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130-636: It is the namesake for the Sachrang Formation . This Bavaria location article is a stub . You can help Misplaced Pages by expanding it . Sachrang Formation The Posidonia Shale ( German : Posidonienschiefer , also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation , is an Early Jurassic (Early to Late Toarcian ) geological formation of southwestern and northeast Germany , northern Switzerland , northwestern Austria , southern Luxembourg and

260-478: A Gharial), the pterosaur Dorygnathus (as a species of Pterodactylus ) in 1830, the fish Lepidotes , the selachian Hybodus or the crinoid Pentacrinites . The first insight on the flora was done in 1845, with partial leaf fragments. Boué in 1829 did a study of the general geology of the Jurassic along Germany, recovering limestone and shale facies, with a superficial assignation of what he considered most of

390-504: A base, as an opposite to Alwin Hauff who wanted to use the layers for industrial production. The Museum was reformed on between the years 1967 and 1971. In the year 2000, an external park with Dinosaur models was added. The museum has several halls with different kinds of fauna found on the layers of the formation, where the vertebrate specimens are exposed on the main parts, including on those Icthyosaur remains and several fishes. The Museum has

520-526: A broader aridification trend. The EMCI ended 18 million years ago, giving way to the Middle Miocene Warm Interval (MMWI), the warmest part of which was the MMCO that began 16 million years ago. As the world transitioned into the MMCO, carbon dioxide concentrations varied between 300 and 500 ppm. Global annual mean surface temperature during the MMCO was about 18.4 °C. MMCO warmth was driven by

650-637: A century, until revisions in 2016 proposed the Sachrang Formation as new name for the Germanic unit, in a same way Altmühltal Formation is the official name of the Solnhofen Limestone. The Posidonia Shales where stablished as a valid vulgar name for this regions lower Toarcian Black Shales. The name Posidonienschiefer, while valid, represents another vulgar nomination, as Posidonia is an invalid genus and junior synonym of Bositra . The type profile

780-492: A change in carbon-isotope excursion in marine and terrestrial life, and was probably a perturbator of the carbon cycle. Global seawater has been proved to be approximately, for the interval of the negative carbon-isotope excursion, close to 1.45‰, less than modern values, with estimated 2.34‰. Waters interchange were one of the major effects on the palatine de-oxygenation showed on most of the Lower Toarcian Layers around

910-519: A clade of large terrestrial predatory crocodyliformes distantly related to modern crocodilians, from which they likely diverged over 180 million years ago, are known from the Miocene of South America. The last Desmostylians thrived during this period before becoming the only extinct marine mammal order. The pinnipeds , which appeared near the end of the Oligocene, became more aquatic. A prominent genus

1040-561: A cooler, drier climate. C 4 grasses, which are able to assimilate carbon dioxide and water more efficiently than C 3 grasses, expanded to become ecologically significant near the end of the Miocene between 6 and 7 million years ago, although they did not expand northward during the Late Miocene. The expansion of grasslands and radiations among terrestrial herbivores correlates to fluctuations in CO 2 . One study, however, has attributed

1170-433: A few genera were able to survive until oxygen conditions got slightly better. The changes on the benthic oxygen where common, with most of the animals dying without being scavenged by bottom-dweller organisms, and sessile life, with this biota limited to "benthic islands" associated with ammonite shells or vertebrate carcasses (Except some Polychaetans on higher oxygen conditions). Towards the middle Toarcian show changes on

1300-427: A focus of scientific interest for the last 100 years. The first fossils were recorded in 1598 by the medical doctor Johannes Bauhin , who interpreted the local ammonites as "metallic things" in rocks and as "miraculous tricks" of nature, while the crinoids where interpreted as either huge flowers or heads of medusa, and evidencie of the biblical flood. Many people did important geological and paleontological research on

1430-473: A good analogue for future warmer climates caused by anthropogenic global warming , with this being especially true of the global climate during the Middle Miocene Climatic Optimum (MMCO), because the last time carbon dioxide levels were comparable to projected future atmospheric carbon dioxide levels resulting from anthropogenic climate change was during the MMCO. The Ross Sea margin of

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1560-435: A good model for a "living fossil". Eucalyptus fossil leaves occur in the Miocene of New Zealand , where the genus is not native today, but have been introduced from Australia . Both marine and continental fauna were fairly modern, although marine mammals were less numerous. Only in isolated South America and Australia did widely divergent fauna exist. In Eurasia, genus richness shifted southward to lower latitudes from

1690-579: A major expansion of Antarctic glaciers. This severed the connection between the Indian Ocean and the Mediterranean Sea and formed the present land connection between Afro-Arabia and Eurasia. The subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea (known as the Messinian salinity crisis ) near

1820-480: A major expansion of grass-grazer ecosystems . Herds of large, swift grazers were hunted by predators across broad sweeps of open grasslands , displacing desert, woodland, and browsers . The higher organic content and water retention of the deeper and richer grassland soils , with long-term burial of carbon in sediments, produced a carbon and water vapor sink. This, combined with higher surface albedo and lower evapotranspiration of grassland, contributed to

1950-610: A major regression of the sea level, marked at Irlbach by white-yellow levels indicating karst funnels or Cenote -like depostion. The posidonia slate has been mined in the Holzmaden area for centuries to make wall, table and window panels. Other uses of the shale included be made into fireplace stones in Gomaringen-Mössingen until was replaced by Eifel pumice stone. At Dotternhausen, the ROHRBACH Zement company uses oil shale in

2080-734: A mostly plain emerged sedimentary structure. Finally, the southernmost part of the Formation, the SWGB was separated from the Tethys Ocean by a series of islands related with the Bern High ( Allemanic Swell ), forming the continuation of the Vindelician High being a small terrestrial setting with similar size to modern Sardinia , with nearby sections like the Salem paleo-swell. The Germanic Epicontinental sea

2210-524: A preliminary stratigraphy and lithology, which would be the basis for most subsequent works. In the 1900, major paleontological addons included the description of Stenopterygius in 1904 (as Ichthyosaurus ). While in 1921, the 1st major fossil inventory was done by Hauff, reporting exquisite specimens, most of them from Holzmaden and some of them nearly complete, including Ammonites , Fish and Marine reptiles, such as Plesiosaurs and Icthyosaurs. Hauff described in 1938 "Acidorhynchus" ( Saurorhynchus ),

