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47-681: The Olenekian saw the deposition of a large part of the Buntsandstein in Europe. The Olenekian is roughly coeval with the regional Yongningzhenian Stage used in China . The Olenekian Stage was introduced into scientific literature by Russian stratigraphers in 1956. The stage is named after Olenëk in Siberia . Before the subdivision in Olenekian and Induan became established, both stages formed

94-628: A decline in continental weathering and a rejuvenation of ocean circulation. In the ocean, many large and mobile species moved away from the tropics , but large fish remained, and amongst the immobile species such as molluscs , only the ones that could cope with the heat survived; half the bivalves disappeared. Conodonts decreased in average size as a result of the extinction. On land, the tropics were nearly devoid of life, with exceptionally arid conditions recorded in Iberia and other parts of Europe then at low latitude. Many big, active animals returned to

141-459: A free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism . In most cases this involves protogyny , fish starting life as females and converting to males at some stage, triggered by some internal or external factor. Protandry , where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization . Of

188-722: A height of up to 25 metres, easily the largest bunter sandstone massif in the Palatinate. On the island of Heligoland , the 47-metre-high Lange Anna ("Tall Anna"), is the best-known landmark on the island and was declared a natural monument in 1969. The Buntsandstein contains a few small saurians, tracks like Chirotherium and plant remnants. Ray-finned fishes Actinopterygii ( / ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ / ; from actino-  'having rays' and Ancient Greek πτέρυξ (ptérux)  'wing, fins'), members of which are known as ray-finned fish or actinopterygians ,

235-652: A result of the extinction. However, transient metazoan reefs reoccurred during the Olenekian wherever permitted by environmental conditions. Ammonoids and conodonts diversified, but both suffered losses during the Smithian-Spathian boundary extinction (see below) at the end of the Smithian subage. Ray-finned fishes largely remained unaffected by the Permian-Triassic extinction event. Coelacanths show their highest post- Devonian diversity during

282-742: A trait still present in Holostei ( bowfins and gars ). In some fish like the arapaima , the swim bladder has been modified for breathing air again, and in other lineages it have been completely lost. The teleosts have urinary and reproductive tracts that are fully separated, while the Chondrostei have common urogenital ducts, and partially connected ducts are found in Cladistia and Holostei. Ray-finned fishes have many different types of scales ; but all teleosts have leptoid scales . The outer part of these scales fan out with bony ridges, while

329-587: Is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia , as opposed to the bulkier, fleshy lobed fins of the sister class Sarcopterygii (lobe-finned fish). Resembling folding fans , the actinopterygian fins can easily change shape and wetted area , providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to

376-604: Is a lithostratigraphic and allostratigraphic unit (a sequence of rock strata ) in the subsurface of large parts of west and central Europe. The Buntsandstein predominantly consists of sandstone layers of the Lower Triassic series and is one of three characteristic Triassic units, together with the Muschelkalk and Keuper that form the Germanic Trias Supergroup . The Buntsandstein

423-697: Is basically a continuation of the same unit. In Germany the Buntsandstein is subdivided into three subgroups with seven formations (from top to base): Upper Buntsandstein Middle Buntsandstein Lower Buntsandstein All of these are reasonably good reservoir rocks for oil and gas. In the Dutch subdivision, the upper two formations are part of the Upper Germanic Trias and the others part of

470-545: Is divided into the infraclasses Holostei and Teleostei . During the Mesozoic ( Triassic , Jurassic , Cretaceous ) and Cenozoic the teleosts in particular diversified widely. As a result, 96% of living fish species are teleosts (40% of all fish species belong to the teleost subgroup Acanthomorpha ), while all other groups of actinopterygians represent depauperate lineages. The classification of ray-finned fishes can be summarized as follows: The cladogram below shows

517-432: Is relatively rare and is found in about 6% of living teleost species; male care is far more common than female care. Male territoriality "preadapts" a species for evolving male parental care. There are a few examples of fish that self-fertilise. The mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to

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564-723: Is similar in age, facies and lithology with the Bunter of the British Isles . It is normally lying on top of the Permian Zechstein and below the Muschelkalk. In the past the name Buntsandstein was in Europe also used in a chronostratigraphic sense, as a subdivision of the Triassic system. Among reasons to abandon this use was the discovery that its base lies actually in the latest Permian. The Buntsandstein

611-590: The Changhsingian to Anisian stages , meaning it is between 252 and 246 million years old. In German lithostratigraphy, it is seen as a group, in the Netherlands and North Sea the name has no official status (though that does not keep geologists from using it). In the official Dutch lithostratigraphy, the Buntsandstein is divided into the Lower and Upper Germanic Trias Groups . The British Bunter Formation

