The remains of Nessie's Yorkshire cousin are uncovered

In a development that is sure to delight devotees of the Loch Ness monster legend, scientists revealed yesterday that a long-necked sea dragon reminiscent of Scotland's finest swam in coastal waters off North Yorkshire 132 million years ago.

In a development that is sure to delight devotees of the Loch Ness monster legend, scientists revealed yesterday that a long-necked sea dragon reminiscent of Scotland's finest swam in coastal waters off North Yorkshire 132 million years ago.

The revelation follows the discovery of a near complete skeleton of a plesiosaur – a 14ft high marine reptile – on a cliff-top at Filey, near Scarborough.

The find is the most significant discovery in a decade on one of the most important geological coastlines in the world. Remains of plesiosaurs that lived 200 million years ago have been found in neighbouring Whitby and species dating back 90 million years have been unearthed in the United States. But nothing has been discovered from the intervening 100 million years, which makes the "new" sea dragon an entirely new species.

Scientists owe the breakthrough to Nigel Armstrong, an electrician from Doncaster, South Yorkshire, who spotted one of the creature's vertebrae in a landslip on the beach while fossil hunting. He sensed it was something unusual so started digging around in the mud 15 metres up the cliff face and followed a trail of bones to the rest of the skeleton.

After a 132-million-year wait, his discovery was just in the nick of time. "If it had been left there for another winter it would probably have been washed away," said Will Watts, Scarborough's Dinosaur Coast project officer. "It really is a one in a million chance because he knew what he was looking at."

A team including the Dinosaur Coast project, English Nature and the National Trust has shifted nine tons of clay to get at the skeleton. It was encased in a jacket of orange clay and appears to be 75 per cent intact, which is remarkable. Most museums are forced to use extensive amounts of "fill" to give the impression of a complete creature.

Mark Evans, the curator of geology at Leicester Museum, said the discovery was "a world first" and plugged a big gap in knowledge. "It dates from a time when we have only had a few glimpses of their evolution," he said.

The apparent absence for 100 million years of the plesiosaur, with its four diamond-shaped flippers and penchant for fish and squid, had previously puzzled scientists. Seas were certainly swarming with the creatures in the middle and late Jurassic period. Swimming like turtles, they would have sculled through coastal and inshore waters, probably laying eggs by hauling themselves on to sandbars or beaches. They vanished at the end of the Cretaceous period along with dinosaurs.

Geologists extracted the skeleton by digging out a one-and-a-half tonne block of clay, covering it in hessian and plaster of paris and sliding it down the 50ft cliffs with ropes. The bones are now in storage and it is hoped they will be reassembled and put on show at a Scarborough museum in about a year's time.

Mr Watts does not a believe a Loch Ness monster exists but he conceded that the new species conformed to most people's idea of the beast.

"If it was swimming with its head out of the water it would look just like that Nessie photograph which proved to be a fake," he said.