Giant Dorset Pliosaur Fossil gets CT Scan

The fossilised remains of the skull and jaws of a giant sea monster of the Late Jurassic are to be scanned by one of the country’s most powerful CT scanners in a bid to learn more about the huge animal.  The analysis of thousands of X-ray images all helping to build up a 3-D image of the beast, a pliosaur, may lead scientists to conclude that this is a new species of marine reptile.

Pliosaur

Last year we reported on the discovery of huge 2.4 metre long fossil jaws that had been discovered on the Dorset coast.  The jaws and part of the skull that was also found belonged to a giant pliosaur, a marine reptile that would have been one of the top predators in the sea during the Late Jurassic, an animal capable of attacking and killing any other animal in its environment.  At the time of the discovery, local palaeontologist and Plesiosaur expert Richard Forrest stated that this pliosaur would have made T. rex “look like a kitten”.

To read the article on the discovery: Giant Dorset Pliosaur Discovery.

The X-rays will help to build up a three dimensional image of the skull, jaws and teeth providing scientists with an opportunity to look inside the fossil without actually having to dissect the fossilised bones.  The scans could establish if the giant fossil represents a new species, perhaps one of the largest carnivores known to science.

The most famous of all the pliosaurs, certainly one popular with young dinosaur fans who have watched the BBC documentary series “Walking with Dinosaurs” is Liopleurodon.  In the television series, Liopleurodon was depicted as being a ferocious hunter that measured over 25 metres in length and weighed a colossal 150 tonnes.  In reality the evidence of pliosaurs this big is not that convincing, Liopleurodon ferox for example, a species of Liopleurodon which has a number of fossil specimens ascribed to it, was perhaps as long as ten metres or so.  The Dorset giant, was probably bigger but without more body fossils it is hard to accurately determine just how large this animal was.

A Model of the Pliosaur Liopleurodon

Picture credit: Everything Dinosaur

At the moment, palaeontologists have estimated that the “Dorset Giant” may have measured between 10 and 16 metres in length and weighed between 7 and 12 tonnes.

The skull, which was unearthed by a local fossil collector and then purchased by Dorset Country Council using Heritage Lottery Funds, is currently being removed from its matrix by expert fossil preparator Scott Moore-Fay.  Scott estimates that to prepare the fossil completely it is going to take more than 1,000 hours.

Diagrams show the potential size of the Dorset pliosaur, comparing it to a Killer Whale (Orca) and a frogman.  Over the last few years a number of fragmentary pliosaur remains have been discovered around the world, from places like Norway, Antarctica and Russia, which ones represent the largest types of pliosaur has led to a lot of debate and discussion amongst palaeontologists.

Commenting on his work Scott said:

“It’s incredibly exciting.  Nobody has ever seen this fossil, so I get to see it as it is coming out of the rock – it is almost like magic.”

However, while preparatory work can reveal the surface of the fossil in remarkable detail, a more hi-tech solution is needed to probe deeper inside.  Once the discovery was publicised, Professor Ian Sinclair at the nearby University of Southampton contacted the fossil’s owners and offered them the opportunity to use the powerful CT scanner that was being erected in the University’s engineering sciences department.

Professor Sinclair stated:

“When we have the situation of rare samples that are precious, like the pliosaur, we have to extract the most amount of information from them and we certainly don’t want to destroy them, so this really is the perfect tool.”

The CT scanner, which has been funded by the Engineering Physical Science Research Council (EPSRC) and the University of Southampton, is one of the most powerful machines of its kind in the UK, and one of the largest.  Such a large and powerful machine is essential if the rock matrix surrounding the precious fossil is to be penetrated and the secrets inside the fossil revealed.

This super scanner works in much the same way as a hospital CT scanner, although at much higher energy and resolution, by taking thousands of X-rays to build up an image of whatever object is inside.

University of Southampton engineer Dr Mark Mavrogordato explained:

“At the end, you have a 3-D volume representing your original specimen.  And you can slice it, dice it, however you want, as if you could dissect it with a knife, but you are doing it digitally and non-destructively.”

The team has begun scanning the prepared fossil one piece at a time to reveal as complete a pliosaur picture possible, including information about the internal bone structure and the positioning of hidden teeth.

Richard Forrest added:

“We hope that these CT scans will show the internal structure of the jaws, and how they are built to withstand such incredible forces.  By understanding this, we can learn more about its behaviour – how it hunted and attacked other creatures.”

The scans will also help to confirm whether this species is new to science.  If it is a new species it will need to be formally named and described.

Mr Forrest went on to comment:

 “From the outside, it looks similar to other pliosaurs found in the UK, although much, much bigger.  By looking at the inner architecture of the skull, in particular the brain-case, we should be able to establish if this is a species that we have not seen before.”

After the scientific analysis is complete and the fossil is fully prepared and mounted, it will go on display to the public in the summer 2011 at the Dorset County Museum in Dorchester.  It is hoped that the fossilised bones and teeth will be exhibited next to a life-size model of the animal’s huge, gaping jaws.  This would give visitors an impression as to just how terrifying this marine reptile would have been, as well as letting them gain an insight into the last view that many an ichthyosaur or plesiosaur would have seen before this huge leviathan gobbled them up.

Museums adviser for Dorset, David Tucker stated:

“The pliosaur will be displayed with its mouth agape, allowing people to get the best possible understanding of what the beast would have looked like in life.  We’ll also have a massive, life-sized model of the head that will demonstrate how terrifying its teeth were.”

To view models and replicas of pliosaurs and other marine reptiles: CollectA Age of Dinosaurs Popular Models.

The Confusion over Pterodactyls

As far as scientists have been able to ascertain from the fossil record, only a very few types of dinosaur evolved the ability of flight.  Of course, technically birds, of which there are something like 10,000 species today; evolved flight and these creatures could be classified as avian dinosaurs.  However, setting aside the Aves (birds) for one moment we know that the early Mesozoic skies came to be dominated by another group of reptiles – pterosaurs.  Pterosaurs seem to have evolved sometime in the Middle Triassic.  Over the course of the next 160 million  years or so, they diversified into a myriad of different forms.  Some of these creatures were no bigger than blackbirds, others, for example a group known as the Azhdarchidae; evolved into flying reptiles the size of small aircraft.  However, all pterosaurs had the same basic skeleton and body plan.

A Replica of a Pterosaur

A colourful model of the pterosaur called Anhanguera by Schleich. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

To view models and replicas of prehistoric animals in the Schleich model range: Schleich Dinosaurs and Prehistoric Animal Models.

Pterosaurs

Pterosaurs (flying or winged lizards) are sometimes referred to as pterodactyls (winged fingers).  Pterodactyl is the name for just one particular family of pterosaurs, and in particular for a German flying reptile called Pterodactylus.  Fossils of Pterodactylus were found in the 19th century and remain some of the most complete and best preserved of all pterosaur fossils.  The name pterodactyl became quite well known and used a lot in popular culture and as a result the name “pterodactyl” – a term used colloquially to describe all pterosaurs became established.