658-506: The Cyprinidae (in goldfish and common carp as recently as 14 million years ago). Ray-finned fish vary in size and shape, in their feeding specializations, and in the number and arrangement of their ray-fins. In nearly all ray-finned fish, the sexes are separate, and in most species the females spawn eggs that are fertilized externally, typically with the male inseminating the eggs after they are laid. Development then proceeds with

705-652: The Induan and Olenekian ages. Their fossils are found in Greenland , Spitsbergen , Pakistan and Madagascar . Others, such as Trematosaurus , inhabited freshwater environments and were less widespread. The first marine reptiles appeared during the Olenekian. Hupehsuchia , Ichthyopterygia and Sauropterygia are among the first marine reptiles to enter the scene (e.g. Cartorhynchus , Chaohusaurus , Utatsusaurus , Hupehsuchus , Grippia , Omphalosaurus , Corosaurus ). Sauropterygians and ichthyosaurs ruled

752-615: The Middle Sakamena Formation ( Madagascar ), Candelaria Formation ( Nevada , United States), and Mikin Formation ( Himachal Pradesh , India), and Daye Formation ( Guizhou , China), and the Smithian aged assemblages of the Vikinghøgda Formation ( Spitsbergen , Norway), and Thaynes Group (western United States ), and Helongshan Formation ( Anhui , China), and several Early Triassic layers of

799-597: The Paleozoic ), thylacocephalans , crustaceans , nautiloids , ammonoids , coleoids , ophiuroids , crinoids , and vertebrates . Such diverse assemblages show that organisms diversified wherever and whenever climatic and environmental conditions ameliorated. An important extinction event occurred during the Olenekian age of the Early Triassic, near the Smithian and Spathian subage boundary. The main victims of this Smithian–Spathian boundary event , often called

846-592: The Smithian–Spathian extinction , were 'disaster taxa': Palaeozoic species that survived the Permian–Triassic extinction event and flourished in the immediate aftermath of the extinction; ammonoids, conodonts, and radiolarians in particular suffered drastic biodiversity losses, which is accentuated, among others, by the cosmopolitan distribution of the ammonoid Anasibirites . Marine reptiles, such as ichthyopterygians and sauropterygians , diversified after

893-607: The Sulphur Mountain Formation (western Canada ). Ray-finned fishes diversified after the mass extinction and reached peak diversity during the Middle Triassic . This diversification is, however, obscured by a taphonomic megabias (Spathian-Bithynian Gap, SBG) during the late Olenekian and early middle Anisian . The earliest large durophagous neopterygian is known from the SBG, suggesting an early onset of

940-592: The deep sea to subterranean waters to the highest mountain streams . Extant species can range in size from Paedocypris , at 8 mm (0.3 in); to the massive ocean sunfish , at 2,300 kg (5,070 lb); and to the giant oarfish , at 11 m (36 ft). The largest ever known ray-finned fish, the extinct Leedsichthys from the Jurassic , has been estimated to have grown to 16.5 m (54 ft). Ray-finned fishes occur in many variant forms. The main features of typical ray-finned fish are shown in

987-424: The oviparous teleosts, most (79%) do not provide parental care. Viviparity , ovoviviparity , or some form of parental care for eggs, whether by the male, the female, or both parents is seen in a significant fraction (21%) of the 422 teleost families; no care is likely the ancestral condition. The oldest case of viviparity in ray-finned fish is found in Middle Triassic species of † Saurichthys . Viviparity

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1034-663: The sister lineage of all other actinopterygians, the Acipenseriformes (sturgeons and paddlefishes) are the sister lineage of Neopterygii, and Holostei (bowfin and gars) are the sister lineage of teleosts. The Elopomorpha ( eels and tarpons ) appear to be the most basal teleosts. The earliest known fossil actinopterygian is Andreolepis hedei , dating back 420 million years ( Late Silurian ), remains of which have been found in Russia , Sweden , and Estonia . Crown group actinopterygians most likely originated near

1081-616: The Early Triassic. Many fish genera show a cosmopolitan distribution during the Induan and Olenekian, such as Australosomus , Birgeria , Parasemionotidae , Pteronisculus , Ptycholepidae , Saurichthys and Whiteia . This is well exemplified in the Griesbachian (early Induan ) aged fish assemblages of the Wordie Creek Formation (East Greenland ), the Dienerian (late Induan ) aged assemblages of

1128-544: The Lower Germanic Trias. Bunter sandstone often forms spectacular rock formations as a result of weathering: including isolated rocks several tens of metres high. Most of them are designated natural monuments , for example, the Devil's Table near Hinterweidenthal . In the Palatinate, near Eppenbrunn , are the so-called Altschlossfelsen ("Old Castle Rocks"). The massif has a length of around 1.5 km and

