Scientists have unearthed the fossil of an ancient aquatic reptile that sported a neck almost twice as long as its meter-long body. The 1.7-meter-long neck appears to have been too rigid to twist around in search of prey, however, so its function was at first uncertain. This animal was one of those things that comes along and says 'wait a minute, you don't know as much as you thought you did' about what long necks are good for, says Michael LaBarbera of the University of Chicago, one of the authors of a paper detailing the find published today in Science.

The Guanling limestone formation in China, where the new specimen was found, was deposited on the ocean floor about 230 million years ago in the Triassic period, when dinosaurs were becoming prevalent on land. The fossil belongs to the carnivorous species Dinocephalosaurus orientalis, which scientists first described only last year. It is a protorosaur, a group of reptiles that includes Tanystropheus, whose ludicrously long neck has stimulated debate since its discovery in the 1850s. Unlike Tanystropheus, however, Dinocephalosaurus had flipper-shaped limbs, indicating a largely aquatic lifestyle.

The authors suggest that the long, thin neck enabled Dinocephalosaurus to sneak up on prey in murky water without revealing its full size. In addition, the 25 neck vertebrae bore ribs running along the spine. Straightening the spine and extending the ribs could have rapidly increased the volume of the neck, sucking in both prey and water. Some modern fish rapidly expand their mouths to accomplish a similar suction feeding.