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Pancrustacea
Pancrustacea is the clade that comprises all crustaceans and all hexapods (insects and relatives). This grouping is contrary to the Atelocerata hypothesis, in which Hexapoda and Myriapoda are sister taxa, and Crustacea are only more distantly related. As of 2010, the Pancrustacea taxon was considered well accepted, with most studies recovering Hexapoda within Crustacea. The clade has also been called Tetraconata, referring to having a four-part cone in the ommatidium. The term "Tetraconata" is preferred by some scientists in order to avoid confusion with the use of "pan-" to indicate a clade that includes a crown group and all of its stem group representatives. Molecular studies A monophyletic Pancrustacea has been supported by several molecular studies, in most of which the subphylum Crustacea is paraphyletic with regard to hexapods (that is, that hexapods, including insects, are derived from crustacean ancestors). This means that within Pancrustacea, only some members are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allotriocarida
Allotriocarida is a clade of Pancrustacea, containing Hexapoda (all insects, springtails & their close relatives). It also contains three non-hexapod classes: Remipedia (blind, venomous crustaceans), Cephalocarida (translucent aquatic detrivores), and Branchiopoda (freshwater, non-decapod 'shrimp'). Newer studies also relocate Copepoda, which traditionally has belonged to the multicrustaceans, to the Allotriocarida. Allotriocarida is one of three major clades within Pancrustacea, being most closely related to its sister clade Multicrustacea (crabs, lobsters, barnacles, etc), and more distantly related to the superclass Oligostraca (seed shrimp, fish lice, and tongue worms). History The idea of hexapods being 'terrestrial crustaceans' is relatively recent, coming from a 2005 molecular analysis study. A 2013 study restructured the relationships within Pancrustacea, and first proposed the name Allotriocarida. The most recent study of Allotriocarida in 2019 provides addit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacea
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese spider ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexapoda
The subphylum Hexapoda (from Greek for 'six legs') or hexapods comprises the largest clade of arthropods and includes most of the extant arthropod species. It includes the crown group class Insecta (true insects), as well as the much smaller clade Entognatha, which includes three classes of wingless arthropods that were once considered insects: Collembola (springtails), Protura (coneheads) and Diplura (two-pronged bristletails). The insects and springtails are very abundant and are some of the most important pollinators, basal consumers, scavengers/ detritivores and micropredators in terrestrial environments. Hexapods are named for their most distinctive feature: a three-part body plan with a consolidated thorax and three pairs of legs. Most other arthropods have more than three pairs of legs. Most recent studies have recovered Hexapoda as a subgroup of Pancrustacea. Morphology Hexapods have bodies ranging in length from 0.5 mm to over 300 mm which are divided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 contrast, a monophyletic grouping (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term received currency during the debates of the 1960s and 1970s accompanying the rise of cladistics, having been coined by zoologist Willi Hennig to apply to well-known taxa like Reptilia (reptiles), which is paraphyletic with respect to birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor exc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatocopina
Phosphatocopina (alternatively Phosphatocopida) is an extinct group of bivalved arthropods known from the Cambrian period. They are generally sub-milimetric to a few millimetres in size. They are typically only known from isolated carapaces, but some found in Orsten-type phosphatized preservation have their bodies preserved in high fidelity in three dimensions. Description The phosphatized bivalved carapace covered the entire body. Members typically grew to a maximum of in length, though ''Cyclotron'' grew up to . In some species, spines were present on the carapace. The head either bore a pair of stalked eyes or a pair of dome-shaped medial eyes. The first appendage pair, dubbed the " antennulae", were uniramous, with the remaining appendage pairs being biramous. The basipods and endopods of the biramous limbs had prominently developed endites, while the exopods were typically annulated, and bore setae. The earliest larval stages of phosphatocopines are known as "head larv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dala (crustacean)
''Dala'' is an extinct genus of pancrustaceans from the Cambrian Orsten. The genus contains a single species, ''Dala peilertae''. Description ''Dala'' is estimated to be around 2 millimetres long extrapolating from partial specimens, with no preserved head in the holotype and only a fragmentary one in the paratype. It has eight pairs of thoracic appendages forming a filter apparatus, four pairs of cephalic appendages, a large labrum and five ring-shaped abdominal segments, alongside a long furca on the posteriormost segment. Two different size groups of ''Dala'' have been identified, although no currently known larvae have been found. A relationship to Cephalocarida was briefly suggested, but ''Dala'' is currently labelled as Pancrustacea ''incertae sedis''. Etymology ''Dala'' is named for the parish of Dala 2 km west-northwest of the discovery site. Its specific name ''peilertae'' honours Mrs. Christa Peilert "on the occasion of her retirement after 14 years (1966 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yicaris
