Fossil hunting is mostly a game of patience and muddy boots. For Ruby Reynolds, one afternoon gave her a once-in-a-lifetime opportunity.
Ruby, then aged 11, was combing the beach at Blue Anchor in Somerset, England with her father Justin when she spotted a large, curved chunk of bone sticking out of the mud. She had no idea she was looking at the jaw of the biggest marine reptile to have ever lived.
Realising they had discovered something significant, they contacted leading ichthyosaur expert Dr Dean Lomax, a Research Fellow at the University of Bristol.
In April 2024, scientists formally named the creature Ichthyotitan severnensis in a study published in PLOS ONE, meaning “giant fish lizard of the Severn.” The fossils are now on display at Bristol Museum and Art Gallery.
HOW BIG WAS THIS PREHISTORIC SEA MONSTER?
This giant of the oceans is estimated to have reached around 25 metres in length, about the size of a modern-day blue whale. The bones are around 202 million years old, dating to the end of the Triassic Period, a prehistoric era that predates even the age of dinosaurs.
Back then, a group of marine reptiles called ichthyosaurs, which were giant dolphin-shaped hunters with razor instincts, ruled the oceans while the earliest dinosaurs were just finding their feet on land.
Ichthyosaurs were in fact the first four-limbed vertebrates to reach truly gigantic sizes, evolving rapidly. Individuals reached up to 17 metres in length just a few million years after the group first appeared.
Ichthyotitan severnensis represents the absolute peak of that evolution, the largest of them all.
What makes it even more staggering is that the ichthyosaur discovered by Ruby had not finished growing. Master’s student Marcello Perillo, from the University of Bonn, examined the bone’s internal structures and revealed that the animal was still growing at the time of its death.
Twenty-five metres may have been the floor, not the ceiling.
WHO ELSE WAS INVOLVED IN THIS DISCOVERY?
The story actually begins in 2016, when seasoned fossil collector Paul de la Salle found a similar, less well-preserved jawbone at Lilstock, Somerset. Ruby and Justin’s find, four years later, provided the confirmation scientists needed.
Dr Lomax said the new specimen was more complete, better preserved, and shared the same unique shape and structure as the bone discovered by Paul. The final piece was recovered in October 2022.
WHY DID THESE GIANTS DISAPPEAR?
Around 201.3 million years ago, a mass extinction event marked the boundary between the Triassic and Jurassic Periods. Massive volcanic activity released so much carbon dioxide and sulphur dioxide that it triggered a dramatic shift in the climate.
As sea levels rose and the oceans became more acidic, the entire giant ichthyosaur family was wiped out. Marine reptiles never reached such sizes again. That distinction eventually passed to whales, millions of years later.
WHAT HAPPENED TO THE FOSSILS, AND WHO GETS CREDIT?
Ruby, Justin and Paul’s discoveries have gone on display at Bristol Museum and Art Gallery.
Ruby, now 15, is a published co-author on the paper. Dr Lomax compared her to Mary Anning, the 19th-century fossil hunter from Dorset who discovered the first ichthyosaur skeleton, calling Ruby a legend in the making.
Paul de la Salle said finding a second bone that confirmed his 2016 discovery filled him with joy. Dr Lomax added that these jawbones offer tantalising evidence that a complete skull or skeleton of one of these giants might one day be found.
Not bad for a usual day at the beach.
