Callaionautilus is a genus of cephalopods included in the nautilid family Clydonautilidae that lived during the Late Triassic.

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.

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