantellisaurus'', ''Barilium'' and ''Hypselospinus.<ref name=":0">{{Cite journal|last=Norman|first=David B.|date=December 2013|title=On the taxonomy and diversity of Wealden iguanodontian dinosaurs (Ornithischia: Ornithopoda)|url=http://eprints.esc.cam.ac.uk/3039/1/pal_32_2_09.pdf|journal=Revue de Paléobiologie, Genève|volume=32|issue=2|pages=385–404|issn=0253-6730}}</ref>''

In 2011, a new genus ''Delapparentia'' was named for a specimen in Spain that was originally thought to belong to ''I. bernissartensis''.<ref name="omenaca11" /> The previous identification was subsequently reaffirmed in a new analysis of individual variation in the Belgian specimens, finding that the ''Delapparentia'' specimen was within the range of ''I. bernissartensis''.<ref name="indvar" /> In 2015 a new species of ''Iguanodon'', ''I. galvensis'', was named based on material including 13 juvenile (perinate) individuals found in the [[Earth:Camarillas Formation|Camarillas Formation]] near Galve, Spain.<ref name="Francisco J. Verdú 2015" /> In 2017 a new study was done of ''I. galvensis,'' with further evidence of distinctiveness from ''I. bernissartensis'' including several new autapomorphies.  It was also found that the ''Delapparentia'' holotype (which is also from the Camarillas Formation)  was not distinguishable from either ''I. bernissartensis'' or ''I. galvensis''.<ref>{{Cite journal|last1=Verdú|first1=Francisco Javier|last2=Royo-Torres|first2=Rafael|last3=Cobos|first3=Alberto|last4=Alcalá|first4=Luis|date=19 May 2018|title=New systematic and phylogenetic data about the early Barremian Iguanodon galvensis (Ornithopoda: Iguanodontoidea) from Spain|journal=Historical Biology|language=en|volume=30|issue=4|pages=437–474|doi=10.1080/08912963.2017.1287179|bibcode=2018HBio...30..437V |s2cid=89715643|issn=0891-2963}}</ref>

==Description==
[[File:Iguanodon scale.png|left|thumb|Size of ''Iguanodon bernissartensis'' compared to a human]]
''Iguanodon'' were bulky herbivores that could shift from [[Bipedalism|bipedality]] to quadrupedality.<ref name=DBN04>{{cite book |last=Norman |first=David B. |editor1-last=Weishampel |editor1-first=D. B. |editor2-last=Dodson |editor2-first=P. |editor3-last=Osmólska |editor3-first=H. |title=The Dinosauria |url=https://archive.org/details/dinosauriandedit00weis |url-access=limited |edition=2nd |year=2004 |publisher=University of California Press |location=Berkeley |isbn=978-0-520-24209-8 |pages=[https://archive.org/details/dinosauriandedit00weis/page/n431 413]–437 |chapter=Basal Iguanodontia}}</ref> The only well-supported species, ''I. bernissartensis'', is estimated to have measured about {{convert|9|m|abbr=off}} long as an adult, with some specimens possibly as long as {{convert|13|m|abbr=off}},<ref name=NM01>{{cite book|last1=Naish |first1=Darren |last2=Martill |first2=David M. |chapter=Ornithopod dinosaurs |title=Dinosaurs of the Isle of Wight |year=2001 |publisher=The Palaeontological Association |location=London |isbn=978-0-901702-72-2 |pages=60–132}}</ref> although this is likely an overestimate, given that the maximum body length of ''I. bernissartensis'' is reported to be {{cvt|11|m|ft}}.<ref name="indvar"/> Although Gregory S. Paul suggested a body mass of {{convert|3.08|MT|ST}} on average,<ref name=DFG97>{{cite book|chapter=Iguanodon |last=Glut |first=Donald F. |title=Dinosaurs: The Encyclopedia |url=https://archive.org/details/dinosaursencyclo04dfgl_143 |url-access=limited |year=1997 |publisher=McFarland & Co |location=Jefferson, North Carolina|pages=[https://archive.org/details/dinosaursencyclo04dfgl_143/page/n493 490]–500 |isbn=978-0-89950-917-4}}</ref> constructing a 3D mathematical model and employing allomery-based estimate suggests an ''I. bernissartensis'' close to {{cvt|8|m|ft}} long (smaller than average) weighs close to {{convert|3.8|MT|ST}} in body mass.<ref>{{cite journal|last=Henderson|first=D.M.|year=1999|title=Estimating the Masses and Centers of Mass of Extinct Animals by 3-D Mathematical Slicing|journal= Paleobiology |volume=25 |issue=1 |pages=88–106|doi=10.1666/0094-8373(1999)025<0088:ETMACO>2.3.CO;2| doi-broken-date=1 August 2023 |jstor=2665994 }}</ref><ref>{{cite journal |last=Seebacher |first=F. |date=2001 |url=https://dinoweb.ucoz.ru/_fr/4/A_new_method_to.pdf |title=A new method to calculate allometric length-mass relationships of dinosaurs |journal=Journal of Vertebrate Paleontology |volume=21 |issue=1 |pages=51–60|doi=10.1671/0272-4634(2001)021[0051:ANMTCA]2.0.CO;2 |jstor=4524171 |citeseerx=10.1.1.462.255 |s2cid=53446536 }}</ref> Specimens of relatively large individuals have been reported in the 2020s: a specimen referred to as ''I.'' cf. ''galvensis'' was measured up to {{cvt|9|-|10|m|ft}} in length,<ref>{{cite journal|author1=Verdú, F.J.|author2=Royo-Torres, R.|author3=Cobos, A.|author4=Alcalá, L.|year=2021|title=Systematics and paleobiology of a new articulated axial specimen referred to ''Iguanodon'' cf. ''galvensis'' (Ornithopoda, Iguanodontoidea)|journal=Journal of Vertebrate Paleontology|volume=40|issue=6|pages=e1878202|doi=10.1080/02724634.2021.1878202|s2cid=233829292 }}</ref> while a new specimen of ''I. bernissartensis'' from the upper [[Earth:Barremian|Barremian]] of the [[Place:Iberian Peninsula|Iberian Peninsula]] was measured up to {{cvt|11|m|ft}} in length.<ref>{{cite journal|author1=Gasulla, J.M.|author2=Escaso, F.|author3=Narváez, I.|author4=Sanz, J.L.|author5=Ortega, F.|title=New ''Iguanodon bernissartensis'' Axial Bones (Dinosauria, Ornithopoda) from the Early Cretaceous of Morella, Spain|year=2022|journal=Diversity|volume=14|issue=2|pages=63|doi=10.3390/d14020063|doi-access=free }}</ref> Such large individuals would have weighed approximately {{convert|4.5|MT|ST}}.<ref>{{cite journal|author1=Nye, E.|author2=Feist-Burkhardt, S.|author3=Horne, D.J.|author4=Ross, A.J.|author5=Whittaker, J.E.|year=2008|title=The palaeoenvironment associated with a partial Iguanodon skeleton from the Upper Weald Clay (Barremian, Early Cretaceous) at Smokejacks Brickworks (Ockley, Surrey, UK), based on palynomorphs and ostracods|volume=29|pages=417–444|journal=Cretaceous Research|issue=3 |doi=10.1016/j.cretres.2008.01.004|bibcode=2008CrRes..29..417N }}</ref>[[File:Iguanodon Skeletal.svg|thumb|right|Modern skeletal diagram of ''I. bernissartensis'']]The arms of ''I. bernissartensis'' were long (up to 75% the length of the legs) and robust,<ref name="NM01" /> with rather inflexible hands built so that the three central fingers could bear weight.<ref name="DBN04" /> The thumbs were conical spikes that stuck out away from the three main digits. In early restorations, the spike was placed on the animal's nose. Later fossils revealed the true nature of the thumb spikes,<ref name="DBN85b">{{cite book |last=Norman |first=David B. |author-link=David B. Norman |title=The Illustrated Encyclopedia of Dinosaurs: An Original and Compelling Insight into Life in the Dinosaur Kingdom |chapter=To Study a Dinosaur |year=1985 |publisher=Crescent Books |location=New York |pages=24–33 |isbn=978-0-517-46890-6}}</ref> although their exact function is still debated. They could have been used for defense, or for foraging for food. The little finger was elongated and dextrous, and could have been used to manipulate objects. The phalangeal formula is 2-3-3-2-4, meaning that the innermost finger (phalange) has two bones, the next has three, etc.<ref>{{cite book |last=Martin |first=Anthony J. |date=2006 |title=Introduction to the Study of Dinosaurs |edition=Second |location=Oxford |publisher=Blackwell Publishing |page=560 |isbn=1-4051-3413-5}}.</ref> The legs were powerful, but not built for running, and each foot had three toes. The backbone and tail were supported and stiffened by ossified [[Biology:Tendon|tendon]]s, which were tendons that turned to bone during life (these rod-like bones are usually omitted from skeletal mounts and drawings).<ref name="DBN04" />

