|Named By:||Edward Drinker Cope in 1868|
|Time Period:||Late Cretaceous, 80.5 Ma|
|Location:||USA, particularly associated with Kansas - Pierre Shale|
|Size:||14 meters long|
|Classification:||| Chordata | Reptilia | Sauropterygia | Plesiosauria | Elasmosauridae ||
Elasmosaurus (from Greek elasmos elasmos 'thin plate' (referring to thin plates in its pelvic girdle) + sauros sauros 'lizard') is a genus of plesiosaur with an extremely long neck that lived in the Late Cretaceous period (Campanian stage), 80.5 million years ago.