Pareiasaurus was a large, herbivorous reptile that lived during the late Permian period, around 260 million years ago. It belonged to a group called pareiasaurs, which were characterized by their thick bodies and distinctive bony plates. This creature could grow up to 3 meters long and had a broad, flat skull with small teeth adapted for grinding plant material. Fossils of Pareiasaurus have been found primarily in what is now South Africa and Russia. Its robust build and unique features suggest it was well-adapted to a terrestrial lifestyle, thriving in a variety of environments. The extinction of pareiasaurs occurred during the mass extinction event at the end of the Permian period.