1. Small extinct marine reptiles from the Permian period, characterized by long slender bodies and sharp teeth, found in fossil records of South America and Africa.
Usage: paleontology; plural form of mesosaur; used in scientific and educational contexts

Examples

• Mesosaurs were among the earliest known marine reptiles.
• Fossils of mesosaurs have been discovered in both Brazil and South Africa.
• The discovery of mesosaurs in distant continents provided evidence for continental drift.
• Mesosaurs had elongated bodies adapted for swimming in shallow seas.
• Paleontologists study mesosaurs to understand the evolution of marine reptiles.