Ennatosaurus is an extinct genus of caseid synapsid that lived during the Middle Permian (late Roadian - early Wordian) in northern European Russia. The genus is only represented by its type species, Ennatosaurus tecton, which was named in 1956 by Ivan Antonovich Efremov. The species is known from at least six skulls associated with their lower jaws (two of them preserved with the hyoid apparatus), as well as from the postcranial bones of several juvenile individuals. Ennatosaurus has the typical caseid skull with a short snout tilted forward and very large external nares. However, it differs from other derived caseids by its postcranial skeleton with smaller proportions compared to the size of the skull. As with other advanced caseids, the teeth of Ennatosaurus were well suited for slicin