2340-585: A pronounced dominance of Illite , along with a significant amount of Montmorillonite . The presence of Quartz and Calcite is relative with other locations of the same region from also the Toarcian, while the Pyrite content is also consistently high. Finally, the Unken Shale samples also show minor levels of Dolomite and Feldspar . There is a great abundance of Foraminiferans and Coccoliths . Dinoflagellates are

2470-511: A regular limestone bank of approximately uniform thicknessis, rarely laminated (Dotternhausen) and often shows traces of minor bioturbation (Dotternhausen, Mössingen, Gomaringen; Aalen-Wasseralfingen), becoming calcified towards the upper limit between Nürtingen and Holzmaden, marked with increased presence of Cucullaea muensteri as well foraminifera and ostracods, as well scoria horizons with fish, cephalopod and larger vertebrate remains, as well often contain belemnite rostrums. The last level of

2600-578: A significant drop in atmospheric carbon dioxide levels. Both continental and oceanic thermal gradients in mid-latitudes during the Early Miocene were very similar to those in the present. Global cooling caused the East Asian Summer Monsoon (EASM) to begin to take on its modern form during the Early Miocene. From 22.1 to 19.7 Ma, the Xining Basin experienced relative warmth and humidity amidst

2730-695: A significant local decline along the northeastern coast of Australia during the Tortonian, most likely due to warming seawater. Cetaceans attained their greatest diversity during the Miocene, with over 20 recognized genera of baleen whales in comparison to only six living genera. This diversification correlates with emergence of gigantic macro-predators such as megatoothed sharks and raptorial sperm whales . Prominent examples are O. megalodon and L. melvillei . Other notable large sharks were O. chubutensis , Isurus hastalis , and Hemipristis serra . Crocodilians also showed signs of diversification during

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2860-627: A zone of low rainfall in the Late Miocene. The Indian Plate continued to collide with the Eurasian Plate , creating new mountain ranges and uplifting the Tibetan Plateau , resulting in the rain shadowing and aridification of the Asian interior. The Tian Shan experienced significant uplift in the Late Miocene, blocking westerlies from coming into the Tarim Basin and drying it as a result. At

2990-448: Is a relatively common presence of blue fittings, as well as Wood and Fish remains (Bones, scales). The younger strata with the fresh outcrops develops on a series of several meters thick wall, that splits into fine paper Slates when weathered. The Slate is among the most common mineral on the strata, with an average lime content of 40.2%, where maximum values are at 58% and minimum values at 26%. Bituminous Claystones are present in

3120-486: Is considered to be an analogue, as compares well to the sedimentation rate in deep-water settings, of the Black Sea . Most of the outcrops (Holzmaden, Dotternhausen, Ohmden or Dormettingen) represent low-energy depositional environments, far from deltaic sediment sources. The Toarcian epicontinental seas of Europe where driven by several global events and changes present on the surface, like the coeval Karoo-Ferrar eruptions in

3250-433: Is made represent blackish gray to dark brown bituminous, fine-leaved, somewhat sandy marl slate , that lies on the profile of the strata, alternated with storage light brown (max. 4 mm) and darker layers (rarely over 2 mm) characteristic. The lighter layers present in the rock get darker while it keeps its fine-plate character. The Shale has a Dark-Gray to brownish tone, alternated with more rarely light gray shades. There

3380-416: Is marked by pyritized lagerstatten fossils, limited to certain areas (Dotternhausen, Holzmaden), and with now well-layered black-brown in color. The Unteren Schiefern layers (Exaratum) appear next marked by the highest bitumen content and characterized by very fine light/dark stratification, abundance of pyrite, fine-grained weathering and the largely absence of bioturbation derived from anoxic conditions while

3510-802: Is mostly eroded in the profiles to evolve into marlstones. Several outcrops, mostly in the NW (ex. Harz hills), shows that relict levels of the Posidonienschiefer lasted until the Upper Toarcian, contemporaneous with the Jurensismergel Fm, known as "Dörntener Schiefer". The Sachrang Shales where cited originally on the restudy of the Alpine Upper Black Slate, composed with dark gray, somewhat sandy, disintegrating into thin but large plates of Marl that overlies Pliensbachian breccia. The definition of

3640-543: Is shown on layers across Bavaria where major events set the fate of the nearshore environments. One example is the case of the Monotis – Dactylioceras beds, that had an extent of +500 km, that has been linked with a possible Tsunami . There is not major indicative of synsedimentary faulting in South Germany, but is present on the western Tethyan Shelf , with breccias created from earthquakes, present on Toarcian levels of

3770-463: Is still located on Dotternhausen . The formation comprises finely laminated layers of oil shales formed of fine-grained sediments intercalated with bituminous limestones and crops out in a number of locations in southwestern Germany, although most remains are from near the village of Holzmaden and Dotternhausen. The European oil shales deposited on a sea floor during the Early Toarcian in

3900-494: The Benzene - Methanol fraction. The main maceral found is Lamalginite , which may derive from thin-walled planktonic and benthic organisms, including Green Algae , Cyanobacteria , and Bacterial mats. There is a clear low frequency of Vitrinite and Inertinite , what suggests that terrestrial inputs of organic matter to be of less importance, although, the main part of OM contained in the basal mudstone, including charred material,

4030-565: The Bächental bituminous marls had a bulk mineralogy where the Calcite is the most abundant fraction (49%), followed by Phyllosilicates (35%), Quartz (11%) and Pyrite (5%). While the Clay mineral distribution includes a large amount of Illite (51%), Montmorillonite (40%) and Kaolinite (9%). According to sedimentologic and palynologic features, a tidally influenced transgressive development within

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4160-539: The Middle Miocene Climate Transition (MMCT). Abrupt increases in opal deposition indicate this cooling was driven by enhanced drawdown of carbon dioxide via silicate weathering. The MMCT caused a sea surface temperature (SST) drop of approximately 6 °C in the North Atlantic. The drop in benthic foraminiferal δ O values was most noticeable in the waters around Antarctica, suggesting cooling

4290-542: The Netherlands , including exceptionally well-preserved complete skeletons of fossil marine fish and reptiles. The Posidonienschiefer , the German translation, takes its name from the ubiquitous fossils of the oyster-related bivalve " Posidonia bronni " (synonym of Bositra buchii and Steinmannia bronni ) that characterize the mollusk faunal component of the formation. The name Posidonia Shale has been used for more than

