1.
Precambrian
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The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon. A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
2.
Cambrian
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The Cambrian Period was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago to the beginning of the Ordovician Period 485.4 mya and its subdivisions, and its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latinised form of Cymru, the Welsh name for Wales, as a result, our understanding of the Cambrian biology surpasses that of some later periods. The rapid diversification of lifeforms in the Cambrian, known as the Cambrian explosion, most of the continents were probably dry and rocky due to a lack of vegetation. Shallow seas flanked the margins of several continents created during the breakup of the supercontinent Pannotia, the seas were relatively warm, and polar ice was absent for much of the period. The United States Federal Geographic Data Committee uses a barred capital C ⟨Є⟩ character similar to the capital letter Ukrainian Ye ⟨Є⟩ to represent the Cambrian Period, the proper Unicode character is U+A792 Ꞓ LATIN CAPITAL LETTER C WITH BAR. Despite the long recognition of its distinction from younger Ordovician Period rocks and older Supereon Precambrian rocks, the base of the Cambrian lies atop a complex assemblage of trace fossils known as the Treptichnus pedum assemblage. Pedum in Namibia, Spain and Newfoundland, and possibly, in the western USA, the stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain. The Cambrian Period followed the Ediacaran Period and was followed by the Ordovician Period, the Cambrian is divided into four epochs and ten ages. Currently only two series and five stages are named and have a GSSP, because the international stratigraphic subdivision is not yet complete, many local subdivisions are still widely used. In some of these subdivisions the Cambrian is divided into three epochs with locally differing names – the Early Cambrian, Middle Cambrian and Furongian, rocks of these epochs are referred to as belonging to the Lower, Middle, or Upper Cambrian. Trilobite zones allow biostratigraphic correlation in the Cambrian, each of the local epochs is divided into several stages. The International Commission on Stratigraphy list the Cambrian period as beginning at 541 million years ago, the lower boundary of the Cambrian was originally held to represent the first appearance of complex life, represented by trilobites. The recognition of small shelly fossils before the first trilobites, and Ediacara biota substantially earlier and this formal designation allowed radiometric dates to be obtained from samples across the globe that corresponded to the base of the Cambrian. Early dates of 570 million years ago quickly gained favour, though the used to obtain this number are now considered to be unsuitable. A more precise date using modern radiometric dating yield a date of 541 ±0.3 million years ago, most continental land was clustered in the Southern Hemisphere at this time, but was drifting north. Large, high-velocity rotational movement of Gondwana appears to have occurred in the Early Cambrian, the sea levels fluctuated somewhat, suggesting there were ice ages, associated with pulses of expansion and contraction of a south polar ice cap. In Baltoscandia a Lower Cambrian transgression transformed large swathes of the Sub-Cambrian peneplain into a epicontinental sea, the Earth was generally cold during the early Cambrian, probably due to the ancient continent of Gondwana covering the South Pole and cutting off polar ocean currents
3.
Ordovician
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The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. Lapworth recognized that the fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods. It received international sanction in 1960, when it was adopted as a period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event considerably increased the diversity of life, fish, the worlds first true vertebrates, continued to evolve, and those with jaws may have first appeared late in the period. Life had yet to diversify on land, about 100 times as many meteorites struck the Earth during the Ordovician compared with today. The Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event and it lasted for about 42 million years and ended with the Ordovician–Silurian extinction event, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary slightly from those found in other sources and this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is highly significant and it correlates well with the occurrence of widespread graptolite, conodont, and trilobite species. The base of the Tremadocian allows scientists to relate these species not only to each other and this makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected an international system of subdivisions. There exist Baltoscandic, British, Siberian, North American, Australian, the Ordovician Period in Britain was traditionally broken into Early, Middle and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, the Floian corresponds to the lower Arenig, the Arenig continues until the early Darriwilian, subsuming the Dapingian. The Llanvirn occupies the rest of the Darriwilian, and terminates with it at the base of the Late Ordovician. The Sandbian represents the first half of the Caradoc, the Caradoc ends in the mid-Katian, during the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole, the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia
4.
