Mesosaurus

Mesosaurus is an extinct genus of small to medium-sized aquatic reptile from the Early Permian. Fossils have been found in southern Africa (notably the Karoo Basin) and in eastern South America (Brazil and Uruguay), indicating an aquatic lifestyle in freshwater environments. Adults were typically about half a meter to around a meter long. The animal had a long, narrow snout with small, conical teeth, and limbs modified into broad paddles with elongated digits. Its body was streamlined and the tail was relatively long, traits suited to swimming in shallow waters.

Ecology: Mesosaurus is interpreted as a freshwater or estuarine swimmer that fed on small fish and invertebrates. It breathed air and probably spent most of its life in water, using paddle-like limbs and tail strokes to propel itself.

Distribution and significance: The distribution of Mesosaurus fossils on continents that are now widely separated—Africa and South America—was early evidence used to argue for continental drift and, later, plate tectonics, supporting the idea that these landmasses once formed a connected southern supercontinent, Gondwana.

Taxonomy and evolution: Mesosaurus belongs to the family Mesosauridae, an early lineage of reptiles. Its exact position within reptile evolution remains debated, but it is widely recognized as one of the earliest reptile-like amniotes.