large pliosaurs, such as Rhomaleosaurus, Liopleurodon, Pliosaurus, Kronosaurus and Brachauchenius, were the superpredators of the Mesozoic seas, measuring 7 to 12 meters in length, and filled a similar ecological role to that of killer whales today. The long-necked plesiosaurs included Plesiosauridae, Cryptoclididae, and Elasmosauridae. Some lineages of long-necked plesiosaurs evolved progressively longer and more flexible necks, reaching 13 meters in total length by the late Cretaceous. With their small heads in proportion to their neck length and body mass, long-necked plesiosaurs were limited to eating relatively small fish, which they probably snared in their tooth-lined jaws with rapid lunges of their long necks. References External links Unit 220: 100: Lepidosauromorpha. Palaeos. July 15, 2003. Retrieved January 19, 2004. A review of the Sauropterygia. Adam Stuart Smith. The Plesiosaur Directory. Retrieved April 17, 2006. Paleofile taxalist - lists every species and synonyms. Retrieved February 26, 2006 Chordate superorders Early Triassic first appearances Maastrichtian extinctions