1175-703: The Lower Triassic series be divided into the Griesbachian, Dienerian, Smithian, and Spathian. The latter two roughly correspond with the Olenekian. Tozer's timescale became popular in the Americas. He named the Smithian after Smith Creek on Ellesmere Island , Canada (the creek itself is named after geologist J. P. Smith ). The Smithian is defined by the Arctoceras bloomstrandi ammonoid zone (contains Euflemingites romunderi and Juvenites crassus ) and

1222-524: The Scythian Stage, which has since disappeared from the official timescale. The base of the Olenekian is at the lowest occurrence of the ammonoids Hedenstroemia or Meekoceras gracilitatis , and of the conodont Neospathodus waageni . It is defined as ending near the lowest occurrences of genera Japonites , Paradanubites , and Paracrochordiceras ; and of the conodont Chiosella timorensis . A GSSP (global reference profile for

1269-432: The Triassic actinopterygian revolution. Olenekian chondrichthyan fishes include hybodonts and neoselachians , but also a few surviving lineages of eugeneodontid holocephalians , a mainly Palaeozoic group that went extinct during the Early Triassic. Marine temnospondyl amphibians , such as the superficially crocodile-shaped trematosaurids Aphaneramma and Wantzosaurus , show wide geographic ranges during

1316-402: The adjacent diagram. The swim bladder is a more derived structure and used for buoyancy . Except from the bichirs , which just like the lungs of lobe-finned fish have retained the ancestral condition of ventral budding from the foregut , the swim bladder in ray-finned fishes derives from a dorsal bud above the foregut. In early forms the swim bladder could still be used for breathing,

1363-484: The base) has not been established as of December 2020. In the 1960s, English paleontologist Edward T. Tozer (sometimes collaborating with American geologist Norman J. Silberling) crafted Triassic timescales based on North American ammonoid zones, further refining it in the following decades. Tozer's nomenclature was largely derived from Mojsisovics 's work, who coined most of the Triassic stages and substages, but he redefined them using North American sites. He recommended

1410-463: The bichirs and holosteans (bowfin and gars) in having gone through a whole-genome duplication ( paleopolyploidy ). The WGD is estimated to have happened about 320 million years ago in the teleosts, which on average has retained about 17% of the gene duplicates, and around 180 (124–225) million years ago in the chondrosteans. It has since happened again in some teleost lineages, like Salmonidae (80–100 million years ago) and several times independently within

1457-706: The different actinopterygian clades (in millions of years , mya) are from Near et al., 2012. Jaw-less fishes ( hagfish , lampreys ) [REDACTED] Cartilaginous fishes ( sharks , rays , ratfish ) [REDACTED] Coelacanths [REDACTED] Lungfish [REDACTED] Amphibians [REDACTED] Mammals [REDACTED] Sauropsids ( reptiles , birds ) [REDACTED] Polypteriformes ( bichirs , reedfishes ) [REDACTED] Acipenseriformes ( sturgeons , paddlefishes ) [REDACTED] Teleostei [REDACTED] Amiiformes ( bowfins ) [REDACTED] Lepisosteiformes ( gars ) [REDACTED] The polypterids (bichirs and reedfish) are

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1504-477: The dominant plants during most of the Mesozoic . Among land vertebrates, the archosaurs - a group of diapsid reptiles encompassing crocodiles , pterosaurs , dinosaurs , and ultimately birds - first evolved from archosauriform ancestors during the Olenekian. This group includes ferocious predators like Erythrosuchus . In the oceans, microbial reefs were common during the Early Triassic, possibly due to lack of competition with metazoan reef builders as

1551-684: The end of the Permian a connection with the Paleo-Tethys Ocean to the south was formed in present-day southeast Poland, causing sea water to flow in periodically. This caused the inflow of more clastic material, which was deposited in the form of large alluvial fans . The same process happened in the Triassic for the Basque-Cantabrian Basin , in the axis of the future Pyrenees . Deposition took place in an arid, continental environment ( playa facies), so that there

1598-533: The existence of this extinction event about 249.4 Ma ago was not recognised. The Smithian–Spathian boundary extinction was linked to late eruptions of the Siberian Traps , which released warming greenhouse gases , resulting in global warming and in acidification, both on land and in the ocean. A large spike in mercury concentrations relative to total organic carbon, much like during the Permian-Triassic extinction, has been suggested as another contributor to

1645-581: The extinction event hypothesises the biotic crisis took place not at the Smithian-Spathian boundary but shortly before, during the Late Smithian Thermal Maximum (LSTM), with the Smithian-Spathian boundary itself being associated with cessation of intrusive magmatic activity of the Siberian Traps, along with significant global cooling, after which a gradual biotic recovery took place over the early and middle Spathian, along with

