by It may be hard to imagine, but the county of Somerset in south-west England was once home to the largest marine reptiles that ever lived, a new study by my team shows.
A strange and gigantic jawbone was discovered on the coast of England eight years ago, but my team hesitated to identify it as a new species until more specimens came to light. Now, with the discovery of a second giant jawbone several years later, we have named a new species of ichthyosaur, an ancient marine reptile.
In 2016, a prolific fossil hunter Paul de la Salle, a huge jawbone was found on the beach at Lilstock in Somerset. It was an incomplete bone from the back of the animal’s lower jaw. My team, including De la Salle, studied this discovery and published our findings in 2018 in the journal PLOS One.
Read more: How we found a giant ichthyosaur almost the size of a blue whale
Its discovery was important because it was recovered from rocks about 202 million years old, it was very large (1 meter long but incomplete), and it clearly belonged to a new species of giant ichthyosaur. The jawbone had an unusual shape and structure (called surangular). But we refrained from giving a name to the discovery, in the hope that more fossil remains would come in the future.
Enter a second, more complete and better preserved specimen, this time showing a proper pronoun from another individual.
This latest discovery was made just six miles along the coast at Blue Anchor in 2020. It was discovered by father and daughter fossil hunters, Justin and Ruby Reynolds (Ruby was 11 at the time). They contacted me almost immediately when they received it. In the next few years, together with De la Salle and some of our family, we collected more fossil fragments, and the last piece was found in October 2022.
As we began to piece together different parts of the same jawbone, we estimated that the whole bone would be just over 2 meters long. The preservation and fine detail provided new information that also helped us to better interpret the original De la Salle bone.
Now, we had two specimens with the same unique features collected from the same geological time zone. And these two bones appeared about 13 million years after the most recently dated and scientifically named giant ichthyosaurs, including Shonisaurus sikanniensis from British Columbia, Canada, and Himalayasaurus tibetensis from Tibet, China, support our identification of new species.
Therefore, we erected a new genus (taxonomic class) and a giant species of ichthyosaur that we called Severnensis Ichthyotitanmeaning “the giant fish lizard of the Severn”.
Giant blue whale
With two huge jawbones, it’s impossible to say exactly how big Ichthyonian really was. However, we do know that both specimens are about 25% larger than the same bone in the giant Shonisaurus sikanniensisan earlier ichthyosaur collected from British Columbia with an estimated body length of 21 meters.
Using a basic formula called a simple scaling factor, we can estimate that our ichthyosaur was up to 26 meters long, about the size of a blue whale. Comparisons with the same bone in other ichthyosaurs suggest that it is Ichthyonian it was between 20 and 26 meters long.
We must be careful with such estimates because of differences among species, such as those with long or short snouts. However, simple scaling is a common way to estimate size in paleontology, especially when dealing with fossil fragments. Therefore, based on the information currently available to us, Severnensis Ichthyotitan it is probably the largest marine reptile formally recognized by scientists.
At 202 million years old, the fossils were virtually non-existent before a global extinction event that wiped out these giants – and marine reptiles would never achieve that again. We think they belonged to a family of ichthyosaurs called Shastasauridae, which went extinct during the final Triassic extinction event. The cause is a source of debate among scientists, but it may have been triggered by the sudden release of large amounts of carbon dioxide.
As part of our research, we also looked at bone histology (microscopic anatomy). This side of the work was led by Marcello Perillo from the University of Bonn. Thin sections of the bones revealed the same microscopic features found in similar giant ichthyosaurian specimens. The research also showed that this giant had yet to reach full maturity and was still growing at the time of death.
Anyone can contribute
When I received the initial email from the Reynolds describing their findings, I smiled knowing that we now had a second specimen. I was also very impressed that they correctly identified the find as another giant jawbone from an ichthyosaur and recognized that it matched De la Salle’s earlier discovery. I asked them if they would like to join my team to study this fossil and they agreed.
Ruby Reynolds is now a published scientist who not only discovered a giant prehistoric reptile but also helped name a giant prehistoric reptile. There are probably not many 15-year-olds who can say that. She, her father and De la Salle all contributed to our understanding of ancient life.
Palaeontology is one of those sciences where anyone can make a significant contribution. You don’t have to be a professor or a world expert. All you need is a keen eye, a lot of patience and a bit of luck.
It is remarkable to think that hundreds of millions of years ago large blue whale reptiles were swimming in the oceans around the UK. These jawbones provide false evidence that one day a complete skull or skeleton of one of these giants may be found.
This article from The Conversation is republished under a Creative Commons license. Read the original article.
Dean Lomax worked with Paul de la Salle, Marcello Perillo, Justin and Ruby Reynolds and Jimmy Waldron from the Dinosaurs Will Always Be Awesome Museum on the reference research. He dedicates the work to Paul de la Salle who discovered the first surangular in 2016.