Silurian
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The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period,419.2 Mya. As with other periods, the rock beds that define the periods start and end are well identified. The base of the Silurian is set at a major Ordovician-Silurian extinction event when 60% of marine species were wiped out, a significant evolutionary milestone during the Silurian was the diversification of jawed and bony fish. However, terrestrial life would not greatly diversify and affect the landscape until the Devonian, the Silurian system was first identified by British geologist Sir Roderick Impey Murchison, who was examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s. He named the sequences for a Celtic tribe of Wales, the Silures, inspired by his friend Adam Sedgwick and this naming does not indicate any correlation between the occurrence of the Silurian rocks and the land inhabited by the Silures. As it was first identified, the Silurian series when traced farther afield quickly came to overlap Sedgwicks Cambrian sequence, however, charles Lapworth resolved the conflict by defining a new Ordovician system including the contested beds. An early alternative name for the Silurian was Gotlandian after the strata of the Baltic island of Gotland, the French geologist Joachim Barrande, building on Murchisons work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge. He divided the Silurian rocks of Bohemia into eight stages and his interpretation was questioned in 1854 by Edward Forbes, and the later stages of Barrande, F, G and H, have since been shown to be Devonian. Despite these modifications in the groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest fossils. The epoch is named for the town of Llandovery in Carmarthenshire, the Wenlock, which lasted from 433.4 ±1.5 to 427.4 ±2.8 mya, is subdivided into the Sheinwoodian and Homerian ages. It is named after Wenlock Edge in Shropshire, England, during the Wenlock, the oldest known tracheophytes of the genus Cooksonia, appear. The first terrestrial animals also appear in the Wenlock, represented by air-breathing millipedes from Scotland. The Ludlow, lasting from 427.4 ±1.5 to 423 ±2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago, and it is named for the town of Ludlow in Shropshire, England. The Pridoli, lasting from 423 ±1.5 to 419.2 ±2.8 mya, is the final and it is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic. Přídolí is the old name of a field area. The high sea levels of the Silurian and the flat land resulted in a number of island chains. The southern continents remained united during this period, the melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity. The continents of Avalonia, Baltica, and Laurentia drifted together near the equator and this event is the Caledonian orogeny, a spate of mountain building that stretched from New York State through conjoined Europe and Greenland to Norway
5.
Devonian
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The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian,419.2 million years ago, to the beginning of the Carboniferous,358.9 Mya. It is named after Devon, England, where rocks from this period were first studied, the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents, by the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established, Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fish. The first ray-finned and lobe-finned bony fish appeared, while the placodermi began dominating almost every aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral, in the oceans, primitive sharks became more numerous than in the Silurian and Late Ordovician. The first ammonites, species of molluscs, appeared, trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placodermi, and all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, while the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, another common term is Age of the Fishes, referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian, Breconian and Farlovian stages, in the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common. The Devonian Period is formally broken into Early, Middle and Late subdivisions, the rocks corresponding to those epochs are referred to as belonging to the Lower, Middle and Upper parts of the Devonian System. Early Devonian The Early Devonian lasted from 419.2 ±2.8 to 393.3 ±2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ±2.8 to 407.6 ±2.5, and was followed by the Emsian, which lasted until the Middle Devonian began,393. 3±2.7 million years ago. Middle Devonian The Middle Devonian comprised two subdivisions, first the Eifelian, which gave way to the Givetian 387. 7±2.7 million years ago. Late Devonian Finally, the Late Devonian started with the Frasnian,382.7 ±2.8 to 372.2 ±2.5, during which the first forests took shape on land. The first tetrapods appeared in the record in the ensuing Famennian subdivision. This lasted until the end of the Devonian,358. 9±2.5 million years ago, the Devonian was a relatively warm period, and probably lacked any glaciers
6.
