National Geographic : 2007 Dec
AMA RGASAURUS X-FACTOR Double row of spines on neck and back iIA WHEN 130-125 million years ago WHERE Argentina Like the tail fins on a 1959 Cadillac, a bizarre double row of spines extending from the vertebrae of Amargasaurus (right) may have served little purpose other than to turn heads. Since the discovery of the sauropod was announced in 1991, paleontologists have pondered the function of the delicate bony rods, which would have offered limited defense at best against predators. Perhaps they were covered with skin, forming sails similar to those on some living lizards. If so, Amar gasaurus might have flushed blood into the sails to help cool its body. But their likely function, says Smithsonian paleontologist Hans-Dieter Sues, was to attract mates or intimidate rivals. "In evolution nothing is really bizarre. Every structure makes perfectly good sense to the organism. In the case of extinct animals the challenge is to identify what the purpose might have been." BASEMODELSFORALL DINOSAURSBY 422SOUTH. ARTBY RENEGADE9; FOSSILPHOTOGRAPHED AT MUSEO ARGENTINODECIENCIASNATURALES(MACN),BUENOSAIRES. SKULLSHOWNISA SPECULATIVECAST.