By: Tia Ghose, LiveScience Contributor
Published: 10/17/2012 09:48 AM EDT on LiveScience

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 (12 meters) and had a massive 6.5-foot-long (2 m) skull with a bite four times as powerful as Tyrannosaurus rex.

"They were the top predators of the sea," said study co-author Patrick Druckenmiller, a paleontologist at the University of Alaska Museum. "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 an ancient Jurassic-era ocean filled with giant predators.

In 2006, scientists unearthed two massive pliosaur skeletons in Svalbard, Norway, a string of islands halfway between Europe 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 last century and a half. [See Images of Predator X]

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The huge pliosaur fossils had to be cast in plaster before being removed from the Svalbard site.

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

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

The new species likely lived closer to 145 million years ago and ate plesiosaurs, related long-necked, small-headed reptiles.

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

In 2008, scientists initially estimated that Predator X could have been up to 50 feet (15 m) long. The current study suggests the creature is smaller than that, but still bigger than the largest living apex predator, the killer whale, which tops out at about 30 feet (9 m) long, Druckenmiller said.

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A size comparison of a killer whale, blue whale, a Pliosaur (Predator X), and a human diver.

The Pliosaurus funkei fossils were just two of nearly 40 specimens discovered at the Svalbard site. In the Oct. 12 issue of the Norwegian Journal of Geology, 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, said study co-author Jorn Hurum of the University of Oslo in an email.

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

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  • Leviathan

    A 36-foot-long Pliosaurus attacks the plesiosaur Cryptoclidus, a marine reptile from the Late Jurassic Period. Also shown: the fish Pachycormus, a shoal of the belemnite Belemnoteuthis, and the ammonite Pectinatites. Acrylic Painting, 2008.

  • Rugops Primus Environmental Scene

    The scavenger Rugops, a dinosaur from the Late Cretaceous that lived in what is now Africa, driving a trio of the pterosaur Tupuxuara from the corpse of the sail-backed iguanadontid Ouranosaurus. The crocodylomorphs, relatives of the modern crocodile, are the 'boar-croc' Kaprosuchus.

  • Double Death

    Working together, a pair of Carcharodontosaurus saharicus, one of the largest carnivorous dinosaurs, steal away a juvenile Paralititan stromeri from its family herd. Paralititans were swamp-dwellers that grew to be one of the largest creatures to ever roam the Earth. Mixed media, 2011.

  • Ammonite Graveyard

    Ammonites, so called after the Egyptian god Ammon, were carnivorous squidlike animals that could be over 3 feet in diameter. Here, several ammonites decay on the sea floor. Material: Gouache, 2011. Based on a prepared slab in Ulster Museum. Courtesy of A. Cowap.

  • Reaper In Paradise

    The giant crocodile, Deinosuchus riograndensis, attacks an Albertosaurs, a smaller relative of the Tyrannosaurus, in Late Cretaceous North America, 75 million years ago. Acrylic painting, 2003.

  • Mammoths And Saber-Toothed Cats

    A pride of Smilodon fatalis, often called a saber-toothed cat, attacks a calf belonging to a herd of mammoths while the mother moves to protect her offspring. Digital painting

  • Aucasaurus Attacking Titanosaur Nests

    During the Late Cretaceous (85 million years ago) Aucasaurus, a pack-hunting dinosaur, attacks a group of startled titanosaurs in Argentina. Pushing past the adults guarding their nests, the Aucasauruses snap up the babies as they hatch. From National Geographic, March 2003, 'Dinosaurs - Flesh & Bone'

  • Gallimimus Bullatus & Tarbosaurus Bataarm

    Tarbosaurus, a predatory reptile that lived 70 million years ago in parts of Asia, chases two Gallimimuses, ostrich-like dinosaurs that could grow nearly 30 feet long. Digital Art, 2010.

  • One Split Second: Triceratops Vs. Tyrannosaurus Rex

    The T-Rex probably preyed on Triceratops, because their territories overlapped 65 million years ago. While the T-Rex had its famous bite to use for a weapon, triceratops' powerful horns were a formidable defense. Digital Painting/photographic composite. 2011. From the Golden Book of Dinosaurs, by Robert Baker/Rey.

  • Ambush In The Late Miocene Of Florida

    This scene shows a prehistoric rhino struggling to escape the sharp claws of two saber-toothed cats. From left to right: Aelurodon, Teleoceras (rhino), Barbourofelis (saber-tooth), Neohipparion (horse), Aepycamelus (giraffe-like camels), Synthetoceras.

  • Smilodon & Paramylodon

    A Smilodon, or saber-toothed cat, dispatches a ground sloth trapped in tar during the Ice Age in North America. Digital painting.

  • Beelzebufo Ampinga

    A huge toad from the late Cretaceous of Madagascar that may have grown to over 16 inches long and could have weighed up to 9 pounds. It was certainly big enough to eat baby dinosaurs. Acrylics on illustration board, 2007.

  • Cretaceous Rodeo (Aka T-Rex Family Life)

    The Tyrannosaurus rex was one of the most formidable predators of all the dinosaurs. The 40-foot-long carnivore had teeth up to twelve inches long. However, there is a debate among paleontologists over whether the T-Rex was an apex predator or a scavenger. Acrylics & ink on cardboard, 2004.

  • Devourer Of Giants

    Five million years ago, several Anacus - a straight-tusked member of the elephant family - have been caught in a flash flood and drowned. Washed out to sea, they attract two adult and a juvenile mega-shark named Carcharodon megalodon - at around 60 feet, probably the largest shark known. Acrylic painting, 2000.

  • Pristichampsus Attacking Early Horses

    Pristichampsus is an extinct crocodile relative that could grow up to 10 feet long. The armored reptile lived mostly on land, and fed on land mammals like these early horses. Detail from composite scene for the TV show Animal Planet. Gouache

  • Megantereon Attacking Bushbuck

    Megantereon, an early saber-toothed cat, may have eaten young rhinos, elephants, and horses. The felines probably bit their prey on the neck to kill them, and then let them bleed to death, like the bushbuck pictured here. Kromdraai A, Early Pleistocene of South Africa. Colored pencils, from Evolving Eden (Columbia University Press)

  • Photos courtesy Titan Books