A jawbone fossil found on a rocky English beach belongs to one of the biggest marine animals on record, a type of seagoing reptile called an ichthyosaur that scientists estimated at up to 26 meters (85 feet) long — approaching the size of a blue whale.

Scientists said on Monday this ichthyosaur, which appears to be the largest marine reptile ever discovered, lived 205 million years ago at the end of the Triassic Period, dominating the oceans just as dinosaurs were becoming the undisputed masters on land. The bone, called a surangular, was part of its lower jaw.

The researchers estimated the animal's length by comparing this surangular to the same bone in the largest ichthyosaur skeleton ever found, a species called Shonisaurus sikanniensis from British Columbia that was 21 meters (69 feet) long. The newly discovered bone was 25 percent larger.