FINDING AN ICHTHYOSAUR
To find an ichthyosaur on the beach at Charmouth is goal of all fossil hunters but that is just the start of the problems. How do you remove the fossil? How do you transport the heavy pile of stone from the beach and how do you clean and prep the creature?
In 2012 a local palaeontologist Richard Edmunds found an Ichthyosaur. Below is a précis of Richard’s ichthyosaur year from discovery to display.
In September the beaches were still busy with visitors catching the last of the summer’s sun. The tides were low and it was during a fossil hunt on a warm early autumn day that Richard Edmunds came across a scattering of vertebrae. The fossil site was hidden by sea weed and was on the outer limestone ledges, near Lyme Regis.
Richard had initially seen a scattering of vertebrae imbedded into one of the ledges, in the low tidal area. Richard noted the position and was unable to little else as the tide had turned and the sea was coming in. He returned a few weeks later when the low spring tides allowed a further glimpse of the area. A brief examination of the ledges showed further vertebrae, ribs and assorted bones.
The search and location for the rest of the ichthyosaur occurred over several weeks, when weather and tides would allow.
By October a further section of fused vertebrae were found in a shallow, muddy pool. Due to the position of the find access was limited to periods during a low spring waters. This tidal flow allowed for no more than an hour of extraction and preparation on the site. The autumn weather played havoc with the schedule at one stage the site was covered in fine silt after the passing of an autumn gale. Luckily the fossil was not destroyed. The weather was cold and much of the delicate work was done in willies and frozen wet fingers.
By early November Richard had recovered and removed sufficient sections to identify that the fossil was that of a juvenile ichthyosaur 85 cm in length.
Most of the creature was encased in a fine shale material which provides little structural strength and had made the extraction difficult. Each recovered section was carefully recorded and photographed and numbered.
By December all that could be recovered from the site had been removed and taken back to the workshop (dining room) and the preparation and cleaning process was started.
The first part of the operation was to clean and remove as much shale as possible from underneath the fossils and carefully take out any organic remains from the lias. This was accomplished by the careful use of an old kitchen knife.
The roughly cleaned blocks of lias were then stored in a damp garage, to slowly dry out. It took nearly four weeks for the stone and lias to dry sufficiently that the stone could be worked on.
The rock on the back of the block containing the fossil was further reduced with an angle grinder and the numbered blocks of lias rock were placed back in their original positions.
The assembly of the Jurassic ichthyosaur jigsaw had started. The large blocks of stone were fixed and glued together and loose bones and vertebrae were, placed back in their original positions.
There was still a further box of assorted bones and vertebrae which had been removed from the site. These were all carefully washed and glued and placed where they had originally been found. This was a time consuming, delicate and protracted process.
Some of the bones required further cleaning. A pneumatic air pen was used that removed attached limestone from the ichthyosaur. The pen vibrates a small needle size chisel. Further delicate cleaning was required. An air abrasives gun carefully blew a stream of sodium bicarbonate abrasive on to the surface of the fossilized bone. This abrasive removed the last of limestone that clung to the fossil. (The sodium bicarbonate was abrasive enough to remove the shale with- out damaging the harder bone structure).
Christmas had been and gone and the final assembly of the ichthyosaur began. Wooden plywood batons were glued to the underside of the fossil and a further coat of fibreglass matting was applied to provide strength and support to the delicate fossil. During February the last jobs were completed. Tiny cracks and missing bones were filled in with special paleo putty which had to be colour matched to the original material and finally a light varnish was applied to the completed fossil.
The ichthyosaur is now finished. Time taken from start to finish about 260 hours of work.