''Yicaris dianensis'' is a species of microscopic pancrustacean found in the Yu’anshan Formation, Yunnan Province, China. ''Yicaris''' discovery is notable because its age suggests that true crustaceans already existed as far back in time as Early Cambrian, much earlier than other fossils known from the Middle and Late Cambrian. Its closest living relatives are believed to be Cephalocaridans. Etymology The name ''Yicaris dianensis'' honors the ethnic minority Yi people of Yunnan Province, while Dian is an ancient kingdom of southern China. The suffix —caris refers to shrimp in Latin. Description ''Yicaris''' body consists of a cephalothorax covered by a head shield and limb-bearing segments. Out of the thirty-four specimens examined, six consecutive growth stages are known, the smallest one being 460 μm while the largest fossil, though fragmentary, reaches 1.8 mm long. Yicaris is also notable for the leaf-like structures on its limbs called epipodites. The d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multicrustacea
The clade Multicrustacea constitutes the largest Superclass (biology), superclass of crustaceans, containing approximately four-fifths of all described non-hexapod crustacean species, including crabs, lobsters, crayfish, Caridea, shrimp, krill, Dendrobranchiata, prawns, woodlice, barnacles, copepods, amphipoda, amphipods, mantis shrimp and others. The largest branch of multicrustacea is the class (biology), class Malacostraca (see below). Classification Superclass Multicrustacea Regier, Shultz, Zwick, Hussey, Ball, Wetzer, Martin & Cunningham, 2010 * Family Priscansermarinidae Newman, 2004 * Class Copepoda Milne-Edwards, 1840 – Copepods ** Infra-class Neocopepoda Huys & Boxshall, 1991 *** Super-order Gymnoplea Giesbrecht, 1882 **** Order Calanoida Sars GO, 1903 *** Super-order Podoplea Giesbrecht, 1882 **** Order Cyclopoida Burmeister, 1834 **** Order Gelyelloida Huys, 1988 **** Order Harpacticoida G. O. Sars, 1903 **** Order Misophrioida Gurney, 1933 **** Order Monstrillo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myriapoda
Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversification in the Cambrian Period, the oldest known fossil record of myriapods dates between the Late Silurian and Early Devonian, with '' Pneumodesmus'' preserving the earliest known evidence of air-breathing on land. Other early myriapod fossil species around the similar time period include '' Kampecaris obanensis'' and '' Archidesmus'' sp. The phylogenetic classification of myriapods is still debated. The scientific study of myriapods is myriapodology, and those who study myriapods are myriapodologists. Anatomy Myriapods have a single pair of antennae and, in most cases, simple eyes. Exceptions are the two classes of symphylans and pauropods, the millipede order Polydesmida and the centipede order Geophilomorpha, which are all ey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wujicaris
''Wujicaris'' is an extinct genus of Early Cambrian crustaceans from the Maotianshan Shales of China. The genus contains a single species, ''Wujicaris muelleri''. Description ''Wujicaris'' is a crustacean known from the Chengjiang Lagerstatte, uniquely fossilised in Orsten-type preservation and known from four larval specimens in the early metanauplius stage roughly 270 μm long. It and the possibly related taxon ''Yicaris'' both heavily resemble the metanaupli of modern crustaceans such as barnacles, thus possibly suggesting the existence of Thecostraca Thecostraca is a class of marine invertebrates containing over 2,200 described species. Many species have planktonic larvae which become sessile or parasitic as adults. The most prevalent subgroup are the barnacles (subclass Cirripedia), const ... during the Cambrian. ''Wujicaris'' possesses a large, pointed cephalic shield with an oval structure tentatively dubbed the "dorsal organ", a pair of possibly median eyes, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skaracarida
''Skara'' is a genus of oligostracan pancrustaceans known from the Upper Cambrian Orsten deposit of Sweden, similarly aged deposits in China, and possibly Poland. It is the only genus in the order Skaracarida and family Skaraidae, and contains three species, ''S. anulata'', ''S. minuta'' and ''S. hunanensis''. Description ''Skara'' has a head with five segments which each contain an appendage pair; two pairs of antennae, a pair of mandibules and two pairs of maxillae. ''S. anulatas head shield resembles an inverted “U” in cross-section, and has been likened to an upside-down dinghy in shape, with a margin at its edge and slightly bulging rims. The forehead bears a rod-shaped process in ''S. minuta'' (however it is likely broken off in ''S. anulata''), with a tiny pore beneath likely representing a gland opening. The labrum is roughly nose-shaped, with shallow depressions near its posterior end likely representing interior muscles able to move the labrum abaxially. A t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
