The Euomphalina comprise a major suborder of mainly Paleozoic

archaeogastropods Archaeogastropoda (also known as Aspidobranchia) was a taxonomic order of sea snails used in older classifications of gastropods, i.e. snails and slugs. Archeogastropoda are marine prosobranch gastropod mollusks, mainly herbivores, typical ...

, shells of which are hyperstophic to depressed orthstrophic, commonly with an angulation at the outer upper whorl surface thought to be coincident with the exhalent channel; shell wall thick, outer layer calcitic, inner layers

aragonitic Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including pre ...

but not nacreous; operculum calcareous and heavy. Their range is from the

Upper Cambrian The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into three ...

to the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

, and possibly as high as the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

.J. Brooks Knight ''et al'' 1960. Systematic Descriptions (''of gastropods'').

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

Part I, Mollusca 1.(1960) Suborder Macluritina pp I 184 - I 196. The suborder Euomphalina de Koninck 1881 is synonymous with Macluritina (Cox and Knight 1960). The suborder Euomphalina includes the extinct superfamilies

Euomphaloidea Euomphaloidea, originally Euomphalacea, is an extinct superfamily of marine molluscs that lived from the Early Ordovician to the Late Cretaceous, included in the Gastropoda Moore R. C., Lalicker & Fischer (1952). ''Invertebrate Fossils''. McGr ...

Macluritoidea The Macluritoidea, or Macluritacea as it was originally spelled, is a superfamily of hyperstrophically coiled, Upper Cambrian to Devonian, archaeogastropods,Treatise on Invertebrate Paleontology, Part I, Mollusca 1. R.C. Moore (ed); Geol Soc o ...

, Ophiletoidea, and

Platyceratoidea Platyceratidae is an extinct family of Paleozoic sea snails, marine gastropod mollusks. This family may belong in the Patellogastropoda or the Neritimorpha. Platyceratids are known for the complex symbiotic relationships they had with crinoids ...

Taxonomy

J.B. Knight ''et al'' 1960, in the

Treatise A treatise is a formal and systematic written discourse on some subject, generally longer and treating it in greater depth than an essay, and more concerned with investigating or exposing the principles of the subject and its conclusions."Treat ...

Part I recognize two superfamilies in the Euomphalina (or Macluritina), the

and the

, in modified spelling. More recent classifications have expanded the Euomphalina to include the superfamilies: : Anomphaloidea : Craspidostomatoidea : Ophiletoidea : Oriostomatoidea : Palaeotrochoidea :

and : Pseudophoroidea
while retaining the original Euomphaloidea and Macluritoidea. The Ophiletoidea were separated from the family Helicotomidae of the Euomphaloidea (Euomphalatacea in the original form). The Oriostomatoidea and Platyceratoidea (in—acea form) are included in the suborder Trochina in the Treatise while (''ibid'') the Craspidostomatoidea, Palaeotrochoidea, and Pseudophoroidea (also as—acea taxa) are regarded simply as

Archaeogastropoda Archaeogastropoda (also known as Aspidobranchia) was a taxonomic order of sea snails used in older classifications of gastropods, i.e. snails and slugs. Archeogastropoda are marine prosobranch gastropod mollusks, mainly herbivores, typically havi ...

of uncertain affinities. P. Jeffery 2003Classification of P. Jeffery 2003
/ref> includes the Euomphaloidea, Macluritoidea, and Playceratacea in the Euomphalina while P. J. Wagner, 1999 included the Anomphaloidea, Euomphaloidea, Ophiletoidea, Oriostomatoidea, and Pseudophoroidea. The taxonomy of Bouchet and Rocroi, 2005 includes the superfamilies Euomphaloidea and Maclurioidea within mollusca with anisotrophically coiled shells of uncertain position (Gastropoda?) but does not give higher taxa such as orders and suborders. The taxonomy of Ponder and Lindberg, 1997 on the other hand is more expansive and includes the Euomphalina as the order Euomphalida within the

Eogastropoda Eogastropoda was a previously used taxonomic category of snails or gastropods, a subclass which was erected by Ponder and Lindberg in 1997. It was one of two great divisions (subclasses) of the class Gastropoda, the snails. The other subclass of ...

, but adding only the Platyceratoidea to the Euomphaloidea and Macluritoidea.

References

{{Taxonbar, from=Q992585 Obsolete gastropod taxa