4420-712: The Pliensbachian - Toarcian locally is observed a significant decrease in the Crinoid skeleton elements, also that of the Ophiurida ; the Echinoids take their place, where really blossomed at that time, while Pedicellaria are observed very often. On the bituminous marls there is a great abundance of saturated Hydrocarbons in the hexanesoluble fraction, Methyl and Methylene where found along long-chain paraffinic molecules (n-alkanes). Benzenemethanol resins are especially strong for

4550-591: The Valais , Briançonnais  [ fr ] and Piemonte - Liguria domains ( Sinemurian - Callovian ), and the Toarcian break-up of the Ligurian-Penninic oceanic realm. There is measurements of reduction of the local salinity on the water where elevated inputs of freshwater due to an accelerated hydrological cycle resulted in a surface-water layer. Occurs only in the south-east of the northern Bavarian Jura region, as appears on places like Bruck in der Oberpfalz ,

4680-550: The carbon cycle occurred approximately 6 Ma, causing continental carbon reservoirs to no longer expand during cold spells, as they had done during cold periods in the Oligocene and most of the Miocene. At the end of the Miocene, global temperatures rose again as the amplitude of Earth's obliquity increased, which caused increased aridity in Central Asia. Around 5.5 Ma, the EAWM underwent a period of rapid intensification. Life during

4810-574: The geology of the Himalaya occurred during that epoch, affecting monsoonal patterns in Asia, which were interlinked with glacial periods in the northern hemisphere. The Miocene faunal stages from youngest to oldest are typically named according to the International Commission on Stratigraphy : Regionally, other systems are used, based on characteristic land mammals; some of them overlap with

4940-523: The " Zanclean flood ". Also during the early Miocene (specifically the Aquitanian and Burdigalian Stages), the apes first evolved, began diversifying, and became widespread throughout the Old World . Around the end of this epoch, the ancestors of humans had split away from the ancestors of the chimpanzees and had begun following their own evolutionary path during the final Messinian Stage (7.5–5.3 Ma) of

5070-598: The "crassumbank" ( Coeloceras cf. crassum , latter found to be C. raquinianum , thus Variabilis in age) at Bodenwöhr, or the Dactylioceras sandstones at Irlbach (NE Regensburg). These levels lack bituminous facies or are interspersed with them in profiles as one moves westward, indicating that they probably belonged to more coastal sectors with better oxygenated waters, with the full transition from shale to sandstone in Regensburg, Bruck and Naab areas considered as caused by

5200-777: The Austrian Adnet Formation . It would start as an initial wave propagation affecting the Altdorf High aiming for the south, where it would have hitten the shoreline of the Bohemian Island. The main terrestrial environments of the Posidonia Shale are the near emerged lands where the Black Forest High/Swell (known thanks to strata containing fine sand in the tenuicostatum Zone, ‘Glaukonit und viel Feinsand’, at Obereggenen im Breisgau ), located at 70 km at

5330-673: The Central Paratethys, cut off from sources of freshwater input by its separation from the Eastern Paratethys. From 13.36 to 12.65 Ma, the Central Paratethys was characterised by open marine conditions, before the reopening of the Bârlad Strait resulted in a shift to brackish-marine conditions in the Central Paratethys, causing the Badenian-Sarmatian Extinction Event. As a result of the Bârlad Strait's reopening,

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5460-621: The Early Jurassic by marine waters, several islands, submarine sills, and deeper subbasins developed, what contributed and controlled the evolution of the paleocurrents. Towards the W is determined by the north–south Kilberg Fault of the Keilberg Rift , the main fault in the Regensburg Basin. Developed by the sinking of the southern German Jura Plateau during the Miocene , it separates

5590-826: The Early to the Middle Miocene. Europe's large mammal diversity significantly declined during the Late Miocene. In the Early Miocene, several Oligocene groups were still diverse, including nimravids , entelodonts , and three-toed equids. As in the previous Oligocene Epoch, oreodonts were still diverse, only to disappear in the earliest Pliocene. During the later Miocene mammals were more modern, with easily recognizable canids , bears , red pandas , procyonids , equids , beavers , deer , camelids , and whales , along with now-extinct groups like borophagine canids , certain gomphotheres , three-toed horses , and hornless rhinos like Teleoceras and Aphelos . The late Miocene also marks

5720-677: The East Antarctic Ice Sheet (EAIS) was highly dynamic during the Early Miocene. The Miocene began with the Early Miocene Cool Event (Mi-1) around 23 million years ago, which marked the start of the Early Miocene Cool Interval (EMCI). This cool event occurred immediately after the Oligocene-Miocene Transition (OMT) during a major expansion of Antarctica's ice sheets, but was not associated with

5850-577: The East Asian Winter Monsoon (EAWM) became stronger synchronously with a southward shift of the subarctic front. Greenland may have begun to have large glaciers as early as 8 to 7 Ma, although the climate for the most part remained warm enough to support forests there well into the Pliocene. Zhejiang, China was noticeably more humid than today. In the Great Rift Valley of Kenya , there

5980-568: The Edge facies of the Sachrang Shale (="Unken Shales"), with green Clay march engagements. There is not clear separation between "Manganese Shale" and "Bituminous shale" in the main localities of the formation, because the Bituminous content fluctuates with the manganese contents, that is always high. The Unken Shales on the Bächental locality is layered on a major Silicate component of the 60% with

6110-457: The LMC; extratropical sea surface temperatures dropped substantially by approximately 7–9 °C. 41 kyr obliquity cycles became the dominant orbital climatic control 7.7 Ma and this dominance strengthened 6.4 Ma. Benthic δ O values show significant glaciation occurred from 6.26 to 5.50 Ma, during which glacial-interglacial cycles were governed by the 41 kyr obliquity cycle. A major reorganisation of

6240-563: The Late Cretaceous, are known from the Miocene of Patagonia, represented by the mole-like Necrolestes . The youngest known representatives of metatherians (the broader grouping to which marsupials belong) in Europe, Asia and Africa are known from the Miocene, including the European herpetotheriid Amphiperatherium , the peradectids Siamoperadectes and Sinoperadectes from Asia, and

