Iguanodon
228798
226134493
2008-07-16T23:42:04Z
J. Spencer
568400
[[WP:UNDO|Undid]] revision 226049989 by [[Special:Contributions/189.162.165.156|189.162.165.156]] ([[User talk:189.162.165.156|talk]])
{{featured article}}
{{Taxobox
| name = ''Iguanodon''
| fossil_range = [[Early Cretaceous]]
| image = Iguanodon bernissartensis skull.JPG
| image_width = 250px
| image_caption = ''Iguanodon bernissartensis'' skull''
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Reptile|Sauropsida]]
| superordo = [[Dinosaur]]ia
| ordo = [[Ornithischia]]
| subordo = [[Cerapoda]]
| infraordo = [[Ornithopod]]a
| familia = '''Iguanodontidae'''
| familia_authority = [[Edward Drinker Cope|Cope]], 1869
| genus = '''''Iguanodon'''''
| genus_authority = [[Gideon Mantell|Mantell]], 1825
| subdivision_ranks = [[Species]]
| subdivision =
* ''I. bernissartensis'' <small>Boulenger, 1881 ([[Type (zoology)|neotype]])</small>
* ''I. anglicus'' <small>Holl, 1829 (''[[nomen dubium]]'')</small>
* ?''I. dawsoni'' <small>[[Richard Lydekker|Lydekker]], 1888</small>
* ?''I. fittoni'' <small>Lydekker, 1889</small>
| synonyms=
*[[Mantellisaurus|?]]''Heterosaurus'' <small>Cornuel, 1850</small>
*''Hikanodon'' <small>Keferstein, 1834</small>
*"Iguanoides" <small>Conybeare ''vide'' Cadbury, 2000 (''[[nomen nudum]]'')</small>
*"Iguanosaurus" <small>[Anonymous] 1824 (''nomen nudum'')</small>
*"Proiguanodon" <small>van den Broeck, 1900 (''nomen nudum'')</small>
*[[Mantellisaurus|?]]''Sphenospondylus'' <small>[[Harry Seeley|Seeley]], 1882</small>
*''Therosaurus'' <small>Fitzinger, 1840</small>
*[[Mantellisaurus|?]]''Vectisaurus'' <small>[[John Hulke|Hulke]], 1879</small>
}}
'''''Iguanodon''''' ({{pronEng|ɪˈgwɑːnədɒn}} or {{IPA|/ɪˈgwænədɒn/}}, meaning "[[Iguana]] [[tooth]]") is a [[genus]] of [[ornithopod]] [[dinosaur]] that lived roughly halfway between the first of the swift [[bipedal]] [[hypsilophodontid]]s and the ornithopods' culmination in the [[hadrosaur|duck-billed]] dinosaurs. Many species of ''Iguanodon'' have been named, dating from the [[Kimmeridgian]] [[faunal stage|age]] of the [[Late Jurassic]] [[Period (geology)|Period]] to the [[Cenomanian]] age of the [[Late Cretaceous]] Period from [[Asia]], [[Europe]], and [[North America]]. However, research in the first decade of the 2000s suggests that there is only one well-substantiated species: ''I. bernissartensis'', that lived from the [[Barremian]] to the early [[Aptian]] ([[Early Cretaceous]]) in [[Europe]], between about 130 and 120 million years ago. ''Iguanodon'''s most distinctive features were its large [[thumb]] spikes, which were possibly used for defence against [[predator]]s.
Discovered in 1822 and described three years later by [[England|English]] [[geologist]] [[Gideon Mantell]], ''Iguanodon'' was the second dinosaur formally named, after ''[[Megalosaurus]]''. Together with ''Megalosaurus'' and ''[[Hylaeosaurus]]'', it was one of the three genera originally used to define [[Dinosaur]]ia. A large, bulky [[herbivore]], ''Iguanodon'' is a member of [[Iguanodontia]], along with the duck-billed [[hadrosaur]]s. 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.
Scientific understanding of ''Iguanodon'' has evolved over time as new information has been obtained from the fossils. The numerous specimens of this genus, including nearly complete skeletons from two well-known [[bone bed|bonebed]]s, have allowed researchers to make informed [[hypothesis|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.
==Description==
[[Image:Iguanodon scale.png|thumb|left|''Iguanodon bernissartensis'' compared in size to a human.]]
[[Image:Iguanodon manus 1 NHM.jpg|left|thumb|Hand of ''Iguanodon'' shown in the Natural History Museum.]]
''Iguanodon'' was a bulky herbivore that could shift from [[bipedalism|bipedality]] to [[quadruped]]ality.<ref name=DBN04>{{cite book |last= Norman|first=David B. |editor= Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.)|title=The Dinosauria |edition=2nd |year= 2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=pp. 413–437 |chapter=Basal Iguanodontia}}</ref> The best-known species, ''I. bernissartensis'', is estimated to have weighed about 3.08 [[tonne]]s (3.5 [[short ton|ton]]s) on average,<ref name=DFG97>{{cite book|chapter=Iguanodon |last=Glut |first=Donald F. |title=Dinosaurs: The Encyclopedia. |year=1997 |publisher=McFarland & Co |location=Jefferson, North Carolina|pages=490–500 |isbn=0-89950-917-7}}</ref> and measured about 10 [[metre]]s long (32.8 [[foot (unit of length)|feet]]) as an adult, with some specimens possibly as a long as 13 metres (42.6 ft).<ref name=NM01>{{cite book |last=Naish |first=Darren |coauthors=David M. Martill |chapter=Ornithopod dinosaurs |title=Dinosaurs of the Isle of Wight |year=2001 |publisher=The Palaeontological Association |location=London |isbn= 0-901702-72-2|pages=60–132}}</ref> Other species were not as large; the similarly robust ''I. dawsoni'' is estimated at 8 metres long (26.2 ft), and its more lightly-built contemporary ''I. fittoni'' at 6 metres (19.7 ft).<ref name=WTB97>{{cite book |last=Blows |first=W. T. |chapter=A review of Lower and middle Cretaceous dinosaurs from England|editor=Lucas, S.G., Kirkland, J.I., and Estep, J.W. (eds.) |title=Lower and Middle Cretaceous Terrestrial Ecosystems |year=1997|series=''New Mexico Museum of Natural History and Science Bulletin'', 14 |publisher=New Mexico Museum of Natural History and Science |pages=29–38}}</ref> This genus had a large, tall but narrow skull, with a toothless [[beak]] probably covered with [[keratin]], and teeth like those of an iguana, but much larger and more closely packed.<ref name=DBN04/>
The arms were long (up to 75% the length of the legs in ''I. bernissartensis'') 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. |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=0-517-468905 }}</ref> although their exact function is still debated. They could have been used for defense, or for foraging for food. The [[little finger]] was elongate and dextrous, and could have been used to manipulate objects. The legs were powerful, but not built for running, and there were three toes on each foot. The backbone and tail were supported and stiffened by [[ossification|ossified]] [[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/> Overall, in body structure, it was not too dissimilar from its later relatives, the hadrosaurids.
