Clionitidae is a family of generally evolute, Upper Triassic,

ammonoids Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

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 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 ammoni ...

and are included in the superfamily

Clydonitoidea Clydonitoidea, formerly 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 ammon ...

. Their fossils have been found in

Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by t ...

and/or

Norian The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic defi ...

sediments in California, Nevada British Columbia, the Alps, Balkans, Himalaya, and on Timor. Among its genera are ''

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

'', ''

Alloclionites ''Alloclionites'' is a genus of extinct ammonoid cephalopods within the family Clionitidae which is part of the ceratitid superfamily Clydonitoidea. ''Alloclionites'' comes from the Upper Triassic of the Alps, Balkans, Himalayas, Timor, and Briti ...

'', '' Californites'', and '' Traskites''

''References''

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

, Part L, Ammonoidea. R. C. Moore (ed). Geological Society of America and Univ of Kansas press, 1957 Clydonitaceae Ceratitida families Late Triassic first appearances Late Triassic extinctions Fossils of Serbia {{Ceratitida-stub