6370-694: The Late Miocene, the Earth's climate began to display a high degree of similarity to that of the present day . The 173 kyr obliquity modulation cycle governed by Earth's interactions with Saturn became detectable in the Late Miocene. By 12 Ma, Oregon was a savanna akin to that of the western margins of the Sierra Nevada of northern California . Central Australia became progressively drier, although southwestern Australia experienced significant wettening from around 12 to 8 Ma. The South Asian Winter Monsoon (SAWM) underwent strengthening ~9.2–8.5 Ma. From 7.9 to 5.8 Ma,

6500-507: The Lower Toarcian is inferred with increased continental matter being moved to marine areas causing anoxic conditions, with the Posidonia Shale being the reference formation for this interval. The Posidonia Shale of Dotternhausen and Schesslitz is well dated on the basis of ammonite and microfossil biostratigraphy. The Lower Toarcian sections are subdivided into three ammonite biozones ( Dactyloceras tenuicostatum , Harpoceras falciferum , and Hildoceras bifrons ) and several subzones. On

6630-511: The Miocene Epoch was mostly supported by the two newly formed biomes , kelp forests and grasslands . Grasslands allow for more grazers, such as horses , rhinoceroses , and hippos . Ninety-five percent of modern plants existed by the end of this epoch . Modern bony fish genera were established. A modern-style latitudinal biodiversity gradient appeared ~15 Ma. The coevolution of gritty , fibrous, fire-tolerant grasses and long-legged gregarious ungulates with high-crowned teeth , led to

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6760-484: The Miocene. As in the Oligocene before it, grasslands continued to expand, and forests to dwindle. In the seas of the Miocene, kelp forests made their first appearance and soon became one of Earth's most productive ecosystems. The plants and animals of the Miocene were recognizably modern. Mammals and birds were well established. Whales , pinnipeds , and kelp spread. The Miocene is of particular interest to geologists and palaeoclimatologists because major phases of

6890-449: The Miocene. The largest form among them was a gigantic caiman Purussaurus which inhabited South America. Another gigantic form was a false gharial Rhamphosuchus , which inhabited modern age India . A strange form, Mourasuchus also thrived alongside Purussaurus . This species developed a specialized filter-feeding mechanism, and it likely preyed upon small fauna despite its gigantic size. The youngest members of Sebecidae ,

7020-413: The North American Great Plains and in Argentina . The global trend was towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture, particularly after 7 to 8 million years ago. Uplift of East Africa in the late Miocene was partly responsible for the shrinking of tropical rain forests in that region, and Australia got drier as it entered

7150-447: The Oberpfälzisch-Obermainisches Hügelland, tectonically part of the Faulkschollenland. The Franconian Jura rocks recovered are west of the Saxothuringian basement bordering the Franconian Line . It is recovered laterally extensive within Germany belonging to the early Toarcian Central European Epicontinental Basin, that evolved gradually from low tophography tidal flat to floodpains to a shallow shelf sea with intermittent N connection with

7280-529: The Oligocene–Miocene transgression. As the southern Andes rose in the Middle Miocene (14–12 million years ago) the resulting rain shadow originated the Patagonian Desert to the east. Far northern Australia was monsoonal during the Miocene. Although northern Australia is often believed to have been much wetter during the Miocene, this interpretation may be an artefact of preservation bias of riparian and lacustrine plants; this finding has itself been challenged by other papers. Western Australia, like today,

7410-491: The Pliensbachian, and are mostly clay marl to marl shales with an organic carbon content of over 2%, with some levels referred as “bitumen-free” or “bitumen-poor”. The lowermost sequence is known as Seegrasschiefer (seagrass slate), appearing just above the limit, being actively burrowed horizons, approximately 15-20 cm thick with clay marl stone appear in the darker, brownish to gray, bituminous clay marl/marl slate. This initial horizons have abundant foraminifera and ostracods as

7540-434: The Posidonia Shale has given different data about the chronology of the formation. Dormettingen shales have been calculated biochronologically and with isochron data, giving an approximate age of 183-181 million years, being close to the Pliensbachian boundary based on the recent revisions of the Early Jurassic Subperiods. The Toarcian and the Pliensbachian are considered as strongly constrained in terms of chronology, where

7670-433: The Qiongdongnan Basin in the northern South China Sea indicates the Pearl River was a major source of sediment flux into the sea during the Early Miocene and was a major fluvial system as in the present. During the Oligocene and Early Miocene, the coast of northern Brazil, Colombia, south-central Peru , central Chile and large swathes of inland Patagonia were subject to a marine transgression . The transgressions in

7800-411: The SW and NW Germanic basins, as part of a shallow epicontinental sea, surrounded and influenced by various highs and emerged lands that provided most of the terrestrial matter found along the Formation. The main outcrops of the formation are disposed along the modern southern Germany, recovering the locations of Holzmaden , Ohmden , as well at Niedersachsen , and others appearing along the east, such as

7930-406: The Sachrang Shales has been convoluted along its history of study of the location, where there are works of the North Alpine Mesozoic that prefer before calling these deposits Sachranger Shale to give it a brief different diagnosis. On the Unken Syncline near Lofen , basinal deposits with abundant Aragonite and Calcite helped to know the major Jurassic basin geometry, where on several layers of

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8060-404: The Shale deposition on Germany, also sharing a epicontinental sea, bordered by carbonate facies, specially towards the south. At the North, the Wenzen Well report little deeper basinal settings, heavily influenced by continental matter coming from the main continental land present anywhere nearby the formation, Fennoscandia . In this area, the main emerged units present was the Rhenish High at

8190-536: The Southern Hemisphere, what created an enhanced hydrological cycle & oxygen depletion, allowing exceptional preservation. This stage was marked with the presence of a general deposition of shale mudrock along with strong variations on the associated organic matter, associated with extincions such as the Toarcian Oceanic Anoxic Event . The black shales characteristic of this unit reveal a shallow marine environment, influenced by arctic and Tethyan waters, with marked episodes of disappearance of benthic biota. Also measure

8320-515: The Swabian Posidonia Shale, including Carl Hartwig von Zieten (1785–1846), Eberhard Fraas (1862–1915), Bernhard Hauff senior (1866–1950) and Adolf Seilacher (1925–2014). The first geological studies were carried out, motivated by the extraction of shales in the southern quarries. Several fossils were reported, studied and named at the time from locations such as Banz Abbey , Ohmden, Holzmaden or Dotternhausen, including Macrospondylus in 1824 (As Steneosaurus , being originally identified as

