Iguanodon

Credit: Gabriel Ugueto.

*Iguanodon* is an extinct genus of ornithopod dinosaur that lived in Europe, Asia and North America from the Middle Jurassic to the Late Cretaceous.

## History

Presumably, Gideon Mantell's wife, Mary Ann Mantell, had discovered *Iguanodon* teeth while her and Gideon were visiting a patient in Cuckfield, East Sussex. At is at this point in the story that his wife's role would end. However, Dennis Dean (1998-1999) reviews the story, finding her part to likely be a fabrication and distortion of the truth. Scholars such as Darren Naish note that her role was likely downplayed by Gideon and others. Mary Ann was skilled and educated, and was also involved in Gideon's work, as she had observed his illustrations. Naish notes that the two separated in 1839, and Gideon, who developed depression and likely mental health issues, had grown to hate her. Gideon had also instructed his some to remove all traces of Mary Ann from his journal in 1852. Additionally, Mantell had claimed to have discovered the *Iguanodon* teeth himself. Martin Simpson and Andy Revell brought to light a newspaper article by an anonymous author known as the Saunterer that described Mary Ann discovering, buying and bringing a fossil to Gideon Mantell. This indicates that Mary Ann Mantell likely discovered, bought and brought Mantell's fossils to him. This also indicates her involvement in discovering *Iguanodon* and other important fossils was extremely downplayed and out-written by Mantell and carried on to the present day.

Nonetheless, *Iguanodon* is the first dinosaur to be discovered, and part of the original 3 (*Iguanodon*, *Megalosaurus* and *Hylaeosaurus*). *Iguanodon* has become influential in the history of Dinosauria.

## Description

Some specimens measure up to 13 meters long. *Iguanodon* are large, with tall, narrow skulls and toothless keratinous beaks and iguana-like teeth. *I. bernissartensis* has arms up to 75% the leg length. They were proportionally massive and robust with somewhat inflexible hands with fingers adapted to bearing walking stresses. The thumbs bore conical  spikes that projected from the body away from the other digits. Earlier restorations place this on the rostrum. Their exact purpose is debated, but some think they were or defense or foraging for food. A small, dextrous, elongate finger could have manipulated objects. The phalangeal formula is 2-3-3-2-4. The legs were powerful and poor for running. The spine was stiffened by ossified tendons. The teeth are larger than an iguana's, having only a single replacement tooth for each at a time, unlike hadrosaurs. the upper jaw had 29 teeth/side, with none at the front, and the lower 25/side; the mandible has broader teeth, so their number can vary. The teeth are set deep inside the jaws, suggesting a cheek-like structure to keep food in the mouth. It is unknown if this structure was muscular or not.

### Predation

Remains associated with spinosaurs such as *Baryonyx* or *Iberospinus* and injuries inflicted by spinosaurs indicate predation.

## Classification

*Iguanodon* is the namesake of Iguanodontia and Iguanodontidae, where it is placed alongside several other taxa, most tentatively placed.

## Species

### Reassigned Species

* *I. seelyi/seeleyi* (=*I. bernissartensis*?)
* *I. albinus*
* *I. dawsoni*
* *I. exogyrarum*
* *I. fittoni*
* *I. hollingtoniensis/hollingtonensis*
* *I. mantelli*
* *I. lakotaensis*
* *"I. mongolensis"*
* *I. orientalis* (=?)
* *I. phillipsi*
* *I. praecursor/precursor*
* *I. prestwichii*
* *I. suessi*
* *I. foxii* (=*I.* sp.?)
* *I. gracilis*
* *I. major*
* *I. valdensis* (=Iguanodontia indet.)
* *I. angilicus* (dubious)
* *I. ottingeri* (dubious)
* *I. atherfieldensis*
* "I. hoggi"

## References

* https://www.britannica.com/animal/Iguanodon
* https://en.wikipedia.org/wiki/Iguanodon
* http://www.dinosaurisle.com/iguanodon.aspx

1. ↑ Naish, Darren. *Dinopedia: A Brief Compendium of Dinosaur Lore*. Princeton University Press, 2021.
2. ↑ https://twitter.com/TetZoo/status/1290974786168991744
3. ↑ https://kidadl.com/dinosaur-facts/baryonyx-facts
4. ↑ https://www.dailymail.co.uk/sciencetech/article-4667166/amp/Experts-uncover-fossilised-skeleton-Iguanodon.html
5. ↑ https://www.nhm.ac.uk/discover/how-did-baryonyx-change-what-we-knew-about-spinosaurs.html
6. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703214/