The Caseodontidae is an extinct family of eugeneodont holocephalans known from the late Paleozoic to earliest Mesozoic of Greenland, Canada and the United States.

[1][2] Members of the group are characterized by a reduced or absent palatoquadrate, elongate upper and mandibular rostra, and bulbous, crushing dentition, including a small symphyseal whorl of teeth on the lower jaw and batteries of teeth fused directly to the neurocranium.

[3][5] Unlike the distantly related helicoprionids, members of this family crossed the Permian-Triassic boundary and persisted into the Olenekian stage of the Early Triassic,[5] after which they became extinct.

It is hypothesized that in life caseodonts fed on hard-shelled prey such as brachiopods due to their crushing tooth batteries,[4] and it has been proposed that the elongated rostra on the upper and lower jaws of some genera was an adaptation for prying prey off of the seabed.

[6] Well preserved specimens are known from the Carboniferous of Nebraska and Indiana,[3] deposits in East Greenland,[2] and from the Sulphur Mountain Formation of British Columbia, which is the last known appearance of the group.