These animals had large, tall but narrow skulls, with toothless beaks probably covered with [[Biology:Keratin|keratin]], and teeth like those of [[Biology:Iguana|iguana]]s, as the name suggests, but much larger and more closely packed.<ref name="DBN04" /> Unlike hadrosaurids, which had columns of replacement teeth, ''Iguanodon'' only had one replacement tooth at a time for each position. The [[Biology:Maxilla|upper jaw]] held up to 29 teeth per side, with none at the front of the jaw, and the lower jaw 25; the numbers differ because teeth in the lower jaw are broader than those in the upper.<ref name="NW90" /> Because the tooth rows are deeply inset from the outside of the jaws, and because of other anatomical details, it is believed that, as with most other ornithischians, ''Iguanodon'' had some sort of [[Medicine:Cheek|cheek]]-like structure, muscular or non-muscular, to retain food in the mouth.<ref name="PMG73">{{cite journal |last=Galton |first=Peter M.|year=1973 |title=The cheeks of ornithischian dinosaurs |journal=Lethaia |volume=6 |pages=67–89 |doi=10.1111/j.1502-3931.1973.tb00873.x |issue=1|bibcode=1973Letha...6...67G }}</ref><ref name="FS04">Fastovsky, D.E., and Smith, J.B. "Dinosaur paleoecology." ''The Dinosauria'', 614–626.</ref>

==Classification and evolution==
{{Main|Biology:Iguanodontia}}

[[File:Iguanodon NT.jpg|thumb|Life restoration of ''I. bernissartensis'']]
[[File:Iguanodon galvensis.png|thumb|Life restoration of ''I. galvensis'']]
[[File:Ornithopods jconway.jpg|thumb|Restoration of ''I. bernissartensis'' (second from left) among other ornithopods]] 
''Iguanodon'' gives its name to the [[Linnaean taxonomy|unranked]] [[Biology:Clade|clade]] Iguanodontia, a very populous group of ornithopods with many species known from the Middle Jurassic to the [[Earth:Late Cretaceous|Late Cretaceous]]. Aside from ''Iguanodon'', the best-known members of the clade include ''[[Biology:Dryosaurus|Dryosaurus]]'', ''[[Biology:Camptosaurus|Camptosaurus]]'', ''[[Biology:Ouranosaurus|Ouranosaurus]]'', and the duck-bills, or [[Biology:Hadrosaurid|hadrosaurs]]. In older sources, Iguanodontidae was shown as a distinct family.<ref name=PMG74>{{cite journal |last=Galton |first=Peter M.|date=September 1974 |title=Notes on ''Thescelosaurus'', a conservative ornithopod dinosaur from the Upper Cretaceous of North America, with comments on ornithopod classification |journal=Journal of Paleontology |volume=48 |issue=5 |pages=1048–1067 |issn=0022-3360 |jstor=1303302}}</ref><ref name=DBN85d>Norman, David B. "Iguanodontidae". ''The Illustrated Encyclopedia of Dinosaurs'', 110–115.</ref> This family traditionally has been something of a [[Wastebasket taxon|wastebasket taxon]], including ornithopods that were neither hypsilophodontids or hadrosaurids. In practice, animals like ''[[Biology:Callovosaurus|Callovosaurus]]'', ''Camptosaurus'', ''[[Biology:Craspedodon|Craspedodon]]'', ''[[Biology:Kangnasaurus|Kangnasaurus]]'', ''[[Biology:Mochlodon|Mochlodon]]'', ''[[Biology:Muttaburrasaurus|Muttaburrasaurus]]'', ''Ouranosaurus'', and ''[[Biology:Probactrosaurus|Probactrosaurus]]'' were usually assigned to this family.<ref name=DBN85d/>

With the advent of [[Biology:Cladistics|cladistic analyses]], Iguanodontidae as traditionally construed was shown to be [[Biology:Paraphyly|paraphyletic]], and these animals are recognised to fall at different points in relation to hadrosaurs on a [[Biology:Cladistics#Cladograms|cladogram]], instead of in a single distinct clade.<ref name=DBN04/><ref name=NW90/> Essentially, the modern concept of Iguanodontidae currently includes only ''Iguanodon''. Groups like Iguanodontoidea are still used as unranked clades in the scientific literature, though many traditional iguanodontids are now included in the superfamily [[Biology:Hadrosauroidea|Hadrosauroidea]]. ''Iguanodon'' lies between ''Camptosaurus'' and ''Ouranosaurus'' in cladograms, and is probably descended from a camptosaur-like animal.<ref name=DBN04/> At one point, Jack Horner suggested, based mostly on skull features, that hadrosaurids actually formed two more distantly related groups, with ''Iguanodon'' on the line to the flat-headed [[Biology:Saurolophinae|hadrosaurines]], and ''Ouranosaurus'' on the line to the crested [[Biology:Lambeosaurinae|lambeosaurines]],<ref name=JRH90>{{cite book |last=Horner |first= J. R.|editor=Kenneth Carpenter |editor2=Phillip J. Currie|title=Dinosaur Systematics: Perspectives and Approaches |url=https://archive.org/details/dinosaursystemat00carp |url-access=limited |year=1990 |publisher=Cambridge University Press |location=Cambridge |isbn=978-0-521-36672-4 |pages=[https://archive.org/details/dinosaursystemat00carp/page/n203 179]–187 |chapter=Evidence of diphyletic origination of the hadrosaurian (Reptilia: Ornithischia) dinosaurs}}</ref> but his proposal has been rejected.<ref name=DBN04/><ref name=NW90>{{cite book |last1=Norman |first1=David B. |last2=Weishampel |first2=David B. |editor1-last=Weishampel |editor1-first=David B. |editor2-last=Dodson |editor2-first=Peter |editor3-last=Osmólska |editor3-first=Halszka |title=The Dinosauria |year=1990 |publisher=University of California Press |location=Berkeley |isbn=978-0-520-06727-1 |pages=510–533 |chapter=Iguanodontidae and related ornithopods}}</ref>

The cladogram below follows an analysis by Andrew McDonald, 2012.<ref name=McDonaldUpdate>{{Cite journal | last1 = McDonald | first1 = A. T. | editor1-last = Farke| editor1-first =Andrew A| title = Phylogeny of Basal Iguanodonts (Dinosauria: Ornithischia): An Update | doi = 10.1371/journal.pone.0036745 | journal = PLOS ONE | volume = 7 | issue = 5 | pages = e36745 | year = 2012 | pmid = 22629328| pmc =3358318 | bibcode = 2012PLoSO...736745M | doi-access = free }}</ref>

{{clade| style=font-size:100%;line-height:80%
|label1=[[Biology:Iguanodontia|Iguanodontia]]
|1={{clade
  |1=[[Biology:Rhabdodontidae|Rhabdodontidae]]
  |2={{clade 
   |1=''[[Biology:Tenontosaurus|Tenontosaurus]]''
   |label2=Dryomorpha
   |2={{clade
     |1=[[Biology:Dryosauridae|Dryosauridae]]
     |label2=[[Biology:Ankylopollexia|Ankylopollexia]]
     |2={{clade
      |1=''[[Biology:Camptosaurus|Camptosaurus]]''
      |label2=Styracosterna
      |2={{clade
        |1=''[[Biology:Uteodon|Uteodon]]''
        |3={{clade
         |1={{clade
           |1=''[[Biology:Hippodraco|Hippodraco]]''
           |2=''[[Biology:Theiophytalia|Theiophytalia]]'' }}
         |2={{clade
           |1=''[[Biology:Iguanacolossus|Iguanacolossus]]''
           |2={{clade
            |1=''[[Biology:Lanzhousaurus|Lanzhousaurus]]''
            |2={{clade
              |1=''[[Biology:Kukufeldia|Kukufeldia]]''
              |2={{clade
               |1=''[[Biology:Barilium|Barilium]]''
               |label2=Hadrosauriformes
               |2={{clade
                 |1='''''Iguanodon'''''
                 |2=[[Biology:Hadrosauroidea|Hadrosauroidea]] <small>(including ''[[Biology:Mantellisaurus|Mantellisaurus]]'', and ''[[Biology:Xuwulong|Xuwulong]]'') </small> }} }} }} }} }} }} }} }} }} }} }} }}

