Cyclotosaurus Fraas, 1889

Hercynosaurus Jaekel, 1914

Hemprichisaurus Kuhn, 1939

Type species: Cyclotosaurus robustus (Meyer and Plieninger, 1844)

Diagnosis (emended after Schoch and Milner, 2000): (1) Frontals with broad descending processes that connect with the roof of the broad sphenethmoid; (2) short choana of round to ovate outline; (3) vomerine plate short; (4) broad triangular area at the base of the cultriform process merging continuously into the cultriform crest; (5) basal plate of parasphenoid delta shaped with elongated basicranial suture (shared with Mastodonsauridae); (6) squamosal embayment closed to otic fenestra (shared with Eocyclotosaurus, Quasicyclotosaurus, Kupferzellia (Tatrasuchus), and Procyclotosaurus); (7) pterygoid–exoccipital contact by means of posterior process of pterygoid (shared with Eocyclotosaurus and Quasicyclotosaurus); (8) frontal contribution to orbital margin limited or obliterated (obliteration shared with Eocyclotosaurus and Quasicyclotosaurus); (9) quadrate ramus of pterygoid laterally aligned and abbreviated (Schoch, 2008; shared with Mastodonsauridae).