''Callaionautilus'' is a genus of cephalopods included in the nautilid family

Clydonautilidae The Clydonautilidae are Middle and Upper Triassic nautiloid cephalopods, which are derivatives of the clydonautiloidean family Liroceratidae, that have generally smooth, involute, globular to compressed shells, characterized by a suture with p ...

that lived during the Late Triassic. Its fossils have been found on the island of Timor. The shell of ''Callaionautilus'' is involute, coiled such that only the outer whorl is exposed. Early whorls have nodes on the ventral shoulder that disappear toward the aperture. Later whorls have a nodose keel bordered by furrows. The

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

position is unknown. ''

Clydonautilus ''Clydonautilus'' is a genus of nautiloids and type for the Clydonautilidae that has been found in the Upper Triassic of Europe, India, and Timor. Its type is ''C. noricus''. ''Clydonautilus'' is the most derived of the Clydonautilitidae, evide ...

'', ''

Cosmonautilus ''Cosmonautilus'' is a genus of cephalopods included in the nautilid family Clydonautilidae. Its shell is involute, with only the outer whorl exposed. Early whorls are with nodes on ventral shoulder, which disappear on the later growth staged. ...

'', '' Proclydonautilus'', and '' Styrionautilus'' are closely related genera belonging to the same family.

References

* Bernhard Kummel, 1964. Nautiloidea-Nautilida. Treatise on Invertebrate Paleontology, Part K. Geological Society of America.
''Callaionautilus''
in Fossilworks gateway. Prehistoric nautiloid genera {{paleo-nautiloidea-stub