Eureptilia

Eureptilia, meaning "true reptiles," is a group that emerged in the Late Carboniferous period, approximately 312 million years ago. These early reptiles, such as Hylonomus and Paleothyris, were small, lizard-like animals that inhabited forests. They are distinguished from a more primitive group called anapsids (or Parareptilia).1

The Eureptilia lineage includes most modern reptiles and many extinct groups. A significant split within Eureptilia led to diapsids, characterized by skulls with temporal openings, which encompass a vast array of reptiles including lizards, snakes, crocodiles, dinosaurs, and birds. While the earliest eureptiles were generally small, this group eventually diversified into a wide range of forms, including marine reptiles like ichthyosaurs and sauropterygians, as well as the flying pterosaurs and the diverse dinosaurs.231