Elasmosaurid

Part of speech: noun, adjective

Definitions

1. Any of a group of long-necked marine reptiles from the Cretaceous period, belonging to the plesiosaur family and possessing paddle-like limbs
2. A prehistoric sea-dwelling reptile with a long neck and small head, classed within the plesiosaur group of extinct aquatic animals
3. An extinct aquatic reptile of the Mesozoic era, a member of the plesiosaur family known for its elongated neck and flippers

Etymology: Elasmosaurid comes from the Greek "elasmos", meaning "metal plate" or "thin plate", combined with "sauros", "lizard". The name refers to the broad, flat plates of bone forming the shoulder girdle, which were thought to be unusually thin and plate-like. The family itself was named in the 19th century, when palaeontologists were describing the first long-necked marine reptiles found in chalk and shale deposits. The best-known member, "Elasmosaurus platyurus", was described by Edward Drinker Cope in 1868 from fossils found in Kansas. Cope's reconstruction placed the skull on the end of the tail, because the long neck and small head were so unlike anything known. The error was pointed out by Othniel Charles Marsh, Cope's rival, who reportedly seized on it in their famous feud. Cope's mistake is what made the family's features memorable: a neck with dozens of vertebrae, and a head that was far from the reptile's true front end.