Carboniferous
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The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period,298.9 Mya. The name Carboniferous means coal-bearing and derives from the Latin words carbō and ferō, and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the system names to be employed. The Carboniferous is often treated in North America as two periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial life was established by the Carboniferous period. Amphibians were the dominant land vertebrates, of one branch would eventually evolve into amniotes. Arthropods were also common, and many were much larger than those of today. Vast swaths of forest covered the land, which would eventually be laid down, the atmospheric content of oxygen also reached their highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. A major marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred in the middle of the period, the later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. In the United States the Carboniferous is usually broken into Mississippian and Pennsylvanian subperiods, the Silesian is roughly contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, and the Westphalian as the Coal Measures and Pennant Sandstone. There was also a drop in south polar temperatures, southern Gondwanaland was glaciated throughout the period and these conditions apparently had little effect in the deep tropics, where lush swamps, later to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major extinction, one that hit crinoids. This sea level drop and the unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation, the Carboniferous was a time of active mountain-building, as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America, in the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, the Late Carboniferous Pangaea was shaped like an O. There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, which was inside the O in the Carboniferous Pangaea, other minor oceans were shrinking and eventually closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean
7.
Permian
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The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era, the following Triassic Period belongs to the Mesozoic Era, the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the groups of the mammals, turtles, lepidosaurs. The world at the time was dominated by two known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior, amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earths history, in which nearly 90% of marine species and it would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian-Triassic extinction event was protracted, on land, the term Permian was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil, the region now lies in the Perm Krai of Russia. This could have in part caused the extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms. During the Permian, all the Earths major landmasses were collected into a supercontinent known as Pangaea. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, a new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmass interiors experience climates with extreme variations of heat and cold, deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian, the climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an Ice Age, glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continents interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles, Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. By the close of the Permian, trilobites and a host of other groups became extinct. Terrestrial life in the Permian included diverse plants, fungi, arthropods, the period saw a massive desert covering the interior of Pangaea
8.
Triassic
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The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period 252.17 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era, both the start and end of the period are marked by major extinction events. Therapsids and archosaurs were the terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic, the vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, however, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another mass extinction, the Triassic-Jurassic extinction event. The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, from the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed. Later in the mid-Triassic a similar sea penetrated along the equator from the west, the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates, thus, the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans. At the beginning of the Mesozoic Era, Africa was joined with Earths other continents in Pangaea, Africa shared the supercontinents relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are common in the south than north. The time boundary separating the Permian and Triassic marks the advent of an event with global impact. At Paleorrota geopark, located in Rio Grande do Sul, Brazil, in these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. Pangaeas large size limited the effect of the global ocean, its continental climate was highly seasonal, with very hot summers. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, the best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. On land, the vascular plants included the lycophytes, the dominant cycadophytes, ginkgophyta, ferns, horsetails
9.
Jurassic
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The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic, Middle, and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, Middle, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, India, South America, Japan, Australasia. As the Jurassic proceeded, larger and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are also poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
10.
Paleogene
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The Paleogene is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 million years ago to the beginning of the Neogene Period 23.03 Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon and this period consists of the Paleocene, Eocene and Oligocene epochs. The terms Paleogene System and lower Tertiary System are applied to the rocks deposited during the Paleogene Period. By dividing the Tertiary Period into two periods instead of directly into five epochs, the periods are more comparable to the duration of periods of the preceding Mesozoic and Paleozoic Eras. The trend was caused by the formation of the Antarctic Circumpolar Current. During the Paleogene, the continued to drift closer to their current positions. India was in the process of colliding with Asia, subsequently forming the Himalayas, the Atlantic Ocean continued to widen by a few centimeters each year. Africa was moving north to meet with Europe and form the Mediterranean, inland seas retreated from North America early in the period. Australia had also separated from Antarctica and was drifting towards Southeast Asia, mammals began a rapid diversification during this period. Some of these mammals would evolve into forms that would dominate the land, while others would become capable of living in marine, specialized terrestrial. Those that took to the oceans became modern cetaceans, while those that took to the trees became primates, the group to which humans belong. Birds, which were well established by the end of the Cretaceous. In comparison to birds and mammals, most other branches of life remained unchanged during this period. As the Earth cooled, tropical plants became less numerous and were now restricted to equatorial regions, deciduous plants, which could survive through the seasonal climates the world was now experiencing, became more common. The Paleogene is notable in the context of offshore oil drilling, and especially in Gulf of Mexico oil exploration and these rock formations represent the current cutting edge of deep-water oil discovery. Lower Tertiary explorations to date include, Kaskida Oil Field Tiber Oil Field Jack 2 Paleogene Microfossils, 180+ images of Foraminifera
11.
