Taxonomic nomenclature
The Order Agoniatitida, named by Ruzhencev, 1957, [1] is a subjective synonym for the Order Anarcestida, named by Miller and Furnish, 1954. [2] Accordingly, the name Anarcerstida is based on the family Anarcestidae (ex Anarcestinae) of Steinmann 1890. That of Agoniatiida is based on the family Agnoniatidae of Holzapfel, 1899.
Saunders, Work, and Nikolaeva, 1999, [3] refer to the Anarcestida, with Agoniatina a suborder, maintaining the priority as found in the Treatise. Shevyrev, 2006 [4] on the other hand follows Ruzhencev, 1957 and used Agonititida.
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.
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Fossil nautiloids are diverse and species rich, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms (orthocones). No orthoconic and only a handful of coiled species, the nautiluses, survive to the present day.
The Bactritida are a small order of more or less straight-shelled (orthoconic) cephalopods that first appeared during the Emsian stage of the Devonian period with questionable origins in the Pragian stage before 409 million years ago, and persisted until the Carnian pluvial event in the upper middle Carnian stage of the Triassic period. They are considered ancestors of the ammonoids, as well as of the coleoids.
Aldanites is an extinct cephalopod genus belonging to the ammonoid order Goniatitida.
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
Uraloceras is an ammonoid cephalopod genus belonging to the goniatitid family Paragastrioceratidae. The genus was named by Ruzhencev 1936 and is a jr. synonym of Pseudogastrioceras Spath 1930 according to Miller, Furnish and Schindeworlf, 1957. More recent classifications however list the two as distinct genera and put Uraloceras in the Paragastrioceratinae and Pseudogastrioceras in the Pseudogastrioceratinae.
Goniatitina is one of two suborders included in the order Goniatitida; extinct Paleozoic ammonoid cephalopods only distantly related to the Nautiloidea.
Prolobitidae is a family of middle and upper Devonian ammonoid cephalopods currently included in the goniatitid suborder Tornoceratina and superfamily Dimeroceratoidea, but previously included in the ancestral Anarcestida.
Cheiloceratidae is a family of ammonoid cephalopods included in the goniatitid suborder Tornoceratina in which the suture has 4 to 12 lobes, the ventral one undivided and those in the lateral areas originating as subdivisions of internal and external lateral saddles.
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.
Gastrioceratoidea is one of 17 superfamilies in the suborder Goniatitina, ammonoid cephalopods from the Late Paleozoic.
Adrianitidae is a family in the Adrianitaceae, a superfamily of ammonites in the cephalopod order, Goniatitida, known from the Middle Pennsylvanian to the Middle Permian.
Texoceras is an extinct ammonoid genus in the monotypic goniatitid subfamily Texoceratinae, included in the family Adrianitidae. These were shelled cephalopods more closely related to squids, belemnites, octopuses, and cuttlefish than to nautiloids from which they are derived.
Agathiceratidae, as revised, makes up the goniatitid superfamily Agathiceratoidea. Agathiceratidae, which lived from the Upper Carboniferous (Pennsylvanian) to the Middle Permian, combine related genera with subdiscoidal to globular shells that have a small umbilicus and goniatitic sutures and are prominently longitudinally lirate. The explanation for the Agathiceratidae is that for the Agathiceratoidea.
Medlicottiidae is a family of ammonoid cephalopods belonging to the Prolecanitida, known from the Upper Carboniferous (Pennsylvanian) to the Early Triassic.
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 Ophiceratidae is a family in the ammonoid order Ceratitida from the Lower Triassic, previously included in the Otocerataceae but now placed in the Noritiaceae as revised.
Clymeniida is an order of ammonoid cephalopods from the Upper Devonian characterized by having an unusual dorsal siphuncle. They measured about 4 cm (1.6 in) in diameter and are most common in Europe, North Africa, and South China but are known from North America and Australia as well.
The Medlicottiinae is a subfamily of the Medlicottiidae, a family of ammonoid cephalopods included in the Prolecanitida, characterized by having discoidal to thinly lenticular shells with a retuse (grooved) venter and sutures with bifid auxiliary lobes.
