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Marrellomorph
Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from areas of exceptional preservation, limiting their fossil distribution. The best known member is ''Marrella'', with thousands of specimens found in the Cambrian aged Burgess Shale of Canada. The group is divided up into two major orders, Marrellida and Acercostraca. Marrellida is recognised by the possession of head shields with two or three pairs of elongate spine-like projections, and three pairs of uniramous appendages on the cephalon, while Acercostraca generally have large ovoid carapaces that cover the entire upper half of the body, and five pairs of uniramous cephalic appendages. Both groups have unbranched antennules and a segmented trunk with biramous appendages. Recent research has suggested the previously enigmatic Cambrian trliobite-like arthropods '' Skania'' and '' Primicaris'' may belong to this group. Their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marrella
''Marrella'' is an extinct genus of marrellomorph arthropod known from the middle Cambrian Burgess Shale of British Columbia. It is the most common animal represented in the Burgess Shale, with tens of thousands of specimens collected. Much rarer remains are also known from deposits in China. History ''Marrella'' was the first fossil collected by Charles Doolittle Walcott from the Burgess Shale, in 1909. Walcott described ''Marrella'' informally as a "lace crab" and described it more formally as an odd trilobite. It was later reassigned to the now defunct class Trilobitoidea in the ''Treatise on Invertebrate Paleontology''. In 1971, Whittington undertook a thorough redescription of the animal and, on the basis of its legs, gills and head appendages, concluded that it was neither a trilobite, nor a chelicerate, nor a crustacean. ''Marrella'' is one of several unique arthropod-like organisms found in the Burgess Shale. Other examples are '' Opabinia'' and ''Yohoia''. The unusual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arachnomorpha
Arachnomorpha is a proposed subdivision or clade of Arthropoda, comprising the group formed by the trilobites and their close relatives (Artiopoda), Megacheira (which may be paraphyletic) and chelicerates. Under this proposed classification scheme, Arachnomorpha is considered the sister group to Mandibulata (including insects, crustaceans and myriapods). The arachnomorph concept has been challenged by suggestions that the artiopods are more closely related to mandibulates, forming the clade Antennulata instead. There is no consensus as to assigning Arachnomorpha a formal Linnean rank. Classification Arachnomorpha Lameere, 1890 Arachnata Paulus, 1979, = Palaeopoda Packard, 1903*†Trilobita Walch, 1771 *† Megacheira Hou & Bergstrom, 1997 *† Strabopida Hou & Bergström, 1997 *†Aglaspida Walcott, 1911 *† Cheloniellida Broili, 1932 *Chelicerata The subphylum Chelicerata (from New Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior organs; it has an open circulatory system. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artiopoda
The Artiopoda is a grouping of extinct arthropods that includes trilobites and their close relatives. It was erected by Hou and Bergström in 1997 to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomorpha. Hou and Bergström used the name Lamellipedia as a superclass to replace Trilobitomorpha that was originally erected at the subphylum level, which they considered inappropriate. Trilobites, in part due to their mineralising exoskeletons, are by far the most diverse and long lived members of the clade, with most records of other members, which lack mineralised exoskeletons, being from Cambrian deposits. Description According to Stein and Selden (2012) artiopods are recognised by the possession of filiform antennulae, limbs with bilobate exopods, with the proximal lobe being elongate and bearing a lamella, while the distal lobe is paddle-shaped and setiforous (bearing hair-or bristle like structures). The limb endopod has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vachonisia
''Vachonisia'' is a Devonian marrellomorph known from the Lower Devonian Hunsrück Slate The Hunsrück () is a long, triangular, pronounced upland in Rhineland-Palatinate, Germany. It is bounded by the valleys of the Moselle-Saar (north-to-west), the Nahe (south), and the Rhine (east). It is continued by the Taunus mountains, past .... It grows in a similar fashion to the other Hunsruck marrellomorph, '' Mimetaster'', and is closely related to the Silurian '' Xylokorys''. It is known from 20 specimens; its whole body is covered by a shield-like carapace. References Devonian animals Prehistoric arthropod genera Fossils of Germany Hunsrück Slate fossils Marrellomorpha {{paleo-arthropod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primicaris
''Primicaris'' is genus of Cambrian arthropod from the Chengjiang biota of China and the Burgess Shale of Canada. It contains a single described species, ''P. larvaformis''. Its specimens were once thought to be meraspids of ''Naraoia spinosa''. Its phylogenetic position has been described as "problematic". Some studies have suggested them to be marrellomorphs belonging to the subgroup Acerostraca. See also * Arthropod * Cambrian explosion * Chengjiang biota ** List of Chengjiang Biota species by phylum This is a list of fossils found at Maotianshan Shales, whose most famous assemblage of organisms are referred to as the Chengjiang biota. Phylum Arthropoda 80 species, not counting Dinocarida, Nektaspida and Trilobita * '' Acanthomerid ... References Cambrian animals Maotianshan shales fossils Prehistoric arthropod genera {{paleo-arthropod-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skania
''Skania'' is a Middle Cambrian fossil arthropod that is closely related to the Early Cambrian '' Primicaris'' from the Chengjiang Biota, China. It bears a superficial resemblance to the Ediacaran organism '' Parvancorina''. A single specimens of ''Skania'' are known from the Greater Phyllopod bed of the Burgess Shale where they comprise < 0.01% of the community. While previously enigmatic, it is now thought to be a marrellomorph
Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from areas of exceptional preservation, limiting their fossil distribution. The best known me ... .