==Species==
[[File:Marsh Iguanodon.jpg|thumb|Skeletal restoration of ''I. bernissartensis'' by [[Biography:Othniel Charles Marsh|O. C. Marsh]], 1896]] 
Because ''Iguanodon'' is one of the first dinosaur genera to have been named, numerous species have been assigned to it. While never becoming the wastebasket taxon several other early genera of dinosaurs (such as ''Megalosaurus'') became, ''Iguanodon'' has had a complicated history, and its taxonomy continues to undergo revisions.<ref name=GSP07>{{cite book|last=Paul|first=Gregory S.|editor=Kenneth Carpenter|chapter=Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England|title=Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs|year=2007|location=Bloomington|publisher=Indiana University Press|pages=69–77|isbn=978-0-253-34817-3}}</ref><ref name=GSP08/><ref name=DBN98>{{cite journal |last=Norman |first=David B. |title=On Asian ornithopods (Dinosauria, Ornithischia). 3. A new species of iguanodontid dinosaur |journal=Zoological Journal of the Linnean Society |date=January 1998 |volume=122 |issue=1–2 |pages=291–348 |doi=10.1006/zjls.1997.0122|doi-access=free }}</ref><ref name=NB02>{{cite book |last1=Norman |first1=David B. |author-link1=David B. Norman |last2=Barrett |first2=Paul M. |editor1-last=Milner |editor1-first=Andrew |editor2-last=Batten |editor2-first=David J. |chapter=Ornithischian dinosaurs from the Lower Cretaceous (Berriasian) of England|title=Life and Environments in Purbeck Times |series=Special Papers in Palaeontology |volume=68 |year=2002 |location=London |publisher=Palaeontological Association|pages=161–189|isbn=978-0-901702-73-9}}</ref> Although Gregory Paul recommended restricting ''I. bernissartensis'' to the famous sample from Bernissart, ornithopod workers like Norman and McDonald have disagreed with Paul's recommendations, except exercising caution when accepting records of ''Iguanodon'' from France and Spain as valid.<ref name=GSP08/><ref name="Francisco J. Verdú 2015">{{cite journal | last1 = Verdú | first1 = Francisco J. | last2 = Royo-Torres | first2 = Rafael | last3 = Cobos | first3 = Alberto | last4 = Alcalá | first4 = Luis | year = 2015 | title = Perinates of a new species of Iguanodon (Ornithischia: Ornithopoda) from the lower Barremian of Galve (Teruel, Spain) | journal = Cretaceous Research | volume = 56 | pages = 250–264 | doi = 10.1016/j.cretres.2015.05.010 | bibcode = 2015CrRes..56..250V }}</ref><ref>Norman, David B. (2011). "Ornithopod dinosaurs". In Batten, D. J. English Wealden Fossils. The Palaeontological Association (London). pp. 407–475.</ref>

''I. anglicus'' was the original [[Biology:Type species|type species]], but the lectotype was based on a single tooth and only partial remains of the species have been recovered since. In March 2000, the [[Organization:International Commission on Zoological Nomenclature|International Commission on Zoological Nomenclature]] changed the type species to the much better known ''I. bernissartensis'', with the new holotype being IRSNB 1534. The original ''Iguanodon'' tooth is held at Te Papa Tongarewa, the national museum of [[Earth:New Zealand|New Zealand]] in [[Place:Wellington|Wellington]], although it is not on display. The fossil arrived in New Zealand following the move of Gideon Mantell's son Walter there; after the elder Mantell's death, his fossils went to Walter.<ref name=RSNZ>{{cite news | author = Royal Society of New Zealand |url=http://www.rsnz.org/topics/biol/dna50/breakfast.php |title = Celebrating the great fossil hunters | access-date = 22 February 2007|archive-url = https://web.archive.org/web/20050826130408/http://www.rsnz.org/topics/biol/dna50/breakfast.php |archive-date = 26 August 2005 |}}</ref>

===Species currently accepted as valid===
Only two species assigned to ''Iguanodon'' are still considered to be valid.<ref name=DBN04/><ref name=GSP08/>
*''I. bernissartensis'', described by George Albert Boulenger in 1881, is the type species for the genus. This species is best known for the many skeletons discovered in the [[Earth:Sainte-Barbe Clays Formation|Sainte-Barbe Clays Formation]] at Bernissart, but is also known from remains across [[Earth:Europe|Europe]]. 
**''Delapparentia turolensis'', named in 2011<ref name="omenaca11">{{cite journal | last1 = Ruiz-Omeñaca | first1 = J. I. | year = 2011 | title = ''Delapparentia turolensis'' nov. gen et sp., un nuevo dinosaurio iguanodontoideo (Ornithischia: Ornithopoda) en el Cretácico Inferior de Galve | journal = Estudios Geológicos | volume = 67| pages = 83–110| doi = 10.3989/egeol.40276.124 | doi-access = free }}</ref> based on a specimen previously assigned to ''Iguanodon bernissartensis'',<ref name=deLapparent>{{cite journal |author=Albert-Félix de Lapparent |year=1960 |title=Los dos dinosaurios de Galve |journal=Teruel |volume=24 |pages=177–197 }}</ref> was argued to be distinct from the latter based on the relative height of its [[Biology:Vertebra#structure|neural spines]].<ref name="gasca">{{cite journal | last1 = Gasca | first1 = J.M. | first2 = M. | last2 = Moreno-Azanza | first3 = J.I. | last3 = Ruiz-Omeñaca | first4 = J.I. | last4 = Canudo | title = New material and phylogenetic position of the basal iguanodont dinosaur ''Delapparentia turolensis'' from the Barremian (Early Cretaceous) of Spain | journal = Journal of Iberian Geology | volume = 41 | issue = 1 | date = 2015 | doi=10.5209/rev_jige.2015.v41.n1.48655| doi-access = free | url = https://zaguan.unizar.es/record/32471/files/texto_completo.pdf }}</ref> However, a 2017 study noted that this is easily within the range of individual variation, and that the difference may also arise from ''D. turolensis'' being an adult older than other specimens of ''I. bernissartensis''.<ref name="indvar">{{cite journal | last1 = Verdú | first1 = F.J. | last2 = Godefroit | first2 = P. | last3 = Royo-Torres | first3 = R. | last4 = Cobos | first4 = A. | last5 = Alcalá | first5 = L. | title = Individual variation in the postcranial skeleton of the Early Cretaceous ''Iguanodon bernissartensis'' (Dinosauria: Ornithopoda) | journal = Cretaceous Research | volume = 74 | pages = 65–86 | date = 2017 | doi = 10.1016/j.cretres.2017.02.006 | bibcode = 2017CrRes..74...65V }}</ref>
**''I. seelyi'' (also incorrectly spelled ''I. seeleyi''), described by John Hulke in 1882, has also been synonymised with ''Iguanodon bernissartensis'', though this is not universally accepted. It was discovered in Brook, on the Isle of Wight, and named after Charles Seely MP, Liberal politician and philanthropist, on whose estate it was found.<ref name=GSP08/><ref name=DNDM08>{{cite journal |last1=Naish |first1=Darren |last2=Martill |first2=David M. |year=2008 |title=Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia |journal=Journal of the Geological Society, London |volume=165 |pages=613–623 |doi=10.1144/0016-76492007-154 |issue=3|bibcode=2008JGSoc.165..613N |s2cid=129624992 }}</ref> 
**David Norman has suggested that ''I. bernissartensis'' includes the [[Biology:Nomen dubium|dubious]] Mongolian ''I. orientalis'' (see also below),<ref name=DBN96>{{cite journal |last=Norman |first=David B. |title=On Asian ornithopods (Dinosauria, Ornithischia). 1. ''Iguanodon orientalis'' Rozhdestvensky, 1952 |journal=Zoological Journal of the Linnean Society |date=March 1996 |volume=116 |issue=2 |pages=303–315 |doi=10.1006/zjls.1996.0021|doi-access=free }}</ref> but this has not been followed by other researchers.<ref name=GSP08/>
*''I. galvensis'', described in 2015, is based on adult and juvenile remains found in [[Earth:Barremian|Barremian]]-age deposits in Teruel, Spain.<ref name="Francisco J. Verdú 2015"/>

