Clionitidae is a family of generally evolute, Upper Triassic, ammonoids with a ventral furrow usually bordered by rows of tubercles and whorl sides ornamented by sigmoidal ribs which may bear spiral rows of tubercles. The suture is ceratitic.

The Clionitidae belong to the Ceratitida

Ceratitida

The Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post Triassic ammonites....

 and are included in the superfamily Clydonitaceae

Clydonitaceae

The Clydonitaceae is a superfamily in the ammonoid cephalopod order Ceratitida characterized by generally costate and turberculate shells with smooth, grooved, or keeled venters and sutures that are commonly ceratitic or ammonitic but goniatic in a few offshoots.-Taxonomy:The Clydonitaceae unites...

. Their fossils have been found in Carnian

Carnian

The Carnian is the lowermost stage of the Upper Triassic series . It lasted from about 228.7 till 216.5 million years ago . The Carnian is preceded by the Ladinian and is followed by the Norian...

 and/or Norian

Norian

The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...

 sediments in California, Nevada British Columbia, the Alps, Balkans, Himalaya, and on Timor.

Among its genera are Clionites

Clionites

Clionites is a genus of the clydonitacean family Clionitidae, and its type. The shell is evolute so as to expose all whorls which are covered with generally bifurcating signmoidal ribs. The suture is ceratitid with two lateral lobes. ....

, Alloclionites

Alloclionites

Alloclionites is an extinct ammonoid cephalopod genus within the family Clionitidae which is part of the ceratitid superfamily Clydonitaceae...

, Californites

Californites

Californites is a genus of the Upper Triassic clydonicacean family Clionitidae with a discoidal, evolute shell and radial tuberculate ribs that end in strong ventrolateral spines. The whorl section is described as trapezoidal...

, and Traskites

References

• Treatise on Invertebrate Paleontology, Part L, Ammonoidea. R. C. Moore (ed). Geological Society of America and Univ of Kansas press, 1957