==Classification and origins==
{{Main|Iguanodont}}
[[Image:Iguanodontia2.png|thumb|right|250 px|A simplified cladogram of Iguanodontia, drawn after Norman (2004).<ref name=DBN04/>]]
''Iguanodon'' gives its name to the [[Linnaean taxonomy|unranked]] [[clade]] [[Iguanodontia]], a very populous group of ornithopods with many species known from the [[Middle Jurassic]] to the [[Late Cretaceous]]. Aside from ''Iguanodon'', the best-known members of the clade include ''[[Dryosaurus]]'', ''[[Camptosaurus]]'', ''[[Ouranosaurus]]'', and the duck-bills, or [[hadrosaur]]s. In older sources, Iguanodontidae was shown as a distinct [[family (biology)|family]].<ref name=PMG74>{{cite journal |last=Galton |first=Peter M.|year=1974 |month=September |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 |url=http://links.jstor.org/sici?sici=0022-3360%28197409%2948%3A5%3C1048%3ANOTACO%3E2.0.CO%3B2-L}} </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]], including ornithopods that were neither hypsilophodontids or hadrosaurids. In practice, animals like ''[[Callovosaurus]]'', ''Camptosaurus'', ''[[Craspedodon]]'', ''[[Kangnasaurus]]'', ''[[Mochlodon]]'', ''[[Muttaburrasaurus]]'', ''Ouranosaurus'', and ''[[Probactrosaurus]]'' were usually assigned to this family.<ref name=DBN85d/> With the advent of [[cladistics|cladistic analyses]], Iguanodontidae was shown to be [[paraphyly|paraphyletic]], and these animals are recognized to fall at different points in relation to hadrosaurs on a [[cladogram]], instead of in a single distinct clade.<ref name=NW90/><ref name=DBN04/> Groups like Iguanodontoidea are still used as unranked clades in the scientific literature, though many traditional iguanodontids are now included in the superfamily [[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 (paleontologist)|Jack Horner]] suggested, based mostly on skull [[synapomorphy|features]], that hadrosaurids actually formed two more distantly-related groups, with ''Iguanodon'' on the line to the flat-headed [[Hadrosaurid|hadrosaurines]], and ''Ouranosaurus'' on the line to the crested [[Hadrosaurid|lambeosaurines]],<ref name=JRH90>{{cite book |last=Horner |first= J. R.|editor=Kenneth Carpenter and Phillip J. Currie (eds.) |title=Dinosaur Systematics: Perspectives and Approaches |year=1990 |publisher=Cambridge University Press |location=Cambridge |isbn=0-521-36672-0 |pages=179–187 |chapter=Evidence of diphyletic origination of the hadrosaurian (Reptilia: Ornithischia) dinosaurs}}</ref> but his proposal has been rejected.<ref name=NW90>{{cite book |last=Norman |first= David B. |coauthors=Weishampel, David B. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.). |title=The Dinosauria |year=1990 |publisher=University of California Press |location=Berkeley |isbn=0-520-06727-4 |pages=510–533 |chapter=Iguanodontidae and related ornithopods}}</ref><ref name=DBN04/>
==Discovery and history==
===Gideon Mantell, Sir Richard Owen, and the discovery of dinosaurs===
[[Image:Mantell's Iguanodon teeth.jpg|thumb|Illustration of fossil ''Iguanodon'' teeth with a modern iguana jaw from Mantell's 1825 paper describing ''Iguanodon''.]]
[[Image:Maidstone fossil Iguanodon 1840.jpg|thumb|Fossil remains found in Maidstone in 1840.]]
The discovery of ''Iguanodon'' has long been accompanied by a popular [[legend]]. The story goes that [[Gideon Mantell]]'s wife, Mary Ann, discovered [http://collections.tepapa.govt.nz/objectdetails.aspx?oid=212194&coltype=history®no=gh004839 the first teeth] of an ''Iguanodon'' in the strata of [[Tilgate, Crawley|Tilgate]] Forest in [[Whiteman's Green]], [[Cuckfield]], [[Sussex]], [[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 and M. K. Brett-Surman (eds.) |title=The Complete Dinosaur |year=1997 |publisher=Indiana University Press |location=Bloomington|isbn=0-253-33349-0 |pages=p.14 |chapter=European Dinosaur Hunters }}</ref> Not everyone agrees that the story is false, though.<ref name=SGL99>{{cite journal |last=Lucas |first=Spencer G.|year=1999 |month=December |title=Book review: Gideon Mantell and the discovery of dinosaurs|journal=PALAIOS |volume=14 |issue=6 |pages=601–602 |issn=0883-1351 |url=http://links.jstor.org/sici?sici=0883-1351%28199912%2914%3A6%3C601%3AGMATDO%3E2.0.CO%3B2-I |accessdate= 2007-02-21 |doi=10.2307/3515316}}</ref> Regardless of the exact circumstances, he combed the area for more fossils, and consulted the fossil experts of the time as to what sort of animal the bones might belong to. Most of the scientists, such as [[William Buckland]] and [[Georges Cuvier]], thought that the teeth were from [[fish]] or [[mammal]]s. However, [[Samuel Stutchbury]], a [[natural sciences|naturalist]] from the [[Royal College of Surgeons]], recognized that they resembled those of an iguana, albeit twenty times larger.<ref name=DFG97/> Mantell did not describe his findings until 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 |url=http://links.jstor.org/sici?sici=0261-0523(1825)115%3C179%3ANOTIAN%3E2.0.CO%3B2-W|accessdate= 2007-02-21 |doi=10.1098/rstl.1825.0010}}</ref><ref name=HDS97/>
In recognition of the resemblance of the teeth to those of the iguana, Mantell named his new genus ''Iguanodon'' or "iguana-toothed", from ''iguana'' and the [[Ancient Greek|Greek]] word ''odontos'' ("tooth").<ref name=NM01/> Based on [[isometric scaling]], he estimated that the creature might have been up to 12 metres (40 ft) long.<ref name=GM25/> His initial idea for a name was ''Iguanasaurus'' ("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 = [[George Olshevsky|Olshevsky, G]] | title = Re: Hello and a question about Iguanodon mantelli (long) | url= http://dml.cmnh.org/1997Aug/msg00339.html | accessdate = 2007-02-11}}</ref> He neglected to add a [[species]] name to form a proper [[binomial nomenclature|binomial]], so one was supplied in 1829 by Friedrich Holl: ''I. anglicum'', which was later amended to ''I. anglicus''.<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>
[[Image:Mantell's Iguanodon restoration.jpg|left|thumb|Mantell's ''Iguanodon'' restoration based on the Maidstone remains.]]
