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Chelediscus
''Chelediscus'' Rushton, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae The Weymouthiidae Kobayashi 1943 are an extinct family of eodiscinid agnostid trilobites. They lived during the late Lower Cambrian and earliest Middle Cambrian (Botomian to Delamaran) in the so-called ''Olenellus''- and ''Eokochaspis''-zon ... Kobayashi T. (1943), Order Agnostida Salter (1864). The Treatise assigns this genus to the Calodiscidae; Cotton and Fortey (2005) however move it to the Weymouthiidae. ''Chelediscus'' lived during the later part of the Botomian stage.. Chelediscus is known from upper lower Cambrian strata in England, Newfoundland, New York State and Russia (Rushton, 1966; Fletcher, 2003; Rasetti, 1967; Jell ''in'' Kaesler, 1997; Distribution * The Holotype of ''C. acifer'' Rushton (1966, p. 19, pl. 2, figs. 26 a - e), is A 57104, held at the Sedgwick Museum of Earth Sciences, University of Cambridge and was collected by Rushton from about ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelediscus Enroled Lateral View Linedrawing
''Chelediscus'' Rushton, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae The Weymouthiidae Kobayashi 1943 are an extinct family of eodiscinid agnostid trilobites. They lived during the late Lower Cambrian and earliest Middle Cambrian (Botomian to Delamaran) in the so-called ''Olenellus''- and ''Eokochaspis''-zon ... Kobayashi T. (1943), Order Agnostida Salter (1864). The Treatise assigns this genus to the Calodiscidae; Cotton and Fortey (2005) however move it to the Weymouthiidae. ''Chelediscus'' lived during the later part of the Botomian stage.. Chelediscus is known from upper lower Cambrian strata in England, Newfoundland, New York State and Russia (Rushton, 1966; Fletcher, 2003; Rasetti, 1967; Jell ''in'' Kaesler, 1997; Distribution * The Holotype of ''C. acifer'' Rushton (1966, p. 19, pl. 2, figs. 26 a - e), is A 57104, held at the Sedgwick Museum of Earth Sciences, University of Cambridge and was collected by Rushton from about ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weymouthiidae
The Weymouthiidae Kobayashi 1943 are an extinct family of eodiscinid agnostid trilobites. They lived during the late Lower Cambrian and earliest Middle Cambrian (Botomian to Delamaran) in the so-called ''Olenellus''- and ''Eokochaspis''-zones in the former paleocontinents of Laurentia, Avalonia, Gondwana. The Weymouthiidae are all blind and lack free cheeks. Taxonomy Ancestors The Weymouthiidae have developed from a stock within the Hebediscidae The Hebediscidae Kobayashi, 1944, are a family of trilobites belonging to the order Agnostida that lived during the Lower Cambrian (Atdabanian to Toyonian). They are small or very small, and have a thorax of two or three segments. The Hebediscida .... Descendants The Weymouthiidae are a paraphyletic family because the Agnostina suborder is nested within it, particularly in the clade that further consists of the genera ''Mallagnostus'', ''Chelediscus'', ''Tannudiscus'' and ''Jinghediscus''. The trend in the Weymouthiid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Botomian
Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commission on Stratigraphy. One proposal is the first appearance of two trilobite genera, ''Olenellus'' or ''Redlichia''. Another proposal is the first appearance of the trilobite species '' Arthricocephalus chauveaui''. Both proposals will set the lower boundary close to million years ago. The upper boundary corresponds to the beginning of the Wuliuan. Naming The International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigra ... has not named the fourth stage of the Cambrian yet. In the widely used Siberian nomenclature stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), 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 exoskeleton, 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 Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilobita
Trilobites (; meaning "three lobes") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian Stage (geology), stage of the Early Cambrian Period (geology), period () and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in Permian–Triassic extinction event, the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostida
Agnostida is an order of arthropod which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda. They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician. Systematics The Agnostida are divided into two suborders — Agnostina and Eodiscina — which are then subdivided into a number of families. As a group, agnostids are isopygous, meaning their pygidium is similar in size and shape to their cephalon. Most agnostid species were eyeless. The systematic position of the order Agnostida within the class Trilobita remains uncertain, and there has been continuing deb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eodiscina
Eodiscina is trilobite suborder. The Eodiscina first developed near the end of the Lower Cambrian period (late Atdabanian) and became extinct at the end of the Middle Cambrian. Species are tiny to small, and have a thorax of two or three segments. Eodiscina includes six families classified under one superfamily, Eodiscoidea. Taxonomy The Eodiscina are mostly considered the more primitive suborder of the Agnostida, and the Agnostina the more advanced. Some scholars do not consider the Agnostina true trilobites, and consequently rejected the idea that they were related to the Eodiscina. Consequently, these scientists have proposed to elevate the group to ordinal level, which would thus be called Eodiscida Kobayashi, 1939. Origin The oldest known eodiscoid is ''Tsunyidiscus''. The glabella of ''Tsunyidiscus'' is extremely similar to that of ''Dipharus clarki'', and distinct from all other eodiscoids. ''D. clarki'' is thought to represent an immature stage of the redlichioid ''Bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eodiscoidea
Eodiscina is trilobite suborder. The Eodiscina first developed near the end of the Lower Cambrian period (late Atdabanian) and became extinct at the end of the Middle Cambrian. Species are tiny to small, and have a thorax of two or three segments. Eodiscina includes six families classified under one superfamily, Eodiscoidea. Taxonomy The Eodiscina are mostly considered the more primitive suborder of the Agnostida, and the Agnostina the more advanced. Some scholars do not consider the Agnostina true trilobites, and consequently rejected the idea that they were related to the Eodiscina. Consequently, these scientists have proposed to elevate the group to ordinal level, which would thus be called Eodiscida Kobayashi, 1939. Origin The oldest known eodiscoid is '' Tsunyidiscus''. The glabella of ''Tsunyidiscus'' is extremely similar to that of ''Dipharus clarki'', and distinct from all other eodiscoids. ''D. clarki'' is thought to represent an immature stage of the redlichioid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type (biology)
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the defining features of that particular taxon. In older usage (pre-1900 in botany), a type was a taxon rather than a specimen. A taxon is a scientifically named grouping of organisms with other like organisms, a set that includes some organisms and excludes others, based on a detailed published description (for example a species description) and on the provision of type material, which is usually available to scientists for examination in a major museum research collection, or similar institution. Type specimen According to a precise set of rules laid down in the International Code of Zoological Nomenclature (ICZN) and the International Code of Nomenclature for algae, fungi, and plants (ICN), the scientific name of every taxon is almost al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Trilobites
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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