1. An extinct marine reptile of the Mesozoic era, characterized by a long neck, four flippers, and a small head.
Usage: paleontology; often used in educational and popular science contexts

Examples

• The plesiosaur was a dominant predator in ancient seas during the age of dinosaurs.
• Fossils of plesiosaurs have been found on every continent, indicating their widespread distribution.
• Unlike dinosaurs, plesiosaurs were fully adapted to life in the ocean.
• The long neck of a plesiosaur allowed it to hunt fish and other small marine animals.
• Scientists study plesiosaur remains to understand the ecosystems of the Mesozoic era.