A walk along the Somerset coastline in southwest England led to the discovery of one of the largest marine reptiles ever identified. The fossil, uncovered by 11-year-old Ruby Reynolds during a family fossil hunt, belonged to a giant ichthyosaur later named Ichthyotitan severnensis.
The remains date back roughly 202 million years to the late Triassic Period, when giant predators roamed the shallow seas covering what is now Britain. The find began in May 2020 at Blue Anchor, a coastal site known for its fossil-rich mudflats and rapidly eroding cliffs. Ruby Reynolds and her father, Justin Reynolds, were searching the shoreline when they noticed unusually large bone fragments exposed in the sediment.
At first, the pieces seemed isolated and incomplete. Yet paleontologist Dean Lomax, affiliated with both the University of Bristol and the University of Manchester, quickly linked them to another mysterious fossil discovered in Somerset several years earlier. That earlier specimen had already suggested the presence of a massive unidentified ichthyosaur in the region.
Fossil Fragments That Changed The Picture
Justin Reynolds first spotted a small section of fossilized bone sticking out of the mud. He later described it as “bigger than any piece of bone I’d ever found before.” Not long afterward, Ruby located another fragment nearby that was twice as large.
The family contacted Dean Lomax, a paleontologist at the University of Bristol and the University of Manchester, after realizing the bones resembled giant ichthyosaur material previously reported in Somerset. In an email sent to the paleontologist, they wrote:
“Hey, Dr. Lomax – we think we’ve found another one of your giant ichthyosaur jawbones.” The message quickly drew the attention of researchers, who returned to the beach and recovered additional fragments exposed by erosion.
Those pieces eventually allowed scientists to reconstruct nearly two-thirds of a lower jawbone measuring more than 6.5 feet long. The study, published inPLOS ONE said that the fossil belonged to a newly recognized species named Ichthyotitan severnensis, meaning “giant fish lizard from the Severn.” Scientists estimated the full animal reached around 82 feet in length.
“These are reptiles only very, very distantly related to things like crocodiles,” said Lomax. “They gave birth to live young. They committed entirely to a life at sea — they didn’t come onto land.”
Giant Predators Ruled Triassic Seas
During the late Triassic, much of modern Britain lay beneath warm shallow oceans inhabited by large marine reptiles and abundant cephalopods. Ichthyosaurs became some of the dominant predators of these environments long before whales evolved.
These reptiles possessed streamlined bodies adapted for fast swimming and open-ocean hunting. Their shape has often been compared to dolphins, though ichthyosaurs were fully reptilian animals.
As explained by the research team, microscopic structures inside the jawbone resembled patterns found in other oversized ichthyosaurs discovered elsewhere in the world. The fossil may belong to the group known as shastasaurids, a lineage known for producing enormous marine reptiles during the Triassic.
Scientists also explained that giant ichthyosaurs reached their peak size shortly before the end-Triassic extinction event. Dean Lomax noted that:
“No marine reptile ever reached such gigantic sizes ever again” after this period.
A Discovery Made Possible By Coastal Erosion
The cliffs and mudstones along the Somerset coast constantly erode during winter storms, exposing fossils hidden for millions of years. Several years earlier, fossil collector Paul de la Salle had uncovered another giant jaw fragment in the same region. Researchers later realized both fossils shared unusual internal bone features and came from the same rock layer, strengthening the case for a newly identified species.
Biomechanist Kelsey Stilson described the Triassic as “a really weird time,” shaped by changing climates and the emergence of early dinosaurs and mammals. She added that :
“There were things that we can’t even possibly imagine in the past. But we can get little hints, and this is one little hint at this larger picture of evolution on Earth.”
Scientists believe more remains could still be buried within Somerset’s coastal cliffs. Lomax said the newly recovered jawbones offer “tantalizing evidence” that acomplete skull or skeleton of one of these giant reptiles may eventually surface.
