 The family is recognized as containing two species, normally classified into two genera; "Aigialosaurus" and "Opetiosaurus".When used as an adaptive grade rather than as an actual monophyletic group, many other basal mosasauroids of uncertain affinities are occasionally referred to as "aigialosaurs", such as the genera "Komensaurus", "Haasiasaurus", "Carsosaurus" and "Dallasaurus" and even entire mosasaur clades, such as the Tethysaurinae.The term "plesiopedal mosasaurs" or "mosasaurs with a plesiopedal limb condition" is a more formal way to refer to such primitive species firmly within the family Mosasauridae.