Sauria

Sauria is the clade of diapsids containing the most recent common ancestor of Archosauria (which includes crocodilians and birds) and Lepidosauria (which includes squamates and the tuatara), and all its descendants. Since most molecular phylogenies recover turtles as more closely related to archosaurs than to lepidosaurs as part of Archelosauria, Sauria likely contains all living reptiles and can be considered the reptile crown group, and may therefore be synonymous with Reptilia under some definitions. Sauria may also include other major extinct reptile groups, such as the marine reptile clades Sauropterygia, Ichthyosauromorpha, and Thalattosauria.

Sauria lies within the larger total group Sauropsida, which also contains various stem-reptiles which are more closely related to reptiles than to mammals. Prior to its modern usage, "Sauria" was used as a name for the suborder occupied by lizards, which included crocodilians in 18th century classifications.