Neogene
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The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene, some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. During this period, mammals and birds continued to evolve into modern forms. Early hominids, the ancestors of humans, appeared in Africa near the end of the period, some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the ocean currents from the Pacific to the Atlantic ocean. The global climate cooled considerably over the course of the Neogene, the terms Neogene System and upper Tertiary System describe the rocks deposited during the Neogene Period. The continents in the Neogene were very close to their current positions, the Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas, sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America. The global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, and by the end of the period the first of a series of glaciations of the current Ice Age began, marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the part of the period. Mammals and birds continued to be the dominant terrestrial vertebrates, the first hominids, the ancestors of humans, appeared in Africa and spread into Eurasia. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones, grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. The Neogene traditionally ended at the end of the Pliocene Epoch, just before the definition of the beginning of the Quaternary Period. However, there was a movement amongst geologists to also include ongoing geological time in the Neogene, by dividing the Cenozoic Era into three periods instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras. The International Commission on Stratigraphy once proposed that the Quaternary be considered a sub-era of the Neogene, with a date of 2.58 Ma. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene epochs, thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. Digital Atlas of Neogene Life for the Southeastern United States — by San Jose State University via Web Archive
12.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
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Parts per million
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In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e. g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement, commonly used are ppm, ppb, ppt and ppq. Parts-per notation is often used describing dilute solutions in chemistry, for instance, the unit “1 ppm” can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL, therefore, it is common to equate 1 kilogram of water with 1 L of water. Consequently,1 ppm corresponds to 1 mg/L and 1 ppb corresponds to 1 μg/L, similarly, parts-per notation is used also in physics and engineering to express the value of various proportional phenomena. For instance, a metal alloy might expand 1.2 micrometers per meter of length for every degree Celsius. For instance, the accuracy of distance measurements when using a laser rangefinder might be 1 millimeter per kilometer of distance, this could be expressed as “Accuracy =1 ppm. ”Parts-per notations are all dimensionless quantities, in mathematical expressions. In fractions like “2 nanometers per meter” so the quotients are pure-number coefficients with positive values less than 1, when parts-per notations, including the percent symbol, are used in regular prose, they are still pure-number dimensionless quantities. However, they take the literal “parts per” meaning of a comparative ratio. Parts-per notations may be expressed in terms of any unit of the same measure, in nuclear magnetic resonance spectroscopy, chemical shift is usually expressed in ppm. It represents the difference of a frequency in parts per million from the reference frequency. The reference frequency depends on the magnetic field and the element being measured. It is usually expressed in MHz, typical chemical shifts are rarely more than a few hundred Hz from the reference frequency, so chemical shifts are conveniently expressed in ppm. Parts-per notation gives a quantity that does not depend on the instruments field strength. One part per hundred is generally represented by the percent symbol and denotes one part per 100 parts, one part in 102, and this is equivalent to approximately one drop of water diluted into 5 milliliters or about fifteen minutes out of one day. One part per thousand should generally be spelled out in full and it may also be denoted by the millage symbol. Note however, that specific disciplines such as oceanography, as well as educational exercises, one part per thousand denotes one part per 1000 parts, one part in 103, and a value of 1 × 10−3. This is equivalent to one drop of water diluted into 50 milliliters or about one, one part per ten thousand is denoted by the permyriad symbol
14.
