Archaeogastropoda (also known as Aspidobranchia) was a taxonomic order of

snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...

s used in older classifications of

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

s, i.e.

s and

slug Slug, or land slug, is a common name for any apparently shell-less Terrestrial mollusc, terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced ...

s. Archeogastropoda are primarily marine

prosobranch Prosobranchia was a large Taxonomy (biology), taxonomic Class (biology), subclass of sea snails, land snails and freshwater snails. This taxon of gastropods dates back to the 1920s. It has however been proven to be polyphyly, polyphyletic (consis ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s, mainly

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s, typically having two

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

s and a double-chambered heart, with the eggs and sperm discharged directly into the water, excepting terrestrial species. They were traditionally regarded as a relatively primitive group. This older classification of the gastropods is based on the classification of

Johannes Thiele Johannes Thiele may refer to: *Johannes Thiele (zoologist) *Johannes Thiele (chemist) {{hndis, Thiele, Johannes ...

(1925). This classification was not based on true

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships, but on more general affinities between the groups. In the last few years, two new

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

taxonomies of the gastropods have been published (in 1997 and 2005). This has led to an extensive reclassification of gastropod taxa. The taxon Archaeogastropoda was found to be a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

group, and therefore unacceptable in a strictly cladistic classification. In the 1997 classification, most of the former Archaeogastropoda were included in: *subclass Eogastropoda **order

Patellogastropoda The Patellogastropoda, common name true limpets and historically called the Docoglossa, are members of a major phylogenetic group of marine (ocean), marine gastropods, treated by experts either as a clade or as a taxonomic Order (biology), order. ...

(limpets) *subclass Orthogastropoda **Superorder

Vetigastropoda Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. Taxonomically the Vetigastropoda are sometimes treated as an order, although they are treated as an unranked clade in Bouch ...

Salvini-Plawen, 1989 **Superorder Neritaemorphi Koken, 1896 (with the order Neritopsina Cox & Knight, 1960). A more detailed classification can be found on

Gastropoda Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

Older system of classification

*Order Archaeogastropoda **Superfamily Pleurotomariacea ***Family Pleurotomariidae ***Family

Haliotidae ''Haliotis'', common name abalone, is the only genus in the family Haliotidae. This genus once contained six subgenera. These subgenera have become alternate representations of ''Haliotis''. The genus consists of small to very large, edible, ...

***Family

Scissurellidae Scissurellidae, sometimes known by the common name little slit snails, are a Taxonomy (biology), taxonomic family (biology), family of minute sea snails, marine (ocean), marine gastropod molluscs or micromolluscs in the clade Vetigastropoda (acc ...

**Superfamily Fissurellacea ***Family

Fissurellidae Fissurellidae, common name the keyhole limpets and slit limpets, is a taxonomic family of small to medium-sized limpet-like sea snails, marine gastropod molluscs in the clade Vetigastropoda.Rosenberg, G. (2012). Fissurellidae. Accessed throu ...

**Superfamily Patellacea ***Family

Patellidae Patellidae is a taxonomic family of true limpets, marine gastropod molluscs in the superfamily Patelloidea. (The superfamily Patelloidea should not be confused with the similar-sounding genus of true limpets '' Patelloida'' which is in the ...

***Family Acmaeidae ***Family Lepetidae **Superfamily Trochacea ***Family Calliostomatidae ***Family

Trochidae The Trochidae, common name top-snails or top-shells, are a family of various sized sea snails, marine gastropod molluscs in the subclass Vetigastropoda. This family is commonly known as the top-snails because in many species the shell resembles ...

***Family Stomatellidae ***Family Cyclostrematidae ***Family Turbinidae ***Family Phasianellidae **Superfamily Neritacea ***Family

Neritidae Neritidae, common name the nerites, is a Taxonomy (biology), taxonomic Family (biology), family of small to medium-sized saltwater and freshwater snails which have a gill and a distinctive Operculum (gastropod), operculum. MolluscaBase eds. (202 ...

***Family Helicinidae ***Family Hydrocenidae

References

External links

* Sasaki T. (1998)
"Comparative anatomy and phylogeny of the recent Archaeogastropoda (Mollusca: Gastropoda)"
''Bulletin'' 38. Tokyo. {{Authority control Obsolete gastropod taxa Extant Cambrian first appearances Taxa named by Johannes Thiele (zoologist)

Older system of classification

See also

References

External links