A better specimen was discovered in a quarry in [[Maidstone]], [[Kent]], in 1834, which Mantell soon acquired. He was able to identify it as an ''Iguanodon'' from its distinctive teeth. The Maidstone slab allowed the first skeletal reconstructions and artistic renderings of ''Iguanodon''. As such, he made some mistakes, the most famous of which was the placement of what he thought was a [[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 [[Natural History Museum]] in [[London]]. The borough of Maidstone commemorated this find by adding an ''Iguanodon'' as a [[supporters|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 |year=1968 |publisher=Dutton & Company |location=New York |isbn=0140212884 }}</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 [[rock formation|formation]] than the original ''I. mantelli''/''I. anglicus'' material.<ref name=GO97/>
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 1832|Reform Act]]-era British politics and science. Owen, a firm [[creationist]], opposed the early versions of [[evolution|evolutionary science]] ("[[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 61 metres (200 ft), determined that they were not simply giant lizards, and put forward that they were advanced and mammal-like, characteristics given to them by [[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>
[[Image:Crystal palace iguanodon.jpg|thumb|left|The famous (crowded) banquet in [[Waterhouse Hawkins]]'s standing [[The Crystal Palace Dinosaurs|Crystal Palace]] ''Iguanodon'']]
Shortly before his death in 1852, Mantell realized that ''Iguanodon'' was not a heavy, [[Pachydermata|pachyderm]]-like animal,<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 his passing left him unable to participate in the creation of the [[The Crystal Palace Dinosaurs|Crystal Palace dinosaur sculptures]], and so Owen's vision of the dinosaurs became that seen by the public for decades.<ref name=HT97/> With [[Waterhouse Hawkins]], he had nearly two dozen lifesize [[sculpture]]s of various prehistoric animals built out of [[concrete]] sculpted over a [[steel]] and [[brick]] framework; two ''Iguanodon'', one standing and one resting on its belly, were included. Before the sculpture of the standing ''Iguanodon'' 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 (ed.) |year=2000 |publisher=St. Martin's Press |location=New York|chapter= brief history of dinosaur paleontology |isbn=0-312-26226-4 |pages=10–44}}</ref><ref name=CY96>{{cite journal |last=Yanni |first=Carla |year=1996 |month=September |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 }}</ref><ref name=DBN85>Norman, David B. ''The Illustrated Encyclopedia of Dinosaurs.'' p. 11.</ref>
===Bernissart===
[[Image:Bernissart Iguanodon mounted skeleton.jpg|thumb|Photograph of a Bernissart ''Iguanodon'' skeleton being mounted.]]
The largest find of ''Iguanodon'' remains to date occurred in 1878 in a coal mine at [[Bernissart]] in [[Belgium]], at a depth of 322 m (1056 ft).<ref name=DBN85b/> With the encouragement of [[Alphonse Briart]], supervisor of mines at nearby [[Morlanwelz]], [[Louis Dollo]], with Louis de Pauw, oversaw excavation of the skeletons and 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.|year=1987 |month=March |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}}</ref> Many of them went on public display beginning in 1882 and are still present for viewing; 11 are displayed as standing mounts, and 20 as they were (approximately) found.<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'', a larger and much more robust animal than the English remains had yet revealed, but one specimen was referred to the nebulous, gracile ''I. mantelli'' (now ''[[Dollodon|Dollodon bampingi]]''). 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 [[crocodilian]] ''[[Bernissartia]]''.
[[Image:Iguanodon4.jpg|thumb|left|''Iguanodon bernissartensis'' fossil drawn as it was found in 1882.]]
