Mesenosaurus

Mesenosaurus is an extinct genus of synapsid belonging to the family Varanopidae. This genus includes two species: the type species Mesenosaurus romeri from the middle Permian (upper Kazanian) Mezen River Basin of northern Russia, and Mesenosaurus efremovi from the early Permian (Artinskian) Richards Spur locality (Oklahoma, United States). M. romeri’s stratigraphic range is the middle to late Guadalupian while M. efremovi’s stratigraphic range is the Cisuralian.