SCIENTISTS have identified the largest ever Ichthyosaurus, the so-called ‘sea dragon’ in a museum after it was initially mislabelled.

The Ichthyosaurus somersetensis — one of six species in the Ichthyosaurus genus — was first found on the UK coast in the nineties before ending up on display in the Lower Saxony State Museum in Hannover, Germany.

The fossil of the ancient ocean dweller’s true identity was unknown until palaeontologist Sven Sachs, of Germany’s Bielefeld Natural History Museum, examined it while working on marine research, Science Alert reported.

“I found it very extraordinary,” Professor Sachs told National Geographic. “[It was] way bigger than any specimen I had examined.”

Professor Sachs contacted his colleague Dean Lomax from the University of Manchester and after they both studied the fossil they realised it was indeed an Ichthyosaurus somersetensis.

“It amazes me that specimens such as this can still be ‘rediscovered’ in museum collections,” said Professor Lomax. “You don’t necessarily have to go out in the field to make a new discovery.”

According to Science Alert, one of the reasons the specimen went unnoticed for so long was because of the addition of a fake, cosmetic tail by museum staff.

The ‘sea dragon’ which lived 200 million years ago was estimated to have been between 3 to 3.5 metres long. The fossil was of a pregnant female and analysis of the mother’s fossil revealed the presence of an incomplete embryo preserved inside her.