Shepherding the “Belle Epoque” Bernissart Iguanodon collection into the 21st century

  • Claeys, Philippe (Administrative Promotor)
  • Godefroit, Pascal (Co-Promotor)
  • Baele, Jean-Marc (Co-Promotor)
  • Fisher, Valentin (Co-Promotor)

Project Details


In 1878, the Bernissart coalmine produced one of the greatest palaeontological discoveries ever: more than 20 complete articulated skeletons of the dinosaur Iguanodon. As the first complete skeletons ever discovered, they gave scientists and the public an impressive demonstration of what dinosaurs really looked like. As early as 1878, the Bernissart treasure became of the major asset of the Belgian scientific patrimony and was entrusted to the care of the Belgian State and deposited at the Musée royal d’Histoire naturelle in Brussels (now, RBINS). The astonishing array of Iguanodon skeletons remains one of the most impressive displays of dinosaurs worldwide and the main attractor for visitors in the RBINS Museum.
Despite their huge size and massive morphology, the Bernissart Iguanodons are extremely fragile. After their death around a swamp 125 million years ago, their carcasses were rapidly covered by clay sediments and their decomposition occurred in an oxygen-free environment. In such conditions, sulphate-reducing bacteria produced hydrogen sulphide by hydrolysis of the organic matter present in this environment and its combination with detritic and biologic iron led to the crystallization of abundant pyrite in bone pores. In contact with damp air, the pyrite oxidises to form limonite and iron sulphate, inevitably leading to the disintegration of the bone containing them
(Leduc, 2012). As soon as they were extracted from the Bernissart pit, this process led to the embrittlement of Iguanodon bones. Once they arrived in Brussels, the bones were impregnated with a carpenter’s glue-based gelatine and the pyrite was systematically curetted from the bones. Some vertebrae contained more than 1 kg of pyrite, and some long bones, up to 3 kg! Despite their fragility, the bestpreserved Iguanodon specimens were mounted in a lifelike gait
and exhibited to the public as soon as 1883. Between 1933 and 1937, all the skeletons were dismantled to treat important damages resulting from 30 years of exposure to varying temperatures and humidity sustained as museum exhibit.
A mixture of alcohol and a coccid insect-based lacquer (shellac) was used to soak the bones in the hope of stopping the degradation of pyrite. However, at the time, the Janlet Wing was in utter disrepair after WWII; in the 1970’s, the mounted Iguanodon skeletons were even covered by plastic sheeting as it was regularly raining inside their cage! Consequently, from 2004 until 2007, a full preservation treatment was needed: the Iguanodon skeletons were again completely restored at the occasion of the renovation of the Janlet Wing. All the bones were reinforced by a solution of acetone and synthetic polyvinyl acetate alcohol and new glass cages were constructed to protect the skeletons. On that occasion, the RBINS realized that previous restoration campaigns, at the end of the 19th century and in the 1930’s had not been documented, which led to an uncomfortable feeling of working in the dark. The 19th Century decision to display the complete Bernissart Iguanodon collection in the permanent galleries of the Museum evidently had important long-term implications on the preservation of this inestimable treasure. Limiting further pyrite degradation and hampering
its growth requires controlled temperatures and hygrometry, as it is the case today. Regular thorough inspection of the bones to detect fragilized areas is complicated by the iron structure enchasing the specimens and by the fact that their skulls stand over 4 meters.
Moreover, the Bernissart Iguanodons constitute one of the key reference collections for dinosaur scientists, who regularly request access the original specimens for their studies. Each visit inside the Iguanodons cages poses a risk to security of the visitors and of the precious fossils. Therefore, a full scale, state of the art preservation and conservation project is imperative.
Effective start/end date1/01/2131/12/24

Flemish discipline codes

  • Geochemistry not elsewhere classified
  • Biogeochemistry
  • Palaeontology


  • long-term preservation
  • Bernissart Iguanodons
  • Natural History collections