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Iguanodon bernissartensis


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Reconstruction : Christophe Mallet (Institute of Natural Sciences) and Samba Soussoko (Laetoli Production) - CC-BY-ND

Species description:

Iguanodon bernissartensis is an ornithischian dinosaur that lived during the Lower Cretaceous (Upper Barremian-Lower Aptian: 126-122 million years ago) in England, Belgium, Germany and Spain. It was a large herbivorous dinosaur (adults measured between 9 and 11 metres long), weighing around 8 tonnes. The posture and mode of locomotion of this dinosaur are still debated: some palaeontologists think that it ran in a bipedal position, (its immense tail counterbalancing the weight of the front of its body), but could rest on its front legs when walking. Its thumb formed an enlarged spur, covered by a horny sheath, which it could use as a defensive weapon.


Description of the specimen :

IRSNB R51 is the holotype of Iguanodon bernissartensis, on display in the dinosaur gallery of the Royal Belgian Institute of Natural Sciences (Brussels, Belgium). The first Iguanodon bones were discovered in April 1878 in the Bernissart colliery (Mons Basin, Belgium). Miners digging an exploratory gallery through a clay pocket 322 metres below ground unearthed a series of bones, which they brought to the surface. Following this discovery, Belgium's Royal Museum of Natural History quickly organised a large-scale dig lasting more than two years in Bernissart and unearthed around thirty remarkably well-preserved Iguanodon skeletons. This was the very first discovery of complete, articulated skeletons of large dinosaurs, enabling palaeontologists to finally gain a precise idea of the anatomy of these long-extinct giants. IRSNB R51 is the first specimen to be reassembled in a position as it was thougth to have been during his life time. It was presented to the general public for the first time in May 1883.

Osteological descriptions


Skull and mandibles:
With its elongated snout, the skull of Iguanodon superficially resembles that of modern horses. Its jaws and teeth are particularly sophisticated, which may explain the astonishing evolutionary success of these dinosaurs. The anterior part of the jaws is formed by two distinct elements - the premaxilla on the upper jaw and the predentary on the anterior jaw - which were devoid of teeth but covered by a horny beak. Further back in the jaws, the teeth are organised in particularly effective arrays on the maxilla (upper jaw) and the dentary (mandible). Each tooth is diamond-shaped, typical of herbivorous dinosaurs. They are closely interlocked, forming several successive rows, only one of which was used at a time for chewing. As soon as a tooth wore out, it fell out and was immediately replaced by a tooth from the next row. Another striking feature of Iguanodon jaws is the extensive development of coronoid processes at the back of each mandible. These processes form long lever arms along which very powerful masticatory muscles were inserted.


The bones of the skull and mandible of Iguanodon were not completely fused together, even in adults, but some of them formed distinct articular surfaces allowing some intracranial mobility. The two hemi-mandibles are not fused at the front of the snout, but instead form a very loose articular surface, somewhat reinforced by the presence of a median bone characteristic of ornithischian dinosaurs, the predentary. At the back, the articulation of the lower jaw to the rest of the skull, via two long vertical bones called quadrates, was also particularly mobile. Thanks to this high degree of cranial mobility, Iguanodon was able to use both sides of its jaws independently when chewing, whereas today's chewing mammals (cows, for example) can only use one side at a time.


Reconstruction : Christophe Mallet (Institute of Natural Sciences) and Samba Soussoko (Laetoli Production) - CC-BY-ND
Discover the full description on Vertebrates (computers only).  
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Original Drawing: Gustave Lavalette,1883 (Institute of Natural Sciences) - CC-BY
Original Drawing: Gustave Lavalette,1883 (Institute of Natural Sciences) - CC-BY





Project: BRAIN-be 2.0 Iguanodon 2.0 

Christophe Mallet, Filippo Bertozzo, Aurore Mathys, EDDyLab / ULi├Ęge, Jamie MacLaren
Christophe Mallet, Samba Soussoko
Scanner types:
Artec Eva, Artec Spider, HDI FlexScan, photogrammetry
March 2021 - July 2023
Video: Stijn Pardon, RBINS - CC-BY

Video: Samba Soussoko (Laetoli Production) and Christophe Mallet (Institute of Natural Sciences) - CC-BY-ND
Permanent Exhibition  


Picture: Thierry Hubin, RBINS - CC-BY

More info


Picture: Thierry Hubin, RBINS - CC-BY

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In the cage 3#4

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In the cage 3#4

Swiss Army Knife  

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