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Identity of Jurassic plesiosaur fossils from Dorset could finally be revealed
A famous fossil reptile is returning to the limelight six decades after it was uncovered.
Though more fossils have since been discovered, the Portland plesiosaur has never been formally described, but the ongoing digitisation of the Natural History Museum’s collections could help to change this.
Fossils which made headlines in the 1960s are making a long-overdue comeback.
While the discovery of the Portland plesiosaur by teenager Richard Cooper featured in TV news bulletins and newspaper articles at the time, there was a lack of scientific interest. As a result, the ancient marine reptile has spent most of the past 60 years kept in a number of collections, remaining as much a mystery now as it did when it was excavated.
That could all be about to change, however. Now in the Natural History Museum, ongoing efforts to digitise its collections mean that scientists are better placed than ever to uncover the secrets of this celebrity specimen.
Dr Marc Jones, the Curator of Fossil Reptiles who looks after the Portland plesiosaur, says, ‘There are a lot of uncertainties about this specimen, not least what species it might be.’
‘Partly, this is due to a historic lack of funding and focus on marine reptile fossils in British palaeontology. However, by digitising specimens like this, we’re hoping that more researchers will be able to study them and help bring our understanding of these ancient animals right up to date.’
Following the discovery of the first fossils by Richard, further segments of the plesiosaur were discovered by others including Stephen Bankler-Jukes. Image © The Trustees of the Natural History Museum, London.
The discovery of the Portland plesiosaur
The story of the Portland plesiosaur begins not on the beaches of the Dorset island, but instead in one of its schools. Richard first became aware of the fossils thanks to a chat with a member of staff, who had found a few small bones in her spare time.
‘The headmaster’s secretary had a shoebox full of fossil bones on her desk,’ Richard recalls. ‘She told me all about where she’d found them. As my father worked for the stone firms on Portland, we’d always had an interest in fossils, so I decided to go and have a look.’
Richard could not have chosen a better place to look. The Isle of Portland is the most southerly part of the Jurassic Coast, a UNESCO World Heritage Site recognised for the extraordinary fossils it contains.
Further down the coast, in Lyme Regis, was where Mary Anning first discovered the plesiosaurs in the early 1800s. Many different specimens have been discovered since then, with the Portland plesiosaur the latest in a long line of fossils when Richard found it in 1966.
‘When I got to the site, there were bits of bone sticking up out of the ground, from a layer known as the Kimmeridge Clay,’ Richard says. ‘I was lucky, because on Portland the Kimmeridge Clay can often be buried under pebbles or landslips, so isn’t always exposed.’
During many visits across the next two years, Richard dug the bones out of the rock, assisted by his father. Together, they excavated over 100 bones from the specimen, mostly from the body and limbs.
With their house beginning to fill up, however, Richard and his family decided to donate the bones to Dorset Museum. While many scientists expressed an interest in the Portland plesiosaur at the time, the number of letters began to die down, and Richard moved on to become a maths teacher.
While interest in the plesiosaur waned, it was never completely forgotten. More of its fossils were discovered over the years, gradually building up a better picture of the specimen.
Eventually, the plesiosaur made the move to the Natural History Museum, where technological advances are allowing the fossils to be understood in greater detail than ever before.
The Natural History Museum is currently working to digitise its collection so that specimens are available to researchers all over the world. Image © The Trustees of the Natural History Museum, London.
Digitising the marine reptiles
At present, there’s not that much known about the identity of the Portland plesiosaur, as it’s not been formally described.
It has been referred to as a pliosaur, a subgroup of the plesiosaurs that had shorter necks and more crocodile-like heads than their relatives. However, with the head of the Portland plesiosaur yet to be identified, it’s hard to tell for sure.
Other researchers have referred to it as Colymbosaurus, but as this species is based on a limited number of fossils there are doubts whether this is actually the case.
Part of the issue is that, although the fossils of marine reptile were discovered before those of dinosaurs, the latter group have typically received more attention.
‘Given the volume of marine reptile fossils which have been found in the UK, British marine reptiles are perhaps not as well studied as they should be,’ Marc says. ‘I’d estimate that the study of marine reptiles is about 20 years behind the study of dinosaurs.’
‘Part of the recent boom in dinosaur studies is driven by a desire to understand how birds evolved, but as plesiosaurs have no close living relatives, they don’t benefit from this kind of interest.’
‘It’s a shame that plesiosaurs are not better known because they existed for well over 100 million years all over the world, with their combination of a long neck and four paddles representing a unique body-plan that’s never been replicated.’
New scanning technology, however, could help to close the knowledge gap. As part of a project to digitise all 80 million objects in the Natural History Museum’s collections, parts of the Portland plesiosaur have recently been scanned to get a closer look at its skeleton and make it more easily available to scientists everywhere.
3D scans can be digitally manipulated to allow researchers to examine the fossils from a variety of angles that wouldn't be possible with the original specimens. Image © The Trustees of the Natural History Museum, London.
Tom Ranson is a 3D digitisation specialist who worked on the Portland plesiosaur using a scanning arm.
‘The scanner works by bouncing a laser off the target and into a detector, which is used to measure the fossils,’ he explains. ‘These need to be lined up properly to work, so it can be difficult to access narrow parts of the fossil, such as the neural canal.’
‘For this, we can use scanning software to intelligently fill in these gaps and give a reasonable approximation of the area. Once both sides of a fossil are scanned, they can be stitched together to give a 3D model of the whole bone.’
Marc hopes that these scans will be invaluable to the next generation of researchers who study the Portland plesiosaur.
‘The Natural History Museum is hoping to get a PhD student to examine and describe these fossils,’ Marc says. ‘Scanning technology should allow us to rearticulate the individual bones to make a digital model of the whole skeleton. This offers new ways to study the animal, and could help to understand how it moved.’
The team also plans to present Richard with a 3D printed copy of one of the Portland plesiosaur’s vertebrae in honour of his discovery.
‘I’m glad that the plesiosaur is finally getting the chance to be studied,’ Richard says. ‘It’s been a long wait, but I’m looking forward to finding out what my small contribution to palaeontology reveals.’
