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Bellerophontidae
The Bellerophontidae are an extinct Family (biology), family of specialized globose Bellerophontoidea, bellerophontids, Paleozoic and early Triassic mollusca, mollusks of the class Gastropoda. Geological range These mollusks appeared in the Late Cambrian and continued until the Early Triassic. Shell description The shell resembles a miniature ''Nautilus'', with greatly overlapping, rounded Whorl (mollusc), whorls, in which the Body whorl, last whorl completely encompasses the others, leaving either a very narrow Umbilicus (mollusc), umbilicus on either side, or none at all. At the aperture (mollusc), aperture of the shell is a slit, which results in a sort of low ridge that runs along the length of shell. The shell has a low profile and these possibly were active, fast-moving molluscs. Taxonomy 1960 taxonomy Knight ''et al.'' 1960 in the ''Treatise on Invertebrate Paleontology'' consider the Bellerophontidae a very large family made up of a number of subfamilies and tribes. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellerophontoidea
Bellerophontoidea, common name "bellerophonts",Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdes A. & Warén A. 2005. ''Classification and nomenclator of gastropod families''. Malacologia: International Journal of Malacology, 47(1-2). ConchBooks: Hackenheim, Germany. . ISSN 0076-2997. 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278 is a superfamily of extinct planospirally-coiled globose molluscs. This superfamily is generally included within the Gastropoda, but may instead be a group of monoplacophorans. The taxon first appeared late in the Cambrian and continued until late in the Triassic. Biology Unlike normal gastropods, the shells of Bellerophonts are characterised by a completely planispiral pattern of coiling, such as one finds in shelled cephalopods. Experts disagree whether Bellerophontids should be classified as torted gastropods, or as untorted Tergomya, or whether the group Bellerophontida is perhaps an artificial construct, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellerophon (genus)
''Bellerophon'' is a genus of extinct marine molluscs of uncertain position (Gastropoda or Monoplacophora) in the family Bellerophontidae. The genus was named after Bellerophon, the ancient Greek hero. ''Bellerophon'' is the type genus of the family Bellerophontidae. Shell description The genus is characterised by a shell which is globose, convolute, and planispiral (symmetrically coiled). The shell of ''Bellerophon'' superficially resembles that of a miniature cephalopod (e.g. ''Nautilus'' or an ammonite), except that Septum (cephalopod), septa are lacking. The shell of ''Bellerophon'' is often a couple of centimeters in maximum dimension. The external surface is smooth, Sculpture (mollusc), ornamented only by growth lines. There is a low crest or ridge running along the midline of the shell. Many specimens of ''Bellerophon'' show something resembling a "waterline" about halfway up the shell, suggesting that a large amount of the mantle (mollusc), mantle and foot were expos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellerophontida
The Bellerophontida is a taxonomic order of extinct marine mollusks that are found in the fossil record from the Lower Cambrian to the Lower Triassic. They are considered by some experts to be primitive sea snails with primarily symmetrically coiled shells, marine gastropod mollusks. R.C Moore and J. Brooks Knight ''et al'' 1960 Treatise on Invertebrate Paleontology, Part I Mollusca 1 recognized bellerophonts as true gastropods, placing them as the suborder Bellerophontina in the subclass Prosobranchia, order Archaeogastropoda. Some more recent workers in the field have expressed uncertainty as to the taxonomic placement of this group. Shell morphology Shells of bellerophontids are most commonly isotrophic (coiled symmetrically), rarely slightly asymmetric. Most are closely coiled with some general more openly coiled, cyrtiform; predominantly with a median slit in the upper lip of the aperture, or with a series of openings known as tremata, usually generating a selenizone whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisian
In the geologic timescale, the Anisian is the lower stage (stratigraphy), stage or earliest geologic age, age of the Middle Triassic series (stratigraphy), series or geologic epoch, epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Epoch) and precedes the Ladinian Age. Stratigraphic definitions The stage and its name were established by Austrian geologists Wilhelm Heinrich Waagen and Carl Diener in 1895. The name comes from ''Anisus'', the Latin name of the river Enns (river), Enns. The original type locality (geology), type locality is at Großreifling in the states of Austria, Austrian state of Styria. The base of the Anisian Stage (also the base of the Middle Triassic series) is sometimes laid at the first appearance of conodont species ''Chiosella, Chiosella timorensis'' in the stratigraphic record. Other stratigraphers prefer to use the base of magnetic chronozone MT1n. There is no accept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoplacophora
Shell of Monoplacophora Monoplacophora , meaning "bearing one plate", is a polyphyletic class of molluscs with a cap-like shell, inhabiting deep sea environments. Extant representatives were not recognized as such until 1952; previously they were known only from the fossil record, and were thought to have become extinct 375 million years ago. Although the shell of many monoplacophorans is limpet-like in shape, they are not gastropods, nor do they have any close relation to gastropods. Definition Discussion about monoplacophorans is made difficult by the slippery definition of the taxon; some authors take it to refer to all non-gastropod molluscs with a single shell, or all single-shelled molluscs with serially repeated units; whereas other workers restrict the definition to cap-shaped forms, excluding spiral and other shapes of shell. The inclusion of the gastropod-like Bellerophontoidea within the group is also contentious. One attempt to resolve this confusion was to separ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy Of The Gastropoda (Bouchet & Rocroi, 2005)
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 (Gastropods are a taxonomic class of animals which consists of snails and slugs of every kind, from the land, from freshwater, and from saltwater). 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. The Bouchet & Rocroi system was the first complete gastropod taxonomy that primarily employed the concept of clades, and was derived from research on molecular phylogenetics; in this context a clade is a "natural grouping" of organisms based upon a statistical cluster analysis. In contrast, most of the previous overall taxonomic schemes for gastropods relied on morphological features to classify these animals, and used taxon ranks such as order, superorder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
