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Cheirurid
Cheiruridae is a family of phacopid trilobites of the suborder Cheirurina. Its members, as with other members of the suborder, had distinctive pygidium, pygidia modified into finger-like spines. They first appeared in the uppermost Cambrian (upper Furongian), and persisted until the end of the Middle Devonian (Givetian). Currently about 657 species assigned to 99 genera are included. Distribution The subfamily Cheirurinae with 269 species in 38 genera occur from the Floian to the Givetian and are probably monophyletic. The 109 species in 15 genera of the Acanthoparyphinae are also probably monophyletic, and are known from the Floian to the Ludfordian. The Cyrtometopinae were present between the Floian and the Upper Katian, enveloping 22 species in 5 genera, of which the monophyly is unclear. The Deiphoninae are probably monophyletic, occur from the Dapingian to the Gorstian, having 71 species assigned to 6 genera. The possibly paraphyletic Eccoptochilinae with 67 species in 13 g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraceraurus Exsul
''Paraceraurus exsul'' is a species of trilobite that lived in St. Petersburg Region and Tver Region (in erratic blocks) of Russia, Estonia, Finland (Åland, in erratic blocks), Sweden, North Germany (in erratic blocks), Lithuania and Belarus during the Upper Llanvirnian Stage (463.5-460.9 Ma) of the Middle Ordovician. These trilobites can reach a length of about . They show a square front edge, large genal spines on the cheeks and characteristic long pygidial spines. Genal spines are curved usually inward and upward. References * Trilobites of the families Cheiruridae and Encrinuridae from Estonia. Geoloogia Instituudi Uurimused (Trud Inst Geol Acad Sci Est SSR) Tallinn, 3 1958: 165–205, 210–212. [Zoological Record Volume 95] * V. Klikushin, A. Evdokimov, A. Pilipyuk. Ordovician Trilobites of the St. Petersburg Region, Russia. 2009. External links PaleoartFossil ID Cheiruridae Ordovician trilobites {{phacopida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheirurina
Cheirurina is a suborder of the trilobite order Phacopida. Known representatives range from the uppermost Cambrian (upper Furongian) to the end of the Middle Devonian (Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in Fra ...). Cheirurina is made up of a morphologically diverse group of related families. References Phacopida Prehistoric animal suborders Arthropod suborders Cambrian trilobites Ordovician trilobites Silurian trilobites Devonian trilobites Furongian first appearances Givetian extinctions {{phacopida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
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 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 Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilekiidae
Pilekiidae is a family of trilobites in the order Phacopida, specifically within Suborder Cheirurina. It includes the following genera: *'' Anacheiruraspis'' *''Anacheirurus'' *'' Chashania'' *''Demeterops'' *''Emsurina'' *'' Koraipsis'' *''Landyia'' *''Macrogrammus ''Macrogrammus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the early part of the Arenig, Arenig stage of the Ordovician Period, a faunal stage which lasted from approximately 478 to 4 ...'' *'' Metapilekia'' *'' Metapliomerops'' *'' Parapilekia'' *'' Pilekia'' *'' Pliomeroides'' *'' Pseudopliomera'' *'' Seisonia'' *'' Sinoparapilekia'' *'' Victorispina'' References Trilobite families {{phacopida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic group (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 Synapomorphy and apomorphy, synapomorphies and symplesiomorphy, symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term was coined by Willi Hennig to apply to well-known taxa like Reptilia (reptiles) which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorstian
In the geologic timescale, the Gorstian is an age of the Ludlow Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 427.4 ± 0.5 Ma and 425.6 ± 0.9 Ma (million years ago), approximately. The Gorstian Age succeeds the Homerian Age and precedes the Ludfordian Age. The age is named after Gorsty village southwest of Ludlow Ludlow () is a market town in Shropshire, England. The town is significant in the history of the Welsh Marches and in relation to Wales. It is located south of Shrewsbury and north of Hereford, on the A49 road which bypasses the town. The t .... The base of the age is marked by '' Graptolites tumescens'' and '' Graptolites incipiens''. The type section is located in a quarry in the Elton Formation at Pitch Coppice, Shropshire, United Kingdom. References Ludlow epoch Silurian geochronology {{geochronology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dapingian
The Dapingian is the third stage of the Ordovician period and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The top of the Floian is defined as the first appearance of the conodont species ''Baltoniodus triangularis'' which happened about million years ago. The Dapingian lasted for about 2.7 million years until about million years ago.Note: there is an apparent typo in the article referenced; they give the coordinates as "a latitude of 30°51’37.8"N and a longitude of 110°22’26.5"E", but their map and location description better corresponds to 30°51’37.8"N 111°22’26.5"E. History The Ordovician was divided into three series and six global stages in 1995; in 2005, this was amended to seven stages with the formalization of the Hirnantian stage as the last stage in the Late Ordovician. The Dapingian was the last Ordovician stage to be ratified, and was initially referred to as an informal and unnamed "third ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Katian
The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian million years ago. During the Katian the climate cooled which started the Late Ordovician glaciation. Naming The name Katian is derived from Katy Lake (Atoka County, Oklahoma, United States). GSSP The GSSP of the Katian Stage is the Black Knob Ridge Section in southeastern Oklahoma (United States). It is an outcrop of the Womble Shale and the Bigfork Chert, the latter containing the lower boundary of the Katian. The lower boundary is defined as the first appearance datum of the graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and ... spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludfordian
In the geologic timescale, the Ludfordian is the upper of two chronostratigraphic stages within the Ludlow Series. Its age is the late Silurian Period, and within both the Palaeozoic Era and Phanerozoic Eon. The rocks assigned to the Ludfordian date to between 425.6 ± 0.9 Ma and 423.0 ± 2.3 Ma (million years ago). The Ludfordian Stage succeeds the Gorstian Stage and precedes the Pridoli Epoch. It is named for the village of Ludford in Shropshire, England. The GSSP for the Ludfordian is represented as a thin shale seam, coincident with the base of the Leintwardine Formation, overlying the Bringewood Formation in England. Paleoclimate The Lau event is a rapid pulse of cooling during the Ludfordian, about ; it is identified by a pulse of extinctions and oceanic changes. It is one of the series of fast sea-level and excursions in oxygen isotope ratios that signal fast switches between warm and cold climate states, characteristic of the Silurian climatic instability. The Lau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic groups are typically characterised by shared derived characteristics ( synapomorphies), which distinguish organisms in the clade from other organisms. An equivalent term is holophyly. The word "mono-phyly" means "one-tribe" in Greek. Monophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. A ''paraphyletic group'' consists of all of the descendants of a common ancestor minus one or more monophyletic groups. A '' polyphyletic group'' is characterized by convergent features or habits of scientific interest (for example, night-active primates, fruit trees, aquatic insects). The features by which a polyphyletic group is differentiated from others are not inherited from a common ancestor. These definitions have tak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
