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Two grey-green Iguanodon, one on four legs and one on two, in side view
Life restoration of Iguanodon bernissartensis in a quadrupedal and a bipedal pose, by Davide Bonadonna.Image credit: Davide Bonadonna, CC BY 4.0, via Wikimedia CommonsCC BY 4.0Source (opens in a new tab)

Iguanodon bernissartensis

Pronounced ig-WAH-noh-don ber-nis-ar-TEN-sis

Iguanodontia · Iguanodontidae

A large plant-eating ornithopod from the Early Cretaceous of Europe with a conical thumb spike. About thirty skeletons were found 322 m underground in a Belgian coal mine at Bernissart in 1878.

  • Famous specimen
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Period
Cretaceous· Barremian
Diet
Herbivore
Length
6.3–10 m
Mass
4,500 kg
Location
Hainaut, Belgium, Europe

Quick answers

How big was Iguanodon bernissartensis?
Iguanodon bernissartensis was about 6.3–10 m long. It stood about 2.2–2.8 m tall at the hips. It weighed about 4.5 t. (Sciences 2026; Museum & London 2026)
When did Iguanodon bernissartensis live?
Iguanodon bernissartensis lived during the Early Cretaceous, about 125.8–119.6 million years ago. (Paleobiology Database: Iguanodon occurrences 2026)
Where have Iguanodon bernissartensis fossils been found?
Fossils of Iguanodon bernissartensis have been found in Sainte-Barbe Clays Formation (Hainaut) and Belgium. (Mantell 1825; Boulenger 1881)
What did Iguanodon bernissartensis eat?
Iguanodon bernissartensis was a herbivore. (Mantell 1825; Boulenger 1881)
Who named Iguanodon bernissartensis, and when?
Iguanodon bernissartensis was described by George A. Boulenger in 1881. (Boulenger 1881; Paleobiology Database: Iguanodon occurrences 2026)
Was Iguanodon bernissartensis in Jurassic Park?
Yes. Iguanodon bernissartensis appears in Jurassic World Dominion (2022). A herd herbivore in Dominion. One of the first dinosaurs ever named (1825), from its teeth; its thumb spike is real, its exact use is not known. (Wikipedia: Dinosaurs in Jurassic Park 2026; Mantell 1825)

On this page

Period
Cretaceous125.8–119.6 Ma
Diet
Herbivore
Length
6.3–10 m
Mass
4.5 t
Location
Belgium, Europe
Classification
Iguanodontia · Iguanodontidae
Described
1881, George A. Boulenger

Overview

Iguanodon was the second dinosaur ever named. Gideon Mantell named it in 1825 from teeth found in Sussex that resembled those of an iguana, and he placed a spike on its nose. Only the complete skeletons from Belgium showed that the spike belonged on the thumb.

In 1878 miners at Bernissart, Belgium, found dinosaur bones 322 m underground in a coal mine. Some thirty fairly complete skeletons were recovered, most of them Iguanodon bernissartensis, named by George Boulenger in 1881. From 1882 Louis Dollo and Louis De Pauw mounted them in Brussels, where they are still displayed.

Iguanodon was a heavy animal that could walk on four legs or two. Its hand combined a spike-like thumb, three middle fingers that could bear weight and a grasping fifth finger. It lived in the Barremian to early Aptian, and I. bernissartensis is now the type species of the genus.

Name meaning

"Iguana tooth", from iguana and Greek odous ("tooth") (Mantell 1825); bernissartensis for Bernissart, Belgium (Boulenger 1881).

Biology & evidence

What scientists think about how this animal lived, and how strong the evidence for each idea is.

Teeth

  • Iguanodon was named for teeth that look like an iguana's.

    Evidence level: Direct evidence

    Mantell compared the worn fossil teeth with those of a living iguana, much smaller but similar in shape.

