The bones of an enormous jawbone more than two metres long have been found on a beach in Somerset in south-west England.
Scientists have identified the fossilised remains as belonging to a new species of giant ichthyosaur, a type of prehistoric marine reptile that lived during the Late Triassic period, more than 200 million years ago.
Experts believe the gigantic oceanic reptile would have been more than 25 metres long.
It is the second giant jawbone to be found in the area – the first was discovered in May 2016 further up the coast at Lilstock – an important fact that supports the identification of the new species, according to the paper published today in the journal PLOS ONE.
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Multimillion-year-old jigsaw
The first pieces of the jawbone were found in May 2020 by 11-year-old Ruby Reynolds and her father Justin as they were hunting for fossils on the beach at Blue Anchor in Somerset. Ruby found the first chunk of giant bone before the pair set about searching the area for more pieces.
It was clear they had discovered something important, so they contacted Dr Dean Lomax, a palaeontologist at the University of Bristol and leading ichthyosaur expert.
Thrilled by the discovery, Dr Lomax notified Paul de la Salle, a seasoned fossil collector who found the first giant jawbone at Lilstock in 2016.
“I was amazed by the find. In 2018, my team (including Paul de la Salle) studied and described Paul’s giant jawbone and we had hoped that one day another would come to light," says Dr Lomax.
"This new specimen is more complete, better preserved, and shows that we now have two of these giant bones (called a surangular) that have a unique shape and structure. I became very excited, to say the least.”
Without delay, Dr Lomax and de la Salle made their way to the site, joining Justin and Ruby, and several family members, to hunt for more pieces of the ichthyosaur.
The team found further parts of the same jaw, which fit together like a jigsaw.
“When Ruby and I found the first two pieces," says Justin, "we were very excited as we realised that this was something important and unusual. When I found the back part of the jaw, I was thrilled because that is one of the defining parts of Paul's earlier discovery.”
The final piece of bone was recovered in October 2022.
Back in the lab
Having gathered all the pieces of the jawbone, the research team, led by Dr Lomax, set about identifying the find.
Analysis revealed that the jawbones belong to a new species of giant ichthyosaur that would have measured 25m long – about the size of a blue whale. Importantly, says Dr Lomax, having two examples of the same bone from the same geologic time zone supports this identification.
Analysis revealed that the jawbones belong to a new species of giant ichthyosaur that would have measured 25m long – about the size of a blue whale.
The team have called the new genus and species Ichthyotitan severnensis, which means 'giant fish lizard of the Severn'.
“I was highly impressed that Ruby and Justin correctly identified the discovery as another enormous jawbone from an ichthyosaur," comments Dr Lomax. "They recognised that it matched the one we described in 2018. I asked them whether they would like to join my team to study and describe this fossil, including naming it. They jumped at the chance. For Ruby, especially, she is now a published scientist who not only found but also helped to name a type of gigantic prehistoric reptile. There are probably not many 15-year-olds who can say that! A Mary Anning in the making, perhaps.”
When asked about her find, Ruby says: “It was so cool to discover part of this gigantic ichthyosaur. I am very proud to have played a part in a scientific discovery like this.”
The bones are around 202 million years old, dating to the end of the Triassic Period, a time when the gigantic ichthyosaurs would have roamed the seas as dinosaurs walked on land.
However, it was the ocean titan's final chapter; a cataclysmic event, known as the Late Triassic global mass extinction event, led to the extinction of giant ichthyosaurs.
The giant ichthyosaur puzzle
Ichthyotitan is not the world’s first giant ichthyosaur, but the discoveries made on the Somerset coast are unique among those known to science, say the researchers. These two bones found by the Reynolds and de la Salle appear approximately 13 million years after their closest geologic relatives: Shonisaurus sikanniensis from British Columbia in Canada and Himalayasaurus tibetensis from Tibet in China.
The research team were keen to provide supporting evidence that the bones belonged to giant ichthyosaurs, so they called in Marcello Perillo, a master’s student from the University of Bonn in Germany. Perillo took core samples of the new specimens discovered on the Somerset coast, along with others, which confirmed the ichthyosaur origin of the bones. The samples also revealed that the reptile was still growing at the time of death.
“We could confirm the unique set of histological characters typical of giant ichthyosaur lower jaws," says Perillo.
"The anomalous periosteal growth of these bones hints at yet to be understood bone developmental strategies, now lost in the deep time, that likely allowed late Triassic ichthyosaurs to reach the known biological limits of vertebrates in terms of size. So much about these giants is still shrouded by mystery, but one fossil at a time we will be able to unravel their secrets."
"So much about these giants is still shrouded by mystery, but one fossil at a time we will be able to unravel their secrets."
Jimmy Waldron, research team member and founder of the DWABA museum in Orlando, Florida is creating scaled 3D replicas of the giant ichthyosaur bones for displays and outreach programmes around the world.
“Every fossil fan dreams of an experience like Ruby’s," says Waldon, "and she deserves all the joy and excitement. To be the first human eyes to look upon this incredible fossil after 202 million years is truly special.
"Justin is setting a grand example by supporting his daughter’s interests in science and palaeontology. Fossils like Ichthyotitan offer glimpses into unknown chapters of life on Earth, and it’s our responsibility to share these wonders and the processes with the public."
Paul de la Salle says: “To think that my discovery in 2016 would spark so much interest in these enormous creatures fills me with joy. When I found the first jawbone, I knew it was something special. To have a second that confirms our findings is incredible. I am overjoyed.”
Dr Lomax concludes: “This research has been ongoing for almost eight years. It is quite remarkable to think that gigantic, blue whale-sized ichthyosaurs were swimming in the oceans around what was the UK during the Triassic Period. These jawbones provide tantalising evidence that perhaps one day a complete skull or skeleton of one of these giants might be found. You never know.”
The new research is published in the open access journal PLOS ONE, the same journal that published the first study in 2018.
Ruby, Justin and Paul’s discoveries will soon go on display at the Bristol Museum and Art Gallery.