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Xylokorys
''Xylokorys'' is a genus of marrellomorph Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from areas of exceptional preservation, limiting their fossil distribution. The best known me ... known from two specimens from the Silurian Herefordshire lagerstatte; it filter-fed on mud particles on the sea floor. It is the only marrellomorph known from the Silurian period. References Silurian arthropods of Europe Marrellomorpha {{paleo-arthropod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandibulata
Mandibulata, termed "mandibulates", is a clade of arthropods that comprises the extant subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects and others). Mandibulata is currently believed to be the sister group of the clade Arachnomorpha, which comprises the rest of arthropods (Chelicerata and Trilobita). The mandibulates constitute the largest and most varied arthropod group. The name "Mandibulata" refers to the mandibles or jaws, which are the characterizing feature of its member arthropods. Molecular phylogenetic studies suggest that the living arthropods are related as shown in the cladogram below. Crustaceans do not form a monophyletic group as insects and other hexapods have evolved from within them. See also *Atelocerata * Marrellomorpha * Myriochelata *Pancrustacea *Crustaceomorpha Crustaceomorpha is a proposed clade of arthropods that includes crustaceans and numerous extinct groups. Synapomorphies for the clade are that the larval anten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wuliuan
The Wuliuan stage is the fifth stage of the Cambrian, and the first stage of the Miaolingian Series of the Cambrian. It was formally defined by the ICS in 2018. Its base is defined by the first appearance of the trilobite species '' Oryctocephalus indicus''; it ends with the beginning of the Drumian Stage, marked by the first appearance of the trilobite '' Ptychagnostus atavus'' around million years ago. The 'golden spike' that formally defines the base of the period is driven into the Wuliu-Zengjiayan(乌溜-曾家崖)section of the Kaili formation, near Balang Village in the Miaoling Mountains, Guizhou, China. GSSP Three sections were discussed as GSSP candidates: the Wuliu-Zengjiayan section near Balang in Guizhou province (China), a section on Split Mountain in Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Ari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Stage 3
Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approximately to the first appearance of trilobites, about million years ago, though the globally asynchronous appearance of trilobites warrants the use of a separate, globally synchronous marker to define the base. The upper boundary and beginning of Cambrian Stage 4 is informally defined as the first appearance of the trilobite genera '' Olenellus'' or ''Redlichia'' around million years ago. Naming The International Commission on Stratigraphy has not officially named the 3rd stage of the Cambrian. The stage approximately corresponds to the "Atdabanian", which is used by geologists working in Siberia. Biostratigraphy The oldest trilobite known is '' Lemdadella'' which appears at the beginning of the '' Fallotaspis'' zone. The Cambrian radiat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maotianshan Shales
The Maotianshan Shales are a series of Early Cambrian deposits in the Chiungchussu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized organisms or traces. The Maotianshan Shales form one of some forty Cambrian fossil locations worldwide exhibiting exquisite preservation of rarely preserved, non-mineralized soft tissue, comparable to the fossils of the Burgess Shale. They take their name from Maotianshan Hill (, Literal meaning: Hat Sky Mountain) in Chengjiang County, Yunnan Province, China. The most famous assemblage of organisms are referred to as the Chengjiang biota for the multiple scattered fossil sites in Chengjiang. The age of the Chengjiang Lagerstätte is locally termed Qiongzhusian, a stage correlated to the late Atdabanian Stage in Siberian sequences of the middle of the Early Cambrian. The shales date to ≤. The shales also contain the slightly younger Guanshan biota from Malong District in Yunna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