8450-410: The Viking Corridor and the Proto- Atlantic Ocean and with the Tethys Ocean towards the S, that filled with seawater the area, subdivided in several subasins with heterogeneous conditions and biotas, from the Netherlands to the Tirol Area. The CEB stablished a relatively shallow transcontinental seaway between the Tethyan and Boreal Arctic Sea biota, thus mixing cold and hot waters. In the Mesozoic

8580-415: The accumulation of exceptional preserved fossils indicate very weak water movement. The next, Untere Stein, is the most important level of the formation, specially in southwest Germany, southern France and Alsace - Lorraine . It appears across the area either as a concretionary "laibstein" horizon (Aalen region) or as a uniformly layered limestone bank ( Wutach area), with Leptolepis coryphaenoides as

8710-423: The activity of the Columbia River Basalts and enhanced by decreased albedo from the reduction of deserts and expansion of forests. Climate modelling suggests additional, currently unknown, factors also worked to create the warm conditions of the MMCO. The MMCO saw the expansion of the tropical climatic zone to much larger than its current size. The July ITCZ, the zone of maximal monsoonal rainfall, moved to

8840-426: The ancient Tethys Ocean are described as being deposited in an anoxic , or oxygen-depleted, deep water environment, although the details of the depositional environment are the subject of debate by researchers of the formation. The Posidonia Shale was originally referred to as the Schwarzjura lias was first recovered from the Franconian Jura , that borders to the northeast on the Obermainisches Hügelland and

8970-472: The aridity of the former. Unequivocally-recognizable dabbling ducks , plovers , typical owls , cockatoos and crows appear during the Miocene. By the epoch's end, all or almost all modern bird groups are believed to have been present; the few post-Miocene bird fossils which cannot be placed in the evolutionary tree with full confidence are simply too badly preserved, rather than too equivocal in character. Marine birds reached their highest diversity ever in

9100-422: The beginning of the Miocene, the northern margin of the Arabian plate, then part of the African landmass, collided with Eurasia; as a result, the Tethys seaway continued to shrink and then disappeared as Africa collided with Eurasia in the Turkish – Arabian region. The first step of this closure occurred 20 Ma, reducing water mass exchange by 90%, while the second step occurred around 13.8 Ma, coincident with

9230-400: The bioturbation of the seegrasschiefer merges into the subsequent ash-gray marls without a sharp facies boundary. The Aschgrauen Mergel (ash-gray marl) mark the start of the Posidonia Shale made by dark gray marl, abundant in pyrite with bituminous marl slate intrusions. This horizon, marks a sea transgression, as it extends from Asselfingen / Wutach to Aalen-Reichenbach and then wedges out to

9360-561: The changes and potential presence of the Shale Oil on the main quarries of the southern realm. Based on several core samples with abundant organic material (Dinoflagellate cysts and other microorganism fragments, such as microscopic algae) different thermal maturity has been found, especially on the samples from the Hils Syncline strata. The maturation of this strata has implied losing organic carbon and loss of hydrogen index values. Beyond that,

9490-513: The character fossil of this limestone bank. The Mittleren Schiefer/Schieferklotz (upper exaratum to lower elegans subzones) become increasingly poorly layered until it becomes a small brittle limestone bank, the "Stinkkalkbank" (Dotternhausen to Gomaringen and Nürtingen) with Coelodiscus shells, low on bitumen and with biota that marks better oxygenated conditions, such as foraminifera and occasional ostracods. The Obere and Wilder Stein (upper elegans) medium to brown-gray always remain formed as

9620-566: The characteristics of the deposition, the type of environment and the conditions that led to the exquisite preservation were produced, where paleocurrents where found to be nfluenced from the North and the South of the Central European Basin. The Black shale deposition was found to be related with changues in the oxygen levels. Thanks to the renewed information, a new cycle of publications reviewing

9750-481: The climate slowly cooled towards a series of ice ages . The Miocene boundaries are not marked by distinct global events but by regionally defined transitions from the warmer Oligocene to the cooler Pliocene Epoch. During the Early Miocene, Afro-Arabia collided with Eurasia, severing the connection between the Mediterranean and Indian Oceans, and allowing the interchange of fauna between Eurasia and Africa, including

9880-566: The course of this epoch . The youngest representatives of Choristodera , an extinct order of aquatic reptiles that first appeared in the Middle Jurassic , are known from the Miocene of Europe, belonging to the genus Lazarussuchus , which had been the only known surviving genus of the group since the beginning of the Eocene. The last known representatives of the archaic primitive mammal order Meridiolestida , which dominated South America during

10010-661: The deposition has been estimated to have lasted 3.2 Myr in the South Germany Basin with the uppermost sequences estimated to be Bifrons in age. The Posidonienschiefer lasts until the Late Toarcian (Variabilis Biozone) in the NW German Basin with the "Dörntener Schiefer", while it mostly disappears in the SW, substituted by the Jurensismergel Fm, with few deposits where it lasts (Wutach area, Nürtingen). The Posidonia Shale has been

10140-570: The dispersal of proboscideans and hominoids into Eurasia. During the late Miocene, the connections between the Atlantic and Mediterranean closed, causing the Mediterranean Sea to almost completely evaporate. This event is referred to as the " Messinian salinity crisis ". Then, at the Miocene–Pliocene boundary, the Strait of Gibraltar opened, and the Mediterranean refilled. That event is referred to as

10270-447: The east from Aalen-Wasseralfingen. This initial sequence is overlied by extremely thin (2-5 cm), unnamed bituminous, seegrasschiefer clay marl, followed then by a darker layers with the same lithology . The next are the called "Koblenzer-Hainzen" clay successions of upper the semicelatum subzone, initially poorly layered and more or less bituminous with abundance of Steirmannia radiata and Dactylioceras semieelatum . This section

10400-404: The east, which temporarily lowered the salinity of the seawater in the whole basin or in parts. The margins of the SWGB as well as the hinterland relief had very gentle topography, and therefore fine-grained siliciclastic sediments where easily transported and deposited in the nearshore area of the basin, as well long transported driftwood, and the lack of insects or terrestrial vertebrates. In

