Plesiosaurs split into two main groups early in their evolutionary history. The pliosaurs had a short neck and elongated head. The plesiosaurids had a relatively small head and the neck was snake-like.
Elasmosaurus mauritanicus - Elasmosaur is Greek (elasos for "thin plate" - referring to the thin pelvic girdle plates, and saurus for "lizard"). Elasmosaurs descended from the Plesiosauria family. They were the longest necked of all the Plesiosaurs, with the neck equal to more than half of its total length. Elasmosaurs reached a total length of 45 feet and a neck of 26 feet. There were 71 vertebrae in their necks. The earliest plesiosaurs had only 28 neck vertebrae. Their long necks allowed them to dart their small heads filled with sharp teeth back and forth rapidly to catch fish (their primary diet). They lived from the Late Triassic through the Cretaceous (220-65 million years ago) and may be found in North America and Africa.
These specimens come from The Ganntour Basin Phosphate Deposits, of Khourigba, Morocco. The fossil Elasmosaur teeth offered here are among the best specimens that I have seen offered anywhere.
Kingdom: Animalia, Phylum: Chordata, Class: Reptilia, Super-Order: Sauropterygia, Order: Plesiosauria, Family: Elasmosauridae, Genus: Elasmosaurus, Species: mauritanicus.