===Reassigned species of ''Iguanodon''===
[[File:Mantellisaurus left side.jpeg|thumb|Mounted skeleton of ''Mantellisaurus atherfieldensis'', Natural History Museum, London]]
[[File:Cumnoria incomplete skeleton.jpg|thumb|Mounted skeleton of ''[[Biology:Cumnoria|Cumnoria prestwichii]]'', Oxford University Museum of Natural History]]
* ''I. albinus'' (or ''Albisaurus scutifer''), described by Czech [[Biology:Paleontology|palaeontologist]] Antonin Fritsch in 1893, is a dubious nondinosaurian [[Biology:Reptile|reptile]] now known as ''[[Biology:Albisaurus|Albisaurus albinus]]''.<ref name=WB88>{{cite book|last=Brikman|first=Winand|title=Zur Fundgeschichte und Systematik der Ornithopoden (Ornithischia, Reptilia) aus der Ober-Kreide von Europa| year= 1988 |series= ''Documenta Naturae'', 45| location= Munich |publisher= Kanzler| language= de |isbn= 978-3-86544-045-7}}</ref>
* ''I. atherfieldensis'', described by R.W. Hooley in 1925,<ref name=RWH25/> was smaller and less robust than ''I. bernissartensis'', with longer neural spines. It was renamed ''[[Biology:Mantellisaurus|Mantellisaurus atherfieldensis]]'' in 2007.<ref name=GSP07/> The Bernissart specimen RBINS 1551 was described as ''Dollodon bampingi'' in 2008, but McDonald and Norman returned ''Dollodon'' to synonymy with ''Mantellisaurus''.<ref name=DBN10 /><ref name=McDonald2011>{{cite journal |last=McDonald|first=Andrew T. |year=2011 |title=The status of Dollodon and other basal iguanodonts (Dinosauria: Ornithischia) from the upper Wealden beds (Lower Cretaceous) of Europe |journal=Cretaceous Research |doi=10.1016/j.cretres.2011.03.002 |volume=33 |pages=1–6 |issue=1}}</ref>
* ''I. dawsoni'', described by Lydekker in 1888,<ref name=RL88>{{cite journal |last=Lydekker |first=Richard|year=1888|title=Note on a new Wealden iguanodont and other dinosaurs |journal=Quarterly Journal of the Geological Society of London |volume=44|pages=46–61 |doi=10.1144/GSL.JGS.1888.044.01-04.08 |issue=1–4|s2cid=129803661|url=https://zenodo.org/record/2350732}}</ref> is known from two partial skeletons found in East Sussex, {{wipe|England}},<ref name=DBN04/> from the middle [[Earth:Valanginian|Valanginian]]-age [[Earth:Early Cretaceous|Lower Cretaceous]] Wadhurst Clay.<ref name=GSP08/> It is now the type species of ''[[Biology:Barilium|Barilium]]''.<ref name=DBN10>{{cite journal |last=Norman |first=David B. |year=2010 |url=http://mapress.com/zootaxa/2010/f/z02489p066f.pdf |title=A taxonomy of iguanodontians (Dinosauria: Ornithopoda) from the lower Wealden Group (Cretaceous: Valanginian) of southern England |journal=Zootaxa |volume=2489 |pages=47–66|doi=10.11646/zootaxa.2489.1.3 }}</ref>
* ''I. exogyrarum'' was described by Fritsch in 1878. It is a ''nomen dubium'' based on very poor material and was renamed ''[[Biology:Ponerosteus|Ponerosteus]]'' in 2000.<ref name=GO00>{{cite journal| last=Olshevsky |first= George| year=2000| title=An annotated checklist of dinosaur species by continent|journal= Mesozoic Meanderings|series=''Mesozoic Meanderings'', 3|location=San Diego|publisher=G. Olshevsky Publications Requiring Research| issn=0271-9428|oclc=44433611}}</ref>
* ''I. fittoni'' was described by Lydekker in 1889.<ref name=RL89>{{cite journal |last=Lydekker |first=Richard|year=1889|title=On the remains and affinities of five genera of Mesozoic reptiles |journal=Quarterly Journal of the Geological Society of London |volume=45 |pages=41–59 |doi=10.1144/GSL.JGS.1889.045.01-04.04 |issue=1–4|s2cid=128586645}}</ref> Like ''I. dawsoni'', this species was described from the Wadhurst Clay<ref name=GSP08/> of East Sussex.<ref name=DBN04/> It is now the type species of ''[[Biology:Hypselospinus|Hypselospinus]]''.<ref name=DBN10/>
* ''I. hilli'', coined by Edwin Tully Newton in 1892 for a tooth from the early [[Earth:Cenomanian|Cenomanian]] [[Earth:Late Cretaceous|Upper Cretaceous]] Lower Chalk of Hertfordshire, has been considered an early [[Biology:Hadrosaurid|hadrosaurid]] of some sort.<ref name=HWF04>Horner, John R., David B. Weishampel and Catherine A. Forster. "Hadrosauridae". ''The Dinosauria'', pp 438–463.</ref> However, recent work places it as indeterminate beyond [[Biology:Hadrosauroidea|Hadrosauroidea]] outside [[Biology:Hadrosauridae|Hadrosauridae]].<ref>Barrett, P., D. C. Evans, and J J. Head, 2014. A re-evaluation of purported hadrosaurid dinosaur specimens from the 'middle' Cretaceous of England In The Hadrosaurs: Proceedings of the International Hadrosaur Symposium (D. A. Eberth and D. C. Evans, eds), Indiana University Press, Bloomington.</ref>
* ''I. hoggi'' (also spelled ''I. boggii'' or ''hoggii''), named by Owen for a lower jaw from the Tithonian–[[Earth:Berriasian|Berriasian]]-age Upper Jurassic–[[Earth:Early Cretaceous|Lower Cretaceous]] Purbeck Beds of Dorset in 1874, has been reassigned to its own genus, ''[[Biology:Owenodon|Owenodon]]''.<ref name=PMG09>{{cite journal |last=Galton |first=Peter M. |year=2009 |title=Notes on Neocomian (Late Cretaceous) ornithopod dinosaurs from England – ''Hypsilophodon'', ''Valdosaurus'', "Camptosaurus", "Iguanodon"&nbsp;– and referred specimens from Romania and elsewhere |journal=Revue de Paléobiologie |volume=28 |issue=1 |pages=211–273}}</ref>
* ''I. hollingtoniensis'' (also spelled ''I. hollingtonensis''), described by Lydekker in 1889, has variously been considered a synonym of ''Hypselospinus fittoni''<ref name=DBN04/><ref name=DBN10/> or a distinct species assigned to the genus ''[[Biology:Huxleysaurus|Huxleysaurus]]''.<ref name=paul2012>Paul, G. S. (2012). "[http://www.gspauldino.com/Risingdiversity2011.pdf Notes on the rising diversity of Iguanodont taxa, and Iguanodonts named after Darwin, Huxley, and evolutionary science]" ''Actas de V Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno, Salas de los Infantes, Burgos''. pp. 123–133.</ref> A specimen from the [[Earth:Valanginian|Valanginian]] [[Earth:Wadhurst Clay Formation|Wadhurst Clay Formation]],<ref name=paul2012 /> variously assigned to ''I. hollingtoniensis'' and ''I. mantelli'' over the years, has an unusual combination of hadrosaurid-like lower jaw and very robust forelimb;<ref name=GSP08/> Norman (2010) assigned this specimen to the species ''Hypselospinus fittoni'',<ref name=DBN10/> while Paul (2012) made it the holotype of a separate species ''[[Biology:Darwinsaurus|Darwinsaurus evolutionis]]''.<ref name=paul2012 />
* ''I. lakotaensis'' was described by David B. Weishampel and Philip R. Bjork in 1989.<ref name=WB89>{{cite journal |doi=10.1080/02724634.1989.10011738 |last1=Weishampel |first1=David B. |last2=Bjork |first2=Phillip R. |year=1989 |title=The first indisputable remains of ''Iguanodon'' (Ornithischia: Ornithopoda) from North America: ''Iguanodon lakotaensis'', sp. nov |journal=Journal of Vertebrate Paleontology |volume=9 |issue=1 |pages=56–66|bibcode=1989JVPal...9...56W }}</ref> The only well-accepted [[Earth:North America|North America]]n species of ''Iguanodon'', ''I. lakotaensis'' was described from a partial skull from the [[Earth:Barremian|Barremian]]-age [[Earth:Early Cretaceous|Lower Cretaceous]] [[Earth:Lakota Formation|Lakota Formation]] of South Dakota. Its assignment has been controversial. Some researchers suggest that it was more [[Biology:Basal (phylogenetics)|basal]] than ''I. bernissartensis'', and related to ''[[Biology:Theiophytalia|Theiophytalia]]'',<ref name=BC07>Brill, Kathleen and Kenneth Carpenter. "A description of a new ornithopod from the Lytle Member of the Purgatoire Formation (Lower Cretaceous) and a reassessment of the skull of ''Camptosaurus''." ''Horns and Beaks'', 49–67.</ref> but David Norman has suggested that it was a [[Biology:Synonym (taxonomy)|synonym]] of ''I. bernissartensis''.<ref name=DBN98/> [[Biography:Gregory S. Paul|Gregory S. Paul]] has since given the species its own genus, ''[[Biology:Dakotadon|Dakotadon]]''.<ref name=GSP08/>
* ''I. mantelli'' described by Christian Erich Hermann von Meyer in 1832, was based on the same material as ''I. anglicus''<ref name=GO97/> and is an objective junior synonym of the latter.<ref name=Wealdenornithopods>{{cite book |last=Norman |first=David B. |year=2011 |chapter=Ornithopod dinosaurs |editor-last=Batten |editor-first=D. J. |title=English Wealden Fossils |publisher=The Palaeontological Association (London) |pages=407–475}}</ref> Several taxa, including the holotype of ''[[Biology:Mantellisaurus|Mantellisaurus]]'' and ''[[Biology:Mantellodon|Mantellodon]]'', but also the dubious hadrosauroid ''Trachodon cantabrigiensis'' the hypsilophodont ''[[Biology:Hypsilophodon|Hypsilophodon]]'', and ''[[Biology:Valdosaurus|Valdosaurus]]'', were previously mis-assigned to ''I. mantelli''.
* "I. mongolensis" is a ''[[Biology:Nomen nudum|nomen nudum]]'' from a photo caption in a book by Whitfield in 1992<ref>Philip Whitfield, 1992, ''Children's Guide to Dinosaurs and other Prehistoric Animals'', Simon & Schuster pp. 96</ref> of remains that would later be named ''Altirhinus''.<ref name=GOASIA>{{cite web|author=Olshevsky, G |title=Dinosaurs of China, Mongolia, and Eastern Asia [under ''Altirhinus''] |url=http://dinosauricon.com/rigby/asia.doc |access-date=7 July 2016 |url-status=dead|archive-url=https://web.archive.org/web/20050213130059/http://dinosauricon.com/rigby/asia.doc |archive-date=13 February 2005 }}</ref>
* ''I. orientalis'', described by A. K. Rozhdestvensky in 1952,<ref name=AKR52>{{cite journal |last=Rozhdestvensky |first= Anatoly K. |year= 1952 |script-title=ru:Открытие игуанодона в Монголии |trans-title=Discovery of an iguanodon in Mongolia |journal=Doklady Akademii Nauk SSSR |volume=84 |issue=6 |pages=1243–1246|language=ru }}</ref> was based on poor material, but a skull with a distinctive arched snout that had been assigned to it was renamed ''[[Biology:Altirhinus|Altirhinus kurzanovi]]'' in 1998.<ref name=DBN98/> At the same time, ''I. orientalis'' was considered to be a ''nomen dubium'' because it cannot be compared to ''I. bernissartensis''.<ref name=DBN98/><ref name=DBN96/>
* ''I. phillipsi'' was described by Harry Seeley in 1869,<ref name=HGS69>{{cite book|last=Seeley|first=Harry G.|year=1869|title=Index to the fossil remains of Aves, Ornithosauria, and Reptilia, from the secondary system of strata arranged in the Woodwardian Museum of the University of Cambridge|location=Cambridge|publisher=Deighton, Bell, and Co.|oclc=7743994}}</ref> but he later reassigned it to ''[[Biology:Priodontognathus|Priodontognathus]]''.<ref name=HGS75>{{cite journal |last=Seeley|first=Harry G. |year=1875|title=On the maxillary bone of a new dinosaur (''Priodontognathus phillipsii''), contained in the Woodwardian Museum of the University of Cambridge |journal=Quarterly Journal of the Geological Society of London |volume=31 |pages=439–443 |doi=10.1144/GSL.JGS.1875.031.01-04.30 |issue=1–4|s2cid=129113503 |url=https://zenodo.org/record/2025651 }}</ref>
* ''I. praecursor'' (also spelled ''I. precursor''), described by E. Sauvage in 1876 from teeth from an unnamed Kimmeridgian (Late Jurassic) [[Earth:List of rock formations|formation]] in Pas-de-Calais, {{wipe|France}}, is actually a [[Biology:Sauropoda|sauropod]], sometimes assigned to ''[[Biology:Neosodon|Neosodon]]'',<ref name=HS88>{{cite journal |last=Sauvage |first=H. E. |year=1888 |title=Sur les reptiles trouvés dans le Portlandian supérieur de Boulogne-sur-mer |journal=Bulletin du Muséum National d'Historie Naturalle, Paris |volume=3 |issue=16 |page=626|language=fr}}</ref> although the two come from different formations.<ref name=UBD04>Upchurch, Paul, Paul M. Barrett, and Peter Dodson. "Sauropoda". ''The Dinosauria''</ref>
* ''I. prestwichii'' (also spelled ''I. prestwichi''), described by John Hulke in 1880, has been reassigned to ''[[Biology:Camptosaurus|Camptosaurus prestwichii]]'' or to its own genus ''[[Biology:Cumnoria|Cumnoria]]''.
* ''I. suessii'', described by Emanuel Bunzel in 1871, has been reassigned to ''[[Biology:Mochlodon|Mochlodon suessi]]''.<ref name=DBN04/>

