What Are Plasiosaurs?

Pleziosaur aren't dinosaurs, because to be a dinosaur you have to have a certain kind of hip joint. There were actually a bunch of pleziosaur species that are grouped together in a biological order known as Plasiosauria. The general range for adults was between 5 feet long and 50 feet long. A different species also had different body proportions with short necks and some having longer necks.