A rare 200 million-year-old fossil of a marine dinosuar has been identified more than two decades after it was discovered in a Somerset quarry.

The fossil, which was found near Doniford Bay in Watchet in the 1990's, is only the second example of Wahlisaurus massarae, a new species of ichthyosaur, discovered by Manchester University palaeontologist, Dean Lomax.

Ichthyosaurs recently featured in the BBC documentary Attenborough And The Sea Dragon. They were a type of sea-going reptile that lived during the time of the dinosaurs.

Their fossils are often found in Britain and in recent years Lomax has described five different species of the prehistoric reptile.

In 2016, Lomax described an ichthyosaur skeleton that he had examined in the collections of Leicester's New Walk Museum and Art Gallery.

He spotted several unusual features of the bones and determined that the features were unique and represented a new species, which he called Wahlisaurus massarae, in honour of two of his colleagues and mentors: Bill Wahl and Prof. Judy Massare.

He said: "When Wahlisaurus was announced, I was a little nervous about what other palaeontologists would make of it, considering the new species was known only from a single specimen.

"As a scientist you learn to question almost everything, and be as critical as you can be.

"My analysis suggested it was something new, but some palaeontologists questioned this and said it was just 'variation' of an existing species."

In the new study, Lomax teamed up with Dr Mark Evans, palaeontologist and curator at the New Walk Museum, Leicester, and fossil collector, Simon Carpenter, of Somerset.

The study focused on a specimen Lomax identified in Mr Carpenter's collection, which is an almost complete coracoid bone that has the same unique features of the same bone in Wahlisaurus.

The specimen was originally found in 1996, in a quarry in northern Somerset.

Once the specimen's rarity was realised, Mr Carpenter immediately donated it to Bristol Museum and Art Gallery.

Lomax added: "You can only imagine my sheer excitement to find a specimen of Wahlisaurus in Simon's collection.

"It was such a wonderful moment. When you have just one specimen, 'variation' can be called upon, but when you double the number of specimens you have it gives even more credibility to your research."

The new discovery is from a time known as the Triassic-Jurassic boundary, immediately after a world-wide mass extinction.

The team have been unable to determine exactly whether the ichthyosaur was latest Triassic or earliest Jurassic in age, although it is roughly 200 million-year-old.

Lomax added: "The discovery of the new specimen in a private collection helps to recognise the important contribution of dedicated and responsible fossil collectors.

"I am especially grateful to Simon for donating the specimen and collecting all of the data available with the specimen when he found it."

The study was published in the Geological Journal.