Wikipedia
Siberionautilidae is a family in the nautilid superfamily Clydonautilaceae that contains only the genus Siberionautilus, which comes from the Upper Triassic ( Carnian) of Siberia, Russia.
The family, and genus, are characterized by an involute, globular shell covered by fine radial ribs, with flattened flanks that converge toward a rounded venter, distinct umbilicus with rounded shoulders, differentiated suture, and central siphuncle. The suture is goniatitic with the ventral or median saddle of the Clydonautilidae, subdivided so as to have a deep finger-like median ventral lobe bracketed by finder-like secondary lobes and saddles, and on either side, a large claw-like asymmetric lateral lobe.
Like Gonionautilus, Siberionautilus is derived from the Clydonautilidae, only the genus is unspecified. As with Gonionautilus and more advanced Clydonautilidae, Siberionautilus is one of a handful of nautilids that have goniatitic sutures as found in primitive ammonoids.