===Species reassigned to ''Iguanodon''===
* ''I. foxii'' (also spelled ''I. foxi'') was originally described by [[Biography:Thomas Henry Huxley|Thomas Henry Huxley]] in 1869 as the type species of ''Hypsilophodon''; Owen (1873 or 1874) reassigned it to ''Iguanodon'', but his assignment was soon overturned.<ref name=HW85>{{cite journal|last=Woodward|first=Henry|title=On ''Iguanodon mantelli'', Meyer| journal=Geological Magazine |series=Series 3|year=1885|volume=2|issue=1|pages=10–15|oclc=2139602|doi=10.1017/S0016756800188211|bibcode=1885GeoM....2...10W|s2cid=140635773 |url=https://zenodo.org/record/1731979}}</ref>
* ''I. gracilis'', named by Lydekker in 1888 as the type species of ''Sphenospondylus'' and assigned to ''Iguanodon'' in 1969 by Rodney Steel, has been suggested to be a synonym of ''Mantellisaurus atherfieldensis'',<ref name=DBN04/> but is considered dubious nowadays.<ref name=DBN86/><ref name=McDonald2011/>
* ''I. major'', a species named by Justin Delair in 1966,<ref>{{cite journal | last1 = Delair | first1 = J.B. | year = 1966 | title = New records of dinosaurs and other fossil reptiles from Dorset | journal = Proceedings of the Dorset Natural History and Archaeological Society | volume = 87 | pages = 57–66 }}</ref> based on vertebrae from the Isle of Wight and Sussex originally described by Owen in 1842 as a species of ''[[Biology:Streptospondylus|Streptospondylus]]'', ''S. major'', is a ''[[Biology:Nomen dubium|nomen dubium]]''.<ref name=DNDM08/>
* ''I. valdensis'', a renaming of ''Vectisaurus valdensis'' by Ernst van den Broeck in 1900.<ref>Van den Broeck, Ernst, 1900, "Les dépôts à iguanodons de Bernissart et leur transfert dans l'étage purbeckien ou aquilonien du Jurassique Supérieur" ''Bulletin de la Société Belge Géologique'' XIV Mem., 39–112</ref> Originally named by Hulke as a distinct genus in 1879 based on vertebral and [[Biology:Pelvis|pelvic]] remains, it was from the [[Earth:Barremian|Barremian]] [[Physics:Stage (stratigraphy)|stage]] of the Isle of Wight.<ref name="Galton">{{cite journal|last=Galton|first=P.M.| year=1976|title=The Dinosaur ''Vectisaurus valdensis'' (Ornithischia: Iguanodontidae) from the Lower Cretaceous of England| journal=Journal of Paleontology|volume=50|issue=5|pages=976–984| jstor=1303593}}</ref> It was considered a juvenile specimen of ''Mantellisaurus atherfieldensis'',<ref>{{Citation|last=Norman|first=David B.|title=A review of Vectisaurus valdensis , with comments on the family Iguanodontidae|date=30 November 1990|url=https://www.cambridge.org/core/product/identifier/CBO9780511608377A025/type/book_part|work=Dinosaur Systematics|pages=147–162|editor-last=Carpenter|editor-first=Kenneth|edition=1|publisher=Cambridge University Press|doi=10.1017/cbo9780511608377.014|isbn=978-0-521-36672-4|access-date=29 December 2019|editor2-last=Currie|editor2-first=Philip J.}}</ref> or an undetermined species of ''Mantellisaurus'',<ref name=GSP08/> but is indeterminate beyond Iguanodontia.<ref name=McDonald2011/>
* The ''nomen nudum'' "Proiguanodon" (van den Broeck, 1900) also belongs here.<ref name=GO99>{{cite web | author = Olshevsky, G | title = Re: What are these dinosaurs? | url = http://dml.cmnh.org/1999Nov/msg00507.html | access-date = 16 February 2007 |  archive-date = 9 December 2007 | archive-url = https://web.archive.org/web/20071209063230/http://dml.cmnh.org/1999Nov/msg00507.html | url-status = dead }}</ref>

===Dubious species===
[[File:Original Iguanodon teeth and thumb spike.jpg|thumb|Original ''I. anglicus'' teeth and thumb spike described by Mantell]] 
* ''I. anglicus'', described by Friedrich Holl in 1829,<ref name=FH29>{{cite book |last=Holl |first=Friedrich|title=Handbuch der Petrifaktenkunde, Vol. I. Ouedlinberg |year=1829 |publisher=P.G. Hilscher |location=Dresden |oclc= 7188887}}</ref> is the original type species of ''Iguanodon'', but, as discussed above, was replaced by ''I. bernissartensis''. In the past, it has been spelled as ''I. angelicus'' (Lessem and Glut, 1993) and ''I. anglicum'' (Holl, 1829 [[Biology:Emendation (taxonomy)|emend.]] Bronn, 1850). It is possible teeth ascribed to this species belong to the genus now called ''[[Biology:Barilium|Barilium]]''.<ref name="norman2011a">{{cite journal | url=http://eprints.esc.cam.ac.uk/2230/ | title=On the osteology of the lower wealden (valanginian) ornithopod barilium dawsoni (iguanodontia: styracosterna) | author=Norman, David B. | journal=Special Papers in Palaeontology | year=2011 | volume=86 | pages=165–194}}</ref> The name ''Therosaurus'' (Fitzinger, 1840),<ref>{{cite journal | last1 = Fitzinger | first1 = L. J. | year = 1840 | title = Über ''Palaeosaurus sternbergii'', eine neue Gattung vorweltlicher Reptilien und die Stellung dieser Thiere im Systeme überhaupt | journal = Wiener Museum Annalen | volume = II | pages = 175–187 }}</ref> is a junior objective synonym, a later name for the material of ''I. anglicus''.
* ''I. ottingeri'', described by Peter Galton and James A. Jensen in 1979, is a ''nomen dubium'' based on teeth from the possibly [[Earth:Aptian|Aptian]]-age lower Cedar Mountain Formation of Utah.<ref name=galton1979>{{cite journal | last1=Galton | first1=Peter | last2=Jensen | first2=James A. | url=http://geology.byu.edu/Home/sites/default/files/geo-stud-vol-25-part-3-galton-jensen.pdf | title=Galton, P. M., & Jensen, J. A. (1979). Remains of ornithopod dinosaurs from the Lower Cretaceous of North America | journal=Brigham Young University Geology Studies | year=1979 | volume=25 | issue=3 | pages=1–10 | issn=0068-1016 | access-date=26 June 2019 | archive-date=26 January 2021 | archive-url=https://web.archive.org/web/20210126122029/http://geology.byu.edu/Home/sites/default/files/geo-stud-vol-25-part-3-galton-jensen.pdf | url-status=dead }}</ref>

