How to resurrect a sea dragon
A new virtual reality experience uses the bones of a sea dragon to recreate life in Jurassic waters. We asked palaeontologists on the project how it was done.
A long-dead sea dragon and Jurassic mystery, Rhomaleosaurus cramptoni is known only from bones preserved for millions of years in mudstone rocks.
It roamed seas and lagoons at the same time as dinosaurs dominated the land, and died out more than 180 million years ago.
But thanks to the latest technology, viewers anywhere in the world can get a close look at the ancient reptile.
Palaeontologists have revived the animal for Rhomaleosaurus: Back to Life in Virtual Reality, an experience created by the Museum in collaboration with Google Arts & Culture.
Rhomaleosaurus is brought back to life as water floods the Museum, allowing the huge reptile to swim alongside the virtual visitor.
Angela Milner, a Scientific Associate at the Museum, was one of the scientists who created the experience.
She says, 'By making use of technology, the fossils in our collection become something more than old bones.
'Fossils are the starting point, and they form the basis of all our knowledge of prehistoric creatures. But as time goes on, we find new ways of reconstructing how these animals lived, how they moved and what they ate.'
The riddle of Rhomaleosaurus
Palaeontologists at the Museum collaborated with Dr Adam Smith, a leading expert on Rhomaleosaurus and Curator of Natural Sciences at Nottingham Natural History Museum, Wollaton Hall.
For his PhD, Dr Smith worked with the original holotype specimen of Rhomaleosaurus cramptoni - the specimen that the description of this species is based on.
He advised the team on the colour, skin and movement of the underwater giant.
Dr Smith says, 'Rhomaleosaurus is fascinating to me, much more than dinosaurs.
'We have some complete skeletons, so we know about its anatomy, but in many respects it is a mystery.
'This animal belongs to the plesiosaur order - carnivorous reptiles that lived in seas and lagoons. They had four flippers to move about and fed on fish and other, smaller reptiles.
'Compared to the dinosaurs, there is a huge amount we don't know. We don't know how they moved, what they did with their flippers or what their long necks were for.
'We have no modern-day creature to compare them to. There are no long-necked whales or sharks, no creatures with four flippers like that. It's what attracted me to study them in the first place.'
Old bones and new life
The holotype specimen was an old and crumbling skeleton found in 1848. Despite its age, Dr Smith could use its body shape to help create the virtual reality (VR) experience.
'It is an exceptionally old fossil, and many subsequent studies have changed our understanding of the animal even more.
'And of course, having the bones alone is not enough. To create a believable 3D model, we have to speculate about soft parts such as skin and eyes.'
When it came to body shape and colour of Rhomaleosaurus, Dr Smith made an educated guess.
Modern-day whales and sharks have darker skin on the top of their bodies and lighter skin underneath. This makes them more difficult to see when the light is coming from the surface of the water. It is likely Rhomaleosaurus would have had the same feature.
How did it move?
Making the virtual reptile glide through the water was even more difficult because scientists have no direct evidence of its movement.
Dr Smith has been researching how Rhomaleosaurus and others plesiosaurs might have used their flippers.
He says, 'They are unique because they have four large flippers. There is no living animal that has that combination of limbs - for instance, no fish has large flippers at the back of its body. Penguins and turtles have flippers but only one large pair.
'Scientists are trying to understand how all four moved. We have tried creating robots or making plastic flippers and strapping them on to humans, but all these methods are biologically inaccurate.
'I'm part of a team that has created a computer simulation to solve the problem. We designed a 3D virtual model of a plesiosaur and asked the computer to determine the most efficient way to propel that body through water.
'It concluded that the animal "flew" underwater - it moved the limbs up and down, rather than pushing them back and forth.
'The limbs at the front were the powerhouse, and the back limbs probably helped with direction. That's why we went for that motion in the VR experience.'
The marine environment
Dr Smith says it is possible to understand what kind of world the reptile would have lived in.
He explains, 'With dinosaurs, we have fossil footprints and fossil plants. We have similar contextual evidence for underwater animals as well.
'Plesiosaur fossils are not found in isolation in rocks. Corals and sponges have also been preserved, as well as fishes and ammonites, so we have a good picture of the underwater Jurassic environment. This knowledge was also useful in building the VR experience.'
The VR experience also shows Rhomaleosaurus snapping at prey with its huge jaws.
'I was asked what prey Rhomaleosaurus would have eaten,' says Dr Smith. 'We know it is a carnivore because of its teeth. We also have some fossilised dung and preserved stomach contents.
'It's fairly certain that it had a diet like a killer whale's - it ate whatever it wanted to.
'We have lots of fossil material to work with. There are so many plesiosaur fossils that our view on them is always changing. For every dinosaur that got preserved, we have about 200 marine reptiles.
'That makes an exhaustive study on them daunting, but it is part of what makes them fascinating.'
Years of study have transformed how scientists think of plesiosaurs.
The Victorians depicted some plesiosaurs with a swan-like neck that could curl around. But in reality their necks were rigid to allow them to swim.
Dr Milner has witnessed many changes in the Museum's collections over the decades, as well as new ways of thinking about ancient animals.
She says, 'There is still a lot we don't know about marine reptiles, but there is so much that we do, thanks to technologies like CT scanning and computer reconstructions.
'We can go back to old specimens in the collections and get a completely new understanding of them because we have much more sophisticated ways of studying them.
'Virtual reality technology demonstrates how much we have learnt, and this project also highlights the threat of extinction many species are facing. It is the role of the Museum to make people aware of how some species are suffering. Any tool we can use to do that is a positive one, and virtual reality can help us to reach new audiences.'
See 11 online exhibitions, based on the Museum's collections and created in partnership with Google Arts & Culture.