Related Research Articles
The Cambrian Period was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago (mya) to the beginning of the Ordovician Period 485.4 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 lagerstätte 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 biology surpasses that of some later periods.
Opabinia regalis is an extinct, stem group arthropod found in the Middle Cambrian Burgess Shale Lagerstätte of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and its segmented trunk had flaps along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a clawed proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they constitute less than 0.1% of the community.
Skania is a Middle Cambrian fossil arthropod that is closely related to the Early Cambrian Primicaris larvaformis 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, where they comprise < 0.01% of the community. While previously enigmatic, it is now thought to be a marrellomorph.
Dinocaridida is a proposed fossil taxon of basal arthropods flourished in the Cambrian period with occasional Ordovician and Devonian records. Characterized by a pair of frontal appendages and series of body flaps, the name of Dinocaridids comes from Greek, "deinos" and "caris", referring to the suggested role of some of these members as the largest marine predators of their time. Dinocaridids are occasionally referred to as the 'AOPK group' by some literatures, as the group compose of Radiodonta, Opabinia, Pambdelurion and Kerygmachela. It is most likely paraphyletic, with Kerygmachela and Pambdelurion more basal than the clade compose of Opabinia, Radiodonta and other arthropods.
Vernanimalcula guizhouena is an acritarch dating from 600 to 580 million years ago; it was between 0.1 and 0.2 mm across. Vernanimalcula means "small spring animal", referring to its appearance in the fossil record at the end of the Marinoan Glaciation and the belief upon discovery it was an animal.
The Kaili Formation is a stratigraphic formation which was deposited during the Lower and Middle Cambrian. The formation is approximately 200 metres (660 ft) thick and was named after the city Kaili in the Guizhou province of southwest China.
The Cambrian explosion or Cambrian radiation was an event approximately 541 million years ago in the Cambrian period when practically all major animal phyla started appearing in the fossil record. It lasted for about 13 – 25 million years and resulted in the divergence of most modern metazoan phyla. The event was accompanied by major diversifications in other groups of organisms as well.
Megacheira is an extinct class of predatory arthropods that possessed a pair of great appendages, hence the class name as well as the common name "great appendage arthropods". Their neural structures and deutocerebral appendages resemble those of chelicerates. Most of them were found in marine environments throughout the world from the lower to middle Cambrian. Megacheirans were important components of several faunas, including the Burgess, Wheeler and Maotianshan Shales Lagerstatten.
Tuzoia is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments in what is now the Burgess Shale, Emu Bay Shale (Australia), Kaili, the Rockslide Formation, the Spence Shale, Wheeler Formation, and Marjum Formation (Utah), and the Kinzers Formation (Pennsylvania). This arthropod reached lengths of 180 mm long. There are currently 7 valid species recognized.
Eldonia is an extinct soft-bodied cambroernid animal of unknown affinity, best known from the Fossil Ridge outcrops of the Burgess Shale, particularly in the 'Great Eldonia layer' in the Walcott Quarry. In addition to the 550 collected by Walcott, 224 specimens of Eldonia are known from the Greater Phyllopod bed, where they comprise 0.43% of the community. Species also occur in the Chengjiang biota, and in Upper Ordovician strata of Morocco.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2010.
Paropsonema is a discoidal animal known from the Cambrian Chengjiang biota and classified with the eldoniids.
Rotadiscus is a genus of discoidal animal known from the Cambrian Chengjiang biota and classified with the eldoniids.
Byronia is a genus of theca-bearing cnidarians with a close affinity to the coronatid scyphozoans.
The cambroernids are an unranked clade of deuterosome animals. They include a number of early Paleozoic genera whose affinities with other animals, living or extinct, have been uncertain. This includes Herpetogaster and Phlogites, as well as the eldoniids. Cambroernids are defined by a set of common features including at least one pair of bifurcated or divided oral tentacles, and a large stomach and narrower intestine enclosed together in a coiled sac. The proposed evolutionary transformation is from more mobile forms living in the water column to less mobile forms living on the sea floor. Herpetogaster shows a clockwise-curved body attached to the substrate with a narrow mobile stolon, the caylx of Phlogites would be such a body fused into a complete circle, permanently attached to the substrate by a thick stalk, and eldoniids are a flattened form in which the stolon has been lost, resulting in a disc-shaped external form with a large curved stomach on one side. These translations of form are parallel to those seen in echinoderms. Relationships to tentaculate lophotrochozoans are considered and rejected, with the balance of evidence currently supporting the clade as either stem echinoderms, stem hemichordates, or stem ambulacrarians (echinoderms+hemichordates).
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 504.5 million years ago.
The Miaolingian is the third Series of the Cambrian period, and was formally named in 2018. It lasted from about 509 to 497 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.
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 521 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 514 million years ago.
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 514 million years ago. The upper boundary corresponds to the beginning of the Wuliuan.
Cambrian Series 2 is the unnamed 2nd series of the Cambrian. It lies above the Terreneuvian series and below the Miaolingian. Series 2 has not been formally defined by the International Commission on Stratigraphy, lacking a precise lower boundary and subdivision into stages. The proposed lower boundary is the first appearance of trilobites which is estimated to be around 521 million years ago.
References
- ↑ Zhu, M.; Zhao, Yuan-Long; Chen, Jun-Yuan (2002). "Révision des animaux discoïdes cambriens Stellostomites eumorphus et Pararotadiscus guizhouensis de Chine du Sud". Geobios. 35 (2): 165–185. doi:10.1016/S0016-6995(02)00025-6.
- ↑ Caron, J.; Conway Morris, S.; Shu, D.; Soares, D. (2010). Soares, Daphne (ed.). "Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes". PLOS ONE. 5 (3): e9586. doi: 10.1371/journal.pone.0009586 . PMC 2833208 . PMID 20221405.
 | This article related to a Cambrian animal is a stub. You can help Wikipedia by expanding it. |