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.
Alaoceras is an ammonoid cephalopod from the upper Paleozoic included in the goniatitid family Cravenoceratidae, named by Ruzhentsev & Bogoslovskaya in 1971.
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
Beyrichoceras is a genus belonging to the goniatitid family Maxigoniatitidae that lived during the Mississippian Period
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.
Gastrioceratoidea is one of 17 superfamilies in the suborder Goniatitina, ammonoid cephalopods from the Late Paleozoic.
Goniatitinae is one of six subfamilies into which the Goniatitidae is subdivided according to Miller, Furnish, and Schindewolf, 1957. The diagnostic character is the narrow bifurcated ventral lobe of the suture, which lies along the outer rim. As with the inclusive Goniatitidae, sutures have eight lobes, shells are without prominent ornament, umbilici are small to moderate in size.
Thalassoceratidae a family of late Paleozoic ammonites included in the goniatitid superfamily Thalassoceratoidea along with the Bisatoceratidae. Some eight genera are included, although the specific number and exactly which depends on the particular classification.
Uraloclymenia is an extinct ammonoid cephalopod genus from the Late Devonian, Famennian stage. The type species is Uraloclymenia volkovi Bogoslovskii, 1977
Prolecanitida is an order of extinct ammonoid cephalopods, the major Late Paleozoic group of ammonoids alongside the order Goniatitida. Prolecanitids had narrow shells, discoidal (disc-shaped) to thinly lenticular (lens-shaped). They retained a retrochoanitic siphuncle, a simple form with septal necks extending backwards. As is typical for ammonoids, the siphuncle sits along the ventral margin of the shell.
The Daraelitidae form a family in the ammonoid order Prolecanitida from the Upper Mississippian - Middle Permian characterized by discoidal shells with no prominent sculpture, moderately large umbilicus, and goniatitic or ceratitic sutures with a trifid ventral lobe and few auxiliary lobes.
Clyclolobus is a smooth, essentially involute subdiscoidal goniatitid ammonoid that has sutures with a bifurcate ventral lobe, flared outwardly at the end, in which the halves may be secondarily trifurcated, ending in sharp, narrow projections. Lateral sutural elements follow an acuate line that swings first to the front, then sharply to the rear before becoming hidden by the next whorl. Saddles are narrow, cumulous in appearance with short, irregular, rounded sub-endings. Ventro-lateal lobes are trifurcate with pointed, thorn-like projections.
Neoaganides is a small, 1–2 cm diameter subdiscoidal to subglobular goniatitid belonging to the family Pseudohaloritidae that lived from the Late Pennsylvanian to the Late Permian, existing for some 56 million years.
Pachylyroceras is a large, generally subglobular, Upper Mississippian gonitite and included in the cephalopod subclass Ammonoidea.
Lyrogoniatitites is a neoglyphioceratoidean ammonite, in the order Goniatitida, related to genera like Alaoceras, Cravenoceras, Dumbarigloria and Pachylyroceras.
Cravevoceras is an Upper Paleozoic ammonite in the goniatite family Cravenoceratidae, probably derived from Pachylyroceras and contemporary with other cravenoceratid genera like Caenolyroceras, Tympanoceras and later Alaoceras and Lyrogoniatites. It is also a member of the Neoglyphioceratoidea.
The Uddenitinae a subfamily of the Medlicottiidae, a family of ammonoid cephalopods included in the Prolecanitida. The Uddenitinae, proposed by Miller and Furnish, and known from the Pennsylvanian and Lower Permian, are transitional between the ancestral Pronoritidae and the more traditional medlicottiids.
Biloclymenia is a genus in the ammonoid order Clymeniida which is characterized by a dorsal retrosiphonitic siphuncle with long adapically pointing septal necks.
Neoglaphyrites is a goniatitid ammonite that lived during the latest Pennsylvanian and early Permian. Its shell is ellipsoidal and moderately involute; the umbilicus deep and typically less than 15 per cent of the shell diameter but in some species closer to 20 per cent. Delicate growth lines forming ventral and lateral sinuses and ventrolateral and dorsolateral salients have been found on Canadian Arctic specimens. The suture is characterized by the ventral lobe split into two broad prongs that are separated by a high median ventral saddle; prongs closely approximate the width of the first lateral lobe. The first lateral saddle is evenly rounded and is nearly symmetrical. The umbilical lobe is V-shaped and internal lobes are deep and narrow.
