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47-679: The Lower Triassic series is coeval with the Scythian Stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein , a lithostratigraphic unit of continental red beds . The Early Triassic and partly also the Middle Triassic span the interval of biotic recovery from the Permian-Triassic extinction event ,

94-500: A disaster taxon (although this view was questioned), Lystrosaurus had a wide range across Pangea. In the southern part of the supercontinent, it co-occurred with the non-mammalian cynodonts Galesaurus and Thrinaxodon , early relatives of mammals . The first archosauriforms appeared, such as Erythrosuchus ( Olenekian - Ladinian ). This group includes the ancestors of crocodiles and dinosaurs (including birds ). Fossilized foot prints of dinosauromorphs are known from

141-399: 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,

188-712: 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

235-654: 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

282-625: 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

329-920: The Muschelkalk and Keuper that form the Germanic Trias Supergroup . The Buntsandstein 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

376-598: 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

423-598: 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

470-460: The Spathian subage, the flora changed back to gymnosperm and pteridophyte dominated. These shifts reflect global changes in precipitation and temperature. Floral diversity was overall very low during the Early Triassic, as plant life had yet to fully recover from the Permian-Triassic extinction. Microbially induced sedimentary structures (MISS) are common in the fossil record of North China in

517-545: 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

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564-731: The geologic timescale , the Olenekian is an age in the Early Triassic epoch ; in chronostratigraphy , it is a stage in the Lower Triassic series . It spans the time between 251.2 Ma and 247.2 Ma (million years ago). The Olenekian is sometimes divided into the Smithian and the Spathian subages or substages. The Olenekian follows the Induan and is followed by the Anisian ( Middle Triassic ). The Olenekian saw

611-728: The Dutch subdivision, the upper two formations are part of the Upper Germanic Trias and the others part of 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

658-481: The Early Triassic has been interpreted as a signal of increased bioturbation and recovery of terrestrial ecosystems. In the oceans, the most common Early Triassic hard-shelled marine invertebrates were bivalves , gastropods , ammonoids , echinoids , and a few articulate brachiopods . Conodonts experienced a revival in diversity following a nadir during the Permian. The first oysters ( Liostrea ) appeared in

705-521: The Early Triassic may have been caused by late volcanic eruptions of the Siberian Traps , which had probably triggered the Permian-Triassic extinction event and accelerated the rate of global warming into the Triassic. Studies suggest that Early Triassic climate was very volatile, punctuated by a number of relatively rapid global temperature changes, marine anoxic events, and carbon cycle disturbances, which led to subsequent extinction events in

752-620: 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

799-435: The Early Triassic. They grew on the shells of living ammonoids as epizoans. Microbial reefs were common, possibly due to lack of competition with metazoan reef builders as a result of the extinction. However, transient metazoan reefs reoccurred during the Olenekian wherever permitted by environmental conditions. Ammonoids show blooms followed by extinctions during the Early Triassic. Aquatic vertebrates diversified after

846-640: 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

893-559: The Olenekian. The Early Triassic entomofauna is very poorly understood because of the paucity of insect fossils from this epoch. The flora was gymnosperm -dominated at the onset of the Triassic, but changed rapidly and became lycopod -dominated (e.g. Pleuromeia ) during the Griesbachian-Dienerian ecological crisis . This change coincided with the extinction of the Permian Glossopteris flora. In

940-752: The Permian-Triassic extinction, has been suggested as another contributor to 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

987-607: The Siberian Traps ended very shortly after the end-Permian extinction and did not span the entire Early Triassic epoch, thus not being the primary culprit for the climatic changes throughout this epoch. The Triassic Period opened in the aftermath of the Permian–Triassic extinction event . The massive extinctions that ended the Permian Period (and with that the Paleozoic Era ) caused extreme hardships for

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1034-519: The Southern Hemisphere, ceased to exist. Other groups, such as Actinopterygii , appear to have been less affected by this extinction event and body size was not a selective factor during the extinction event. Animals that were most successful in the Early Triassic were those with high metabolisms. Different patterns of recovery are evident on land and in the sea. Early Triassic faunas lacked biodiversity and were relatively homogeneous due to

1081-437: 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

1128-613: The aftermath of the Permian-Triassic extinction event . On the other hand, an alternative hypothesis proposes these Early Triassic climatic perturbations and biotic upheavals that inhibited the recovery of life following the P-T mass extinction to have been linked to forcing driven by changes in the Earth's obliquity defined by a roughly 32.8 thousand year periodicity with strong 1.2 million year modulations. According to proponents of this hypothesis, radiometric dating indicates that major activity from

1175-543: The axis of the future Pyrenees . Deposition took place in an arid, continental environment ( playa facies), so that there 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

1222-484: 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

1269-671: 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 the Scythian Stage, which has since disappeared from

1316-521: The deposition of the Buntsandstein and marking the beginning of the deposition of the Muschelkalk. The Buntsandstein belongs to 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

1363-532: 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

1410-467: The effects of the extinction. The ecological recovery on land took 30 million years, well into the Late Triassic . Two Early Triassic lagerstätten stand out due to their exceptionally high biodiversity , the Dienerian aged Guiyang biota and the earliest Spathian aged Paris biota . The most common land vertebrate was the small herbivorous synapsid Lystrosaurus . Often interpreted as

1457-400: 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

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1504-521: 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

1551-470: 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

1598-509: The extinction: Buntsandstein The Buntsandstein (German for coloured or colourful sandstone ) or Bunter sandstone 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

1645-466: 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

1692-507: The immediate aftermath of the Permian-Triassic extinction, indicating that microbial mats dominated local terrestrial ecosystems following the Permian-Triassic boundary. The regional prevalence of MISS is attributable to a decrease in bioturbation and grazing pressure as a result of aridification and temperature increase. MISS have also been reported from Early Triassic fossil deposits in Arctic Canada. The disappearance of MISS later in

1739-659: The most severe mass extinction event in Earth's history. A second extinction event, the Smithian-Spathian boundary event , occurred during the Olenekian. A third extinction event occurred at the Olenekian-Anisian boundary, marking the end of the Early Triassic epoch. The climate during the Early Triassic Epoch (especially in the interior of the supercontinent Pangaea ) was generally arid, rainless and dry and deserts were widespread; however

1786-647: 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

1833-603: The official Dutch lithostratigraphy, the Buntsandstein is divided into the Lower and Upper Germanic Trias Groups . The British Bunter Formation 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

1880-407: 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

1927-651: 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

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1974-423: The poles possessed a temperate climate . The pole-to-equator temperature gradient was temporally flat during the Early Triassic and may have allowed tropical species to extend their distribution poleward. This is evidenced by the global distribution of ammonoids . The extremely hot ocean temperatures facilitated extremely powerful hurricanes that frequently hit the coast of North China. The mostly hot climate of

2021-490: The so-called Altschlossfelsen ("Old Castle Rocks"). The massif has a length of around 1.5 km and 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. Spathian In

2068-411: The surviving species. The Early Triassic Epoch saw the biotic recovery of life after the biggest mass extinction event of the past, which took millions of years due to the severity of the event and the harsh Early Triassic climate. Many types of corals , brachiopods , molluscs , echinoderms , and other invertebrates had disappeared. The Permian vegetation, which was dominated by Glossopteris in

2115-469: 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 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.

2162-629: Was covered by inland seas which deposited the Zechstein evaporites . At 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

2209-603: Was the discovery that its base lies actually in the latest Permian. The Buntsandstein 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

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