A FOSSIL that was discovered in Melksham more than 140 years ago has been identified as a new species of prehistoric sea creature with powerful jaws and serrated teeth that roamed Jurassic Britain alongside the dinosaurs 163 million years ago.

Nicknamed the ‘Melksham Monster’, the 10ft long apex predator, a distant relative of modern crocodiles, would have patrolled the warm, shallow seas covering much of what is now Europe on the hunt for large prey, such as prehistoric squid.

The fossil was acquired by the Natural History Museum from ‘Master William Cunnington’ in July 1875 for an unknown sum and is believed to have been unearthed during quarrying or railway/road building activities in the Melksham area.

William Cunnington 3rd (1813-1906) was a local fossil collector from the age of seven onwards and the principal founder of Wiltshire Archaeological and Natural History Society in 1853. After moving from Devizes to London in 1874, he donated his collection of 20,000 fossils to the Wiltshire Museum and the British Museum.

Mark Graham, the senior fossil preparator at the Natural History Museum, said: “Our records do not include the exact location in Melksham that the specimen was found, but it may have been discovered during quarrying as there are much younger sand and gravel deposits overlying the Oxford Clay in the area.

“We don’t know who was the finder, but it was purchased by the museum (sum unrecorded) from ‘Master William Cunnington’ in July 1875. He may have collected it himself, or obtained it from a third party. The museum has several other specimens in its Cunnington Collection.”

The fossil had lain hidden in the Museum archives until a team of palaeontologists from the University of Edinburgh made the remarkable discovery, naming the ancient reptile Ieldraan melkshamensis. It was identified as a new species based on the distinctive features of its skull, lower jaw and teeth.

Until now, it was thought the sub-family of prehistoric crocodiles to which the new species belongs originated in the Late Jurassic period, between 152 and 157 million years ago.

The latest find, together with re-analysis of other fossil evidence, suggests the group arose millions of years earlier, in the Middle Jurassic spell.

Mr Graham said: “It was completely enclosed in a super-hard rock nodule with veins of calcite running through, which had formed around it during the process of fossilisation.

“This unyielding matrix had to be removed by force, using carbon steel tipped chisels and grinding wheels encrusted with industrial diamonds.

“The work took many hours over a period of weeks, and great care had to be taken to avoid damaging the skull and teeth as they became exposed. This was one tough old croc in life and death.”

Dr Steve Brusatte, of Edinburgh University’s School of GeoSciences, said: “The Melksham Monster would have been one of the top predators in the oceans of Jurassic Britain, at the same time that dinosaurs were thundering across the land.”

Davide Foffa, a PhD student in the university’s School of GeoSciences, who led the study, said: “It’s not the prettiest fossil in the world, but the Melksham Monster tells us a very important story about the evolution of these ancient crocodiles and how they became the apex predators in their ecosystem.”