Stephanoceratidae is a family of planulate and coronate

ammonites Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

within the

Stephanoceratoidea Stephanoceratoidea, formerly Stephanocerataceae, is a superfamily of middle- upper Jurassic ammonoid cephalopods within the order Ammonitida containing diverse forms, generally with sharp ribbing and complex suture lines. Aptychi are believed t ...

.Arkell, Kummel, and Wright, 1957. Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Shells are evolute so that all whorls are exposed and have strong ribbing that bifurcates, that is splits in two, on the flanks. Many have tubercles at the point of bifurcation. Whorl sections are generally subequant; the outer rim, or venter, commonly rounded. Stephanoceratidae is derived from the

Otoitidae Otoidtidae: stephanoceratoid ammonitina from the early Middle Jurassic that begin as cadicones but become more planualte with age; derived from the Hammitoceratidae (Hildoceratoidea), probably through '' Erycites'' by way of ''Abbasites''. Sh ...

. Their fossils are found in upper Middle- and lower Upper Jurassic sediments.

Subfamilies and genera

* Cadomitinae * Frebolditinae * Garantianinae * Mollistephaninae * Stephanoceratinae *'' Ermoceras'' *'' Kosmermoceras'' *'' Kumatostephanus'' *'' Skirroceras'' *'' Skolekostephanus'' *'' Stemmatoceras'' *'' Telermoceras''

References

Ammonitida families Stephanoceratoidea Middle Jurassic first appearances Late Jurassic extinctions {{ammonitina-stub