captorhinomorph

Captorhinomorphs were an early group of reptiles that lived during the Permian Period, approximately 299 to 251 million years ago. These reptiles, like the genus Captorhinus, were small, typically around 30 cm (12 inches) in length, and resembled modern lizards. They are characterized by their nearly solid skulls, which lacked openings for jaw muscle attachment, distinguishing them from later reptiles with stronger jaws. Captorhinomorphs are considered "stem reptiles," meaning they are thought to be ancestral to most other reptile groups, and possibly even mammals and birds. While common in the early Permian, only a small lineage survived into the Triassic Period before becoming extinct.123