Temporal range: Early Cretaceous–Recent
|The shell of a neogastropod, the muricid species Chicoreus palmarosae|
|Clade:|| Neogastropoda |
Neogastropoda is a clade of sea snails, both freshwater and marine gastropod molluscs.
The available fossil record of Neogastropoda is relatively complete, and supports a widely accepted evolutionary scenario of an Early Cretaceous origin of the group followed by two rapid diversification rounds in the late Cretaceous and the Paleocene.
These sea snails only have one auricle, one kidney and one monopectinate gill, i.e. the gill filaments develop on only one side of the central axis.
The shell has a well-developed siphonal canal. The elongated trunk-like siphon is an extensible tube, formed from a fold in the mantle. It is used to suck water into the mantle cavity. At the base of the siphon is the bipectinate (branching from a central axis) osphradium, a sensory receptacle and olfactory organ, that is more developed than the one in the Mesogastropoda. They achieved important morphological changes including e.g., the elongation of the siphonal canal, a shift in the mouth opening to a terminal position on the head, and the formation of a well-developed proboscis.
The nervous system is very concentrated. Many species have the ganglia in a compact space.
The rachiglossate (rasp-like) radula, a layer of serially arranged teeth within the mouth, has only three denticles (small teeth) in each transverse row.
The Neogastropoda have separate sexes.
There are about 16,000 species. Neogastropoda includes many well-known gastropods including the cone snails, conchs, mud snails, olive snails, oyster drills, tulip shells, and whelks. The Neogastropoda all live in the sea, except Clea , and Rivomarginella that are freshwater genera. The neogastropods are most diverse in tropical seas.They are mostly predators, but some are saprophagous (scavengers).
According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the clade Neogastropoda consists of these superfamilies:
When Neogastropoda was an order, it was placed within the prosobranch gastropods according to the taxonomy developed by Thiele (1921). The families which used to form the order Neogastropoda are now included in the clade Neogastropoda Cox, 1960.
Ever since Thiele (1929),Neogastropoda have been considered a natural group, clearly differentiated from other Caenogastropoda. The monophyly of the group is widely accepted among morphologists, and it is based on several synapomorphies mostly related with the anatomy of the digestive system. Current classifications of Neogastropoda generally recognize up to six superfamilies: Buccinoidea, Muricoidea, Olivoidea, Pseudolivoidea, Conoidea, and Cancellarioidea. Phylogenetic relationships among neogastropod superfamilies based on morphological characters are rather unstable, and for instance, Cancellarioidea or Buccinoidea have been alternatively proposed as the sister group of the remaining Neogastropoda.
According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the taxonomy of clade Neogastropoda is as follows:
Orthogastropoda was a major taxonomic grouping of snails and slugs, an extremely large subclass within the huge class Gastropoda according to the older taxonomy of the Gastropoda.
Volutoidea is a taxonomic superfamily of predatory sea snails, marine gastropod mollusks in the clade Neogastropoda.
Stylommatophora is an order of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This taxon includes the majority of land snails and slugs.
Conoidea is a superfamily of predatory sea snails, marine gastropod mollusks within the suborder Hypsogastropoda. This superfamily is a very large group of marine mollusks, estimated at about 340 recent valid genera and subgenera, and considered by one authority to contain 4,000 named living species.
Olive snails, also known as olive shells and olives, scientific name Olividae, are a taxonomic family of medium to large predatory sea snails with smooth, shiny, elongated oval-shaped shells.
Buccinoidea is a taxonomic superfamily of very small to large predatory sea snails, marine gastropod mollusks.
Basommatophora was a term that was previously used as a taxonomic informal group, a group of snails within the informal group Pulmonata, the air-breathing slugs and snails. According to the taxonomy of the Gastropoda, whenever monophyly has not been tested, or where a traditional taxon of gastropods has now been discovered to be paraphyletic or polyphyletic, the term "group" or "informal group" was used.
The Melongenidae, the crown conchs and their relatives, are a taxonomic family of large to very large marine gastropods in the clade Neogastropoda.
Trochoidea is a superfamily of small to very large vetigastropod sea snails with gills and an operculum. Species within this superfamily have nacre as the inner shell layer. The families within this superfamily include the Trochidae, the top snails. This superfamily is the largest vetigastropodan superfamily, containing more than 2,000 species.
The taxonomy of the Gastropoda as it was revised in 2005 by Philippe Bouchet and Jean-Pierre Rocroi is a system for the scientific classification of gastropod mollusks. The paper setting out this taxonomy was published in the journal Malacologia. The system encompasses both living and extinct groups, as well as some fossils whose classification as gastropods is uncertain.
Olivellinae, common name the "dwarf olives", are a subfamily of small predatory sea snails with smooth, shiny, elongated oval-shaped shells. The shells sometimes show muted but attractive colors, and may have some patterning.
The taxonomy of the Gastropoda, as revised by Winston Ponder and David R. Lindberg in 1997, is an older taxonomy of the class Gastropoda, the class of molluscs consisting of all snails and slugs. The full name of the work in which this taxonomy was published is Towards a phylogeny of gastropod molluscs: an analysis using morphological characters.
Apogastropoda was previously used as a major taxonomic grouping of sea snails, marine gastropod molluscs. This infraclass mostly consisted of marine limpets and operculate snails. At least 20,000 species were considered to exist within the two clades that were included, Heterobranchia and Caenogastropoda.
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 Bouchet and Rocroi, 2005.
Pseudolivoidea is a taxonomic superfamily of sea snails, marine gastropod mollusks in the clade Neogastropoda.
Olivoidea is a taxonomic superfamily of minute to medium-large predatory sea snails, marine gastropod mollusks in the clade Neogastropoda.
Hygrophila is a taxonomic clade of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks within the clade Panpulmonata.
Mitroidea is a superfamily of Recent and fossil sea snails, marine gastropod mollusks within the order Neogastropoda.
The Bellolividae is a taxonomic family of sea snails, marine gastropod molluscs in the superfamily Olivoidea.
The Benthobiidae is a taxonomic family of sea snails, marine gastropod molluscs in the superfamily Olivoidea.
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