The science of conserving fossil remains was in its infancy, and was ill-equipped to deal with what soon became known as "[[pyrite]] disease". Pyrite in the bones was changing to [[iron sulfate|iron sulphate]], damaging the remains by causing them to crack and crumble. When in the ground, the bones were exposed to moisture that prevented this from happening, but when removed into the drier open air, the natural chemical conversion began to occur. Not knowing the true cause, and thinking it was an actual infection, the staff at the Museum in Brussels attempted to treat the problem with a combination of [[alcohol]], [[arsenic]], and [[shellac]]. This combination was intended to simultaneously penetrate (alcohol), kill any biological agent (arsenic), and harden (shellac) the fossils. This treatment had the unintended effect of sealing in moisture and extending the period of damage. Modern treatments instead involve either monitoring the humidity of fossil storage, or, for fresh specimens, preparing a special coating of [[polyethylene glycol]] that is then heated in a vacuum pump, so moisture is immediately removed and pore space is infiltrated with polyethelene glycol to seal and strengthen the fossil.<ref name=DBN85b/>
[[Image:Iguanodon 28-12-2007 14-18-33.jpg|thumb|One of the many skeletons displayed at Brussels]]
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 [[emu]] and [[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 |issue= |pages=161–180 language=French}}</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 |issue= |pages=205–221 language=French}}</ref> He was not completely correct, but he also had the disadvantage of being faced with some of the first complete dinosaur remains. A problem that was later recognized was the bend he introduced into the [[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 [[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.<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=45A |issn=0272-4634}} Abstracts of Papers, Sixty-Third Annual Meeting.</ref> During [[World War I]], when the town was occupied by [[German Empire|German forces]], preparations were made to reopen the mine for palaeontology, and [[Otto Jaekel]] was sent from [[Berlin]] to supervise. The [[Allies of World War I|Allies]] recaptured Bernissart just as the first fossiliferous layer was about to be uncovered. Further attempts to reopen the mine were hindered by financial problems and were stopped altogether in 1921 when the mine flooded.<ref name=DBN85b/>
===To the present: Worldwide finds===
Research on ''Iguanodon'' decreased during the early part of the 20th century as World Wars and the [[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 [[Reginald Hooley|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}}</ref> However, what had been a European genus was now being found worldwide, with material in [[Africa]] (teeth from [[Tunisia]]<ref name=AFL51>{{cite journal |last=Lapparent |first=A. F. de |year=1951 |title=Découverte de Dinosauriens associés à une faune de Reptiles et de Poissons, dans le Crétacé inférieur de l'Extrême Sud Tunisien |journal=Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences |volume=232 |pages=1430 |issn=0567-655X |language=French}}</ref> and elsewhere in the [[Sahara Desert]]),<ref name=AFL60>{{cite journal |last=Lapparent |first=A. F. de |year=1960 |title= Les dinosauriens du "Continental Intercalaire" du Sahara Central|journal=Mémoires de la Socété Géologique de France (Nouvelle Série) |volume=88A|pages=1–57|language=French}}</ref> [[Mongolia]] (''I. orientalis''),<ref name=AKR52>{{cite journal |last=Rozhdestvensky |first= A.K.|year= 1952 |title=[Discovery of an iguanodont in Mongolia] |journal=Dokladi Akademii Nauk S.S.S.R. |volume=84 |issue=6 |pages=1243–1246|language=Russian }}</ref> and the [[United States]] in [[North America]] (''I. ottingeri'' from [[Utah]]<ref name=GJ79>{{cite journal |last=Galton |first=P. M. |coauthors=J. A. Jensen |year=1979 |title=Remains of ornithopod dinosaurs from the Lower Cretaceous of North America |journal=Brigham Young University Geology Studies |volume=25 |issue=3 |pages=1–10 |issn=1041-7184}}</ref>). Another North American species, from [[South Dakota]], once assigned to ''Iguanodon'' as ''I. lakotaensis'',<ref name=WB89>{{cite journal |last=Weishampel |first=David B. |coauthors=Phillip R. Bjork |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}}</ref> has since been re-classified as the genus ''[[Dakotadon]]''.<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}}</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. |year=1984|title=Evolution in jaw mechanics in ornithopod dinosaurs |series=''Advances in Anatomy, Embryology, and Cell Biology'', 87|location=Berlin; New York|publisher=Springer-Verlag |pmid=6464809|isbn=0387131140 |issn=0301-5556}}</ref> and [[David B. Norman]]'s work on numerous aspects of the genus has made it one of the best-known dinosaurs.<ref name=DBN80/><ref name=DBN85b/><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><ref name=DBN04/> In addition, a further find of numerous ''Iguanodon'' skeletons, in Nehden, [[North Rhine-Westphalia|Nordrhein-Westphalen]], [[Germany]], has provided evidence for [[herd|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 [[flash flood]]s. At least 15 individuals, from 2 to 8 metres long (6.6 to 26.2 ft), have been found here, although at least some of them belong to the closely related ''[[Mantellisaurus|Mantellisaurus atherfieldensis]]'' (at that time believed to be another species of ''Iguanodon'').<ref name=DBN87/>
''Iguanodon'' material has also been used in the search for dinosaur [[DNA]] and other [[biomolecule]]s. In research by Graham Embery ''et al,'' ''Iguanodon'' bones were processed to look for remnant [[protein]]s. In this research, identifiable remains of typical bone proteins, such as [[phosphoprotein]]s and [[proteoglycan]]s, were found in a [[rib]].<ref name=GEetal03>{{cite journal|last=Embery |first=Graham |coauthors=Milner, Angela C.; Waddington, Rachel J.; Hall, Rachel C.; Langley, Martin S.; and Milan, 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=10.1080/713713598<!--this doi appears to be nonfunctional, even though it's listed here: http://www.informaworld.com/openurl?genre=issue&issn=0300-8207&issue=1&sid=informa:informaworld&title=Connective Tissue Research&volume=44 -->}}</ref>
==Species==
[[Image:Iguanodon de Bernissart IRSNB 01.JPG|thumb|''Iguanodon bernissartensis'' correctly mounted in a quadrupedal posture, Institut Royal des Sciences naturelles de Belgique, Bruxelles.]]
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 became (such as ''[[Megalosaurus]]'' and ''[[Pelorosaurus]]''), ''Iguanodon'' has had a complicated history, and its taxonomy continues to undergo revisions.<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| year=1998 |month=January |volume=122 |issue=1–2 |pages=291–348 |doi=10.1006/zjls.1997.0122}}</ref><ref name=NB02>{{cite book|last=Norman|first=David B.|coauthors=Barrett, Paul M. |editor=Milner, Andrew, and Batten, David J. (eds.)|chapter=Ornithischian dinosaurs from the Lower Cretaceous (Berriasian) of England|title=Life and Environments in Purbeck Times |series=Special Papers in Palaeontology '''68''' |year=2002 |location=London |publisher=Palaeontological Association|pages=161–189|isbn=0901702730}}</ref><ref name=GSP06>{{cite book|last=Paul|first=Gregory S.|editor=Kenneth Carpenter (ed.)|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=2006|location=Bloomington|publisher=Indiana University Press|pages=69-77|isbn=0-253-34817-X}}</ref><ref name=GSP08/> Remains of the best-known species have come from [[Belgium]], [[England]], [[Germany]], [[Spain]] and [[France]]. Remains of similar animals possibly belonging to this genus have been found in [[Tunisia]] and [[Mongolia]], and distinct species are present in [[Utah]] and [[South Dakota]], USA.
