A giant prehistoric reptile that patrolled the waters off Scotland 170 million years ago has been identified by scientists, they said Monday.

The creatures, which resembled a menacing dolphin and grew up to 14 foot (four metres) long, were identified by fossils from the Isle of Skye in northwest Scotland.

A team led by Edinburgh University scientists have named the new species Dearcmhara shawcrossi in honour of Brian Shawcross, an amateur fossil collector who gathered many of the fossils in 1959.

These were later donated to a museum, allowing scientists to study them and identify the new species.

"During the time of dinosaurs, the waters of Scotland were prowled by big reptiles the size of motor boats," said Steve Brusatte of Edinburgh University's School of GeoSciences.

"Their fossils are very rare and only now, for the first time, we've found a new species that was uniquely Scottish."

Scotland's most famous reptile, real or imaginary, is the Loch Ness monster, the myth of which draws thousands of visitors a year to Loch Ness in northern Scotland. AFP