Named By: McLearn - 1927.
Classification: Mollusca, Cephalopoda, Ammonoidea, Ammonitida, Stephanocerataceae, Otoitidae.
Species: Z. armatus, Z. corona.
Known locations: Australia - Newmarracarra Limestone Formation. Possible also North America.
Time period: Bajocian of the Jurassic.
Fossil representation: Many individuals represented by fossilised shells.
Zemistephanus is a genus of ammonite that lived in the Mid Jurassic seas.
- Treatise on Invertebrate Paleontology, Part L, Mollusca 4, Cephalopoda - Ammonoidea 1-490. - W. J. Arkell, W. M. Furnish, B. Kummel, A. K. Miller, R. C. Moore, O. H. Schindewolf, P. C. Sylvester-Bradley & C. W. Wright - 1957.