Iguanodon is a genus of the iguanodont family, which was named after it. It lived in the early Cretaceous in Europe; specimens from Asia and North America have been reassigned to Altirhinus and Dakotadon, respectively. It lived 125/126 million years ago.[1] Its most famous feature was the spikes on each opposable thumb. It could switch from being bipedal to quadrupedal.
Iguanodon was discovered in 1822 and described three years later by English doctor and fossil-collector Gideon Mantell. It's name means "iguana tooth". 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 Dinosauria. A large, bulky herbivore, Iguanodon is a member of 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.
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 bonebeds, have allowed researchers to make informed hypotheses regarding many aspects of the living animal, including feeding, movement, and social behavior. 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.
A large, bulky herbivore, Iguanodon is thought by some to be in the same family as the duck-billed hadrosaurs. The taxonomy of the genus continues to be a topic of study as new species are named or long-standing ones reassigned to other genera.
History[]
The original I. anglicus teeth from Mantell's 1825 paper
The discovery of Iguanodon has long been accompanied by a popular legend. The story goes that Gideon Mantell's wife, Mary Ann, discovered the first teeth of an Iguanodon in the strata of Tilgate Forest in Whitemans 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, although he had previously stated in 1827 that Mrs. Mantell had indeed found the first of the teeth later named Iguanodon. Other later authors agree that the story is not certainly false. It is known from his notebooks that Mantell first acquired large fossil bones from the quarry at Whitemans Green in 1820.[2][3]
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.[3]
However, assistant-curator Samuel Stutchbury recognised that they resembled those of an iguana he had recently prepared, albeit twenty times longer.
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 Greek word ὀδών (odon, odontos or "tooth").
Based on isometric scaling, he estimated that the creature might have been up to 18 metres (59 feet) long, more than the 12-metre (39 ft) length of Megalosaurus.
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 Iguanoids ("Iguana-like") or Iguanodon.
Fossil iguanodont remains found in Maidstone in 1834, now classified as Mantellisaurus
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".
Mantell's "Iguanodon" restoration based on the Maidstone Mantellodon remains
A more complete specimen of similar animal was discovered in a quarry in Maidstone, [4][5][6] Kent, in 1834 (lower Lower Greensand Formation), which Mantell soon acquired. The Maidstone slab was utilized in the first skeletal reconstructions and artistic renderings of Iguanodon, but due to its incompleteness, Mantell made some mistakes, the most famous of which was the placement of what he thought was a horn on the nose. The discovery of much better specimens in later years revealed that the horn was actually a modified thumb.
Still 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 supporter to their coat of arms in 1949.
- It is classified as cf. Mantellisaurus by McDonald (2012); as cf. Mantellisaurus[7] atherfieldensis by Norman (2012); and made the holotype of a separate species Mantellodon carpenteri by Paul (2012), but this is considered dubious and it is generally considered a specimen of Mantellisaurus Statues in Crystal Palace Park[8] based on the Maidstone specimen of "Iguanodon", designed by Benjamin Waterhouse Hawkins, after restoration in 2002.
Statues in Crystal Palace Park based on the Maidstone specimen of "Iguanodon", designed by Benjamin Waterhouse Hawkins, after restoration in 2002
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 creationist, opposed the early versions of 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 feet), determined that they were not simply giant lizards, and put forward that they had advanced and mammal-like, characteristics.[2]
In 1849, a few years before his death in 1852, Mantell realised that iguanodonts were not heavy, pachyderm-like animals, as Owen was putting forward, but had slender forelimbs; however, his passing left him unable to participate in the creation of the Crystal Palace dinosaur sculptures, and so Owen's vision of the dinosaurs became that seen by the public for decades.
Description[]
Size of Iguanodon bernissartensis compared to a human
Iguanodon was a large herbivore that could shift from two legs to four legs.[9] The best-known one, I. bernissartensis, weighed about 3.5 tons,[10] and was about 33 ft long as an adult; some may have been as long as 43 ft.[11] It had a large, tall but slim skull, with a toothless beak probably covered with keratin, and teeth like those of an iguana, but much larger and more closely packed.[9]
Modern skeletal diagram of I. bernissartensis
The arms were long (up to 75% the length of the legs in I. bernissartensis) and stout,[11] with hands that were hard to bend and built so that the three central fingers could bear weight.[9] The thumbs were cone-shaped spikes that stuck out from the three main digits. In early restorations, the spike was placed on its nose. Later fossils revealed the true place of the thumb spikes,[12] but their true role is still debated. They could have been used for defense, or to get food. The little finger was slim and dextrous, and could have been used to operate objects. The phalangeal formula is 2-3-3-2-4, meaning that the innermost finger (phalange) has two bones, the next has three, etc. The legs were strong, but not built to run, and each foot had three toes. The spine and tail were supported and stiffened by ossified tendons, which were tendons that turned to bone during life (these rod-like bones are left out from most skeletal mounts and drawings).[9] As a whole, its form was a lot like that of its later relatives, the hadrosaurids.
