A remarkable discovery made by an 11-year-old girl during a simple beach walk has led scientists to identify what may be the largest marine reptile ever to have lived on Earth. The finding is now reshaping scientific understanding of prehistoric oceans and the true size of ancient marine predators.
The fossil, a massive lower jawbone measuring more than two metres in length, was discovered in 2020 on the coast of Blue Anchor in Somerset, southwest England. The bone was found by schoolgirl Ruby Reynolds and her father while fossil hunting along the shoreline. Scientists later confirmed that it belongs to a previously unknown species of giant ichthyosaur, now named Ichthyotitan severnensis.
Researchers determined that the newly identified species lived around 202 million years ago, during the final phase of the Triassic period. The jawbone closely matched another fragment found in 2016 at Lilstock, about 10 kilometres away. Both fossils were preserved in the Westbury Mudstone Formation, a geological layer known for holding remains from just before one of Earth’s largest mass extinction events.
Detailed analysis by scientists from the University of Bristol and the University of Manchester revealed unique features in the jaw structure that had never been seen in other ichthyosaurs. These included an unusual curvature at the back of the jaw, distinct muscle attachment points, and internal bone textures that confirmed it belonged to a new genus and species. The research has been published in the peer-reviewed journal PLOS ONE.
By comparing the jawbone with those of other large ichthyosaurs, scientists estimate that Ichthyotitan severnensis may have reached a length of 20 to 25 metres. This puts it in the same size range as modern blue whales, making it potentially the largest marine reptile ever discovered. Bone microstructure studies also suggest that the animal was still growing when it died, indicating that some ichthyosaurs may have grown even larger under favourable conditions.
The fossil comes from a critical moment in Earth history, just before the Triassic–Jurassic extinction event, which wiped out many large species. After this period, ichthyosaurs survived but never again reached such enormous sizes. Other marine reptiles later filled the oceans, but evolved in very different ways.
Although only jawbones have been formally linked to the species so far, researchers say the consistency between the two fossils is strong enough to confirm the discovery. Scientists believe that further exploration of the area could reveal more remains and deepen understanding of how such enormous marine creatures once thrived.
What began as a child casual beach walk has now become one of the most important paleontological discoveries in recent years, offering a rare glimpse into a time when giant reptiles ruled the seas.