    Evidence for / against · 1
    Evidence for

    • Specimen · Mantell's Iguanodon teeth

      Large fossil teeth from Sussex that resembled those of an iguana, the basis of the name Iguanodon.

Behavior

  • Iguanodon used its thumb spike as a weapon.

    Evidence level: Hypothesis

    The spike was probably sheathed in sharp horn and could have been used in defence or combat; food handling has also been suggested. No direct evidence of its use is known.

    Evidence for / against · 1
    Evidence for

    • Comparative anatomy · Iguanodon hand and thumb spike

      The thumb is a large conical spike; with the three middle fingers and a grasping fifth finger the hand has three different functions.

      Specimen: IRSNB 1534

Other

  • The spike of Iguanodon was on its thumb, not on its nose.

    Evidence level: Direct evidence

    Mantell had placed a lone spike on the nose. Articulated skeletons from Bernissart showed it sits on the hand.

    Evidence for / against · 2
    Evidence for

    • Comparative anatomy · Iguanodon hand and thumb spike

      The thumb is a large conical spike; with the three middle fingers and a grasping fifth finger the hand has three different functions.

      Specimen: IRSNB 1534

    • Specimen · Bernissart Iguanodon skeletons

      About thirty relatively complete skeletons recovered 322 m underground in the Bernissart coal mine; eight I. bernissartensis are mounted in Brussels.

      Specimen: IRSNB 1534

Size

Length
6.3–10 m

(32.8 ft)

Based on Bernissart mounts (IRSNB)

Height
2.5 mpublished range 2.2–2.8 m

(8.2 ft)

Based on Bernissart skeletons (femur c. 1.0-1.1 m)

Mass
4,500 kg
Iguanodon bernissartensis was about 10 m (32.8 ft) long, roughly 5.6 times the height of a 1.8 m adult human.

Timeline

Lived from about 125.8 to 119.6 million years ago (Ma), within the Mesozoic era (252–66 Ma).

Periods: Barremian (125.8–121.4 Ma), Aptian (121.4–113 Ma), Early Cretaceous (145–100.5 Ma)

Barremian-early Aptian bounds of the Bernissart collection in PBDB (PBDB time scale).

Location

Formations

Map data: Natural Earth (public domain). Modern positions, not where the continents were then.

These are the places where fossils have been found, not the full area where the animal lived.

Ecosystem

Lived in: Weald Clay

136–125 million years ago · river system, lake, swamp / wetland, coastal plain

Early Cretaceous lagoons, lakes and rivers of south-east England, fresh to brackish, in a semi-arid, fire-prone climate.

Same ecosystem

Baryonyx walkeri

Cretaceous· BarremianPiscivoreCarnivore

Lived in: Bernissart

lake, swamp / wetland

Early Cretaceous lake in the Mons Basin, Belgium, with laminated clays and lignite; ferns such as Weichselia grew around it.

Classification

  1. cladeDinosauria
  2. cladeOrnithischia
  3. cladeOrnithopoda
  4. cladeIguanodontia
  5. familyIguanodontidae
  6. genusIguanodon
  7. speciesIguanodon bernissartensis

Taxonomic status: Valid

Fossil record

Cast of a Bernissart Iguanodon bernissartensis skeleton at the Muséum national d'Histoire naturelle, Paris, mounted in the old upright posture.Image credit: LadyofHats, Public domain, via Wikimedia Commons, Muséum national d'Histoire naturelle, ParisPublic domainSource (opens in a new tab)
Specimens
Catalog numberStatusInstitutionFound
IRSNB 1534HolotypeRoyal Belgian Institute of Natural Sciences (IRSNB)1878

Which bones each specimen preserves has not been recorded yet.

