Weymouth Bay pliosaur

The world's biggest bite!

From: Dorset Museum & Art Gallery

The pliosaur was the largest marine reptile that ever lived. This pliosaur skull dates back around 155 million years, and was discovered on the Jurassic Coast World Heritage Site. It is one of the largest and best preserved fossils of its kind ever found.

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Most powerful marine monster of all time

The pliosaur was an oceanic predator measuring up to 12 metres in length. It had a short neck and a huge, crocodile-like head. Its immensely strong jaws contained a set of huge, razor-sharp teeth. 

  • This skull is a staggering 2.4 metres long.
  • Its bite is believed to have been powerful enough to break a small car in half.
  • It would have been capable of biting in half the biggest great white shark alive today (although they never existed at the same time).
  • The pliosaur would have weighed up to 12 tonnes.
  • It is believed to be 155m years old.

A new species

The pliosaur belongs to the plesiosaur family of long-necked marine reptiles. This pliosaur was declared as a species new to science, and named in honour of its finder, amateur fossil collector, Kevan Sheehan. The new name it was given is Pliosaurus kevani.

The incredible discovery

The fossil bones of the pliosaur skull were recovered by Kevan Sheehan as they were washed out of a landslide on Weymouth Bay. Firstly, in 2003, he found three massive sections of the jaw lying at the base of the cliff. Over the next five years he returned to the site after rough weather, patiently recovering the pieces as they became exposed.

The largest piece weighed over 80 kg. Kevan missed only four pieces, three of which were recovered by two other collectors. One small piece at the back of the jaw is lost.

New home at Dorset Museum

The skull was purchased by Dorset County Council for display at Dorset Museum. Preparation (cleaning) and piecing the bones back together took 18 months of skilled, professional work.

Alongside this conservation work, the Jurassic Coast team and Dorset Museum worked together to create an exciting way to showcase the fossil.

The restored skull was formally unveiled by Sir David Attenborough, on 8th July 2011.

Model to show what the pliosaur looked like when alive. Shown underwater.
Model to show what the pliosaur would have looked like when alive.
Pliosaur photographed with the fossil collector who discovered it, Kevan Sheehan.
Kevan Sheehan standing beside the pliosaur he discovered.
Child lying beside the pliosaur showing how easily he could fit into its mouth!skull, showing
Child lying beside the pliosaur to show the relative size.

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 was scanned at the University of Southampton using its high-energy, micro-focus CT scanner. The results were 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 are studying 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 is being studied by experts in the Natural History Museum in search of bones and teeth of animals that may have hunted around the dead skeleton.

More about pliosaurs

Despite their giant size, the oldest pliosaurs had many teeth, indicating they had a diet of fish. But over time they developed fewer, stronger teeth suggesting they evolved to hunt large prey such as big fish and other marine reptiles. Just like many of today’s predators, pliosaurs probably disabled their prey and allowed them to weaken through blood loss before going in for the kill.

The Weymouth Bay pliosaur, one of the most complete and best preserved skulls ever found, has provided new insights into our understanding of how these enormous animals evolved. Giant pliosaurs were first found in the UK in the early 1800s, but most fossils were fragmentary, so their species diversity has been uncertain.

One of the most significant finds is that the genus Pliosaurus appears to have developed a highly effective body plan that remained little changed for millions of years. During that time, just a handful of species evolved and this is unlike most top predators in the fossil record which reach dominance but were then typically swiftly replaced by different forms.

The research has been undertaken by a team of vertebrate palaeontologists from Oxford, Bristol and Cambridge universities and with Leicester, Nottingham and the Sedgwick (Cambridge) museums together with independent researchers.

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