This long-necked fish eating fiend is one the most iconic prehistoric marine reptiles around, and a personal favorite of mine since childhood. Most people would recognize this animal as the more generic term, plesiosaur. Some people would just recognize him as the "Lochness Monster."
Elasmosaur is a genus of plesiosaur that lived in the Late Cretaceous period about 80 million years ago. This guy was almost 50 feet long, making him the largest of all plesiosaurs. While he distinctly had lots and lots of teeth it is the number of vertebrae that makes him stand out in the crowd having the most vertebrae of any known animal- enough to make any giraffe jealous.