''I. anglicus'' was the original [[type species]], but the [[holotype]] was based on a single tooth and only partial remains of the species have been recovered since. In March of 2000, the [[International Commission on Zoological Nomenclature]] changed the type species to the much better known ''I. bernissartensis''. The original ''Iguanodon'' tooth is held at [[Museum of New Zealand Te Papa Tongarewa|Te Papa Tongarewa]], the national museum of [[New Zealand]] in [[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://web.archive.org/web/www.rsnz.org/topics/biol/dna50/breakfast.php |title = Celebrating the great fossil hunters | accessdate = 2007-02-22|archiveurl = http://web.archive.org/web/20050826130408/http://www.rsnz.org/topics/biol/dna50/breakfast.php |archivedate = 2005-08-26 |url= }}</ref>
===Species currently accepted as valid===
Only a few of the many species assigned to ''Iguanodon'' are still considered to be valid and to fall within the genus ''Iguanodon''.<ref name=DBN04/><ref name=GSP08/> ''I. bernissartensis'', described by [[George Albert Boulenger]] in 1881, is the [[type species|neotype]] for the genus. This species is best known for the many skeletons discovered in Bernissart, but is also known from remains across [[Europe]]. David Norman suggested that it includes the [[nomen dubium|dubious]] Mongolian ''I. orientalis'',<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| year=1996|month=March| volume=116|issue=2 |pages=303–315|doi=10.1006/zjls.1996.0021}}</ref> but this has not been followed by other researchers.<ref name=GSP08/>
Two species described by [[Richard Lydekker]] in the late 1800s are valid, but rarely discussed. ''I. dawsoni'', 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}}</ref> is known from two partial skeletons from the [[Valanginian]]-[[Barremian]]-age [[Lower Cretaceous]] Hastings Beds of [[East Sussex]], [[England]].<ref name=DBN04/> ''I. fittoni'' was also 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}}</ref> Like ''I dawsoni'', this species is known from the Hastings Beds of East Sussex. It may also have been found in Spain. Three partial skeletons are known.<ref name=DBN04/> The two species are separated on the basis of vertebral and pelvic characters, size, and build.<ref name=WTB97/> For example, ''I. dawsoni'' was more robust than ''I. fittoni'', with large ''[[Camptosaurus]]''-like [[vertebra]]e featuring short [[neural spine]]s, whereas ''I. fittoni'' is known for its "long, narrow, and steeply inclined neural spines".<ref name=DBN04/> Neither of these species may actually pertain to ''Iguanodon''.<ref name=GSP08/>
===Reassigned species===
Two species of ''Iguanodon'' named by Richard Owen have since been reassigned to other genera. ''I. hoggi'' (also spelled ''I. boggii'' or ''hoggii''), named by Owen for a lower jaw from the [[Tithonian]]-[[Berriasian]]-age [[Upper Jurassic]]-[[Lower Cretaceous]] [[Purbeck Beds]] of [[Dorset]] in 1874, has been reassigned to ''Camptosaurus'' by David Norman and Paul Barrett.<ref name=NB02/> ''I. major'', a vertebra from the [[Isle of Wight]] described by Owen in 1842 as a species of ''[[Streptospondylus]]'', is a ''[[nomen dubium]]'' which is now thought to be a synonym of ''I. anglicus''.<ref name=DBN04/>
Other than the two species described by Owen which have been reassigned to other genera, fourteen other species have since been reclassified. ''Iguanodon albinus'' (or ''Albisaurus scutifer''), described by [[Czechs|Czech]] [[paleontologist]] [[Antonin Fritsch]] (correctly Frič) in 1893, is a dubious nondinosaurian [[reptile]] now known as ''[[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= German |isbn= 3865440452}}</ref> ''I. atherfieldensis'', described by [[Reginald Hooley|R.W. Hooley]] in 1925,<ref name=RWH25/> was smaller and less robust than ''I. bernissartensis'', with longer neural spines. It was renamed ''[[Mantellisaurus|Mantellisaurus atherfieldensis]]'' in 2006.<ref name=GSP06/> ''I. exogyrarum'' (also spelled ''I. exogirarum'' or ''I. exogirarus'') was described by Fritsch in 1878. It is a ''nomen dubium'' based on very poor material and has been reassigned, by [[George Olshevsky]], to ''[[Ponerosteus]]''.<ref name=GO00>{{cite book| last=Olshevsky |first= George| year=2000| title=An annotated checklist of dinosaur species by continent|series=''Mesozoic Meanderings'', 3|location=San Diego|publisher=G. Olshevsky Publications Requiring Research| issn=0271-9428|oclc=44433611}}</ref> ''I. valdensis'', described by Hulke in 1879 from vertebral and [[pelvis|pelvic]] remains, was from the [[Barremian]] [[faunal stage|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| url= http://links.jstor.org/sici?sici=0022-3360%28197609%2950%3A5%3C976%3ATDVV%28I%3E2.0.CO%3B2-H |volume=50|issue=5|pages=976–984 }}</ref> Originally named ''Vectisaurus'', it is probably a partially-grown specimen of ''Mantellisaurus atherfieldensis''.<ref name=DBN90>Norman, David B. "A review of ''Vectisaurus valdensis'', with comments on the family Iguanodontidae". ''Dinosaur Systematics'', 147–161.</ref> ''I. gracilis'', named by Lydekker in 1888 as the type species of ''Sphenospondylus'' and assigned to ''Iguanodon'' in 1969 by Rodney Steel, may belong to ''Mantellisaurus atherfieldensis''.<ref name=DBN04/>
''I. foxii'' (also spelled ''I. foxi'') was originally described by [[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 3|year=1885|volume=2|issue=1|pages=10–15|oclc=2139602}}</ref>''I. hollingtoniensis'' (also spelled ''I. hollingtonensis''), described by Lydekker in 1889, is a synonym of ''I. fittoni''. ''I. prestwichii'' (also spelled ''I. prestwichi''), described by [[John Hulke]] in 1880, has been reassigned to ''[[Camptosaurus|Camptosaurus prestwichii]]''. ''I. seeleyi'' (also spelled ''I. seelyi''), described by Hulke two years after ''I. prestwichii'', has been synonymized with ''I. bernissartensis''. ''I. suessii'', described by [[Emanuel Bunzel]] in 1871, has been reassigned to ''[[Mochlodon|Mochlodon suessi]]''.<ref name=DBN04/>
''I. lakotaensis'' was described by [[David B. Weishampel]] and [[Philip R. Bjork]] in 1989.<ref name=WB89/> The only well-accepted [[North America]]n species of ''Iguanodon'', ''I. lakotaensis'' was described from a partial skull from the [[Barremian]]-age [[Lower Cretaceous]] [[Lakota Formation]] of [[South Dakota]], [[United States|USA]]. Its assignment has been controversial. Some researchers suggest that it was more [[Basal (phylogenetics)|basal]] than ''I. bernissartensis'', and related to ''[[Theiophytalia]]'',<ref name=BC06>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 [[synonym (taxonomy)|synonym]] of ''I. bernissartensis''.<ref name=DBN98/> [[Gregory S. Paul]] has since given the species its own genus, ''[[Dakotadon]]''.<ref name=GSP08/>
