pleurosaurs

Pleurosaurs were a group of extinct marine reptiles belonging to the order Pleurosauria. They lived during the Late Triassic and Jurassic periods. These reptiles are characterized by their elongated bodies, long necks, and small heads, which gave them a serpentine appearance. Their limbs were typically short and paddle-like, adapted for swimming.

Fossil evidence suggests that pleurosaurs inhabited shallow marine environments, likely preying on fish and invertebrates. Their exact phylogenetic relationships have been debated, but they are generally considered to be a type of archosauriform reptile, meaning they are related to crocodiles and birds. Some studies have placed them closer to dinosaurs or other archosaurs, while others have suggested a more basal position within the Archosauriformes.

The name "pleurosaur" translates to "rib lizard," a reference to the distinctive structure of their ribs, which were often unusually shaped or fused. This feature may have provided additional support or stability in their aquatic lifestyle.

Notable genera include Pleurosaurus itself, discovered in Europe, and other related forms found in various parts of the world. The extinction of pleurosaurs likely occurred at the end of the Jurassic period, possibly due to competition from more advanced marine reptiles that emerged during the Cretaceous. Their unique morphology and evolutionary history make them an interesting subject in the study of Mesozoic marine ecosystems.