When we think of palaeontology, the image that springs to mind is usually one of field researchers scratching and sifting through rock to uncover the remains of ancient creatures. But sometimes, new discoveries are waiting right under our noses, where they have been sitting for decades: in the collections of the world's museums. 

Thanks to a scientist's keen eye, a newly identified type of 200-million-year-old ichthyosaur has just joined the roster of prehistoric marine reptiles.

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Artist's recreation. Image: James McKay

The fossil in question belonged to a sea creature that lived alongside dinosaurs some 200 million years ago. They might look more like a dolphin or shark, but ichthyosaurs a group of ancient beasts whose name roughly translates to "fish lizard" are more closely related to terrestrial reptiles. 

University of Manchester honorary scientist Dean Lomax first came across the specimen while on a visit to Leicester’s New Walk Museum, where it had been resting since 1951. After giving the skeleton a thorough look, a few things caught Lomax’s eye.

“I knew it was unusual," he says. "It displays features in the bones that I had not seen before in Jurassic ichthyosaurs anywhere in the world. The specimen had never been published, so this rather unusual individual had been awaiting detailed examination,” says Lomax.

Ichthyosaurs cruised the world's waters during the Triassic, Jurassic and Cretaceous periods before finally going extinct around 90 million years ago. In fact, these animals were the very first large, extinct reptiles to be truly recognised by science – decades before the word "dinosaur" was invented. But only a handful of the ocean giants are known from the lower Jurassic period, when this particular animal would have lived. That makes this discovery very exciting for palaeontologists like Lomax. 

"Parts of the skeleton had previously been on long-term loan to ichthyosaur specialist and former museum curator Dr Robert Appleby," adds Dr Mark Evans, palaeontologist and curator at New Walk Museum. "[It] only returned to the museum in 2004 after he sadly passed away. He was clearly intrigued by the specimen."

Although Appleby worked on the ichthyosaur for many years, he mistook it for a previously known species. This isn't entirely surprising as the skeleton itself, though near-complete, was a bit of a mishmash. It's thought that this animal took a nosedive into the sea floor in its final hours.

After close examination of the skeleton's caudal girdle (where tail meets body), Lomax determined that this animal is not only a new species, but also the first member of a new genus. Tasked with giving the specimen a permanent name, he opted to combine the names of two palaeontologists who inspired him over the years, Judy Massare and Bill Wahl. The behemoth is now officially known as Wahlisaurus massare.

"I feel quite privileged to be able to study such fossils that have previously been collected and studied by palaeontologists from over 100 years ago," adds Lomax. "My favourite thing about this kind of work is the fact that you never quite know what you’re going to discover. [You've got] a collection full of wonders that have been sitting there, awaiting rediscovery." 

Although thousands of specimens from this time have been discovered, this is the first new genus described in thirty years from the British early Jurassic. As is the case with all new fossil finds, the hope is that this newest member of the family could reveal more information on ichthyosaurs in general, and provide a clearer picture of their ecology and distribution. 

"There are some stomach contents preserved in the specimen of W. massarae," says Lomax. "They have not been studied in detail yet, but it’s probable that they contain tiny hooklets from the arm tentacles of squid. Many other ichthyosaurs also have stomach contents preserved and they often contain squid hooks and fish scales, so it’s likely that Wahlisaurus also fed on squid and fish."

Are any other new species of ichthyosaur hiding in museum collections? You can help scientists find out by donating here

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Top header image: Kevin Walsh/Flickr