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This list of ammonites is a comprehensive listing of genera that are included in the subclass †Ammonoidea, excluding purely vernacular terms. The list includes genera that are commonly accepted as valid, as well as those that may be invalid or doubtful ( nomina dubia ), or were not formally published ( nomina nuda ), as well as junior ...
A primary difference between ammonites and nautiloids is the siphuncle of ammonites (excepting Clymeniina) runs along the ventral periphery of the septa and camerae (i.e., the inner surface of the outer axis of the shell), while the siphuncle of nautiloids runs more or less through the center of the septa and camerae.
Ammonitida or "True ammonites" are an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures. Ammonitida is divided into four suborders, the Phylloceratina , Lytoceratina , Ancyloceratina , and Ammonitina .
Ammonites — members of the Ammonoidea subclass of molluscan prehistoric cephalopods. Pages in this category should be moved to subcategories where applicable. This category may require frequent maintenance to avoid becoming too large.
Ammonitina comprises a diverse suborder of ammonite cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods.
Arietitidae is a family of true ammonites that make up part of the superfamily Psiloceratoidea, named after the type genus Arietites.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.
Otoites is the type genus of the ammonite family Otoitidae that live during the Middle Jurassic. [1] [3]The Otoitidae, which is part of the superfamily Stephanoceratoidea, are part of the well known subclass of prehistoric cephalopods known in general terms as ammonites [3]
Oxynoticeras is an extinct genus of ammonite from the Early Jurassic [1] of Europe and North America. [2] This genus is characterized by its smooth shell, with almost invisible undulations on the flank, and a sharp keel. [3] Synonym Oxynotoceras was created by Buckman as misspelling. [4]