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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] |
Monoplacophora (YPM IZ 021295) 001
file:Monoplacophora_(YPM_IZ_021295)_001.jpeg, Shell of Monoplacophora Monoplacophora , meaning "bearing one plate", is a polyphyletic Class (biology), class of molluscs with a cap-like shell, inhabiting deep sea environments. Extant taxon, 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 grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusc
Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The number of additional fossil species is estimated between 60,000 and 100,000, and the proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine biology, marine phylum, comprising about 23% of all the named marine organisms. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat, as numerous groups are freshwater mollusc, freshwater and even terrestrial molluscs, terrestrial species. The phylum is typically divided into 7 or 8 taxonomy (biology), taxonomic class (biology), classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurobiology, neurologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tryblidiida
Tryblidiida is a taxon of monoplacophoran molluscans containing the only extant representatives: 37 species are still alive today, inhabiting the ocean at depths of between . History of discoveries The first captured living monoplacophoran was '' Veleropilina zografi'' in 1896, but at that time it was described as if it were an archaeogastropod, a true limpet, mainly because of its patelliform (limpet-like) shell. This species was finally revealed to be monoplacophoran 87 years later, in 1983. In April 1952, a living specimen was collected from deep depths in the Middle America Trench off Costa Rica's Pacific coast. In 1957 that species was described and named '' Neopilina galatheae'' by its discoverer, Danish biologist Henning Mourier Lemche (1904–1977). An expert in the field has called this discovery "one of the greatest sensations in the wentiethcentury."Schwabe, above, at p. 205. As of 2008, there were 31 living species known, discovered in waters from 200 meters in d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neopilina
''Neopilina'' is a highly derived genus of modern monoplacophoran.Organisms, Genes and Evolution: Evolutionary Theory at the Crossroads ; Proceedings of the 7th International Senckenberg Conference. By Dieter Stefan Peters, Michael Weingarten. Contributor: Dieter Stefan Peters. Published by Franz Steiner Verlag, 2000. , 9783515076593. 243 pages. Species Four species are recognized: * '' Neopilina bruuni'' Menzies, 1968 * '' Neopilina galatheae'' Lemche, 1957 * '' Neopilina rebainsi'' Moskalev, Starobogatov & Filatova, 1983 * '' Neopilina starobogatovi'' Ivanov & Moskalev, 2007 Phylogeny Some molecular results show that they fall within the polyplacophoran clade, although these results have been called into question. Fossil and morphological data show that they are rather derived and bear very little resemblance to an 'ancestral mollusc'. Anatomy Its anatomy led researchers to believe that the cephalopods evolved from the Monoplacophora. Its pair of preoral tentacles are co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropods
Gastropods (), commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and from the land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, land snails and slugs. The class Gastropoda is a diverse and highly successful class of mollusks within the phylum Mollusca. It contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,00 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopoda
A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles ( muscular hydrostats) modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by ''Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been iden ... [...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] |
Helcionelloids
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 Parkhaev, helc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyrtolitidae
Cyrtolitidae is an extinct family of monoplacophorans in the order Cyrtonellida. Genera * '' Cloudia'' * '' Cyclocyrtonella'' * '' Cyrtolites'' * '' Cyrtonellopsis'' * '' Kolihadiscus'' * '' Neocyrtolites'' * '' Paracyrtolites'' * '' Quasisinuites'' * '' Sinuella'' * '' Sinuitopsina'' * '' Sinuitopsis'' * '' Telamocornu'' * '' Yochelsonellis'' References External links * Prehistoric monoplacophorans Prehistoric mollusc families Ordovician first appearances Devonian extinctions {{Paleo-mollusc-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly '' Plebejus idas longinus'' is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University. In botany and mycology, an isotype is a duplicate of the holotype, generally pieces from the same individual plant or samples from the same genetic individual. A holotype is not necessarily "ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
