Ichthyoтιтan severnensis: Triᴀssic Ocean’s Jaw-Dropping Giant – The Largest Marine Reptile Ever?

In a discovery that has stunned paleontologists, the colossal jaw of Ichthyoтιтan severnensis — the “giant fish lizard of the Severn” — has been confirmed as belonging to one of the largest marine reptiles that ever lived.

Described in April 2024 in PLOS ONE by Dean Lomax and colleagues, the two mᴀssive surangular bones (part of the lower jaw) were found years apart along the Somerset coast in England’s Westbury Mudstone Formation. One fragment, nicknamed the “Lilstock monster,” was collected in 2016; the second surfaced near Blue Anchor in 2020. Together they reconstruct a lower jaw exceeding two metres in length — larger than any previously known ichthyosaur jaw.

At an estimated 25 metres (82 feet) long and weighing perhaps 80–100 tonnes, Ichthyoтιтan rivalled or exceeded the size of a modern blue whale. It lived 202 million years ago in the final days of the Triᴀssic, when giant shastasaurid ichthyosaurs dominated the seas as apex predators — the orcas of their time.

The sheer scale of the jaw suggests a powerful bite capable of tackling large prey, possibly including other marine reptiles. The fossils will soon go on public display at Bristol Museum & Art Gallery, where they continue to rewrite the record of Triᴀssic marine giants.

Lomax noted the bones represent “the largest marine reptile yet known from the fossil record.” While exact dimensions carry some uncertainty due to the fragmentary material, Ichthyoтιтan proves that true leviathans ruled Earth’s oceans long before the famous Jurᴀssic ichthyosaurs — cementing the Late Triᴀssic as the golden age of marine megafauna.