==Palaeobiology==
===Feeding===
[[File:Iguanodon bernissartensis.jpg|thumb|left|''I. bernissartensis'' skull and neck]]
One of the first details noted about ''Iguanodon'' was that it had the teeth of a herbivorous reptile,<ref name=GM25/> although there has not always been consensus on how it ate. As Mantell noted, the remains he was working with were unlike any modern reptile, especially in the toothless, scoop-shaped form of the lower jaw symphysis, which he found best compared to that of the two-toed sloth and the [[Biology:Extinction|extinct]] ground sloth ''[[Biology:Mylodon|Mylodon]]''. He also suggested that ''Iguanodon'' had a [[Biology:Prehensility|prehensile]] [[Biology:Tongue|tongue]] which could be used to gather food,<ref name=GM48>{{cite journal |last=Mantell |first=Gideon A.|year=1848 |title=On the structure of the jaws and teeth of the ''Iguanodon''|journal=Philosophical Transactions of the Royal Society of London |volume=138 |pages=183–202|doi=10.1098/rstl.1848.0013 |jstor=111004|doi-access= |s2cid=110141217 }}</ref> like a [[Biology:Giraffe|giraffe]]. More complete remains have shown this to be an error; for example, the [[Biology:Hyoid bone|hyoid bone]]s that supported the tongue are heavily built, implying a muscular, non-prehensile tongue used for moving food around in the mouth.<ref name="DBN80">{{cite journal |last=Norman |first=David B. |year=1980 |title=On the ornithischian dinosaur ''Iguanodon bernissartensis'' of Bernissart (Belgium) |url=https://biblio.naturalsciences.be/rbins-publications/memoirs-of-the-royal-belgian-institute-of-natural-sciences-first-series/178-1980/vol-178-013074p-text.pdf |journal=Mémoires de l'Institut Royal des Sciences Naturelles de Belgique |volume=178 |pages=1–105}}</ref> The giraffe-tongue idea has also been incorrectly attributed to Dollo via a broken lower jaw.<ref name=DBN85c>Norman, D.B. (1985). ''The Illustrated Encyclopedia of Dinosaurs'', 115.</ref>

The skull was structured in such a way that as it closed, the bones holding the teeth in the upper jaw would bow out. This would cause the lower surfaces of the upper jaw teeth to rub against the upper surface of the lower jaw's teeth, grinding anything caught in between and providing an action that is the rough equivalent of mammalian [[Biology:Chewing|chewing]].<ref name=DBW84/> Because the teeth were always replaced, the animal could have used this mechanism throughout its life, and could eat tough [[Biology:Plant|plant]] material.<ref name=RTB86>{{cite book |last=Bakker |first=Robert T. |title=The Dinosaur Heresies |journal=PALAIOS |volume=2 |issue=5 |year= 1986 |publisher=William Morrow |location=New York |isbn=978-0-14-010055-6 |pages=160–178 |chapter=Dinosaurs At Table|bibcode=1987Palai...2..523G |doi=10.2307/3514623 |jstor=3514623 }}</ref> Additionally, the front ends of the animal's jaws were toothless and tipped with bony nodes, both upper and lower,<ref name=DBN04/> providing a rough margin that was likely covered and lengthened by a keratinous material to form a cropping beak for biting off [[Biology:Twig|twig]]s and [[Biology:Shoot (botany)|shoot]]s.<ref name=DBN85b/> Its food gathering would have been aided by its flexible little finger, which could have been used to manipulate objects, unlike the other fingers.<ref name=DBN04/>
[[File:Hand of an Iguanodon 28-12-2007 15-22-03.jpg|thumb|upright|A hand in Brussels; the extended digit is the prehensile fifth finger]]
Exactly what ''Iguanodon'' ate with its well-developed jaws is not known. The size of the larger species, such as ''I. bernissartensis'', would have allowed them access to food from ground level to [[Earth:Tree|tree]] [[Biology:Leaf|foliage]] at {{convert|4|–|5|m}} high.<ref name=NM01/> A diet of [[Biology:Equisetum|horsetails]], [[Biology:Cycad|cycad]]s, and [[Biology:Pinophyta|conifers]] was suggested by David Norman,<ref name=DBN85b/> although iguanodonts in general have been tied to the advance of [[Biology:Flowering plant|angiosperm]] plants in the [[Earth:Cretaceous|Cretaceous]] due to the dinosaurs' inferred low-browsing habits. Angiosperm growth, according to this [[Hypothesis|hypothesis]], would have been encouraged by iguanodont feeding because gymnosperms would be removed, allowing more space for the weed-like early angiosperms to grow.<ref name=RTB86b>Bakker, R.T. "When Dinosaurs Invented Flowers". ''The Dinosaur Heresies'', 179–198</ref> The evidence is not conclusive, though.<ref name=DBN04/><ref name=BW01>{{cite journal|last1=Barrett |first1=Paul M. |last2=Willis |first2=K. J. |year=2001 |title=Did dinosaurs invent flowers? Dinosaur–angiosperm coevolution revisited|journal=Biological Reviews |volume=76|issue=3 |pages=411–447|doi=10.1017/S1464793101005735 |pmid=11569792|s2cid=46135813 |url=http://doc.rero.ch/record/16152/files/PAL_E2450.pdf }}</ref> Whatever its exact diet, due to its size and abundance, ''Iguanodon'' is regarded as a dominant medium to large herbivore for its [[Earth:Ecosystem|ecological communities]].<ref name=DBN04/> In England, this included the small predator ''[[Biology:Aristosuchus|Aristosuchus]]'', larger predators ''[[Biology:Eotyrannus|Eotyrannus]]'', ''[[Biology:Baryonyx|Baryonyx]]'', and ''[[Biology:Neovenator|Neovenator]]'', low-feeding herbivores ''Hypsilophodon'' and ''[[Biology:Valdosaurus|Valdosaurus]]'', fellow "iguanodontid" ''Mantellisaurus'', the [[Biology:Armour (zoology)|armoured]] herbivore ''[[Biology:Polacanthus|Polacanthus]]'', and sauropods like ''[[Biology:Pelorosaurus|Pelorosaurus]]''.<ref name=DBWetal04>Weishampel, D.B., Barrett, P.M., Coria, R.A., Le Loeuff, J., Xu Xing, Zhao Xijin, Sahni, A., Gomani, E.M.P., and Noto, C.R. "Dinosaur Distribution". ''The Dinosauria'', 517–606.</ref>

===Posture and movement===
[[File:Iguanodon feeding.jpg|thumb|upright|left|Nineteenth-century painting showing ''I. bernissartensis'' in outdated tripod pose]]
Early fossil remains were fragmentary, which led to much speculation on the posture and nature of ''Iguanodon''. ''Iguanodon'' was initially portrayed as a quadrupedal horn-nosed beast. However, as more bones were discovered, Mantell observed that the forelimbs were much smaller than the hindlimbs. His rival Owen was of the opinion it was a stumpy creature with four pillar-like legs. The job of overseeing the first lifesize reconstruction of dinosaurs was initially offered to Mantell, who declined due to poor health, and Owen's vision subsequently formed the basis on which the sculptures took shape. Its bipedal nature was revealed with the discovery of the Bernissart skeletons. However, it was depicted in an upright posture, with the tail dragging along the ground, acting as the third leg of a tripod.<ref name=DBN05/>

