London: A skull belonging to one of the largest "sea monsters" ever unearthed is now going on public display at the Dorset County Museum.
The beast, which is called a pliosaur, has been described as the most fearsome predator the Earth has seen.
Scientists suspect the creature may be a new species or even genus.
Local collector Kevan Sheehan discovered the 155-million-year-old fossil between 2003 and 2008, as it gradually tumbled out of the cliffs near Weymouth.
He told BBC News: "It was sheer luck - I was sitting on the beach, and saw three pieces. I had no idea what they were, but I proceeded to drag them back. Then over several years, I``d go back every year and find a new piece. I``m a beach magpie."
At first it more closely resembled huge lumps of rock than a marine monster, but a lengthy preparation process that has been carried out by fossil expert Scott Moore-Faye has revealed the fine details of the fossil.
Palaeontologist Richard Forrest said: "This is an iconic specimen - one of the most exciting we have seen in years.
"It was probably the most fearsome predator that ever lived. Standing in front of the skull you can imagine this enormous beast staring straight back at you, fixing you with its binocular vision, and attacking. Just thinking about it raises the hairs on the back of your neck."
New estimates from scientists, based on the 2.4m-long skull, suggest that the predator would have measured between 15-18m from tip to tail.