[[Image:Dollodon.jpg|thumb|IRSNB 1551, the holotype of ''Dollodon bampingi'', formerly ''Iguanodon mantelli'' , displayed in the Belgian Royal Institute for the Natural Sciences at Brussels]]
''Iguanodon mantelli'' (also spelled ''I. manteli'' or ''I. mantellii''), described by Christian Erich Hermann von Meyer in 1832, is actually based on the same material as ''I. anglicus''.<ref name=GO97/> Several skeletons, however, including the Maidstone specimen and one of the Bernissart skeletons have been assigned here over the years, and their attribution is not complete. The gracile Bernissart skeleton, for example, has been reassigned, first to ''Mantellisaurus atherfieldensis'',<ref name=DBN86/> and upon further review, to its own genus and species, ''[[Dollodon|Dollodon bampingi]]''.<ref name=GSP08/> ''I. orientalis'', described by [[Anatoly Konstantinovich Rozhdestvensky|A. K. Rozhdestvensky]] in 1952,<ref name=AKR52/> was based on poor material, but a skull with a distinctive arched snout that had been assigned to it was renamed ''[[Altirhinus|Altirhinus kurzanovi]]'' in 1998.<ref name=DBN98/> At the same time, ''I. orientalis'' was considered to be a ''nomen dubium'' indistinguishable from ''I. bernissartensis''.<ref name=DBN96/><ref name=DBN98/> [[Harry Seeley]] described ''I. phillipsi'' 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 later reassigned it to ''[[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}}</ref>
===Dubious species===
Five ''Iguanodon'' species are considered to be ''nomina dubia'' or undescribed. ''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 emend. Bronn, 1850). It is known from teeth from the [[Valanginian]]-[[Barremian]]-age [[Lower Cretaceous]] Tilgate Forest of [[East Sussex]], England. ''I. hillii'', coined by Edwin Tully Newton in 1892 for a tooth from the early [[Cenomanian]] [[Upper Cretaceous]] Lower Chalk of [[Hertfordshire]], is an early [[hadrosaurid]] of some sort.<ref name=HWF04>Horner, John R., David B. Weishampel and Catherine A. Forster. "Hadrosauridae". ''The Dinosauria'', pp 438–463.</ref> "I. mongolensis" (Whitfield, 1992) is a ''[[nomen nudum]]'' from a photo caption in a book, of remains that would later be named ''Altirhinus''.<ref name=GOASIA>{{cite web | author = [[George Olshevsky|Olshevsky, G]] | title = Dinosaurs of China, Mongolia, and Eastern Asia [under ''Altirhinus''] | url=http://web.archive.org/web/*/http://dinosauricon.com/rigby/asia.doc | accessdate = 2007-02-22}}</ref>
''I. ottingeri'', described by [[Peter Galton]] and [[James A. Jensen]] in 1979, is a ''nomen dubium'' based on teeth from the possibly [[Aptian]]-age lower Cedar Mountain Formation of Utah.<ref name=GJ79/> ''I. praecursor'' (also spelled ''I. precursor''), described by E. Sauvage in 1876 from teeth from an unnamed [[Kimmeridgian]] ([[Late Jurassic]]) [[rock formation|formation]] in [[Pas-de-Calais]], [[France]], is actually a [[sauropod]], sometimes assigned to ''[[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 |pages=626|language=French}}</ref> although the two come from different formations.<ref name=UBD04>Upchurch, Paul, Paul M. Barrett, and Peter Dodson. "Sauropoda". ''The Dinosauria''</ref>
Finally, several other poorly known genera and species are included with ''Iguanodon'' without being separate species, although their assignment is less certain with the renaming of ''I. atherfieldensis''. These include ''Heterosaurus neocomiensis'' (Cornuel, 1850), ''Hikanodon'' (Keferstein, 1834), and ''Therosaurus'' (Fitzinger, 1840), and the species "Streptospondylus" ''recentior'' (Owen, 1851), "[[Cetiosaurus]]" ''brachyurus'',<ref name=DFG97/> and part of "C." ''brevis'' (Owen, 1842; "C." ''brevis'' is a [[chimera (paleontology)|chimera]]).<ref name=UM03>{{cite journal |last=Upchurch |first=Paul |coauthors=John Martin |year=2003 |month=March |title=The Anatomy and Taxonomy of ''Cetiosaurus'' (Saurischia, Sauropoda) from the Middle Jurassic of England |journal=Journal of Vertebrate Palaeontology |volume=23 |issue=1 |pages=208–231 |doi=10.1671/0272-4634(2003)23[208:TAATOC]2.0.CO;2 |doilabel=10.1671/0272-4634(2003)23[208:TAATOC]2.0.CO;2}}</ref> The ''nomen nudum'' "Proiguanodon" (van den Broeck, 1900) also belongs here,<ref name=GO99>{{cite web | author = [[George Olshevsky|Olshevsky, G]] | title = Re: What are these dinosaurs? | url= http://dml.cmnh.org/1999Nov/msg00507.html | accessdate = 2007-02-16}}</ref> and possibly the very obscure "Streptospondylus" ''grandis'' (Owen, 1851) and ''meyeri'' (Owen, 1854).<ref name=GO97/>
==Paleobiology==
===Feeding and diet===
[[Image:Iguanodon skull.JPG|left|thumb|''Iguanodon'' skull from [[Oxford University Museum of Natural History]]]]
One of the first details noted about ''Iguanodon'' was that it had the teeth of a [[herbivore|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 menti|symphysis]], which he found best compared to that of the [[two-toed sloth]] and the [[extinct]] ground sloth ''[[Mylodon]]''. He also suggested that ''Iguanodon'' had a [[prehensile]] [[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| url=http://links.jstor.org/sici?sici=0365-0855(1843%2F1850)5%3C757%3AOTSOTJ%3E2.0.CO%3B2-K |doi=10.1098/rstl.1848.0013}}</ref> like a [[giraffe]]. More complete remains have shown this to be an error; for example, the [[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)|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>
''Iguanodon'' teeth are, as the name suggests, like those of an iguana, but larger. Unlike [[hadrosaurid]]s, which had columns of replacement teeth, ''Iguanodon'' only had one replacement tooth at a time for each position. The [[maxilla|upper jaw]] held up to 29 teeth per side, with none at the [[premaxilla|front of the jaw]], and the [[dentary|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 [[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}}</ref><ref name=FS04>Fastovsky, D.E., and Smith, J.B. "Dinosaur paleoecology." ''The Dinosauria'', 614–626.</ref>
[[Image:Hand of an Iguanodon 28-12-2007 15-22-03.jpg|right|thumb|The hand of ''Iguanodon'' shown in Brussels; the extended digit is the prehensile fifth finger.]]