Iguanodon teeth are, as the name suggests, like those of an iguana, but larger. Unlike hadrosaurids, which had columns of replacement teeth, Iguanodon only had one replacement tooth at a time for each position. The 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. 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. Quite similar to modern herbivores of today; such as Bovines and Cervids.
Classification[]
Life restoration of I. bernissartensis
Life restoration of I. galvensis
Restoration of I. bernissartensis (second from left) among other ornithopods
Iguanodon gives its name to Iguanodontia, a large group of ornithopods from the Middle Jurassic to the Late Cretaceous. Aside from Iguanodon, some of the best-known of the clade are Dryosaurus, Camptosaurus, Ouranosaurus, and the duck-bills, or hadrosaurs. In old sources, Iguanodontidae was shown as a distinct family.[13][14] 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. With the advent of cladistic analyses, Iguanodontidae as traditionally construed was shown to be paraphyletic, and these animals are recognised to fall at different points in relation to hadrosaurs on a cladogram, instead of in a single distinct clade. 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 Hadrosauroidea. Iguanodon lies between Camptosaurus and Ouranosaurus in cladograms, and is likely descended from a camptosaur-like animal.[9] At one point, Jack Horner thought, based on skull traits, that hadrosaurids formed two more distantly related groups, with Iguanodon on the line to the flat-headed hadrosaurines, and Ouranosaurus on the line to the crested lambeosaurines,[15] but this has been rejected.[9][16]
The cladogram below follows an analysis by Andrew McDonald, 2012.
| Iguanodontia |
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Species[]
Skeletal restoration of I. bernissartensis by 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.
Mounted skeleton of Mantellisaurus atherfieldensis, Natural History Museum, London
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.
Mounted skeleton of Cumnoria prestwichii, Oxford University Museum of Natural History
I. anglicus was the original 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 International Commission on Zoological Nomenclature changed the type species to the much better known I. bernissartensis, with the new holotype being IRSNB 1534.
Original I. anglicus teeth and thumb spike described by Mantell
The original Iguanodon tooth is held at 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.
Paleobiology[]
I. bernissartensis skull and neck
When the first Iguanodon skeleton was discovered it 1822, was believed to walk much like an iguana, on all four legs. Its thumb spike was believed to be a horn on its head (only one thumb spike was found). At one point it was also thought to have lived in trees, but this has been long since proven completely wrong.
A hand in Brussels; the extended digit is the prehensile fifth finger
One of the more noticeable and clearly observable characteristics of the Iguanodon species is its "thumbs". Instead of a thumb it had a large spike that paleontologists believed Iguanodon individuals used for defensive purposes, and could also been used for getting food. The "pinky" finger of an Iguanodon is believed to have acted as its thumb.
I. bernissartensis hand with spike
Paleontologists believe and theorize that Iguanodon may have traveled in herds. In large herds of Iguanodons and other dinosaurs, mainly the ankylosaur family, would join in the migrations to gain protection to the herd as a whole, and also additionally providing an escort.
Restoration of an I. bernissartensis group, with other dinosaurs from the Wessex Formation
Iguanadon's anatomical gait generally thought as quadupedal, although it could have stood up on its hind legs as well. Its purpose for bipedal gait is generally to reach taller, harder to reach plants, as well as for a fast getaway and even stood on guard against potential predators such as Neovenator, Baryonyx, and other such theropods. They didn't have too flat of bills or like their hadrosaur descendants, but still had many teeth within its cheeked jaws and could chew tough food pretty easily. Thanks to this revolutionary adaptation, Iguanodon was perhaps the most successful dinosaur genus, with it and its relatives being found on nearly every continent across multiple eras.
Posture and movement[]
Nineteenth-century painting showing I. bernissartensis in outdated tripod pose
The first fossil remains were incomplete, which led to much speculation on the gait and life of Iguanodon. Iguanodon was first shown as a four-legged horn-nosed beast, but as more bones were found, Mantell saw that the front legs weren't as long as the back legs. His rival Owen thought 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 two-legged nature was revealed with the discovery of the Bernissart skeletons. But, it was depicted in an upright posture, with the tail dragging on the ground, acting as the third leg of a tripod.
