This image of the gigantic dinosaur Spinosaurus, from Dinosaur Planet, is only half-right. New research shows that these massive, sailbacked animals probably didn't rear up on their hind legs much. But they did spend most of their time in the water, engaging in badass battles with sharks.

Over at the Washington Post, Rachel Feltman reports on the discovery, published today in Science magazine. A new reconstruction of a Spinosaurus skeleton reveals that these predators may have been the biggest hunters on Earth, surpassing even the T-rex in size. Growing up to 50 feet long, they were mostly aquatic — at least, judging from the positioning of their nostrils, which are positioned high enough on the snout that they could avoid taking in too much water.

Writes Feltman:

The dinosaur's skeletal shape indicates that it would have been a strange sight to us on land. The Spinosaurus's center of gravity was pushed forward by its long neck, so it was almost certainly impossible for it to walk on two legs. In fact, the Spinosaurus's legs and pelvis are quite like those seen in early whales — much better for paddling than for walking. Like whales, these dinosaurs probably evolved from land-dwelling ancestors to become semi-aquatic.

Other hints that the beasts roved the waters rather than land include the paddle-like shapes of their feet and a bone density best suited for a life in the water. They may have wandered around on land once in a while, but scientists now believe Spinosaurus would have been most at home hunting in the oceans. And that's where the sharks come in. Because if you were a fifty-foot-long predator with sharp teeth and a huge sail on your back, of course you would eat sharks.

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Actually, this kind of reminds me of Dimetrodon, another sail-backed prehistoric predator who may have eaten sharks. Dimetrodon was a synapsid, an animal with characteristics of both mammals and reptiles, who went extinct long before many dinosaurs evolved. Still, as this excellent song by The Doubleclicks makes clear, the spirit of Dimetrodon lives on.

Read the full scientific paper in Science