Fossil sea monster's bite makes T-Rex look feeble

The pliosaur, estimated to have weighed 45 metric tons, was similar to but had more massive bones than another fossil sea monster found on Svalbard in 2007, also estimated at 50 feet long and the largest pliosaur to date.

"It's not complete enough to say it's really bigger than 15 meters," Hurum said of the new fossil.

Hurum had said of the first fossil pliosaur that it was big enough to chomp on a small car. He said the bite estimates for the latest fossil forced a rethink.

"This one is more like it could crush a Hummer," he said. referring to General Motors' large sport utility vehicle.

Among other findings were that the pliosaur had a small thin brain shaped like that of a great white shark, according to scans by Patrick Druckenmiller of the University of Alaska.

Pliosaurs preyed upon squid-like animals, fish, and other marine reptiles. Predator X had four huge flippers to propel itself along, perhaps using just two at cruising speeds and the others for a burst of speed.

-- For Reuters latest environment blogs click on: blogs.reuters.com/environment/

(Editing by Dominic Evans)