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 [[mastication|chewing]].<ref name=DBW84/> Because the teeth were always replaced, the animal could have used this mechanism throughout its life, and could eat tough [[plant]] material.<ref name=RTB86>{{cite book |last=Bakker |first=Robert T. |title=The Dinosaur Heresies |year= 1986 |publisher=William Morrow |location=New York |isbn=0140100555 |pages=160–178 |chapter=Dinosaurs At Table}}</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 [[keratin]]ous material to form a cropping beak for biting off [[twig]]s and [[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/>
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 [[tree]] [[leaf|foliage]] at 4–5 metres high (13–16.5 ft).<ref name=NM01/> A diet of [[Equisetum|horsetails]], [[cycad]]s, and [[pinophyta|conifers]] was suggested by David Norman,<ref name=DBN85b/> although iguanodonts in general have been tied to the advance of [[flowering plant|angiosperm]] plants in the [[Cretaceous]] due to the dinosaurs' inferred low browsing habits. Angiosperm growth, according to this [[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=BW01>{{cite journal |last=Barrett |first=Paul M.|coauthors=Willis, 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}}</ref><ref name=DBN04/> Whatever its exact diet, due to its size and abundance, ''Iguanodon'' is regarded as a dominant medium to large herbivore for its [[ecosystem|ecological communities]].<ref name=DBN04/> In England, this included the small predator ''[[Aristosuchus]]'', larger predators ''[[Eotyrannus]]'', ''[[Baryonyx]]'', and ''[[Neovenator]]'', low-feeding herbivores ''[[Hypsilophodon]]'' and ''[[Valdosaurus]]'', fellow "iguanodontid" ''Mantellisaurus'', the [[armour (zoology)|armoured]] herbivore ''[[Polacanthus]]'', and [[sauropod]]s like ''[[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===
[[Image:Goodrich Iguanodon.jpg|thumb|Reconstruction by [[Samuel Griswold Goodrich]] from ''Illustrated Natural History of the Animal Kingdom''.<ref name=SGG59>{{cite book|first=Samuel Griswold| last=Goodrich|origyear=1859|year=2004|title=Illustrated Natural History of the Animal Kingdom|publisher=University of Michigan Library|isbn= 1418158844}}</ref>]]
Early fossil remains were fragmentary, which led to much speculation on the posture and nature of ''Iguanodon''. As discussed, ''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.
[[Image:Iguanodon feeding.jpg|thumb|left|Nineteenth century painting showing ''Iguanodon'' in a tripod pose.]]
During his re-examination of ''Iguanodon'', David Norman was able to show that this posture was unlikely, due to the presence of a long tail 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 [[hoof]]-like [[phalanx bones|phalanges]], and able to [[extension (kinesiology)|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/>
[[Image:Iguanodon BW.jpg|thumb|Illustration of ''Iguanodon'' as a quadruped.]]
Furthermore, it appears that ''Iguanodon'' became more quadrupedal as it got older and heavier; [[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 [[Hand|palm]]s faced each other, as shown by iguanodontian trackways and the anatomy of this genus' arms and hands.<ref name=JLW96>{{cite paper |author=Wright, J.L. |title=Fossil terrestrial trackways: Preservation, taphonomy, and palaeoecological significance. |publisher=University of Bristol |date=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=David M. Unwin (ed.) |title=Cretaceous Fossil Vertebrates |year=1999|series=''Special Papers in Palaeontology'', '''60''' |publisher=Palaeontological Association |pages=209–219|isbn=0901702676wright}}</ref> The three toed [[pes (zoology)|pes]] (''foot'') of ''Iguanodon'' was relatively long, and when walking, both the hand and the foot would have been used in a [[digitigrade]] fashion (on the fingers and toes).<ref name=DBN04/> The maximum speed of ''Iguanodon'' has been estimated at 24 [[kilometres per hour|km/h]] (14.9 [[miles per hour|mph]]),<ref name=WPCJ78>{{cite journal |last=Coombs Jr. |first=Walter P.|year=1978 |title=Theoretical aspects of cursorial adaptations in dinosaurs |journal=Quarterly Review of Biology |volume=53|issue=4 |pages=393–418|url= http://links.jstor.org/sici?sici=0033-5770%28197812%2953%3A4%3C393%3ATAOCAI%3E2.0.CO%3B2-3 |doi=10.1086/410790}}</ref> which would have been as a biped; it would not have been able to [[Horse gait#Gallop|gallop]] as a quadruped.<ref name=DBN04/>
Large three-toed footprints are known in Early Cretaceous rocks of England, particularly [[Wealden]] beds on the Isle of Wight, and these [[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 [[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 |pages=267}}</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}}</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 |pages=1–26}}</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 | accessdate = 2007-02-14}}</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]], [[Svalbard]], [[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=0-7864-1166-X |pages=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 — Svalbard |journal=Arbok Norsk Polarinstitutt, 1960 |pages=13–21}}</ref>
===Thumb spike===
[[Image:Iguanodon thumb spike.jpg|thumb|The original thumb spike found in Maidstone in 1840]]
The thumb spike is one of the most well-known features of ''Iguanodon''. Although it was originally placed on the animal's nose by Mantell, the complete Bernissart specimens allowed Dollo to correctly place it on the hand, as a modified thumb. (This would not be the last time a dinosaur's modified thumb claw would be misinterpreted; ''[[Noasaurus]]'', ''[[Baryonyx]]'', and ''[[Megaraptor]]'' are examples since the 1980s where an enlarged thumb claw was first put on the foot, as in [[dromaeosauridae|dromaeosaurids]].)
