Original: Paleothyris was an early sauropsid, yet it still had some features that were more primitive, more labyrinthodont-like than reptile-like, especially its skull, which lacked fenestrae, holes found in the skulls of most modern reptiles and mammals.
Simplified: Paleothyris was an early sauropsid, yet it still had some features that were more labyrinthodont-like than reptile-like. Its skull lacked fenestrae, holes found in the skulls of most reptiles and mammals.