Plesiosaurus , an early plesiosaur, was about 4.5 metres (15 feet) long, with a broad, flat body and a relatively short tai.... head neck

Plesiosaurus , an early plesiosaur, was about 4.5 metres (15 feet) long, with a broad, flat body and a relatively short tail. The neck was long and flexible, and the animal may have fed by swinging its head from side to side through schools of fish, capturing prey by using the long, sharp teeth present in the jaws. Early in their evolutionary history, the plesiosaurs split into two main lineages: the pliosaurs, in which the neck was short and the head elongated; and the plesiosaurids, in which the head remained relatively small and the neck assumed snakelike proportions and became very flexible. Elasmosaurus , a plesiosaurid, had as many as 76 vertebrae in its neck alone and reached a length of about 13 metres, fully half of which consisted of the head and neck. head neck