During his re-examination of ''Iguanodon'', David Norman was able to show that this posture was unlikely, because the long tail was stiffened with ossified tendons.<ref name=DBN80/> To get the tripodal pose, the tail would literally have to be broken.<ref name=DBN85b/> Putting the animal in a horizontal posture makes many aspects of the arms and pectoral girdle more understandable. For example, the hand is relatively immobile, with the three central fingers grouped together, bearing [[Biology:Hoof|hoof]]-like [[Biology:Phalanx bone|phalanges]], and able to hyperextend. This would have allowed them to bear weight. The wrist is also relatively immobile, and the arms and shoulder bones robust. These features all suggest that the animal spent time on all fours.<ref name=DBN80/>
[[File:2011-07-09 gasometer 38.JPG|thumb|Assigned track from Germany]]
Furthermore, it appears that ''Iguanodon'' became more quadrupedal as it got older and heavier; [[Biology:Juvenile (organism)|juvenile]] ''I. bernissartensis'' have shorter arms than adults (60% of hindlimb length versus 70% for adults).<ref name=DBN04/> When walking as a quadruped, the animal's hands would have been held so that the palms faced each other, as shown by iguanodontian trackways and the anatomy of this genus's arms and hands.<ref name=JLW96>{{cite thesis |last=Wright |first=J. L. |title=Fossil terrestrial trackways: Preservation, taphonomy, and palaeoecological significance |type=PhD thesis|publisher=University of Bristol |year=1996 |pages=1–300 }}</ref><ref name=JLW99>{{cite book |last=Wright |first=J. L. |chapter=Ichnological evidence for the use of the forelimb in iguanodontians |editor-last=Unwin |editor-first=David M. |title=Cretaceous Fossil Vertebrates |year=1999 |series=Special Papers in Palaeontology |volume=60 |publisher=Palaeontological Association |pages=209–219 |isbn=978-0-901702-67-8}}</ref> The three-toed [[Biology:Pes (anatomy)|pes]] (''foot'') of ''Iguanodon'' was relatively long, and when walking, both the hand and the foot would have been used in a [[Biology:Digitigrade|digitigrade]] fashion (walking on the fingers and toes).<ref name=DBN04/> The maximum speed of ''Iguanodon'' has been estimated at {{convert|24|km/h|abbr=on}},<ref name=WPCJ78>{{cite journal|last=Coombs |first=Walter P. Jr.|year=1978 |title=Theoretical aspects of cursorial adaptations in dinosaurs |journal=Quarterly Review of Biology |volume=53|issue=4 |pages=393–418|doi=10.1086/410790 |issn=0033-5770 |jstor=2826581|s2cid=84505681}}</ref> which would have been as a biped; it would not have been able to gallop as a quadruped.<ref name=DBN04/>

Large three-toed footprints are known in Early Cretaceous rocks of England, particularly [[Earth:Wealden Group|Wealden]] beds on the Isle of Wight, and these [[Biology:Trace fossil|trace fossil]]s were originally difficult to interpret. Some authors associated them with dinosaurs early on. In 1846, E. Tagert went so far as to assign them to an [[Biology:Ichnotaxon|ichnogenus]] he named ''Iguanodon'',<ref name=ET46>{{cite journal |last=Tagert |first=E.|year=1846 |title=On markings in the Hastings sands near Hastings, supposed to be the footprints of birds |journal=Quarterly Journal of the Geological Society of London |volume=2 |page=267 |doi=10.1144/GSL.JGS.1846.002.01-02.45 |issue=1–2|s2cid=128406306|url=https://zenodo.org/record/2311747}}</ref> and Samuel Beckles noted in 1854 that they looked like bird tracks, but might have come from dinosaurs.<ref name=SB54>{{cite journal |last=Beckles |first=Samuel H. |year=1854 |title=On the ornithoidichnites of the Wealden |journal=Quarterly Journal of the Geological Society of London |volume=10 |pages=456–464 |doi=10.1144/GSL.JGS.1854.010.01-02.52 |issue=1–2|s2cid=197536154 }}</ref> The identity of the trackmakers was greatly clarified upon the discovery in 1857 of the hind leg of a young ''Iguanodon'', with distinctly three-toed feet, showing that such dinosaurs could have made the tracks.<ref name=RO58>{{cite journal |last=Owen |first=Richard|year=1858 |title= Monograph on the Fossil Reptilia of the Wealden and Purbeck Formations. Part IV. Dinosauria (''Hylaeosaurus'') |journal=Paleontographical Society Monograph |volume=10 |issue=43|pages=1–26|doi=10.1080/02693445.1858.12027916}}</ref><ref name=LHL>{{cite web | publisher = Linda Hall Library of Science, Engineering & Technology | title = Bird-Footed Iguanodon, 1857| work=Paper Dinosaurs 1824–1969 | url = http://www.lindahall.org/events_exhib/exhibit/exhibits/dino/owe1857.htm | access-date = 14 February 2007| archive-url = https://web.archive.org/web/20060928114251/http://www.lindahall.org/events_exhib/exhibit/exhibits/dino/owe1857.htm| archive-date = 28 September 2006}}</ref> Despite the lack of direct evidence, these tracks are often attributed to ''Iguanodon''.<ref name=DBN85b/> A trackway in England shows what may be an ''Iguanodon'' moving on all fours, but the foot prints are poor, making a direct connection difficult.<ref name=DBN80/> Tracks assigned to the ichnogenus ''Iguanodon'' are known from locations including places in Europe where the body fossil ''Iguanodon'' is known, to Spitsbergen, [[Place:Svalbard|Svalbard]], {{wipe|Norway}}.<ref name=DFG03>{{cite book |last=Glut |first=Donald F. |title=Dinosaurs: The Encyclopedia. 3rd Supplement |year=2003 |publisher=McFarland & Company, Inc. |location=Jefferson, North Carolina |isbn=978-0-7864-1166-5 |page=[https://archive.org/details/dinosaursencyclo00glut_2/page/626 626] |url=https://archive.org/details/dinosaursencyclo00glut_2/page/626 }}</ref><ref name=AFL62>{{cite journal |last=Lapparent |first=Albert-Félix de|year=1962 |title=Footprints of dinosaurs in the Lower Cretaceous of Vestspitsbergen&nbsp;— Svalbard |journal=Arbok Norsk Polarinstitutt, 1960 |pages=13–21}}</ref>

===Thumb spike===
[[File:Iguanodon manus 1 NHM.jpg|thumb|''I. bernissartensis'' hand with spike]] 
The thumb spike is one of the best-known features of ''Iguanodon''. Although it was originally placed on the animal's nose by Mantell, the complete Bernissart specimens allowed Dollo to place it correctly on the hand, as a modified thumb.<ref name=DBN05>{{cite book |last=Norman |first=David B. |title=Dinosaurs: A Very Short Introduction |year=2005 |publisher=Oxford University Press |isbn=978-0192804198 |url=https://archive.org/details/dinosaurs00norm_0 }}</ref> (This would not be the last time a dinosaur's modified thumb claw would be misinterpreted; ''[[Biology:Noasaurus|Noasaurus]]'', ''Baryonyx'', and ''[[Biology:Megaraptor|Megaraptor]]'' are examples since the 1980s where an enlarged thumb claw was first put on the foot, as in [[Biology:Dromaeosauridae|dromaeosaurids]].<ref name=noasaurus>{{Cite journal | last1 = Agnolin | first1 = F. L. | last2 = Chiarelli | first2 = P. | doi = 10.1007/s12542-009-0044-2 | title = The position of the claws in Noasauridae (Dinosauria: Abelisauroidea) and its implications for abelisauroid manus evolution | journal = Paläontologische Zeitschrift | volume = 84 | issue = 2 | pages = 293–300 | year = 2009 | s2cid = 84491924 }}</ref><ref name=megaraptor1998>{{Cite journal | last1 = Novas | first1 = F. E. | doi = 10.1080/02724634.1998.10011030 | title = Megaraptor namunhuaiquii, gen. Et sp. Nov., a large-clawed, Late Cretaceous theropod from Patagonia | journal = Journal of Vertebrate Paleontology | volume = 18 | pages = 4–9 | year = 1998 | issue = 1 | bibcode = 1998JVPal..18....4N }}</ref>)

This thumb is typically interpreted as a close-quarter [[Engineering:Stiletto|stiletto]]-like weapon against predators,<ref name=DBN04/><ref name=DBN85b/> although it could also have been used to break into [[Biology:Seed|seed]]s and [[Biology:Fruit|fruit]]s,<ref name=DBN04/> or against other ''Iguanodon''.<ref name=NM01/> One author has suggested that the spike was attached to a [[Biology:Venom|venom]] gland,<ref name=EG87>{{cite book |last1=Elting |first1=Mary |last2=Goodman |first2=Ann |title=Dinosaur Mysteries |date=1987 |publisher=Platt & Munk |location=New York, New York |isbn=0448192160 |page=46 |url=https://archive.org/details/dinosaurmysterie0000elti/page/46/mode/1up |access-date=28 August 2022}}</ref><ref name=MT77>{{cite book |last=Tweedie |first=Michael W.F. |title=The World of the Dinosaurs |year=1977 |publisher=Weidenfeld & Nicolson |location=London |isbn=978-0-688-03222-7 |page=[https://archive.org/details/worldofdinosaurs00twee/page/143 143] |url=https://archive.org/details/worldofdinosaurs00twee/page/143 }}</ref> but this has not been accepted, as the spike was not hollow,<ref name=NM01/> nor were there any grooves on the spike for conducting venom.<ref name=DN98>{{cite web | author = Naish, D | title = Venomous & Septic Bites | url = http://dml.cmnh.org/1998Nov/msg00387.html | access-date = 14 February 2007 |  archive-date = 9 December 2007 | archive-url = https://web.archive.org/web/20071209050430/http://dml.cmnh.org/1998Nov/msg00387.html | url-status = dead }}</ref>{{refn|group=nb|Naish's works cite Tweedie (1977) as the source of the venomous spike proposal, but this work does not explicitly attribute venom to ''Iguanodon'', only noting on page 69 that there is no hard-tissue evidence for venom in stingray tails and platypus spurs.<ref name=MT77/> Elting and Goodman (1987:46) explicitly report a venom spike proposal, attributing it to "one scientist".<ref name=EG87/>}}

