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Sinodiscus
''Sinodiscus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the late Atdabanian stage, which lasted from 530 to 524 million years ago during the early part of the Cambrian Period The Cambrian Period ( ; sometimes symbolized C with bar, 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 .... Dai and Zhang (2013) were able to reconstruct both the morphology and ontogeny of ''S. changyangensis'' Zhang based on a large number of well preserved examples from the lower Cambrian Shuijingtuo Formation in Changyang, Hubei Province, South China. DAI, T., ZHANG, X. 2013. Morphology and ontogeny of the eodiscoid trilobite ''Sinodiscus changyangensis'' from the lower Cambrian of South China. ''Palaeontology'', 56, 2, 411 – 420. https://doi.org/10.1111/j.1475-4983.2012.01208.x References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calodiscidae
The Calodiscidae Kobayashi, 1943 'nom. transl.'' Öpik, 1975 ''ex'' Calodiscinae Kobayashi, 1943are a family of trilobites belonging to the order Agnostida that lived during the Lower Cambrian (Botomian and Toyonian). They are small or very small, and have a thorax of two or three segments. The Calodiscidae includes five genera (see box). Taxonomy The probable ancestors of the Calodiscidae are among the Tsunydiscidae. The Calodiscidae had no descendants. cited ''in'' Description Like all Agnostida, the Calodiscidae are diminutive and the headshield (or cephalon) and tailshield (or pygidium) are of approximately the same size (or isopygous) and outline. The central raised area of the cephalon (or glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ...) has parallel sid ... [...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 ''B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atdabanian
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 rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the abs ... [...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 bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Period
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 biolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilobite
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the 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 of the Early Cambrian 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 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 wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. Th ... [...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] |
Extinct
Extinction is the termination of a kind of organism or of a group of kinds ( taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. '' Panthera leo'' (lion) and '' Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should c ... [...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] |
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