Il Plesiosaurus non è un dinosauro, bensì un grande rettile acquatico. ''Plesiosaur'' in greco significa "più vicino ai rettili". Gli è stato assegnato questo nome perché questa creatura è a metà fra un rettile ed un pesce.
== Cosa non sappiamo ancora di loro? ==
[[Image:Nessie ill artlibre jn.jpg|left|thumb|Il misterioso mostro di Loch Ness]]
The most famous mysteries around these creatures is the Loch Ness Monster. There are alot of stories of some large creatre in the lake called Loch Ness in Scotland. Most descriptions of the monster are close to what the Plesiosaurs must have looked like. Many people belive in it.
In 1977, some Japanese fishermen off the coast of New Zealand found a very rotten carcass of some large creature with flippers. It was so rotten that it was very hard to tell anything from it, but a lot of people believed that it was a Plesiosaur. Some scientists however think it was just a certain type of shark, just fallen to bits because it was so rotten.
== What do we need to learn? ==
*How flexible were their necks? Scientists don't agree on this.
*Is there any truth to the stories around them?