Elasmosaurus

Elasmosaurus was a 46 foot long swimming reptile that lived in the North American Inland Sea. It was a plesiosaur. 

It was first discovered in 1868 by a scientist named Edward Drinker Cope who accidentally put the head on the tail. It had 71 cervical vertebrae.Sachs S. 2005. Redescription of Elasmosaurus platyurus, Cope 1868 (Plesiosauria: Elasmosauridae) from the Upper Cretaceous (lower Campanian) of Kansas, U.S.A. Paludicola 5(3): 92-106. 

It was suggested by D.M.S. Watson that their method was as surface swimmers, mostly eating with their head above water, darting down to snatch smaller fish which were feeding on plankton.Watson D.M.S. 1951. Palaeontology and modern biology. Yale, CT.Watson D.M.S. 1958. Studies on fossil vertebrates. London.Alexander, R. McNeill 1989. Dynamics of dinosaurs and other extinct giants. Columbia N.Y. p137 It is hard to see the benefit of a long neck under water. Aquatic mammals operating under water all have a streamlined torpedo-shape, as did pliosaurs and ichthyosaurs. All the longer-necked families were, from the setting of the teeth and jaws, eaters of small fish. The large number of neck vertebrae is probably linked to the modest degree of flexibility between adjacent vertebrae.

 References 

Category:Plesiosaurs