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 than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appeared during the Devonian, and the last species either vanished in the Cretaceous–Paleogene extinction event, or shortly after, during the Danian epoch of the Paleocene.
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.
Arkanites is a goniatitid ammonite that lived during the Early Pennsylvanian that has been found in Arkansas and Oklahoma in the U.S.
Aristoceratoides is an extinct ammonoid genus belonging to the goniatitid family Thalassoceratidae that lived during the Middle Permian. Named by Ruzhentsev, 1960, the type species is "Thalassoceras" varicosum Gemmellaro, 1887.
Arctoceras is a genus of ceratitid ammonoids from the Lower Triassic with a moderately narrow discoidal shell and ceratitic suture.
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
Gastrioceratoidea is one of seventeen 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.
The Cravenoceratidae is one of six families included in the ammonoid superfamily Neoglyphioceratoidea, which lived during the latter part of the Paleozoic era.
Prolecanitida is an order of extinct ammonoid cephalopods with discoidal to thinly lenticular shells with goniatitic or ceratitic sutures and which retained the simple retrochoanitic siphuncle with backward extending septal necks. As typical for ammonoids the siphuncle is along the ventral margin. Prolecanitids form a relatively small and stable order within the Ammonoidea with 43 named genera and about 1250 species, but with a long-ranging lineage of about 108 m.y. stretching from the Lower Carboniferous to the Triassic. Although not as diverse as their goniatitid contemporaries, the Prolecanatida provided the stock from which all later Mesozoic ammonoids were derived.
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.
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 gonititid 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.
Eowellerites is genus of ammonoid cephalopods belonging to the Welleritidae family. Species belonging to this genus lived in middle Pennsylvanian (Moscovian). Its fossils were found in USA and Japan. It had thinly discoidal shells with a quite wide umbilicus (U/D = 0.3 - 0.5). While in juvenile stages (up to 15 mm in diameter) venter is moderately rounded, it becomes slightly rounded to flattened when becoming mature (100 mm in diameter). 12-lobed suture has adventitious lobe on the first lateral saddle and is also characterized by an addition of an umbilical lobe. Sutural formula is (V1 V1) L1 L (U1 U2): I D. It has evolved from Winslowoceras henbesti and gave rise to genus Wellerites.