When David Norman looked at Iguanodon, he showed that this posture was unlikely, as its long tail was stiff from ossified tendons.[17] If Iguanodon tried to lean on its tail, it would break.[12] If you put it in a horizontal stance, it explains many traits of the arms and pectoral girdle. For example, the hand is relatively stiff, with the three central fingers fused in a hoof-like structure. This would have let them bear weight. The wrist is quite still, and the arms and shoulder bones strong. All these traits show that they spent time on all fours.[17]
Assigned track from Germany
It also seems that Iguanodon spent more time on all fours as it got old and heavier; young I. bernissartensis have shorter arms (60% of hind limb length) than adults (70%).[9] When they walked on all fours, their hands would have been held so that the palms faced each other, as shown by tracks and the form of their arms and hands.[18][19] The three toed foot of Iguanodon was long, and when they walked, both the hand and the foot would have been used on the fingers and toes.[9] The top speed of Iguanodon may have been 14.9 mph,[20] which would have been on two legs; it could not have galloped on four legs.[9]
Large three-toed footprints are known in Early Cretaceous rocks of England, like Wealden beds on the Isle of Wight. Some authors linked them with dinosaurs early on. Samuel Beckles said in 1854 that they looked like bird tracks, but might have come from dinosaurs.[21] In 1857, the hind leg of a young Iguanodon, with three-toed feet, was found and these tracks may be from the Iguanodon.[22][23] While there's no firm proof, these tracks are often said to be Iguanodon.[12] Footprints in England show what may be an Iguanodon on all fours, but the foot prints are poor, which makes a direct connection hard.[17]
Predation and Predators[]
A Neovenator chases the herd of iguanadons.
Its unclear if Iguanadon; at the very least fully mature specimens; had any significant natural predators given to their rather large size; bulky anatomy and natural defenses such as their infamous hand spike. Meanwhile the adults could assumed to be far safer from the opportunistic predators such as Neovenator, Baryonyx, Larger species of Dromaeosauridae and similar theropods; the subadults as well as the juveniles; on the other hand; were in direct threat from all the aforementioned theropods. Presumably the elderly, ill, injured and disabled specimens were prone to danger as well.
A direct evidence for the predation on Iguanadontids comes from the Spinosaurid Baryonychinae Baryonyx. The only known Specimen's cavity found with fish bones as well as digested remains belonging to a subadult iguanadontid. Its unknown if this represents a scavenging event or an occurance of direct predation.
Another noteworthy evidence comes from Iberian Baryonychinae Spinosaur Iberospinus, this theropod if found to be in direct association to several iguanadontid; likely Iguanadon specimens.
Its unknown if these specimens represent scavenging or actual predation; albeit given the number of occurances and the number of directly attributed iberian spinosaurid-iguanadontid fossils; the predation theory seem to be more probable; instead of a one-time scavenging event.
Paleoecology[]
Living during the Early Cretaceous period, around 140–110 million years ago and said to have been among the most successful dinosaurs ever known, Iguanodon occupied a wide range of habitats across western Europe (Belgium, Germany, England, and Spain), ranging from forests to coastlines to swamps while its relatives (such as Dakotadon) inhabited North America as well as Africa (Ouranosaurus), Asia (Altirhinus), and Australia (Muttaburrasaurus). It was a versatile large herbivore that normally walked on all fours but could rise onto its back legs to reach food or run. The famous thumb spikes may have been effective weapons against predators, such as the large theropod Baryonyx and Neovenator, however, this is still debated. Unlike the later hadrosaurs, Iguanodon also had a prehensile fifth finger to grasp food. Analysis of Iguanodon jaws suggests that it was able to eat tough plant material by grinding its food.
JPInstitute.com Description[]
Iguanodon has become quite famous as a result of its starring role in Dinosaur, but before that it helped people understand what dinosaurs really looked like. It was one of the first complete skeletons ever found. This allowed scientists who had never seen a complete dinosaur, to figure out what it would have looked like in life. In fact, the first time this common dinosaur was found as just a partial skeleton, scientists put its thumb spike on its nose!
This was only the second dinosaur to be described, after Megalosaurus. Its teeth were discovered in the early 1820's in England - these original fossils were "rediscovered" in the British Museum in 1977. As nothing like it had ever been described in scientific literature, the teeth of this creature were a puzzle that an amateur paleontologist named Gideon Mantell solved by comparing them to the teeth of living animals. Mantell found that the teeth looked like those of a modern iguana and named it Iguanodon. He speculated that it was a huge extinct version of this modern reptile. It was in 1878 in a coal mine in Belgium that 24 fairly complete and articulated specimens were found. Although they were of a larger species, they clearly showed what this creature looked like in life.
