Archaeologists have spent months piecing together dozens of old bones found encased in limestone on Britain's Jurassic Coast by a fossil hunter.

After nearly completing the jigsaw-like puzzle they have disclosed that the skeleton, which is 70 per cent complete, is that of a 12ft long plesiosaur.

The marine reptile resembled the Loch Ness monster with its long thin neck and tail, four large flippers and razor-sharp teeth.

Plesiosaurs existed during the Jurassic period 150 to 200 million years ago when what is now the Channel was a shallow, tropical sea.

Detailed examination of the bones revealed teeth marks from where a predatory dinosaur would have feasted on the carcass of the "lake monster".