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Helcionelloids
Helcionellid or Helcionelliformes is an order (biology), order of small fossil Small shelly fauna, shells that are universally interpreted as molluscs, though no sources spell out why this taxonomic interpretation is preferred. These animals are first found about in the late Nemakit-Daldynian Geologic time scale#Terminology, age, which is the earliest part of the Cambrian period. A single species persisted to the Early Ordovician. These fossils are component of the small shelly fossils (SSF) assemblages. These are thought to be early molluscs with rather snail-like shells, although they lack any compelling molluscan synapomorphies and thus may not belong to the group. They have been alleged to represent ancestors of the modern conchiferans, a group that includes all the well-known modern classes – gastropods, cephalopods and bivalves. They have also been considered to represent direct ancestors to the cephalopods. Parkhaev (2006, 2007) considers these animals to be crown-gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latouchella
''Latouchella'' is an extinct genus of marine invertebrate animal, that is considered to be a mollusk and which may be a sea snail, a gastropod. It is a helcionellid from the Tommotian epoch of what is now Siberia. Its tightly coiled, spiral shell contains a number of low "walls" running up the front surface of the interior; these would have directed water currents within its shell. Between these walls are a series of furrows, parallel to the shell's aperture, giving casts of the internal structure the appearance of a railway line, with sleepers (created by furrows) tying together paired rails that run towards the apex of the shell. Description This genus had a curved, segmented shell, and it is often reconstructed as a snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class G ... ... [...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] |
Yochelcionella Water Flow
''Yochelcionella'' is an extinct genus of basal molluscs which lived during the Tommotian epoch, the first epoch of the Cambrian period. This genus is often reconstructed to resemble snails. ''Yochelcionella'' is the type genus of the family Yochelcionellidae. Description This genus of molluscs possessed shells which were shaped like curved caps, with an exhaust pipe shaped " snorkel" emanating underneath where the apex (point of the shell) curves over. It is believed that the "snorkel" was used in breathing, allowing waste water to flow away from the gills. Taxonomy When they were first discovered, they were originally thought to be monoplacophorans. Their snorkel may represent a move towards a tubular shell, such as is seen in the modern scaphopods. It has also been interpreted as a precursor to the cephalopod funnel or siphuncle. The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdes A. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stenothecidae
Stenothecidae is an extinct family of fossil univalved Cambrian molluscs which may be either gastropods or monoplacophorans. The name of this taxon should not be confused with that of the class Stenothecoida, a group of problematic Cambrian invertebrates that have a bivalved (dorsal and ventral) shell. Morphology The group comprises conical laterally compressed shells that may be smooth or ornamented with folds or ribs. The shells are broadly limpet-like, which led to their initial consideration as monoplacophoran molluscs. Taxonomy The taxonomic position of the group is unclear; it has been classified as a Yochelcionelloid or Helcionelloid. It is not obviously in the stem group of any modern molluscan class, and has been referred to the monoplacophora, although the monoplacophora are no longer considered to be a clade, and thus that classification means little more than "primitive mollusc". Genera The family Stenothecidae consists of two subfamilies and the fol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yochelcionellidae
''Yochelcionella'' is an extinct genus of basal molluscs which lived during the Tommotian epoch, the first epoch of the Cambrian period. This genus is often reconstructed to resemble snails. ''Yochelcionella'' is the type genus of the family Yochelcionellidae. Description This genus of molluscs possessed shells which were shaped like curved caps, with an exhaust pipe shaped " snorkel" emanating underneath where the apex (point of the shell) curves over. It is believed that the "snorkel" was used in breathing, allowing waste water to flow away from the gills. Taxonomy When they were first discovered, they were originally thought to be monoplacophorans. Their snorkel may represent a move towards a tubular shell, such as is seen in the modern scaphopods. It has also been interpreted as a precursor to the cephalopod funnel or siphuncle. The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdes A. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trenellidae
