More than 20 years ago, the BBC documentary series Walking with Dinosaurs showed a 25-meter liopleurodon. This sparked heated debates about the size of this plesiosaur as it was thought to have been greatly overestimated and likely only reached an adult size of over six metres.
Speculation was destined to continue, but now a serendipitous discovery at Oxfordshire Museum has led University of Portsmouth paleontologists to publish a paper on a similar species that likely reached 14.4m in length – twice the size of the killer whale.
Professor David Martell, from the University of Portsmouth’s School of Environment, Geography and Earth Sciences, said: “I was a consultant for the BBC pilot program ‘Cruel Sea’ and I put my hands up – I’ve got the size of liopleurodon Awful mistake. I have based my calculations on some fragmentary material suggested by A liopleurodon It can reach 25 meters in length, but evidence was scarce and it caused a lot of controversy at the time.
“The size estimate on the BBC in 1999 was an exaggeration, but we now have some more reliable evidence after the serendipitous discovery of four enormous vertebrates.”
Professor Martell’s co-author Megan Jacobs was photographing an ichthyosaur skeleton at Abingdon County Hall Museum, while Dave was looking through a fossil drawer. He found a large vertebrae and was delighted to find that the curator had three more vertebrae in storage.
Paragraphs can be clearly identified as closely related to a pliosaurus similar species or animals. Pliosaurs were like plesiosaurs, but with a larger, crocodile-like elongated head and a shorter neck. They had four flippers, which served as powerful paddles for propelling them through the water, and a relatively short tail.
After performing topographic surveys, Prof. Martell and his colleagues calculated that this late Jurassic marine reptile had grown to between 9.8 and 14.4 metres.
He said: ‘We know that these pliosaurs were very fearsome animals that swam the seas that covered Oxfordshire 145-152 million years ago. They had a huge skull with huge teeth protruding like daggers – as big, if not larger than t-rexAnd certainly more powerful.
“They were at the top of the marine food chain and may have preyed on ichthyosaurs, long-necked plesiosaurs and possibly even smaller marine crocodiles, simply by biting them in half and removing small pieces from them. We know they were butchering small marine reptiles because you could see bite marks in the ichthyosaur bones in Examples shown are in the Etches Collection in Dorset.”
The vertebrae were originally discovered during temporary excavations at Warren Farm in the Thames River Valley in Oxfordshire and come from the Kimmeridge Clay Formation. This deposit is late Jurassic, about 152 million years old.
Professor Martell added: “It is remarkable that a truly gigantic pliosaur species existed in the late Jurassic seas. Although it was not quite on par with the claims made for liopleurodon In the popular BBC TV series Walk with dinosaursI wouldn’t be surprised if we ever find clear evidence that this feral species was even larger. “