Mesozoic
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The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. This Era is also called from a paleobotanist view the Age of Conifers, Mesozoic means middle life, deriving from the Greek prefix meso-/μεσο- for between and zōon/ζῷον meaning animal or living being. It is one of three eras of the Phanerozoic Eon, preceded by the Paleozoic and succeeded by the Cenozoic. The era is subdivided into three periods, the Triassic, Jurassic, and Cretaceous, which are further subdivided into a number of epochs. The Mesozoic was a time of significant tectonic, climate and evolutionary activity, the era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions. The climate of the Mesozoic was varied, alternating between warming and cooling periods, overall, however, the Earth was hotter than it is today. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs, the first mammals also appeared during the Mesozoic, but would remain small—less than 15 kg —until the Cenozoic. Following the Paleozoic, the Mesozoic extended roughly 186 million years and this time frame is separated into three geologic periods. It is also known as the Great Dying because it is considered the largest mass extinction in the Earths history, the upper boundary of the Mesozoic is set at the Cretaceous–Paleogene extinction event, which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. Towards the Late Cretaceous large volcanic eruptions are believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs, the Triassic ranges roughly from 252 million to 201 million years ago. The Triassic is a time in Earths history bracketed between the Permian Extinction and the Triassic–Jurassic extinction event, two of the big five, and precedes the Jurassic Period and it has three major epochs, the Early Triassic, the Middle Triassic and the Late Triassic. The Early Triassic was between about 252 million to 247 million years ago and was dominated by deserts as Pangaea had not yet broken up, thus the interior was nothing, the Earth had just witnessed a massive die-off in which 95% of all life became extinct. The most common life on earth were Lystrosaurus, labyrinthodonts. Temnospondyls evolved during this time and would be the dominant predator for much of the Triassic, the Middle Triassic spans roughly from 247 million to 237 million years ago. The Middle Triassic featured the beginnings of the breakup of Pangaea, the ecosystem had recovered from the devastation that was the Great Dying. Algae, sponge, corals, and crustaceans all had recovered, new aquatic reptiles evolved, such as ichthyosaurs and nothosaurs. Meanwhile, on land, pine forests flourished, as did groups of insects like mosquitoes, the first ancient crocodilians evolved, which sparked competition with the large amphibians that had since ruled the freshwater world
15.
Berriasian
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In the geological timescale, the Berriasian is an age or stage of the Early Cretaceous. It is the oldest, or lowest, subdivision in the entire Cretaceous and it spanned the time between 145.0 ±4.0 Ma and 139.8 ±3.0 Ma. The Berriasian succeeds the Tithonian and precedes the Valanginian, the Berriasian Stage was introduced in scientific literature by Henri Coquand in 1869. It is named after the village of Berrias in the Ardèche department of France, the largely non-marine English Purbeck Formation is in part of Berriasian age. The base of the Berriasian, which is also the base of the Cretaceous system, has traditionally placed at the first appearance of fossils of the ammonite species Berriasella jacobi. But this is a species that has a problematic and geographically limited distribution. A global reference profile for the Berriasian has been under consideration by the International Subcommission on Cretaceous Stratigraphy of IUGS. A range of contender GSSP localities has been studied in detail by the ISCSs Berriasian Working Group including localities as far apart as Mexico, Ukraine, Tunisia, Iraq, several markers have been employed to refine correlations and to work towards defining a base for the Berriasian Stage. These include calcareous nannofossils, such as Nannoconus, calpionellids, ammonites, palynological data and magnetostratigraphy, in June 2016, the Berriasian Working Group voted to adopt Calpionella alpina as the primary marker for the base of the Berriasian Stage. This is just a little below the first appearance of the ammonite species Thurmanniceras pertransiens, a Geologic Time Scale 2004, Cambridge University Press
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Valanginian
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In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ±3.0 Ma and 132.9 ±2.0 Ma, the Valanginian stage succeeds the Berriasian stage of the Lower Cretaceous and precedes the Hauterivian stage of the Lower Cretaceous. The Valanginian was first described and named by Édouard Desor in 1853 and it is named after Valangin, a small town north of Neuchâtel in the Jura Mountains of Switzerland. The base of the Valanginian is at the first appearance of calpionellid species Calpionellites darderi in the stratigraphic column, a global reference section had in 2009 not yet been appointed. The top of the Valanginian is at the first appearance of the ammonite genus Acanthodiscus, the Valanginian is often subdivided in Lower and Upper substages. The Upper substage begins at the first appearance of ammonite species Saynoceras verrucosum, a Geologic Time Scale 2004, Cambridge University Press. GeoWhen Database - Valanginian Mid-Cretaceous timescale and ühttp, //stratigraphy. science. purdue. edu/charts/Timeslices/5_JurCret
17.
