A huge jawbone found by a father-daughter duo collecting fossils on a beach in Somerset along the English coast belonged to a newly discovered species that is believed to be the largest known marine reptile to swim in Earth's oceans.
Scientists consider the blue whale, which can grow up to 33.5 meters in length, to be the largest known animal to have ever existed on Earth. But it's possible that the 202-million-year-old reptile known as an ichthyosaur or "fish lizard" could rival him in size.
The ichthyosaur's jawbone, or surangular, was a long, curved bone at the top of the lower jaw, just behind the teeth, and was more than 2 meters long. Researchers believe the creature, named Ichthyotitan severnensis, or 'giant fish lizard of the Severn' 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, then 11 years old, saw the first piece of bone, and then she and her father found more pieces together.
The remarkable find could shed more light on the prehistoric giant's role in evolutionary history and the ocean ecosystem he called 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, which appeared Wednesday in the journal PLOS One.
Discovering an unknown ichthyosaur
Encouraged by the thought that the fossil find could be significant, the Reynoldses contacted Dr. Dean Lomax, a paleontologist at the University of Manchester and 1851 Research Fellow at the University of Bristol in the United Kingdom. Lomax, an expert on ichthyosaurs, has named several species new to science in recent years.
Intrigued by the fossil, Lomax contacted fossil collector Paul de la Salle, who in May 2016 had found a gigantic ichthyosaur jawbone that looked remarkably similar. De la Salle discovered the first jawbone about 10 kilometers away from Devon along the coast near Lilstock.
Lomax, who served as lead author on the new report, and co-author de la Salle had studied the earlier find together and co-authored an April 2018 paper on the discovery, hypothesizing that it belonged to a previously unknown species of ichthyosaur could belong. But the researchers needed additional evidence, and a second, nearly identical jawbone offered the opportunity to possibly confirm a new species.
"The thought that my discovery in 2016 would spark so much interest in these enormous creatures fills me with joy," de la Salle said. "When I found the first jawbone, I knew it was something special. It's incredible to have a second that confirms our findings. I am overjoyed."
Together, the Reynoldses, Lomax, de la Salle and others returned to Blue Anchor to search for additional fragments. The team found other pieces that fit together perfectly, like completing a puzzle.
"When Ruby and I found the first two pieces, we were very excited because we realized this was something important and unusual," Justin Reynolds said in a statement. "When I found the back part of the jaw I was very happy because that is one of the defining parts of Paul's earlier discovery."
The researchers reassembled the jawbone in October 2022.
"I was amazed by the find," Lomax said in a statement. "In 2018, my team (including Paul de la Salle) studied and described Paul's gigantic jawbone and we had 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 gigantic bones - called a surangular - that have a unique shape and structure. I got very excited, to say the least."
Assembling a giant ichthyosaur
The bones date to the end of the Triassic, a time known as the Rhaetian, when ichthyosaurs swam the oceans and dinosaurs ruled the land.
The newly discovered jawbone is of better quality than the first and shows the characteristics of the creature's square shape, which sets it apart from other species, Lomax said.
Severnensis jawbones date back about 13 million years after giant icthyosaur fossils of several species previously found in Canada and China.
Ichthyosaurs, which looked somewhat like modern dolphins, first appeared about 250 million years ago. Over time, some of them evolved to larger body sizes, and 202 million years ago, ocean 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 that the surviving ichthyosaurs never grew to that gigantic size again before disappearing 94 million years ago.
The researchers emphasized that further evidence is needed to confirm Severnensis' exact size, 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's bones and found that the reptile was likely still growing at the time of its death, meaning an adult severnensis may have been larger than a blue whale .
Histology can reveal the hidden biological information in fossilized bones, revealing how individual animals developed and adapted to a specialized lifestyle, he said. For example, some ichthyosaurs had bones that helped them dive deep or live in shallow waters.
"Through histology we can also understand how fast and how long they grew; in the case of (the ichthyosaur) we could not see any convincing signs indicating a cessation of growth," Perillo said. "This supports the idea that if the animal had not died, it would probably have continued to grow larger, over the estimated 25 metres. So much about these giants is still shrouded in mystery, but fossil by fossil we will be able to unravel their secret."
Uncovering the history of marine reptiles is crucial to understanding ancient ocean ecosystems, because the creatures filled different niches and formed ocean food chains, Perillo said, creating competition and a "never-ending spiral of evolution."
"From this we can understand how evolutionary laws shaped life, what led life to become what it is today," he said. "We can understand how environmental changes impact 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 fossils of ichthyosaurs in 1811 and 1812, decades before the word dinosaur was even part of our lexicon. Since then, fossils belonging to more than 100 species of ichthyosaurs have been identified around the world.
The Reynoldses and de la Salle's discovery will soon be exhibited at the Bristol Museum and Art Gallery in Britain.
"It was so 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 everyone can make important contributions.
"For Ruby Reynolds, she not only found this important fossil, but also helped name a species of giant 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 have contributed enormously to paleontology and our understanding of the ancient world."
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