''Trenella'' is the sole genus in the Trenellidae, an extinct family of paleozoic Yochelcionellids. 2005 taxonomy The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdés Á. & Warén A. 2005. ''Classification and nomenclator of gastropod families''. Malacologia: International Journal of Malacology, 47(1-2). ConchBooks: Hackenheim, Germany. . . 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278 categorizes Trenellidae in the superfamilia Yochelcionelloidea within the Paleozoic molluscs of uncertain systematic position. This family has no subfamilies. 2006-2007 taxonomy According to P. Yu. Parkhaev, the family Trenellidae is in the superfamily Yochelcionelloidea Runnegar & Jell, 1976 within the order Helcionelliformes Golikov & Starobogatov, 1975, subclass Archaeobranchia Parkhaev, 2001, class Helcionelloida Peel, 1991. Genera Genera in the family Trenellidae include: * ''Trenella ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yochelcionelloidea
Yochelcionelloidea is an extinct superfamily of paleozoic molluscs of uncertain position ( Gastropoda or Monoplacophora). The earliest yochelcionellids are known from the Middle Tommotian, but they are most diverse from the Botomian through the early Middle Cambrian.Pavel Yu. Parkhaev (2008). "The Early Cambrian Radiation of Mollusca.'" In: "''Phylogeny and evolution of the Mollusca.''" Edited by: Ponder WF, Lindberg DR. Berkeley: University of California Press: 33-69. 2005 taxonomy The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005: Yochelcionelloidea * † Yochelcionellidae * † Stenothecidae * † Trenellidae 2006-2007 taxonomy According to the opinion of P. Yu. Parkhaev is in the class Helcionelloida, subclass Archaeobranchia Parkhaev, 2001, Order Helcionelliformes Golikov & Starobogatov, 1975:P. Yu. Parkhaev (2007) ''"The Cambrian ‘basement’ of gastropod evolution"''. In: Vickers-Rich, P. & Komarower, P. (eds.) ''"The Rise and Fall of the Ediacaran Biota"' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coreospiridae
Coreospiridae is an extinct family of Paleozoic molluscs of uncertain position taxonomically. They might be snails ( Gastropoda), Helcionelloida, or they might be Monoplacophora. 2005 taxonomy The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet 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 categorizes Coreospiridae in the superfamily Scenelloidea within the Paleozoic molluscs of uncertain systematic position. 2006–2007 taxonomy According to P. Yu. Parkhaev, the family Coreospiridae is in the family Helcionelloidea ( Wenz, 1938) in the order Helcionelliformes (Golikov & Starobogatov, 1975) within the subclass Archaeobranchia (Parkhaev, 2001) in the class Helcionelloida (Peel, 1991). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carinopeltidae
''Carinopelta'' is a genus within Carinopeltidae, an extinct family of Cambrian molluscs of uncertain position. It is in the superfamily Scenelloidea. Taxonomy The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdés Á. & 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 categorizes Igarkiellidae in the superfamilia Scenelloidea within the Paleozoic molluscs of uncertain systematic position. This family has no subfamilies. According to P. Yu. Parkhaev in 2007, the family is within the superfamily Helcionelloidea Wenz, 1938 in the order Helcionelliformes Golikov & Starobogatov, 1975 within the subclass Archaeobranchia Parkhaev, 2001 in the class Helcionelloida Peel, 1991. ''Carinopelta'' is one of six ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helcionellidae
Helcionellid or Helcionelliformes is an order of small fossil shells that are universally interpreted as molluscs, though no sources spell out why this taxonomic interpretation is preferred. These animals are first found about in the late Nemakit-Daldynian age, which is the earliest part of the Cambrian period. A single species persisted to the Early Ordovician. These fossils are component of the small shelly fossils (SSF) assemblages. These are thought to be early molluscs with rather snail-like shells, although they lack any compelling molluscan synapomorphies and thus may not belong to the group. They have been alleged to represent ancestors of the modern conchiferans, a group that includes all the well-known modern classes – gastropods, cephalopods and bivalves. They have also been considered to represent direct ancestors to the cephalopods. Parkhaev (2006, 2007) considers these animals to be crown-group gastropods. Previous to the 2006 classification by Parkh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
