Sauropod dinosaurs, the largest terrestrial animals ever to have lived on our planet, could float like corks in water, according to computerized buoyancy tests on recreations of sauropods that lived during the Mesozoic Era, which lasted from 248 to 65 million years ago.This ability links the huge dinosaurs with birds, scientist say. Both float in water despite often surprisingly large body sizes. The finding also negates an earlier theory that sauropods escaped predators by hiding themselves underwater. The computerized models were created by Donald Henderson, a paleontologist in the Vertebrate Morphology and Palaeontology Research Group in the Department of Biological Sciences at the University of Calgary. A paper on his research is published in the current Royal Society Biology Letters.Henderson digitized restorations of the animals into a 3-D format. The computerized models show the shape and volume of the dinosaur, which Henderson could then dunk in virtual water. He explained to Discovery News that sauropods floated because air sacs within their bodies gave them a surprising lightness for a reptile that could grow as long as 130 feet and weigh as much as 85 tons, or ten times the size of today's elephants. Sauropods also had lightweight bones.

"The bones of the spine are mostly a form of 'bony foam,'" said Henderson. "There is also good evidence visible in their bones that these animals had a system of air sacs just like birds. The air sac systems of birds fill up a large volume of their bodies, and make them very light, (such as) how a large swan can float on the water." Sauropods were not very good swimmers, however. The shape of their bodies, including their thick, long necks, would have made them tipsy and unstable in water, according to Henderson. Only one species, Brachiosaurus, likely moved with relative ease in water, punting along the bottom mud of lakes.

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