From Mud and Bones to a Museum Specimen

Richard Edmonds and Kevan Sheehan with the Pliosaur skull © DCM

The fossil bones of this pliosaur skull were recovered by amateur fossil collector Kevan Sheehan between 2003 and 2008, as they were washed out of a landslide on the coast in Weymouth Bay. The largest piece weighed over 80 kg. Kevan missed only four pieces, three of which were recovered by two other collectors.

In 2003, Kevan found three massive sections of the jaw lying at the base of the cliff, freshly washed out by the sea. Over the next five years he returned to the site after rough weather and rain, patiently recovering the pieces as they became exposed. This is an incredible achievement for an individual collector, and a sign of his dedication to the recovery of something that would otherwise have been lost to the sea. The three smaller pieces were found by other local collectors, Patrick Clarke and Shirley Swaine. One small piece at the back of one jaw is lost, while the front of the jaw was probably uncovered many years ago. It could have been washed away or it could be lying in a collection somewhere not yet linked to this find.

Funding

The specimen was purchased by Dorset County Council’s Museums Service, half its initial cost going to the collector and the other half to the landowner. Preparation (cleaning) and piecing the bones back together took 18 months of skilled, professional work. Funding has been provided by the Heritage Lottery Collecting Cultures programme, with match funding from Dorset and Devon County Councils. The restored specimen was formally unveiled here by Sir David Attenborough, on 8th July 2011.

About the specimen

As yet, the skull has not been allocated a formal name. It is currently being studied by research groups at several UK Universities, and it is thought probable that the pliosaur will receive a species name new to science (probably crediting its finder)

The skull is 95% complete, but there was no sign of the body at the find site. Entire skeletons are rare as they tended to be broken up before burial. The massive skull probably fell off the decaying body as it rolled about in the Jurassic sea, being ripped apart by scavenging creatures, possibly even other pliosaurs. The complete animal would have measured between 15 and 18 m in length.

Its skull is 2.4 m long, and is believed to have possessed the biggest bite of all time – powerful enough to sever a small car in two! Although they never lived at the same time, it could have torn the biggest great white shark alive today clean in half.

Pliosaurs lived during the ‘Mesozoic Era’, the age where reptiles dominated the animal kingdom. Dinosaurs patrolled the land, pterosaurs soared the skies, and a variety of large aquatic reptiles (such as plesiosaurs, pliosaurs, ichthyosaurs and mozasaurs), ruled the seas. Both the dinosaurs and the marine reptiles died out at the end of the Mesozoic Era, 65 million years ago, when a massive extinction event wiped out two thirds of life on Earth. The bones of this pliosaur were found in Kimmeridge Clay sediments (deposited during the Upper Jurassic Period), and are about 155 million years old.

The Sea Dragon – Pliosaur

Scientists have been able to build a picture of how a complete pliosaur would have looked from various fragmentary remains. Living pliosaurs were air-breathing marine reptiles. They are considered to be a subfamily of the plesiosaurs. Unlike some plesiosaurs, they had short necks with just a few vertebrae. Pliosaurs’ barrel-shaped bodies were equipped with a powerful tail and often a huge skull. The creatures swam by means of two pairs of paddle-shaped limbs (for example the forepaddle on the eastern wall of this gallery). The main identifiable differences between skull specimens are the jaws and dentition, which probably reflect different types of prey favoured by each species. They were able to catch and dismember large prey as they had powerful jaws capable of opening wide, and strong, deeply rooted, conical teeth. There is a model of the head as it perhaps looked when alive, hanging in the window of this gallery.

Ongoing research

Scientific study is underway to discover how the animal lived and died, and how its bones became a living reef for encrusting animals. The specimen has already been scanned at the University of Southampton using its high-energy, micro-focus CT scanner – one of the most powerful of its kind in the UK.

The results have been used to reconstruct a three dimensional digital model of the entire skull, revealing fine details of the creature’s internal structure that would otherwise remain a mystery. The University of Bristol are using this CT scan data to understand just how powerful the bite may have been. Experts from the University of Portsmouth will study the fossilisation process, while mud associated with the bones has been sent to the University of Plymouth, to see if any fossil plankton were preserved. Sediment removed from the bones will be studied by experts in the Natural History Museum in search of bones and teeth of animals that may have hunted around the dead skeleton.

Other examples

The Weymouth Bay Pliosaur skull is exceptional because it is 95% complete, but it is not the biggest in the world. Fragments of larger specimens have been found in the brick pits of Oxfordshire. The skull of Kronosaurus, from Australia, was possibly up to 3 m long. Specimens of comparable size have been found in northern Norway, on the island of Svalbard, and in Colombia, South America.

Other pliosaur specimens are on display around the world at