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Miaolingian Extinctions
The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about to million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is preceded by the unnamed Cambrian Series 2 and succeeded by the Furongian series. It is named after the Miaoling Mountains in southeastern Guizhou Province, China. Definition A number of proposals for fossils and type sections were made before it was formally ratified in 2018. The most promising fossil markers were seen to be the respective first appearances of either trilobite species '' Ovatoryctocara granulata'' or '' Oryctocephalus indicus'', which both have an age close to million years ago. After some deliberation, the FAD of ''Oryctocephalus indicus'' was chosen to be the lower boundary marker, and the GSSP was placed in the Kaili Formation, Wuliu-Zengjiayan, Guizhou, China. The Miaolingian-Furongian boundary has the same definiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Commission On Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, stratigraphical, geology, geological, and chronology, geochronological matters, worldwide. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working committee, working subcommittee, which meets far more regularly than the quadrennial meetings scheduled by the IUGS, when it meets as a congress or committee, membership of the whole. Aims One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontology, paleontological and geobiology, geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype Section and Points ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovatoryctocara Granulata
''Ovatoryctocara granulata'' is a species of corynexochid trilobite from the Cambrian. Its first appearance is one of the proposals for the base of 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 International Commission on Stratigraphy in 2018. Its base is defined by the first appearance of t ... (The other proposal having been '' Oryctocephalus indicus''). The species was first formally described by the Russian paleontologist N.Ye. Tchernysheva in 1962. ''Ovatoryctocara granulata'' appears close to the base of the ''Ovatoryctocara'' trilobite zone and can be found up to the ''Kounamkites'' zone. References Oryctocephalidae Cambrian trilobites Fossil taxa described in 1962 Index fossils {{Corynexochida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemostratigraphy
Chemostratigraphy, or chemical stratigraphy, is the study of the chemical variations within sedimentary sequences to determine stratigraphic relationships. The field is relatively young, having only come into common usage in the early 1980s, but the basic idea of chemostratigraphy is nearly as old as stratigraphy itself: distinct chemical signatures can be as useful as distinct fossil assemblages or distinct lithographies in establishing stratigraphic relationships between different rock layers. Types of chemical variations In some stratigraphic sequences, there is clearly a variation in color between different strata. Such color differences often originate from variations in the incorporation of transition metal-containing materials during deposition and lithification. Other differences in color can originate from variations in the organic carbon content of the rock. However, until relatively recently, these variations were not commonly investigated because of the great effor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurentia
Laurentia or the North American craton is a large continental craton that forms the Geology of North America, ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and the Hebridean terrane in northwest Scotland. During other times in its past, Laurentia has been part of larger continents and supercontinents and consists of many smaller terranes assembled on a network of early Proterozoic Orogenic belt, orogenic belts. Small microcontinents and oceanic islands collided with and Suture (geology), sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today. Etymology The craton is named after the Laurentian Shield, through the Laurentian Mountains, which received their name from the St. Lawrence River, named after Saint Lawrence of Rome. Interior platform In eastern and centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redlichiidae
Redlichiidae is a family (biology), family of Redlichiida, redlichiid trilobites which lived from the Botomian to the Middle Cambrian period. It contains the following genera, divided between five subfamilies: Taxonomy Redlichiinae * ''Redlichia'' (type genus) * ''Conoredlichia'' * ''Latiredlichia'' * ''Pteroredlichia'' * ''Syndianella'' Metaredlichiinae * ''Metaredlichia'' (type genus) * ''Bornemannaspis'' * ''Breviredlichia'' * ''Iglesiella'' * ''Jingyangia'' * ''Maopingaspis'' * ''Nebidella'' * ''Parazhenbaspis'' * ''Pseudoredlichia'' * ''Sardoredlichia'' * ''Ushbaspis'' * ''Xela (trilobite), Xela'' * ''Zhenbaspis'' Neoredlichiinae * ''Neoredlichia'' (type genus) * ''Leptoredlichia'' * ''Olgaspis'' * ''Xenoredlichia'' Pararedlichiinae * ''Eoredlichia'' (type genus) * ''Irgitkhemia'' * ''Lemdadella'' * ''Ningqiangaspis'' * ''Pachyredlichia'' * ''Redlichops'' Wutingaspinae * ''Wutingaspis'' (type genus) * ''Chaoaspis'' * ''Chengjiangaspis'' * ''Kepingaspis'' * ''Ku ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olenellid Biomere Boundary
Olenellidae is an extinct family of redlichiid trilobite arthropods. Olenellids lived during the late Lower Cambrian (Botomian/Toyonian) in the ''Olenellus''-zone in the former paleocontinent of Laurentia and parts of what became the Famatinian orogen in what is now Argentina. This family can be distinguished from most other Olenellina by the partial merger of the frontal (L3) and middle pair (L2) of lateral lobes of the central area of the cephalon, that is called 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 ..., creating two isolated slits. Key to the subfamilies References Olenelloidea Trilobite families Cambrian first appearances Cambrian Series 2 extinctions {{Redlichiida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilobite
Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most successful of all early animals, existing in oceans for almost 270million years, with over 22,000 species having been described. Because trilobites had wide diversity and an easily fossilized mineralised exoskeleton made of calcite, they left an extensive fossil record. The study of their fossils has facilitated important contributions to biostratigraphy, paleontology, evolution, evolutionary biology, and plate tectonics. Trilobites are placed within the clade Artiopoda, which includes many organisms that are morphologically similar to trilobites, but are largely unmineralised. The relationship of Artiopoda to other arthropods is uncertain. Trilobites evolved into many ecological niches; some moved over the seabed as predators, scavengers, or ... [...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 radiation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Stage 4
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 has not named the fourth stage of the Cambrian yet. In the widely used Siberian nomenclature stage 4 would overlap with parts of the Botomian and Toyonian. Biostratigraphy The beginning of Cambrian Stage 4 has been tentatively correlated with the base of the European Leonian faunal stage and the base of the South China Duyunian faunal stage. Durin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jiangshanian
The Jiangshanian is the middle stage of the Furongian series. It follows the Paibian Stage and is succeeded by the still unnamed Stage 10 of the Cambrian. The base is defined as the first appearance of the trilobite '' Agnostotes orientalis'' which is estimated to be million years ago. The Jiangshanian lasted until approximately million years ago. The Jiangshanian stage was named after Jiangshan, a city in China's Zhejiang province, where its GSSP was defined. Stratigraphy The Global boundary Stratotype Section and Point (GSSP) of the Jiangshanian is the "Duibian B Section" (), west of the village of Duibian (碓边), and 10 km north of Jiangshan. The outcrop belongs to the Huayansi Formation (华严寺组). The upper boundary (the base of the Stage 10) is not formally defined by ICS, but there is a proposal to set the first appearance of an agnostoid '' Lotagnostus americanus'' as its marker. In 2012, international research group proposed the Kyrshabakty s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Stage 10
Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. The proposed lower boundary is the first appearance of the trilobite '' Lotagnostus americanus'' around million years ago, but other fossils are also being discussed ( see below). The upper boundary is defined as the appearance of the conodont ''Iapetognathus fluctivagus'' which marks the beginning of the Tremadocian and is radiometrically dated as million years ago. Naming The 10th stage of the Cambrian has not been formally named by the ICS yet, although a number of local names exist. Several authors favor the name "Lawsonian" after Lawson Cove, in the Wah Wah Mountains of Utah. The lower part of the North American Skullrockian Stage corresponds roughly to the Cambrian Stage 10. The name "Nelegerian", after the Neleger River in Yakutia, was also proposed in 2011. Stratotype The ICS is still discussing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