Hauterivian
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The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous epoch or a stage in the Lower Cretaceous series. It spans the time between 132.9 ±2 Ma and 129.4 ±1.5 Ma, the Hauterivian is preceded by the Valanginian and succeeded by the Barremian. The Hauterivian was introduced in literature by Swiss geologist Eugène Renevier in 1873. It is named after the Swiss town of Hauterive at the shore of Lake Neuchâtel, the base of the Hauterivian is defined as the place in the stratigraphic column where the ammonite genus Acanthodiscus first appears. A reference profile for the base had in 2009 not yet been established, the top of the Hauterivian is at the first appearance of ammonite species Spitidiscus hugii. M. A Geologic Time Scale 2004, Cambridge University Press
18.
Barremian
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The Barremian is an age in the geologic timescale between 129.4 ±1.5 Ma and 125.0 ±1.0 Ma). It is a subdivision of the Early Cretaceous epoch and it is preceded by the Hauterivian and followed by the Aptian stage. The original type locality for the Barremian stage is in the vicinity of the village of Barrême, henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites Spitidiscus hugii, the end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite Paradeshayesites oglanlensis. The Barremian falls in the Gallic epoch, a subdivision of the Cretaceous that is no longer used by the ICS and it overlaps the lower part of the Urgonian stage, which is sometimes used in western European stratigraphy. In North America, the late Coahulian and the early Comanchean correspond to the Barremian, in New Zealand, it falls within the Mokoiwian, and in Japan it corresponds to the late Aritan. The Barremian is often subdivided into two substages or subages, Lower/Early and Upper/Late Barremian, le Barrémien supérieur à faciès Urgonien de Brouzet-lès-Alais. Mémoires de la Société Géologique de France, Paléontologie 15, 5-42, a Geologic Time Scale 2004, Cambridge University Press. Assessment of diachronism of biostratigraphic boundaries by magnetochronological calibration of scales for the Lower Cretaceous of the Tethyan
19.
Aptian
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The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ±1.0 Ma to 113.0 ±1.0 Ma, approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous, the Aptian partly overlaps the upper part of the regionally used stage Urgonian. The Aptian was named after the city of Apt in the Provence region of France. The original type locality is in the vicinity of Apt, the Aptian was introduced in scientific literature by French palaeontologist Alcide dOrbigny in 1840. The base of the Aptian stage is laid at magnetic anomaly M0r, a global reference profile for the base had in 2009 not yet been appointed. The top of the Aptian is at the first appearance of coccolithophore species Praediscosphaera columnata in the stratigraphic record. M, & Smith, A. G.2004, A Geologic Time Scale 2004, Cambridge University Press. 1842, Paléontologie française, Terrains crétacés, vol. ii
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Albian
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The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series and its approximate time range is 113.0 ±1.0 Ma to 100.5 ±0.9 Ma. The Albian is preceded by the Aptian and followed by the Cenomanian, the Albian stage was first proposed in 1842 by Alcide dOrbigny. As of 2014, a profile for the base of the Albian stage had not yet been established. The top of the Albian stage is defined as the place where the foram species Rotalipora globotruncanoides first appears in the stratigraphic column, the Albian is sometimes subdivided in Early/Lower, Middle and Late/Upper subages or substages. In western Europe, especially in the UK, a subdivision in two substages is more often used, moffitites The following is a list of Ammonite genera whose fossils are geochronologically found first in lower Albian strata. These genera may survive into later portions of the Albian stage and this list should not be thought of in terms of the lifespan of the genera included. These genera may survive into later portions of the Albian stage and this list should not be thought of in terms of the lifespan of the genera included. These genera may survive into later portions of the Albian stage and this list should not be thought of in terms of the lifespan of the genera included. M. & Smith, A. G.2004, A Geologic Time Scale 2004, & Caron, M.2004, The Global Boundary Stratotype Section and Point for the base of the Cenomanian Stage, Mont Risou, Hautes-Alpes, France, Episodes 27, pp. 21–32. 1842, Paléontologie française, Terrains crétacés, vol. ii
