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.
Goniatites is a genus of extinct cephalopods belonging to the family Goniatitidae, included in the superfamily Goniatitaceae. Hibernicoceras and Hypergoniatites are among related genera.
Arkanites is a goniatitid ammonite that lived during the Early Pennsylvanian that has been found in Arkansas and Oklahoma in the U.S.
Beyrichoceras is a genus belonging to the goniatitid family Maxigoniatitidae that lived during the Mississippian Period
The Posttornoceratidae are Late Devonian goniatites (Ammonoidea) included in the superfamily Tornoceratoidea. The family, Posttornoceratidae, named by Bogoslovsky in 1962, is based on the genus Posttornoceras, named by Wedekind in 1910, originally included in the Tornoceratidae.
Tornoceratidae is a family of goniatitid ammonoids from the middle and upper Devonian. The family is included in the suborder Tornoceratina and the superfamily Tornoceratoidea.
Falcitornoceratinae is one of three subfamilies of the Tornoceratidae family, a member of the Goniatitida order. Shells produced are extremely involute and have no umbilicus. Young and intermediate whorls have ventrolateral grooves. The adventitious lobe, which develops ontogenetically between the external, or ventral, and lateral lobes, is widely rounded. Tornoceratids in which the Falcitornoceratinae are included are involute, subdiscoidal, with sutures that form 6 to 10 lobes.
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 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.
Aphelaeceras is an extinct genus from the nautilid family Trigonoceratidae which is part of the Trigonocerataceae, that lived during the Mississippian Period in the late Paleozoic.
Condraoceras is a genus of liroceratids from the Pennsylvanian of North America and Lower Permian of Europe with a compressed, involute, nautiliconic shell; subcircular whorl section; small umbilicus with a rounded shoulder; suture with shallow ventral and lateral lobes; and narrow subcentral siphuncle.
Liroceras is a genus of nautiloid cephalopod. It is the type genus of the clydonautiliacean family, Liroceratidae, and is characterized by a rapidly expanding, subglobular, nautiliconic shell with a reniform whorl section, small umbilicus, essentially straight sutures, and a siphuncle with a variable but not marginal position.
Phoenixites is an early genus of the Falcitornoceratinae, a subfamily of the goniatitid Tornoceratidae family. This genus was named by Becker in 1995. The type species is "Tornoceras" frechi.
Kourazouceras is an extinct ammonoid genus from the Late Devonian assigned to the tornoceratid subfamily Falcitornoceratinae. As such it is related to Falcitornoceras, Gundolficeras, and Phoenixites.
Planitornoceras is a genus included in the goniatitid subfamily Aulatornoceratinae that lived during the Famennian stage at the end of the Devonian. Its shell is extremely compressed, subinvolute to subevolute with an open umbilicus. Sides are always flat, outer rim (=venter) tabulate to slightly keeled. No constrictions or spiral grooves, but some species have broad spiral depressions. The adventitious lobe of the suture is widely rounded and asymmetric, the ventral lobe and saddle small, the dorsolateral saddle relatively short.
Bisatoceras is a late Paleozoic Ammonoidea, a member of the goniatitid family Bisatoceratidae.
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.