Dinosaur Field Guide Description[]
Iguanodon ("iguana tooth') was the first really huge ornithopod, or two-legged plant-eating dinosaur. The arms were longer than an adult human's, and all the bones of the skeleton were thick. This was a very powerful dinosaur that could defend itself quite well. Its massive arms ended in large hands that carried "thumb spikes." These were the perfect weapons to put out the eye of an attacking theropod. Iguanodon is one of the original three members of the group Dinosauria. When Richard Owen coined the word dinosaur in 1842, he defined it to mean "fearfully great, a lizard." He based the name on three dinosaurs--Megalosaurus, Iguanodon, and Hylaeosaurus. The story of the discovery and naming of Iguanodon has been the subject of several books. No other two-footed plant-eater is as historically famous. One reason for this was a spectacular find in Bernissart, Belgium, in 1878. Workers in a coal mine found over a dozen well-preserved skeletons at a depth of over 1,000 feet (300 m).
Fun Facts[]
Most Iguanodon skeletons are exhibited in the "old style, with the tail dragging on the ground. We now know that dinosaurs did not drag their tails.
Trivia[]
The owners of the coal mine in Belgium shut it down for two years so that scientists could excavate the bones- a very rare case of cooperation between scientists and corporate land owners!
Gallery[]
Appearance in other media[]
Jurassic Park[]
- It appears in 2001's Jurassic Park III: Park Builder game.
- Iguanodon was planned to appear in the 2003 game Jurassic Park Operation Genesis. For unknown reasons, the development of Iguanodon was terminated. The CD-ROM contains two files containing the parameters of the dinosaur.
- Iguanodon appears in Jurassic World: Alive.
- Iguanodon can be unlocked in Jurassic World Evolution, added in the Cretaceous Dinosaur Pack DLC released on December 13, 2018. Its appearance in the game is incredibly accurate (in fact it's one of the most accurate appearances in a video game yet), and is the only ornithopod in the game so far that is capable of defending itself against small and medium carnivores.
- Iguanodon appeared in the movie Jurassic World: Dominion.
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Read more Iguanodon on Jurassic Park Wiki |
The Land Before Time[]
- Iguanodon appear in various The Land Before Time films and TV series episodes, mostly as either minor or background characters, starting with 1995's The Land Before Time III: The Time of the Great Giving.
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List of species in The Land Before Time |
We're Back! A Dinosaur's Story[]
- Iguanodon appears in Your Pet Dinosaur: An Owner's Manual.
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Read more Iguanodon on We’re Back A Dinosaur’s Story Wiki |
Links[]
http://web.archive.org/web/20040214162847fw_/http://www.jpinstitute.com/dinopedia/dinocards/dc_iguan.html https://web.archive.org/web/20080704172803/http://kids.yahoo.com/dinosaurs/52--Iguanodon
References[]
- ↑ Norman, David B. 2004. "Basal Iguanodontia". In Weishampel D.B., Dodson P., and Osmólska H. (eds) The Dinosauria. 2nd ed, Berkeley: University of California Press. pp413–437 ISBN 0-520-24209-2
- ↑ 2.0 2.1 https://www.nhm.ac.uk/discover/the-discovery-of-iguanodon.html
- ↑ 3.0 3.1 https://www.discovermagazine.com/planet-earth/the-many-iterations-of-iguanodon
- ↑ https://www.visitmaidstone.com/inspire/history-of-maidstone/maidstones-iguanadon
- ↑ https://museum.maidstone.gov.uk/explore/collections/geology/maidstone-and-the-iguanodon/
- ↑ https://museum.maidstone.gov.uk/maidstones-iguanodon/
- ↑ https://www.nhm.ac.uk/discover/search-for-the-real-iguanodon.html
- ↑ https://www.londonxlondon.com/crystal-palace-park-iguanodons/
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 Template:Cite book Cite error: Invalid
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- ↑ 11.0 11.1 Template:Cite book
- ↑ 12.0 12.1 12.2 Template:Cite book Cite error: Invalid
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- ↑ Norman, David B. "Iguanodontidae". The Illustrated Encyclopedia of Dinosaurs, 110–115.
- ↑ Template:Cite book
- ↑ Template:Cite book
- ↑ 17.0 17.1 17.2 Norman, David B. (2004). "Basal Iguanodontia". In Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 413–437. ISBN 0-520-24209-2.
- ↑ Template:Cite journal
- ↑ Template:Cite book
- ↑ Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite web