Gonionautilidae
Gonionautilidae is a family in the nautilid superfamily Clydonautiliaceae that contains only the genus Gonionautilus, known from the Upper Triassic of Europe and North America.
Gonionautilus has a smooth, compressed involute shell with a narrow flattened venter and angular ventral shoulders. The suture resembles that of Clydonautilus, from which it must have been derived, except for the more highly developed median saddle and bifurcated dorsal lobe.
Gonionautilus is one of a number of advanced nautiloid cephalopods that developed sutures resembling those of some goniatites in the Ammonoidea.