This thumb is typically interpreted as a close-quarters [[stiletto]]-like weapon against predators,<ref name=DBN85b/><ref name=DBN04/> although it could also have been used to break into [[seed]]s and [[fruit]]s,<ref name=DBN04/> or against other ''Iguanodon''.<ref name=NM01/> One author has suggested that the spike was attached to a [[venom]] gland,<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=0688032222 |pages=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 = [[Darren Naish|Naish, D]] | title = Venomous & Septic Bites | url= http://dml.cmnh.org/1998Nov/msg00387.html | accessdate = 2007-02-14}}</ref>
===Possible social behaviour===
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 [[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 ''Mantellisaurus'' to ''Iguanodon bernissartensis'', and confined geographic nature, may record mortality of herding animals migrating through rivers.<ref name=DBN87/>
Unlike other purported herding dinosaurs (especially hadrosaurs and [[ceratopsidae|ceratopsids]]), there is no evidence that ''Iguanodon'' was [[sexual dimorphism|sexually dimorphic]], with one [[gender]] appreciably different from the other. At one time, it was suggested that the Bernissart ''I.'' "mantelli", or ''I. atherfieldensis'' (both now ''Mantellisaurus'') represented a gender, possibly [[female]], of the larger and more robust, possibly [[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=DBN80/><ref name=DBN85b/><ref name=GSP06/>
==In popular culture==
[[Image:Iguanodons crystal palace email.jpg|thumb|left|Statues of ''Iguanodon'' by [[Benjamin Waterhouse Hawkins]], still visible at [[Crystal Palace, London|Crystal Palace]].]]
Since its description in 1825, ''Iguanodon'' has been a feature of worldwide [[popular culture]]. Two lifesize reconstructions of ''Iguanodon'' built at the [[The Crystal Palace Dinosaurs|Crystal Palace]] in London in 1852 greatly contributed to the popularity of the genus.<ref>{{cite journal| last = Smith | first = Dan | authorlink = | coauthors = | title = A site for saur eyes | journal = New Statesman | volume = | issue = | pages = | publisher = | date = 2001-02-26 | url = http://www.newstatesman.com/200102260031 | doi = | id = | accessdate = 2007-02-22}}</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.
Several [[motion picture]]s have featured ''Iguanodon''. In the Disney film ''[[Dinosaur (film)|Dinosaur]]'', an ''Iguanodon'' named Aladar served as the protagonist with three other iguanodonts as other main characters; a loosely-related [[Dinosaur (Disney's Animal Kingdom)|ride of the same name]] at [[Disney's Animal Kingdom]] is based around bringing an ''Iguanodon'' back to the present. ''Iguanodon'' is one of the three dinosaur genera that inspired [[Godzilla]]; the other two were ''[[Tyrannosaurus]]'' and ''[[Stegosaurus]]''.<ref name="USAToday">{{cite news | last = Snider | first = Mike | coauthors = | title = Godzilla arouses atomic terror | work = USA Today | pages = | language = | publisher = Gannett Corporation | date = 2006-08-29 | url = http://www.usatoday.com/life/movies/news/2006-08-28-godzilla-dvd_x.htm | accessdate = 2007-02-21 }}</ref> ''Iguanodon'' has also made appearances in some of the many ''[[The Land Before Time (series)|Land Before Time]]'' films, as well as episodes of the [[The Land Before Time (TV series)|television series]].
[[Image:Iguanodon model.JPG|right|thumb|A model of ''Iguanodon'' at the [[Oxford University Museum of Natural History]].]]
Aside from appearances on the silver screen, ''Iguanodon'' has also been featured on the [[television]] documentary miniseries ''[[Walking with Dinosaurs]]'' (1999) produced by the [[BBC]], and played a starring role in [[Sir Arthur Conan Doyle]]'s book, ''[[The Lost World (Arthur Conan Doyle)|The Lost World]]''. It also was present in [[Bob Bakker]]'s ''[[Raptor Red]]'' (1995), as a ''[[Utahraptor]]'' prey item. A [[asteroid belt|main belt]] [[asteroid]], {{mp|1989 CB|3}}, has been named <!--no italics here-->[[9941 Iguanodon]]<!--no italics here--> in honour of the genus.<ref>{{cite web | title = JPL Small-Body Database Browser: 9941 Iguanodon (1989 CB3) | publisher = [[NASA]] | url= http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=9941 | accessdate = 2007-02-10}}</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 | accessdate = 2007-02-10}}</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 [[barometer]] of changing public and scientific perceptions on dinosaurs. Its reconstructions have gone through three stages: the [[elephant]]ine quadrupedal horn-snouted reptile of the [[Victorian era|Victorians]]; a bipedal but still fundamentally reptilian animal using its tail to prop itself up; and finally, its current, more agile and dynamic representation, able to shift from two legs to all fours. The second representation dominated the twentieth century, but was slowly overturned during the 1960s.<ref name=SGL00>{{cite book | last = Lucas | first = Spencer G. | | title = Dinosaurs: The Textbook|location=Boston | publisher = McGraw-Hill| date = 2000 | pages = 13 | isbn = 0-07-303642-0}}</ref>
==References==<!-- Palaeogeography, Palaeoclimatology, Palaeoecology 130 (1997) 275-292 [identification may be doubtful or disputed] -->
{{reflist|2}}
== External links ==
{{commons}}
{{wikibooks|Wikijunior Dinosaurs/Iguanodon}}
* [http://www.lhl.lib.mo.us/events_exhib/exhibit/exhibits/dino/man1825.htm Paper Dinosaurs, 1824–1969: 2. Mantell's ''Iguanodon'' Teeth, 1825], from Linda Hall Library.
* [http://www.dinohunters.com/Iguanodon/bernissart_page.htm The Bernissart Iguanodons] (''Iguanodon'' herd found in Belgium).
* [http://www.dinodata.org/index.php?option=com_content&task=view&id=6718&Itemid=67 ''Iguanodon''] DinoData.
* [http://collections.tepapa.govt.nz/objectdetails.aspx?oid=212194&coltype=history®no=gh004839 Mantell's ''Iguanodon'' tooth in the collection of the Museum of New Zealand Te Papa Tongarewa]
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