10530-555: The east. The granites and gneisses resulting from crystallization were eroded from the Paleozoic exposures on the east, and were deposited on the Jurassic prograded alluvial nearshore sandstone that evolved gradually into the Bajocian layers. The slopes of the area are partially covered by till , soliflucted rubble and loess from the Würm glaciation . The bituminous facies overlie

10660-564: The end of the Miocene due to increased habitat uniformity. The expansion of grasslands in North America also led to an explosive radiation among snakes. Previously, snakes were a minor component of the North American fauna, but during the Miocene, the number of species and their prevalence increased dramatically with the first appearances of vipers and elapids in North America and the significant diversification of Colubridae (including

10790-422: The end of the Miocene. The Paratethys underwent a significant transgression during the early Middle Miocene. Around 13.8 Ma, during a global sea level drop, the Eastern Paratethys was cut off from the global ocean by the closure of the Bârlad Strait, effectively turning it into a saltwater lake. From 13.8 to 13.36 Ma, an evaporite period similar to the later Messinian salinity crisis in the Mediterranean ensued in

10920-612: The enigmatic Saint Bathans Mammal . Microbial life in the igneous crust of the Fennoscandian Shield shifted from being dominated by methanogens to being primarily composed of sulphate-reducing prokaryotes . The change resulted from fracture reactivation during the Pyrenean-Alpine orogeny, enabling sulphate-reducing microbes to permeate into the Fennoscandian Shield via descending surficial waters. Diatom diversity

11050-429: The environment reflect more oxygenated waters and different depositional settings with the presence of trace fossils such as Chondrites and Phymatoderma granulata , surfacing deposit-feeding animals, being adapted for effective nutrient searching, becoming more common on the uppermost layers, yet in some areas, the shale remained until the Late Toarcian. The uppermost layers are marked by regressive sea levels, as it

11180-461: The evolution of both groups into modern representatives. The early Miocene Saint Bathans Fauna is the only Cenozoic terrestrial fossil record of the landmass, showcasing a wide variety of not only bird species, including early representatives of clades such as moa , kiwi and adzebills , but also a diverse herpetofauna of sphenodontians , crocodiles and turtles as well as a rich terrestrial mammal fauna composed of various species of bats and

11310-499: The expansion of grasslands not to a CO 2 drop but to the increasing seasonality and aridity, coupled with a monsoon climate, which made wildfires highly prevalent compared to before. The Late Miocene expansion of grasslands had cascading effects on the global carbon cycle, evidenced by the imprint it left in carbon isotope records. Cycads between 11.5 and 5 million years ago began to rediversify after previous declines in variety due to climatic changes, and thus modern cycads are not

11440-711: The extinction of the last-surviving members of the hyaenodonts . Islands began to form between South and North America in the Late Miocene, allowing ground sloths like Thinobadistes to island-hop to North America. The expansion of silica-rich C 4 grasses led to worldwide extinctions of herbivorous species without high-crowned teeth . Mustelids diversified into their largest forms as terrestrial predators like Ekorus , Eomellivora , and Megalictis and bunodont otters like Enhydriodon and Sivaonyx appeared. Eulipotyphlans were widespread in Europe, being less diverse in Southern Europe than farther north due to

11570-483: The fauna is marine, with several terrestrial specimens, and some of them being semiaquatic, such as the sphenodont Palaeopleurosaurus or fully terrestrial like the dinosaur Ohmdenosaurus and several insects. Flora has been found, especially the genus Xenoxylon , but also macrofloral remains Otozamites , Equisetites and Pagiophyllum and palynomorphs, dominated by Classopollis . The Main Museum with

11700-604: The findings of marine invertebrate fossils of both Atlantic and Pacific affinity in La Cascada Formation . Connection would have occurred through narrow epicontinental seaways that formed channels in a dissected topography . The Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene, forming the Chile Triple Junction . At first the Antarctic Plate subducted only in

11830-524: The formation is the Wilden Schiefer (probably reaching Bifrons zone) with the presence of "Monotis bank", from Altdorf to Dotternhausen and Göppingen area, with slates getting poorer in bitumen and less layered. The top section is known as "bollensis camp", marked by the mass deposition of Bositra buchi , closed at the top by a new seegrasschiefer. The limit with the Jurensismergel Formation

11960-467: The formation was revisited, with several suggestions such as stagnant basin models and restricted open marine ones, all suggested to be deposited on a shallow epicontinental sea. The abundance of organic matter and the composition of the shales, chemically or lithologically, went under diverse renoved works. With the addition of multiple new references, the expansion of information thanks to the revision of profiles, boreholes and other outcrops, new works on

12090-605: The higher, older crystallization of the Moldanubian Basement from the Lower Jurassic chalk complex of the eastern Franconian Jura. During the late Pliensbachian, the zone became a relatively narrow, flat deposit area which flooded during the early Toarcian and reemerged during the Bifrons substage with a changing coastline, thanks to rhythmic uplifts and subsidence of older Paleozoic and Triassic siliciclastic deposits from

12220-460: The human lineage) appeared in Africa at the very end of the Miocene, including Sahelanthropus , Orrorin , and an early form of Ardipithecus ( A. kadabba ). The chimpanzee–human divergence is thought to have occurred at this time. The evolution of bipedalism in apes at the end of the Miocene instigated an increased rate of faunal turnover in Africa. In contrast, European apes met their end at

12350-587: The lake levels of the Eastern Paratethys dropped as it once again became a sea. The Fram Strait opened during the Miocene and acted as the only throughflow for Atlantic Water into the Arctic Ocean until the Quaternary period. Due to regional uplift of the continental shelf, this water could not move through the Barents Seaway in the Miocene. The modern day Mekong Delta took shape after 8 Ma. Geochemistry of

12480-564: The latest surviving of the Saurichthyiformes . In 1953, an impressive Insect fauna was revised in the Northern outcrops. On 1978, Wild described the First and only know Dinosaur Fossil from the formation, what he named Ohmdenosaurus , a small sized Sauropod. Latter works revisited the excepcional preservation of the biota, specially the presence od soft parts. The lithology and sedimentology of

