Ammonoids are extinct spiral shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living coleoids than they are to shelled nautiloids. The earliest ammonoids appeared during the Devonian, with the last species vanishing during or soon after the Cretaceous–Paleogene extinction event. They are often called ammonites, which is most frequently used for members of the order Ammonitida, the only remaining group of ammonoids from the Jurassic up until their extinction.
Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago. Goniatites (goniatitids) survived the Late Devonian extinction to flourish during the Carboniferous and Permian only to become extinct at the end of the Permian some 139 million years later.
Goniatites is a genus of extinct cephalopods belonging to the family Goniatitidae, included in the superfamily Goniatitaceae. Hibernicoceras and Hypergoniatites are among related genera.
Beyrichoceras is a genus belonging to the goniatitid family Muensteroceratidae, a group of ammonoids, extinct shelled cephalopods related to belemnites and recent coleoids and more distantly to the nautiloids
Ussuria is a genus of Lower Triassic ammonites with a smooth, involute discoidal shell with submonophyllic sutures, belonging to the ceratitid family Ussuriidae.
Dimeroceratidae is one of three families in the Dimeroceratoidea, a goniatid superfamily included in the Ammonoidea; extinct shelled cephalopods with adorally convex septa and usually narrow ventro-marginal siphuncles.
Paratornoceratinae is a subfamily of oxyconic dimeroceratids included in the order Goniatitida, a group of Paleozoic ammonoids, which have closer affinity to living coleoids than to Nautilus.
Prolecanitoidea is a taxonomic superfamily of ammonoids in the order Prolecanitida. Prolecanitoidea is one of two superfamilies in the order, along with the younger and more complex Medlicottioidea. The Prolecanitoidea were a low-diversity and morphologically conservative group. They lived from the Lower Carboniferous up to the Middle Permian. Their shells are generally smooth and discoidal, with a rounded lower edge, a moderate to large umbilicus, and goniatitic to ceratitic sutures. Suture complexity varies from 10 up to 22 total lobes ; new lobes are added from subdivision of saddles adjacent to the original main umbilical lobe.
The Clydonautiloidea are a superfamily within the nautiloid order Nautilida characterized by smooth, generally globular, shells with nearly straight sutures, in early forms, but developing highly differentiated sutures in some later forms. Where known, the siphuncle tends to be central to subcentral.
The Trigonoceratoidea are a superfamily within the Nautilida that ranged from the Devonian to the Triassic, thought to have contained the source for the Nautilaceae in which Nautilus is found.
Syringonautilidae is a family of Nautiloidea from the middle to late Triassic. Syringonautilidae comprise the last of the Trigonoceratoidea and are the source for the Nautilaceae which continued the Nautiloidea through the Mesozoic and into the Cenozoic right down to the recent. Syringonautilidae is a strictly Triassic family, derived early in the Triassic from the Grypoceratidae.
Grypoceratidae is the longest-lived family of the Trigonoceratoidea, or of the near equivalent Centroceratina; members of the Nautilida from the Upper Paleozoic and Triassic.
The Karagondoceratidae is a small family of tornoceratin Goniatitida from the Lower Carboniferous which typifies the Karagandoceratoidea, in which it is included.
Lophoceras is a genus of Nautilids belonging to the tainoceratoidean family, Koninckioceratidae, found in Lower Carboniferous sediments in Europe, and named by Hyatt, 1893. The shell of Lophoceras is evolute, large, with a slight impressed zone on the inner rim. In early volutions whorl sections are rounded, but later develop an obtusely angular ventral area and venter that disappears toward the front of the mature body chamber. The suture has an angular ventral saddle, broad shallow lateral lobe, and a dorsal lobe. Except for growth line, the shell is smooth.
Biloclymenia is a genus in the ammonoid order Clymeniida which is characterized by a dorsal retrosiphonitic siphuncle with long adapically pointing septal necks.
Raymondiceratinae is a subfamily of Upper Devonian cheiloceratid goniatites in which the sutures have 4 distinct lobes and the growth lines are convex. The subfamily includes three genera.
Lytoceratidae is a taxonomic family of ammonoid cephalopods belonging to the suborder Lytoceratina, characterized by very evolute shells that generally enlarge rapidly, having whorls in contact but mostly overlapping very sightly, or not at all.
Ophiceras is an extinct genus of smooth, evolute ceratitid ammonites from the Griesbachian, with a rounded venter. Fossils of the genus have been found in Armenia, Azerbaijan, China, Greenland, and India.
Meekoceras is an extinct genus of ceratitid ammonites with a discoidal shell that lived during the Early Triassic Epoch.
Clypeoceras is a genus of ammonites with an involute discoidal shell from the Lower Triassic.