1692-671: The extinction, although this is controversial and has been disputed by other research that suggests elevated mercury levels already existed by the middle Spathian. Prior to the Smithian-Spathian Boundary extinction event, a flat gradient of latitudinal species richness is observed, suggesting that warmer temperatures extended into higher latitudes , allowing extension of geographic ranges of species adapted to warmer temperatures, and displacement or extinctions of species adapted to cooler temperatures. Oxygen isotope studies on conodonts have revealed that temperatures rose in

1739-467: The extinction. The flora was also affected significantly. It changed from lycopod dominated (e.g. Pleuromeia ) during the Dienerian and Smithian subages to gymnosperm and pteridophyte dominated in the Spathian. These vegetation changes are due to global changes in temperature and precipitation . Conifers ( gymnosperms ) were the dominant plants during most of the Mesozoic . Until recently

1786-463: The first 2 million years of the Triassic, ultimately reaching sea surface temperatures of up to 40 °C (104 °F) in the tropics during the Smithian. The extinction itself occurred during a subsequent drop in global temperatures (ca. 8°C over a geologically short period) in the latest Smithian; however, temperature alone cannot account for the Smithian-Spathian boundary extinction, because several factors were at play. An alternative explanation for

1833-432: The fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below 19 °C (66 °F) and can fertilise eggs that are then spawned by the female. This maintains genetic variability in a species that is otherwise highly inbred. Actinopterygii is divided into the subclasses Cladistia , Chondrostei and Neopterygii . The Neopterygii , in turn,

1880-438: The inner part is crossed with fibrous connective tissue. Leptoid scales are thinner and more transparent than other types of scales, and lack the hardened enamel - or dentine -like layers found in the scales of many other fish. Unlike ganoid scales , which are found in non-teleost actinopterygians, new scales are added in concentric layers as the fish grows. Teleosts and chondrosteans (sturgeons and paddlefish) also differ from

1927-466: The main clades of living actinopterygians and their evolutionary relationships to other extant groups of fishes and the four-limbed vertebrates ( tetrapods ). The latter include mostly terrestrial species but also groups that became secondarily aquatic (e.g. whales and dolphins ). Tetrapods evolved from a group of bony fish during the Devonian period . Approximate divergence dates for

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1974-645: The oceans during the Mesozoic Era . An example of an exceptionally diverse Early Triassic assemblage is the Paris biota , fossils of which were discovered near Paris , Idaho and other nearby sites in Idaho and Nevada . The Paris Biota was deposited in the wake of the SSBM and it features at least 7 phyla and 20 distinct metazoan orders , including leptomitid protomonaxonid sponges (previously only known from

2021-648: The overlying Meekoceras gracilitatis and Wasatchites tardus subzones. He named the Spathian after Spath Creek on Ellesmere Island (this creek is named after geologist L. F. Spath ), and defined it by the Procolumbites subrobustus ammonoid zone. Life was still recovering from the severe end-Permian mass extinction . During the Olenekian, the flora changed from lycopod dominated (e.g. Pleuromeia ) to gymnosperm and pteridophyte dominated. These vegetation changes are due to global changes in temperature and precipitation . Conifers ( gymnosperms ) were

2068-494: The proximal or basal skeletal elements, the radials, which represent the articulation between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). The vast majority of actinopterygians are teleosts . By species count, they dominate the subphylum Vertebrata , and constitute nearly 99% of the over 30,000 extant species of fish . They are the most abundant nektonic aquatic animals and are ubiquitous throughout freshwater and marine environments from

2115-646: The tropics, and plants recolonised on land, only when temperatures returned to normal. There is evidence that life had recovered rapidly, at least locally. This is indicated by sites that show exceptionally high biodiversity (e.g. the earliest Spathian Paris Biota ), which suggest that food webs were complex and comprised several trophic levels . 31°57′55″N 78°01′29″E  /  31.9653°N 78.0247°E  / 31.9653; 78.0247 Buntsandstein The Buntsandstein (German for coloured or colourful sandstone ) or Bunter sandstone

2162-645: Was deposited in the Germanic Basin , a large sedimentary basin that was the successor of the smaller Permian Basin and spread across present day Poland , Germany, Denmark , the southern regions of the North Sea and Baltic Sea , the Netherlands and south England. In the late Permian this region had an arid climate and it was covered by inland seas which deposited the Zechstein evaporites . At

2209-480: Was little chemical weathering . Therefore, the Buntsandstein deposits are typical red beds , mainly sandstones and conglomerates with little clay . The late Anisian saw a major rise of the global ( eustatic ) sea level. A tropical sea filled the Germanic Basin then, stopping the deposition of the Buntsandstein and marking the beginning of the deposition of the Muschelkalk. The Buntsandstein belongs to

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