Pyrite threatened a palaeontological treasure: the mammoth of Dendermonde, part of our collection. Museum employees and volunteers came together to restore the skeleton.
1968: 16 year old Hugo De Potter finds a bone in a sand extraction site in Dendermonde. His biology teacher suspects it is a mammoth vertebra, so the manager of the quarry gives De Potter permission to dig out the other bones. ‘Every Wednesday afternoon, weekend and holiday, I went there to dig. You can imagine returning home on my bike carrying a mammoth femur was kind of an attraction,’ De Potter remembers. By 1972, he had collected an enormous amount of mammoth bones.
The city of Dendermode claimed the collection and moved it to our Institute. But when De Potter came to work for our palaeontology department, years later, he was reunited with his own mammoth collection. He helped to assemble the skeleton – completed with some pieces from the Institute’s collection – on a metal frame. In 1975, the 29.000 year old treasure received a spot on the upper floor of the Vleeshuismuseum in Dendermonde.
Infesting Pyrite
But the mammoth of Dendermonde, like many other fossils, is threatened by an assassin: pyrite. The gold-resembling mineral, also known as fool’s gold, grows in the bones like a tumour. It can expand the bones to a point at which they break or even pulverize. Specialists from our Institute, together with volunteers of the Belgian Palaeontology Association, gave the skeleton a makeover.
They removed as much pyrite as possible, with scalpels, needles and brushes. After this, the pyrite in the fossil remains had to be stabilized: the bones got coated with an alcohol solution called Monoethanolaminthioglykolat. To remove the solution, the palaeontologists rinsed the remains with pure alcohol. When the bone material had dried, it got a layer of Mowilith, a type of polyvinyl actetate that is dissolved in aceton. This lays a film around the fossils, to close them off from air. And the finishing touch: filling up the cracks with a paste and giving it the right colour. 'All these techniques can slow down the decline, but never fully stop it’, says Annelise Folie, conservator of the palaeontological collections of our Institute. ‘We have to check regularly and the restoration work has to be redone in a few years.’
Two-Fold
The mammoth of Dendermonde was not found in one piece (which palaeontologists call ‘articulated’). The 74 parts are possibly from 74 different mammoths. These are mammoths that probably died in the Scheldt basin. The bodies floated to the lowest point.
The specimen is ‘two-fold’. ‘The skull and tusks are male, the pelvis is clearly female’, says Anthonie Hellemond, head of the Belgian Palaeontology Association, who leads the restauration. The skeleton is near-complete, but the foot- and hand bones are missing. ‘The little bones wash away easier through river activity and end up somewhere else. Or they get detached from the skeleton because scavengers, like hyenas, ripped of legs. One of the bones clearly shows bite marks from hyenas, by the way.’
Even More Mammoth
This restauration project was a great collaboration between a federal research institute, a city government and an association to conserve a unique piece of Belgian heritage and to give the public an image of the remarkable ice age fauna.
Next to the mammoth of Dendermonde, our Institute holds those of Lier and Hoboken. The mammoth of Lier – which you can see in our Museum – was the first that was shown to the public in Western Europe and the second worldwide, behind the natural history museum in Saint Petersburg.
