Skip to main content Skip to Search Box

Definition: plesiosaur from The Macquarie Dictionary
1.

any member of the extinct genus Plesiosaurus which existed in the Jurassic and Cretaceous periods, comprising marine reptiles with small head, very long neck, short tail, and four large flippers.

Plural: plesiosaurs

Etymology: New Latin pl\xc4\x93siosaurus, from Greek pl\xc4\x93sio(s) near + sauros lizard, plesiosauruses


Summary Article: Plesiosaurus
from The Columbia Encyclopedia

(plē´´sēӘsôr'Әs), genus of extinct predatory marine reptiles that arose in the Triassic period of geologic time and continued into the Jurassic and Cretaceous periods. Plesiosaurs became extinct at the close of the Mesozoic era. Fossilized skeletons of them have been found in North America, Europe, and Australia. The plesiosaur had a small, short head, a long, snakelike neck, a broad, solid body, and a short tail. It had sharp interlocking teeth, and its four paddlelike legs were similar to those of a marine turtle. In total length, Plesiosaurus ranged from 10 to 60 ft (3–18 m). The term plesiosaur is sometimes applied more generally to all forms in the order Sauropterygia, which produced two lines of marine reptiles. The Plesiosaurus is an example of one trend. The other group, the pliosaurs, evolved into forms possessing short necks and gigantic skulls; the Kronosaurus, for example, had one of the largest known reptile skulls, reaching 9 ft (2.7 m) in length, and a still unclassified pliosaur first discovered on Spitsbergen in 2006 had a 10-ft (3-m) head. Paleontological evidence suggests that plesiosaurs may have given birth to live young instead of laying eggs. Plesiosaurs are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Sauropterygia.

The Columbia Encyclopedia, © Columbia University Press 2018

Related Articles


Full text Article plesiosaur
The Macmillan Encyclopedia

A widely distributed marine reptile of the Jurassic and Cretaceous periods (200-65 million years ago). Up to about 12 m long, plesiosaurs had...

Full text Article Mesozoic Marine Reptiles of Antarctica
Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth's Polar Regions

Present-day marine life in the Antarctic continent is marked by the presence of medium- to large-sized marine vertebrates that reacquired the abilit

Full text Article 252–65MYA Giant marine reptiles
Ocean

During Triassic, Jurassic, and Cretaceous times, evolution of reptiles, similar to that of the dinosaurs on land, occurred in the oceans....

See more from Credo