Arietitidae

Arietitidae Temporal range: Sinemurian–Pliensbachian PreЄ Є O S D C P T J K Pg N
Asteroceras stellare
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	†Ammonoidea
Order:	†Ammonitida
Superfamily:	†Psilocerataceae
Family:	†Arietitidae Hyatt, 1874
Subfamilies
Alsatitinae Arietitinae Agassiceratinae Pseudotropitinae Asteroceratinae Hypasteroceratinae

Arietitidae is a family of true ammonites that make up part of the superfamily Psilocerataceae. They comprise medium-size to large or gigantic genera which in general are strongly ribbed, tuberculate in some, with keeled or grooved and keeled venters, and well differentiated ammonitic sutures. The aptycus is single valved with a shiny, concentrically striated surface.

Arietitidae dominated Lower Jurassic, Sinemurian ammonites, worldwide, extending into the lower Pliensbachian.

The Arietitidae may have their origin in the Schlotheimiidae if not directly from the Psiloceratidae, and is the probably source for the Oxynoticeratidae.

References

• Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press. 
• Donvan, D.T. and Callomon, J.H. 1981, Classification of the Jurassic Ammonitina., in The Ammonoidea, The Systematics Association Special Volume 18.