A 200-million-year-old fossil that was found in a farmer’s field more than 60 years ago has been studied for the first time using cutting-edge CT scans.
The almost fully intact ichthyosaur skull and mandible has been digitally reconstructed in a world first.
The well-preserved cranium was first found in 1955 at Fell Mill Farm in Shipston-on-Stour, Warwickshire.
It is the first time a 3D impression of a skull and mandible of a large marine reptile has ever been made available for research purposes and to the public.
In 2014, as part of a project at Thinktank Science Museum, Birmingham, palaeontologists Dean Lomax, of Manchester University, and Nigel Larkin began to study the skull and its incomplete skeleton.
Study lead author Dean Lomax told MailOnline: ‘The skull is almost a metre (three feet) long and we estimate the entire body length to up to four metres long.
‘This makes this protoicthyiosaurus specimen the largest of this species ever studied.’
It was originally identified as a common species called Ichthyosaurus communis but later revealed by Mr Lomax’s analysis to be a far rarer species.
Two pieces of research, including this paper published in the journal PeerJ, have concluded its skull features indicate it is the skull of a species called Protoichthyosaurus prostaxalis.
The skull is almost twice as long as any other specimen of Protoichthyosaurus.
Mr Lomax, one of the world’s leading ichthyosaur experts, said: ‘The first time I saw this specimen I was puzzled by its excellent preservation.
‘Ichthyosaurs of this Early Jurassic age are usually “pancaked”, meaning that they are squished so that the original structure of the skull is either not preserved or is distorted or damaged.
‘So to have a skull and portions of the skeleton of an ichthyosaur of this age preserved in three dimensions, and without any surrounding rock obscuring it, is something quite special.’
Co-author Mr Larkin said the skull isn’t quite complete, but several bones of the braincase – which are rarely preserved in ichthyosaurs – are present.
He added: ‘Initially, the aim of the project was to clean and conserve the skull and partially dismantle it to rebuild it more accurately, ready for redisplay at the Thinktank Museum.
‘But we soon realised that the individual bones of the skull were exceptionally well preserved in three dimensions, better than in any other ichthyosaur skull we’d seen.
‘Furthermore, that they would respond well to CT scanning, enabling us to capture their shape digitally and to see their internal details. This presented an opportunity that couldn’t be missed’
To unlock information contained in the skull, the bones were micro-CT scanned at Cambridge University by expert palaeontologist and co-author Dr Laura Porro.
The fossil only preserved bones from the left side of the braincase but researchers used CT scans to digitally mirror and 3D print the remaining braincase to complete it.
Finally, the entire skull was CT scanned at the Royal Veterinary College (RVC) using a scanner typically reserved for horses and other large animals.
Dr Porro, of University College London (UCL), added: ‘CT scanning allows us to look inside fossils – in this case, we could see long canals within the skull bones that originally contained blood vessels and nerves.
‘Scans also revealed the curation history of the specimen since its discovery in the 1950s.
‘There were several areas reconstructed in plaster and clay, and one bone was so expertly modelled that only the scans revealed part of it was a fake.
‘Finally there is the potential to digitally reconstruct the skull in 3D. This is hard – and risky – to do with the original, fragile and very heavy fossil bones; plus, we can now make the 3D reconstruction freely available to other scientists and for education.’
The use of modern technologies, such as medical scanners, have revolutionised the way in which palaeontologists are able to study and describe fossils.
Mr Lomax added: ‘It’s taken more than half a century for this ichthyosaur to be studied and described, but it has been worth the wait.
‘Not only has our study revealed exciting information about the internal anatomy of the skull of this animal, but our findings will aid other palaeontologists in exploring its evolutionary relationship with other ichthyosaurs.’