Pareiasauria

Pareiasauria, commonly known as pareiasaurs, is a clade of parareptile reptiles that lived during the Middle to Late Permian, roughly 270 to 250 million years ago. Fossils have been found in what are now Europe, Asia, and Africa, indicating a wide distribution before the end-Permian extinction.

Anatomy and ecology: Pareiasaurs were large, stocky animals with barrel-shaped bodies and heavy dermal armour formed by osteoderms along the back. They had broad skulls with a beak-like snout and multiple rows of teeth adapted to processing tough plant material, suggesting herbivorous or omnivorous diets. Limbs were short and stout, and their gait was probably slow. The armour and skull ornamentation in some species may have played a role in defense or display.

Taxonomy and diversity: Pareiasauria includes the families Pareiasauridae and Scutosauridae, with well-known genera such as Pareiasaurus and Scutosaurus. In many modern phylogenetic analyses, pareiasaurs are placed within Parareptilia as an early-diverging lineage of reptiles; some authors also refer to Pareiasauroidea as a higher-level grouping.

Evolution and extinction: Pareiasaurs were among the dominant Permian herbivores but began to decline as climate and ecological conditions shifted toward the end of the Permian. They went extinct by the end of the Permian, during the end-Permian mass extinction, along with many other tetrapod groups. Their fossil record provides important insights into the early evolution of parareptiles and the diversity of Permian ecosystems.