Skeletal reconstruction of Iguanodon bernissartensis, based mainly on the holotype and completed with other specimens.Image credit: Slate Weasel, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing)CC BY-SA 4.0 (unmodified)Source (opens in a new tab)

Gallery

Historical reconstruction: Édouard Riou's 1863 engraving of Iguanodon fighting Megalosaurus, in the quadrupedal lizard-like style of the Crystal Palace models.Image credit: Édouard Riou, Public domain, via Wikimedia CommonsPublic domain

All specimens

Discovery

Year described
1881
Described by
George A. Boulenger
Type specimen
IRSNB 1534
Iguanodon bernissartensis specimen 'A' drawn as it was found in the Sainte-Barbe coal mine at Bernissart, Belgium, by Gustave Lavalette.Image credit: Gustave Lavalette, Public domain, via Wikimedia CommonsPublic domainSource (opens in a new tab)

Discovery timeline

  1. 1822 · First material found

    Iguanodon teeth found in Sussex

    Large fossil teeth are found in Sussex; the story that Mary Ann Mantell found them is doubted.

    People: Gideon Mantell

  2. 1825 · Formally described

    Mantell names Iguanodon

    Mantell publishes the "iguana tooth" in the Philosophical Transactions.

    People: Gideon Mantell

  3. 1878 · Specimen recovered

    Iguanodon skeletons found in the Bernissart mine

    Miners find bones 322 m underground; the museum is told by telegram on 12 April 1878 and about thirty skeletons are recovered.

  4. 1881 · Formally described

    Boulenger names Iguanodon bernissartensis

    The Bernissart species is named.

    People: George A. Boulenger

  5. 1882 · Major study

    Dollo and De Pauw begin mounting the Bernissart Iguanodons

    The first skeleton goes on display in 1883.

    People: Louis Dollo, Louis De Pauw

In Jurassic Park & Jurassic World

Films

  • Jurassic World Dominion (2022)

On screen

A herd herbivore in Dominion.

Film vs fossils

  • One of the first dinosaurs ever named (1825), from its teeth; its thumb spike is real, its exact use is not known.

Film titles are used for identification only. DinoDex is not affiliated with or endorsed by the Jurassic Park / Jurassic World franchise. All dinosaurs seen in the films

Sources

  1. (2026). Paleobiology Database: Iguanodon occurrences. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?base_name=Iguanodon&show=coords,paleoloc,strat,loc,ref&pgm=gplates (opens in a new tab)
  2. (2026). Wikipedia: Iguanodon. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Iguanodon (opens in a new tab)
  3. (2026). Wikipedia: Dinosaurs in Jurassic Park. Wikipedia. https://en.wikipedia.org/wiki/Dinosaurs_in_Jurassic_Park (opens in a new tab)
  4. Boulenger, G. A. (1881). Sur l'arc pelvien chez les dinosauriens de Bernissart. Bulletins de l'Académie royale de Belgique, 3e série, 1(5): 1-11.
  5. Charig, A. J. & Chapman, S. D. (1998). Iguanodon Mantell, 1825 (Reptilia, Ornithischia): proposed designation of Iguanodon bernissartensis Boulenger in Beneden, 1881 as the type species, and proposed designation of a lectotype. Bulletin of Zoological Nomenclature 55: 99-104. doi:10.5962/bhl.part.157 (opens in a new tab)
  6. Mantell, G. (1825). Notice on the Iguanodon, a newly discovered fossil reptile, from the sandstone of Tilgate forest, in Sussex. Philosophical Transactions of the Royal Society of London: 179-186. doi:10.1098/rstl.1825.0010 (opens in a new tab)
  7. Natural History Museum, London (2026). Iguanodon: the teeth that led to a dinosaur discovery. nhm.ac.uk. https://www.nhm.ac.uk/discover/the-discovery-of-iguanodon.html (opens in a new tab)
  8. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.
  9. Royal Belgian Institute of Natural Sciences (2026). The Bernissart Iguanodons at a glance. naturalsciences.be. https://www.naturalsciences.be/en/discover-join/discover/the-bernissart-iguanodons-at-a-glance (opens in a new tab)