Fossil may belong to the biggest sea reptile that ever lived

A jawbone fossil found on arocky English beach belongs to one of the biggest marine animalson record, a type of seagoing reptile called an ichthyosaur thatscientists estimated at up to 26 metres (85 feet) long approaching the size of a blue whale.

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

The researchers estimated the animal's length by comparingthis surangular to the same bone in the largest ichthyosaurskeleton ever found, a species called Shonisaurus sikanniensisfrom British Columbia that was 21 metres (69 feet) long. Thenewly discovered bone was 25 per cent larger.

"This bone belonged to a giant," said University ofManchester paleontologist Dean Lomax.

"The entire carcass was probably very similar to a whalefall in which a dead whale drops to the bottom of the sea floor,where an entire ecosystem of animals feeds on the carcass for avery long time. After that, bones become separated, and wesuspect that's what happened to our isolated bone."

Fossil collector Paul de la Salle, affiliated with theEtches Collection in Dorset, England, found the bone in 2016 atLilstock on England's Somerset coast along the Bristol Channel.

"The structure was in the form of growth rings, like that ofa tree, and I'd seen something similar before in the jaws oflate Jurassic ichthyosaurs," he said.

Ichthyosaurs swam the world's oceans from 250 million yearsago to 90 million years ago, preying on squid and fish.

Thebiggest were larger than other huge marine reptiles of thedinosaur age like pliosaurs and mosasaurs. Only today's filter-feeding baleen whales are larger. The blue whale, up toabout 30 metres (98 feet) long, is the biggest animal alivetoday and the biggest marine animal ever.

The researchers estimated the new ichthyosaur at 20 to 26 metres (66 to 85feet long).

It appears to have belonged to an ichthyosaur group calledshastasaurids. Because the remains are so incomplete, it isunclear whether it represents a new ichthyosaur genus or is amember of a previously identified genus, said paleontologistJudy Massare of the State University of New York College atBrockport.

The research was published in the journal PLOS ONE.