12610-486: The main Jurassic Strata, without classifying the layers on a concrete subperiod. Further geological work was then carried out, recovering examples of marine facies representing various biomes, all associated with black shale deposits in other areas, as towards the NW or at Regensburg. The main work that described the facies formally was Quenstedt´s 1843 one, classifying the levels based on the amount of bitumen, providing

12740-606: The major organic component and the most abundant microfossils. Manganese is present, such as in the Toarcian deposits of Hungary. Those are completed by the marl levels, composed by lithoclasts . quartz and smectite are the main minerals, along with illite , chlorite , and plagioclase in minor amounts. Bächental bituminous marls consist mainly of quartz and carbonate minerals. Isorenieratene derivatives are highly abundant on this level, related to several processes such as sedimentary iron, influenced by anoxic conditions. Rhodochrosite and manganese rich calcite are present in

12870-553: The manganese levels, while the Black Shale levels are rich in Pirite . The lower matrix is composed by clay and carbonate minerals, such as muscovite and feldspar . The presence of altered Celadonite , suggest volcanogenic solutions as the most probable source, where the high amounts of dissolved manganese of continental origin was translated to the epicontinental margins of the Tethys. On

13000-529: The medium to light gray color without a brown tint. The Formation evolves from bottom to top: blue-gray marls of the uppermost Pliensbachian spinatum zone, being medium gray, pyrite-rich clay marl stones that are still part of the Amaltheenton Formation , which gradually wedge out to the east in the area of Aalen - Wasseralfingen . Towards the middle they start to include thin disturbed bituminous horizons found throughout southwest Germany. Gradually,

13130-469: The microfacies took place between 1980-1990. The most important works of the XX century where done by Riegraf in 1985-86, being a complete review of all aspects of this formation, updating multiple points based on all the information compiled throughout the century: lithology, stratigraphy, biota list and ammonite biozonation, followed by a focused work on a complete mapping of the microfacies composition and extent of

13260-543: The north, increasing precipitation over southern China whilst simultaneously decreasing it over Indochina during the EASM. Western Australia was at this time characterised by exceptional aridity. In Antarctica, average summer temperatures on land reached 10 °C. In the oceans, the lysocline shoaled by approximately half of a kilometre during warm phases that corresponded to orbital eccentricity maxima. The MMCO ended around 14 million years ago, when global temperatures fell in

13390-452: The north-east of the Banz Abbey , Wittelshofen , Regensburg and Bodenwöhr , composed mostly by coarse grained sediments, clusters of clay sandstone and sand-lime stone facies (shale, slightly bituminous in layers, and sandstone, older lias sand, sand marl, marl, oolithic limestone and sand-lime banks). This series are coeval with the Posidonienschiefer, marked with more thin outcrops such as

13520-523: The origin of many modern genera such as Nerodia , Lampropeltis , Pituophis and Pantherophis ). Arthropods were abundant, including in areas such as Tibet where they have traditionally been thought to be undiverse. Neoisopterans diversified and expanded into areas they previously were absent from, such as Madagascar and Australia. In the oceans, brown algae , called kelp , proliferated, supporting new species of sea life, including otters , fish and various invertebrates . Corals suffered

13650-479: The other hand, Black shale formation in the Toarcian of NW Germany is associated with a major turnover in phytoplankton assemblages interpreted as the response to lowered salinities in surface waters of the epicontinental sea. The presence of the Turnover is essential for the datation and the preservation of the fauna of the formation, with detailed index ammonites preserved. The study of the different layers and strata of

13780-536: The petroleum generation potential of the PS is high in all studied regions due to the high TOC and Hydrogen Index. However, differences exist which can be expressed by SPI values. The latter are highest for northern Germany, where the PS is richest in TOC and has the highest HI values combined with a thickness of 30 to 40 m at most places. Since the first serious evaluations in the 2000s, different organic samples were extracted to revise

13910-463: The possible herpetotheriid Morotodon from the late Early Miocene of Uganda. Approximately 100 species of apes lived during this time , ranging throughout Africa, Asia and Europe and varying widely in size, diet, and anatomy. Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominid clade, but molecular evidence indicates this ape lived between 18 and 13 million years ago. The first hominins ( bipedal apes of

14040-828: The preceding Oligocene and following Pliocene Epochs: Continents continued to drift toward their present positions. Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean , causing both the rise of the Andes and a southward extension of the Meso-American peninsula. Mountain building took place in western North America , Europe , and East Asia . Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in

14170-477: The production of binders, mining in the 80´s up to 1,600 t. Shale oil, specially after World War II , when where burned on coal ovens was temporally obtained from the bituminous slate through smoldering and distillation by oil works near Reutlingen; Frommem or Holzheim near Göppingen, yet this turned out to have low profitability and the fact they produced a lot of slag and sulfur-containing exhaust gases, production lasted not long. Recent studies have shown that

14300-630: The related to the Banz Abbey strata or Regensburg . The deposition of the shales where delimited to several minibasins, including the Southwest German Basin , a hemipelagic deposit, with the influence of open sea currents from the North and the South, with an estimated water depth of 2-100 m, with few deeper shelf environments. Connected to the SW German basin where the Paris Basin , that recovered central France , with correlated sedimentation to

14430-500: The same age was complicated due to the posterior Alpine deformation. Correlated Unken and Diessbach basins developed mostly during the Toarcian, with deposition of abundant material from the near Emerged Landmasses. On the Unken Syncline, the breccias associated with the normal faults were deposited until Oxfordian age. The black shales are the main part of the strata present, with a major composition of bacterial origin. The shale

14560-408: The shale deposits. In the 2000´s the Posidonienschiefer has seen a series of works, focused on enriching the information previously worked on in depth, revising and updating the deposition models. Likewise, the biota has received multiple updates, with the reclassification of some taxa and the discovery of new ones, as well a revision of the biotic interactions. The Posidonia Shale was located in

14690-539: The south-eastern North-German Basin at Hondelange and Schandelah, the Posidonienschiefer was deposited in the "Oberaller Through", a local depression bordered by the emerged " Calvörde Island" and the submerged Altmark Swell to the N, while the shallow submerged Fallstein Swell closed it at the south, and more towards the E the Bohemian Massif hosted a large delta that discharged towards Oberaller. In Microfacies, after

