Xainzanoceras

Xainzanoceras, defined by Chen, 1987, is a nautiloid cephalopod from the Upper Ordovician of China, assigned to the tarphyceratid family Lituitidae. The type, Xainzanoceras xizangense Chen resembles the ophidioceratid genus Ophioceras. The shell is evolute, discoidal, serpenticonic; whorl section rounded, covered with thick, straight, close spaced, radial ribs that curve slightly forward at the ventral margin where they become quickly reduced or lost.

References

• Chen Ting Yan, 1987. Ordovician Nautilus Xainza: Nanjing Institute of Geology and Paleontology Series 11:133-191,1987.