SCIENCE/AAAS, IBRAHIM ET AL.An odd carnivorous dinosaur may have been the earliest land animal to adapt to the life aquatic. With flat-bottomed feet for pedaling, dense bones to regulate buoyancy, and retractable nostrils far back in its skull, Spinosaurus aegyptiacus may have hunted its prey both on land and in lakes and rivers. Its semi-aquatic lifestyle was revealed by an analysis of disparate fossil bones assembled into the most complete spinosaur skeleton, described last week (September 11) in Science.
Paleontologist Nizar Ibrahim of the University of Chicago and his colleagues stumbled upon some of the bones used in this study in a museum in Milan; others were collected by a freelance fossil hunter in Morocco, who led the researchers to a site where they found more remains. These specimens, past descriptions and digital models suggested that 50-foot-long spinosaurs may have hunted in North African waterways approximately 97 million years ago.
Its small pelvis and short hind limbs suggested that S. aegyptiacus may have walked on all fours and had a more forward-positioned center of gravity. Coupled with the foot and bone adaptations proposed, the adaptations would have made it a fearsome swimmer. But the authors wrote in their paper that one of its most ...