14820-695: The southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan . As the southern part of Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate begun to subduct beneath Patagonia so that the Chile Triple Junction advanced to the north over time. The asthenospheric window associated to the triple junction disturbed previous patterns of mantle convection beneath Patagonia inducing an uplift of ca. 1 km that reversed

14950-576: The status of the samples has been stable during at least 40 measured years. In addition to their Posidonia bronni , the shales contain some spectacularly detailed fossils of other Jurassic sea creatures— ichthyosaurs and plesiosaurs , spiral-shelled ammonites and crinoids , or sea-lilies. The best-preserved fossils found on the Early Jurassic can be the ones from the Posidonia Shale. There are also abundant fish fossils (including genera such as Pachycormus , Ohmdenia , Strongylosteus and chondrichthyes like Hybodus or Palaeospinax ). Most of

15080-518: The taxa Found on the Posidonia Shale, the Hauff Museum recovers the best specimens found in the last 150 years, and it is situated on Ohmden . With different expositions, the museum has several spaces for the marine fauna, where it is exposed, including a disposed strata with the layer showing the provenance of every taxon and its fossil. The Museum has been open since 1937-38, and was founded by Bernhard Hauff , using his private collection of fossils as

15210-646: The west and the Ries Swell, W of Regensburg, then far towards the W the Vosges Massif is also suggested to be present (known by the abundant detrital quartz from the EST433 borehole located near Bure, Meuse ). The Environments of this highs are assumed to have been trought phases os aridity and humidy markedby the Toarcian Oceanic Anoxic Event on the basis of Palynology. In the east the SW German sub-basin

15340-650: The west coast of South America are thought to be caused by a regional phenomenon while the steadily rising central segment of the Andes represents an exception. While there are numerous registers of Oligocene–Miocene transgressions around the world it is doubtful that these correlate. It is thought that the Oligocene–Miocene transgression in Patagonia could have temporarily linked the Pacific and Atlantic Oceans, as inferred from

15470-567: The west, being a small land of the size of Sicily , and on the east, the N Bohemian Massif . The Bohemian massif with the Southern Vindelician High represent the major emerged units present on the Central European basin on the Toarcian. The Vindelician Land/High has been represented as a peninsula to the Bohemian Massif, or an isolated landmass, that is due to its connections that had not been recovered in depth, being considered

15600-464: The word, with the connection with the Viking Corridor as one of the main effects, due to the arctic waters freshening and breaking the oceanic circulation. The effect was consequently negative on the German realm, where the environments expose a tropical fluctuation, with conditions similar to the modern Caribbean Sea , which hosted a high variety of sea fauna, except on the bottom layers, where only

15730-463: The world's largest colony of sea lilies, measuring an approximate size of 100 square metres. Rolf Bernhard Hauff is the actual director of the museum. Miocene The Miocene ( / ˈ m aɪ . ə s iː n , - oʊ -/ MY -ə-seen, -⁠oh- ) is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago (Ma). The Miocene

15860-423: Was Allodesmus . A ferocious walrus , Pelagiarctos may have preyed upon other species of pinnipeds including Allodesmus . Furthermore, South American waters witnessed the arrival of Megapiranha paranensis , which were considerably larger than modern age piranhas . New Zealand 's Miocene fossil record is particularly rich. Marine deposits showcase a variety of cetaceans and penguins , illustrating

15990-610: Was a gradual and progressive trend of increasing aridification, though it was not unidirectional, and wet humid episodes continued to occur. Between 7 and 5.3 Ma, temperatures dropped sharply again in the Late Miocene Cooling (LMC), most likely as a result of a decline in atmospheric carbon dioxide and a drop in the amplitude of Earth's obliquity, and the Antarctic ice sheet was approaching its present-day size and thickness. Ocean temperatures plummeted to near-modern values during

16120-509: Was arid, particularly so during the Middle Miocene. Climates remained moderately warm, although the slow global cooling that eventually led to the Pleistocene glaciations continued. Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivalled that of the Oligocene . The climate of the Miocene has been suggested as

16250-722: Was bounded by the Bohemian-Hercynian landmass (Modern Bohemian Massif ), with the Vindelician peninsula at the S-SW, reaching the west area of Augsburg . Between the Hettangian-Toarcian, this threshold was perhaps temporarily connected via a land bridge with an island in the area of the Aarmassif . The Bohemian Massif was located in a relatively warm, precipitation-rich climate with Bavarian shallow areas receiving freshwater inflows from

16380-451: Was derived from terrestrial sources. This Mudstone contains charred organic material typically connected to Wildfires along with large amounts of expandable Smectite possibly derived from alteration of volcanic ash, what indicated a clear contribution of volcanic-derived detritus during deposition. In the Austrian area, the volcanic materials where probably also sourced by the rift history of

16510-671: Was inversely correlated with carbon dioxide levels and global temperatures during the Miocene. Most modern lineages of diatoms appeared by the Late Miocene. There is evidence from oxygen isotopes at Deep Sea Drilling Program sites that ice began to build up in Antarctica about 36 Ma during the Eocene . Further marked decreases in temperature during the Middle Miocene at 15 Ma probably reflect increased ice growth in Antarctica. It can therefore be assumed that East Antarctica had some glaciers during

16640-672: Was marked by the breakup of Pangea during the Late Triassic , what led to the appearance of the early Atlantic connecting with the Boreal waters of the Panthalassa Ocean, and several marine to continental subasins locally. The CEB was part of the Laurasian continental-marine shelf that, resting over the Keuper, slowly openened towards the southeast into the deeper Tethys Ocean. With the flooding in

16770-627: Was most intense there. Around this time the Mi3b glacial event (a massive expansion of Antarctic glaciers) occurred. The East Antarctic Ice Sheet (EAIS) markedly stabilised following the MMCT. The intensification of glaciation caused a decoherence of sediment deposition from the 405 kyr eccentricity cycle. The MMWI ended about 11 Ma, when the Late Miocene Cool Interval (LMCI) started. A major but transient warming occurred around 10.8-10.7 Ma. During

16900-500: Was named by Scottish geologist Charles Lyell ; the name comes from the Greek words μείων ( meíōn , "less") and καινός ( kainós , "new") and means "less recent" because it has 18% fewer modern marine invertebrates than the Pliocene has. The Miocene followed the Oligocene and preceded the Pliocene. As Earth went from the Oligocene through the Miocene and into the Pliocene,

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