It's official: A giant marine reptile that roamed the seas roughly 150 million years ago is a new species, researchers say. The animal, now named Pliosaurus funkei, spanned about 40 feet and had a 6.5-foot-long skull with a bite four times as powerful as Tyrannosaurus rex.

"They were the top predators of the sea," said Patrick Druckenmiller, a paleontologist at the University of Alaska Museum and co-author of the study, published in the Oct. 12 issue of the Norwegian Journal of Geology. "They had teeth that would have made a T. rex whimper."

Combined with other fossil finds, the newly discovered behemoth skeletons of P. funkei paint a picture of a Jurassic-era ocean filled with giant predators.

In 2006, scientists unearthed two massive pliosaur skeletons in the Svalbard islands, halfway between the Norwegian mainland and the North Pole. The giant creatures, one of which was dubbed Predator X at the time, looked slightly different from other pliosaurs discovered in England and France over the past century and a half.

Now, after years of painstaking analysis of the jaw, vertebrae and forelimbs, the researchers have determined that Predator X is a new species, and they have officially named it for Bjorn and May-Liss Funke, volunteers who discovered the fossils.

The pliosaurs, marine reptiles that prowled the seas 160 million to 145 million years ago, had short necks, tear-shaped bodies and four large, paddle-shaped limbs that let them "fly through the water," Druckenmiller said.

P. funkei probably ate plesiosaurs, a related species of long-necked, small-headed reptiles.

The new analysis shows that P. funkei had proportionally longer front paddles than other pliosaurs as well as a slightly different vertebrae shape and different spacing of teeth within the jaw, Druckenmiller said.

In 2008, scientists estimated that Predator X might have been up to 50 feet long. The current study suggests the creature is smaller than that but still about 10 feet bigger than the largest living apex predator — predators with no predators of their own — the killer whale, Druckenmiller said.

The Pliosaurus funkei fossils were just two of nearly 40 specimens discovered at the Svalbard site. The authors also describe two new ichthyosaurs, or dolphinlike reptiles, the longest-necked Jurassic-era plesiosaur on record, and several invertebrates.

Together, the fossils suggest an ancient Arctic sea teeming with fearsome predators and invertebrate fauna, study co-author Jorn Hurum of the University of Oslo said in an e-mail.

"It's not just that we found a new species — we've been discovering a whole ecosystem," Druckenmiller said.

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