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A huge jaw found by a father-daughter fossil collector duo on a beach in Somerset, along the English coast, belonged to a newly discovered species that is probably the largest marine reptile known to swim in Earth’s oceans.
Scientists consider the blue whale, which grows up to 110 feet (33.5 meters) long, making it the largest known animal to ever exist on the planet. But it’s possible that the 202-million-year-old reptile, known as an ichthyosaur or “fish lizard,” could have rivaled it in size.
The ichthyosaur jaw, or surangular, was a long, curved bone in the upper part of the jaw, just behind the teeth, and measured more than 2 meters in length. Researchers believe the creature, called Ichthyotitan severnensis, or “giant Severn fish lizard” in Latin, was more than 25 meters long, or the length of two city buses.
Justin and Ruby Reynolds, who live in Braunton, England, recovered the first pieces of the jawbone in May 2020 while searching for fossils on the beach at Blue Anchor, Somerset. Ruby, 11 at the time, spotted the first piece of bone and then she and her father found additional pieces together.
The remarkable discovery could shed more light on the prehistoric giant’s role in evolutionary history and the ocean ecosystem it calls home, according to Marcello Perillo, a graduate student in evolutionary paleobiology at the University of Bonn in Germany. He is co-author of a new report describing the discovery that appeared Wednesday in PLOS One magazine.
Discovering an unknown ichthyosaur
Encouraged by the idea that the fossil discovery could be significant, the Reynolds approached Dr. Dean Lomax, a paleontologist at the University of Manchester and an 1851 researcher at the University of Bristol in the United Kingdom. An expert on ichthyosaurs, Lomax has named several species new to science in recent years.
Intrigued by the fossil, Lomax contacted fossil collector Paul de la Salle, who had found a giant ichthyosaur jaw that looked remarkably similar in May 2016. De la Salle discovered the first jaw about 10 kilometers away in Devon, along the coast in Lilstock.
Lomax, who served as lead author of the new report, and co-author de la Salle together studied the previous discovery and co-authored an April 2018 paper on the discovery, suspecting that it may belong to a previously unknown species of ichthyosaur. But researchers needed additional evidence, and a second, nearly identical jawbone presented an opportunity to potentially confirm a new species.
“To think that my discovery in 2016 would spark so much interest in these enormous creatures fills me with joy,” said de la Salle. “When I found the first jawbone, I knew it was something special. Having a second one confirm our findings is incredible. I am really happy.”
Together, the Reynolds, Lomax, de la Salle, and others returned to the Blue Anchor in search of additional fragments. The team recovered other pieces that fit together perfectly, like putting together a puzzle.
“When Ruby and I found the first two pieces, we were so excited to realize that this was something important and unusual,” Justin Reynolds said in a statement. “When I found the back of the jaw, I was thrilled because that is one of the defining parts of Paul’s previous discovery.”
Researchers reassembled the jaw in October 2022.
“I was amazed by the discovery,” Lomax said in a statement. “In 2018, my team (including Paul de la Salle) studied and described Paul’s giant jaw and we hoped that one day another would come to light. This new specimen is more complete, better preserved and shows that we now have two of these giant bones – called surangulars – that have a unique shape and structure. I was very excited, to say the least.”
Riding a giant ichthyosaur
The bones date back to the late Triassic Period, during a time known as the Rhaetian, when ichthyosaurs swam the oceans and dinosaurs ruled the land.
The newly discovered jaw is a better quality specimen than the first, featuring the creature’s surangular features that make it distinct from other species, Lomax said.
The jaws of severnensis date back around 13 million years, after giant ichthyosaur fossils belonging to different species that were previously found in Canada and China.
Ichthyosaurs, which slightly resembled modern dolphins, first appeared about 250 million years ago. Over time, some of them evolved to have larger body sizes, and 202 million years ago, oceanic titans like severnensis were probably the largest marine reptiles.
But scientists believe that the giant ichthyosaurs disappeared during an ocean acidification event that occurred about 200 million years ago, and the surviving ichthyosaurs never grew to such gigantic sizes before they disappeared 94 million years ago.
The researchers emphasized that more evidence is needed to confirm the exact size of severnensis, and they remain hopeful that a complete skull or skeleton could be discovered in the future, Lomax said.
Co-author Perillo of the University of Bonn studied the histology, or microscopic anatomy, of the ichthyosaur bones and found that the reptile was probably still growing at the time of its death, meaning that an adult severnensis may have been larger than a blue whale.
Histology can reveal the biological information hidden in fossilized bones, revealing how individual animals developed and adapted to specialized lifestyles, he said. For example, some ichthyosaurs had bones that helped them dive deeply or live in shallow waters.
“Through histology we can also understand how quickly and for how long they grew; in the case (of the ichthyosaur), we could not see convincing signs indicating a growth arrest,” Perillo said. “This supports the idea that, if the animal had not died, it would probably have continued to grow, exceeding the estimated 25 meters. Much about these giants is still shrouded in mystery, but one fossil at a time we will be able to unlock their secret.”
Uncovering the history of marine reptiles is crucial to understanding ancient ocean ecosystems because the creatures filled numerous niches and shaped oceanic food chains, Perillo said, creating competition and an “endless spiral of evolution.”
“From them we can understand how evolutionary laws shaped life, what led it to be what it is now,” he said. “We can understand how changes in the environment affect ecological communities and predict future ecological developments in our current environment.”
The future of paleontology
Paleontologist Mary Anning and her older brother, Joseph, discovered the first known ichthyosaur fossils in 1811 and 1812, decades before the word dinosaur was part of our lexicon. Since then, fossils belonging to more than 100 species of ichthyosaurs have been identified around the world.
The discovery made by the Reynolds and de la Salle will soon be displayed at the Bristol Museum and Art Gallery, in the United Kingdom.
“It was really cool to discover part of this giant ichthyosaur. I am very proud to have played a role in a scientific discovery like this,” Ruby Reynolds said in a statement.
Lomax said he has enjoyed working with fossil collectors in recent years because he believes paleontology is a scientific field in which anyone can make a significant contribution.
“For Ruby Reynolds, not only did she find this important fossil, but she also helped name a type of gigantic prehistoric reptile,” Lomax said in an email. “There probably aren’t many 15-year-olds who can say that! A Mary Anning in the making, perhaps. But whether or not Ruby follows the path of paleontology or science, the important thing is that she, Justin and Paul contributed immensely to paleontology and our understanding of the ancient world.”
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