Plesiosauria

Part of speech: noun

Definitions

1. A diverse clade of large, extinct marine reptiles known for their long necks and flippers that thrived during the Mesozoic era
2. A group of prehistoric beings characterized by elongated necks and robust bodies, commonly found in fossil records from the age of dinosaurs
3. An order of extinct sea-dwelling reptiles recognized for their unique morphology, including paddle-like limbs and a distinctive head-to-body ratio

Etymology: In 1821 the English geologist William Daniel Conybeare named the genus that gave rise to this group, "Plesiosaurus," from Greek "plesios," meaning "near," and "sauros," meaning "lizard." The name reflected Conybeare's view that these marine reptiles were closely related to lizards, which later research showed was mistaken. Plesiosaurs belong to a separate reptile lineage that split off long before lizards as we know them appeared. The name was built on the genus. The "-ia" ending is the Latin plural pattern used for names of groups, so "Plesiosauria" denotes the whole assemblage of plesiosaur-type animals rather than a single genus. Most of the group's fossils come from marine rocks of the Mesozoic era, roughly 200 to 66 million years ago.

Synonyms: plesiosaurs, marine reptiles