===Possible social behaviour===
[[File:Wessex Formation dinosaurs.jpg|left|thumb|Restoration of an ''I. bernissartensis'' group, with other dinosaurs from the Wessex Formation]] 
Although sometimes interpreted as the result of a single catastrophe, the Bernissart finds instead are now interpreted as recording multiple events. According to this interpretation, at least three occasions of mortality are recorded, and though numerous individuals would have died in a geologically short time span (?10–100 years),<ref name=DBN87/> this does not necessarily mean these ''Iguanodon'' were [[Biology:Herd|herd]]ing animals.<ref name=DBN04/>

An argument against herding is that juvenile remains are very uncommon at this site, unlike modern cases with herd mortality. They more likely were the periodic victims of flash floods whose carcasses accumulated in a lake or marshy setting.<ref name=DBN87/> The Nehden find, however, with its greater span of individual ages, more even mix of ''Dollodon'' or ''Mantellisaurus'' to ''Iguanodon bernissartensis'', and confined geographic nature, may record mortality of herding animals migrating through rivers.<ref name=DBN87/>

There is no evidence that ''Iguanodon'' was [[Biology:Sexual dimorphism|sexually dimorphic]] (with one [[Biology:Sex|sex]] appreciably different from the other).<ref name="indvar"/> At one time, it was suggested that the Bernissart ''I.'' "mantelli", or ''I. atherfieldensis'' (''Dollodon'' and ''Mantellisaurus'', respectively) represented a sex, possibly [[Biology:Female|female]], of the larger and more robust, possibly [[Biology:Male|male]], ''I. bernissartensis''.<ref name=VB78>{{cite journal |last=van Beneden|first=P.J.|year=1878 |title=Sur la découverte de reptiles fossiles gigantesques dans le charbonnage de Bernissart, près de Pruwelz |journal=Bulletin de l'Institut Royal d'Histoire Naturelle de Belgique|volume=3 |issue=1 |pages=1–19}}</ref> However, this is not supported today.<ref name=DBN85b/><ref name=DBN80/><ref name=GSP07/> A 2017 analysis showed that ''I. bernissartensis'' does exhibit a large level of individual variation in both its limbs ([[Biology:Scapula|scapula]], [[Biology:Humerus|humerus]], thumb claw, ilium, ischium, [[Biology:Femur|femur]], [[Biology:Tibia|tibia]]) and spinal column (axis, [[Biology:Sacrum|sacrum]], tail vertebrae). Additionally, this analysis found that individuals of ''I. bernissartensis'' generally seemed to fall into two categories based on whether their tail vertebrae bore a furrow on the bottom, and whether their thumb claws were large or small.<ref name="indvar"/>

===Paleopathology===
Evidence of a [[Physics:Fracture|fracture]]d hip bone was found in a specimen of ''Iguanodon'', which had an injury to its ischium. Two other individuals were observed with signs of [[Medicine:Osteoarthritis|osteoarthritis]] as evidenced by bone overgrowths in their anklebones which are called osteophytes.<ref name="rothschild06">{{cite web |last=Hitt |first=Jack |date=1 September 2006 |title=Doctor to the Dinosaurs |url=http://discovermagazine.com/2006/sep/csijurassic#.Umqil-DnDnY |url-status=dead |archive-url=https://web.archive.org/web/20131029211940/https://www.discovermagazine.com/2006/sep/csijurassic#.UnAmdT3P2eE |archive-date=29 October 2013 |access-date=25 October 2013 |work=Discover Magazine}}</ref>

==In popular culture==
[[File:Page 187 (The Lost World, 1912).jpg|upright|thumb|''Iguanodon'' appearing in [[Biography:Arthur Conan Doyle|Arthur Conan Doyle]]'s ''The Lost World'']]
Since its description in 1825, ''Iguanodon'' has been a feature of worldwide [[Social:Popular culture|popular culture]]. Two lifesize reconstructions of ''Mantellodon'' (considered ''Iguanodon'' at the time) built at the Crystal Palace in London in 1852 greatly contributed to the popularity of the genus.<ref>{{cite journal|last=Smith |first=Dan |title=A site for saur eyes |journal=New Statesman |date=26 February 2001 |url=http://www.newstatesman.com/200102260031 |access-date=22 February 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070930222933/http://www.newstatesman.com/200102260031 |archive-date=30 September 2007 }}</ref> Their thumb spikes were mistaken for horns, and they were depicted as elephant-like quadrupeds, yet this was the first time an attempt was made at constructing full-size dinosaur models. In 1910 Heinrich Harder portrayed a group of ''Iguanodon'' in the classic German collecting cards about extinct and prehistoric animals "''Tiere der Urwelt''".

Several motion pictures have featured ''Iguanodon''. In the 2000 Disney animated film ''Dinosaur'', an ''Iguanodon'' named Aladar served as the protagonist with three other iguanodonts as other main and minor characters are Neera, Kron and Bruton. A loosely related ride of the same name at Disney's Animal Kingdom is based around bringing an ''Iguanodon'' back to the present.<ref>{{Cite web |last=Radulovic |first=Petrana |date=26 December 2019 |title=Dinosaur is still the scariest ride at Disney World |url=https://www.polygon.com/2019/12/26/21031982/disney-world-dinosaur-ride |access-date=15 July 2022 |website=Polygon |language=en-US}}</ref> ''Iguanodon'' is one of the three dinosaur genera that inspired Godzilla; the other two were ''[[Biology:Tyrannosaurus rex|Tyrannosaurus rex]]'' and ''[[Biology:Stegosaurus|Stegosaurus]]''.<ref name="USAToday">{{cite news | last = Snider | first = Mike | title = Godzilla arouses atomic terror | work = USA Today | publisher = Gannett Corporation | date = 29 August 2006 | url = https://www.usatoday.com/life/movies/news/2006-08-28-godzilla-dvd_x.htm | access-date = 21 February 2007 }}</ref> ''Iguanodon'' has also made appearances in some of the many ''The Land Before Time'' films, as well as episodes of the television series.

Aside from appearances in movies, ''Iguanodon'' has also been featured on the [[Engineering:Television|television]] documentary miniseries ''Walking with Dinosaurs'' (1999) produced by the BBC (along with then-undescribed [[Biology:Dakotadon|''Dakotadon lakotaensis'']]) and played a starring role in [[Biography:Arthur Conan Doyle|Sir Arthur Conan Doyle]]'s book, ''The Lost World'' as well as featuring in the 2015 documentary ''Dinosaur Britain''. It also was present in Bob Bakker's ''Raptor Red'' (1995), as a ''[[Biology:Utahraptor|Utahraptor]]'' prey item. A [[Astronomy:Asteroid belt|main belt]] [[Astronomy:Asteroid|asteroid]], {{mp|1989 CB|3}}, has been named [[Astronomy:9941 Iguanodon|9941 Iguanodon]] in honour of the genus.<ref>{{cite web | title = JPL Small-Body Database Browser: 9941 Iguanodon (1989 CB3) | publisher = [[Organization:NASA|NASA]] | url= http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=9941 | access-date = 10 February 2007}}</ref><ref name="Williams">{{cite web | author = Williams, Gareth | title = Minor Planet Names: Alphabetical List |publisher = Smithsonian Astrophysical Observatory | url= http://www.cfa.harvard.edu/iau/lists/MPNames.html | access-date = 10 February 2007}}</ref>

Because it is both one of the first dinosaurs described and one of the best-known dinosaurs, ''Iguanodon'' has been well-placed as a [[Engineering:Barometer|barometer]] of changing public and scientific perceptions on dinosaurs. Its reconstructions have gone through three stages: the [[Biology:Elephant|elephant]]ine quadrupedal horn-snouted reptile satisfied the [[History:Victorian era|Victorians]], then a bipedal but still fundamentally reptilian animal using its tail to prop itself up dominated the early 20th century, but was slowly overturned during the 1960s by its current, more agile and dynamic representation, able to shift from two legs to all fours.<ref name=SGL00>{{cite book | last = Lucas | first = Spencer G. | title = Dinosaurs: The Textbook | location = Boston | publisher = McGraw-Hill | year = 2000 | page = [https://archive.org/details/dinosaurstextboo00luca/page/13 13] | isbn = 978-0-07-303642-7 | url = https://archive.org/details/dinosaurstextboo00luca/page/13 }}</ref>

==Notes==
{{reflist|group=nb}}
==References==<!-- Palaeogeography, Palaeoclimatology, Palaeoecology 130 (1997) 275–292 [identification may be doubtful or disputed] -->
{{Reflist|30em}}

==External links==
* [https://web.archive.org/web/20060113142619/http://www.dinohunters.com/Iguanodon/bernissart_page.htm The Bernissart Iguanodons] (''Iguanodon'' herd found in Belgium).
* [https://collections.tepapa.govt.nz/object/212194 Mantell's ''Iguanodon'' tooth in the collection of the Museum of New Zealand Te Papa Tongarewa]

{{Taxonbar|from=Q130980}}

[[Category:Iguanodonts]]
[[Category:Barremian genus first appearances]]
[[Category:Aptian genus extinctions]]
[[Category:Camarillas Formation]]

{{Sourceattribution|Iguanodon}}