It is defined as the most inclusive clade containing Stomatosuchus inermis but not Notosuchus terrestris, Simosuchus clarki, Araripesuchus gomesii, Baurusuchus pachecoi, Peirosaurus torminni, or Crocodylus niloticus.

[1] This platyrostral condition is similar to what is seen in the "nettosuchid" Mourasuchus, which is not closely related to stomatosuchids as it is a more derived alligatoroid that existed during the Miocene.

Additionally, the glenoid is rounded rather than cupped at the posterior end of the jaw, and the retroarticular process is straight rather than dorsally curving like in Mourasuchus and other extant crocodylians.

The genus Stomatosuchus is known only from a holotype skull collected from the Bahariya Formation in Egypt, which was destroyed in World War II with the bombing of the Munich Museum.

[4] Because Stomatosuchus is known only from brief accounts by Ernst Stromer and Franz Nopcsa (1926) and no additional material has ever been found, the genus remains enigmatic.