A Jurassic-era fossil of four perfectly-preserved vertebrae from what is believed to have been a 35-foot long plesiosaur was found by a man who plucked it from shallow water on the bank of the loch.
Gerald McSorley, 67, turned it over to the National Museum of Scotland, who are conducting tests on the rare find, the first of its kind in Scotland for more than a century.
"Chances that the fossil originated where it was found are very slim... it was deposited there either by natural or artificial means," said museum spokesperson Hannah Dolby.
"Borings on the fossil show it comes from a marine environment rather than a fresh water