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Cenomanian
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The Cenomanian is, in the ICS geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology, it is a unit of time, both age and stage bear the same name. As a unit of time measure, the Cenomanian age spans the time between 100.5 ±0.9 Ma and 93.9 ±0.8 Ma. In the geologic timescale it is preceded by the Albian and is followed by the Turonian, the Cenomanian is coeval with the Woodbinian of the regional timescale of the Gulf of Mexico and the early part of the Eaglefordian of the regional timescale of the US East Coast. At the end of the Cenomanian an anoxic event took place, called the Cenomanian-Turonian boundary event or the Bonarelli Event, the Cenomanian was introduced in scientific literature by French palaeontologist Alcide dOrbigny in 1847. Its name comes from the New Latin name of the French city of Le Mans, the base of the Cenomanian stage is placed at the first appearance of foram species Rotalipora globotruncanoides in the stratigraphic record. An official reference profile for the base of the Cenomanian is located in an outcrop at the flank of Mont Risou. The base is, in the profile, located 36 meters below the top of the Marnes Bleues Formation. The top of the Cenomanian is at the first appearance of ammonite species Watinoceras devonense, important index fossils for the Cenomanian are the ammonites Calycoceras naviculare, Acanthoceras rhotomagense and Mantelliceras mantelli. The late Cenomanian represents the highest mean sea-level observed in the Phanerozoic eon, a corollary is that the highlands were at all time lows, so the landscape on Earth was one of warm broad shallow seas inundating low-lying land areas on the precursors to todays continents. What few lands rose above the waves were made of old mountains and hills, upland plateaus, tectonic mountain building was minimal and most continents were isolated by large stretches of water. Without highlands to brake winds, the climate would have been windy and waves large, adding to the weathering, & Smith, A. G.2004, A Geologic Time Scale 2004, Cambridge University Press. & Caron, M.2004, The Global Boundary Stratotype Section and Point for the base of the Cenomanian Stage, Mont Risou, Hautes-Alpes, France, Episodes 27, pp. 21–32
22.
Turonian
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The Turonian is, in the ICS geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.9 ±0.8 Ma and 89.8 ±1 Ma, the Turonian is preceded by the Cenomanian stage and underlies the Coniacian stage. At the beginning of the Turonian an anoxic event took place which is called the Cenomanian-Turonian boundary event or the Bonarelli Event, the Turonian was defined by the French paleontologist Alcide dOrbigny in 1842. Orbigny named it after the French city of Tours in the region of Touraine, the base of the Turonian stage is defined as the place where the ammonite species Wutinoceras devonense first appears in the stratigraphic column. The official reference profile for the base of the Turonian is located in the Rock Canyon anticline near Pueblo, the top of the Turonian stage is defined as the place in the stratigraphic column where the inoceramid bivalve species Cremnoceramus rotundatus first appears. The Turonian is sometimes subdivided in Lower/Early, Middle and Upper/Late substages or subages, inoceramids are bivalve Mollusca related to todays mussels. & Smith, A. G.2004, A Geologic Time Scale 2004, & Cobban, W. A.2005, The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous, Pueblo, Colorado, U. S. A
23.
Coniacian
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The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series, the Coniacian is preceded by the Turonian and followed by the Santonian. The Coniacian is named after the city of Cognac in the French region of Saintonge and it was first defined by French geologist Henri Coquand in 1857. The base of the Coniacian stage is at the first appearance of the bivalve species Cremnoceramus rotundatus. An official reference profile for the base had in 2009 not yet been appointed, the top of the Coniacian is defined by the appearance of the inoceramid bivalve Cladoceramus undulatoplicatus. The Coniacian overlaps the regional Emscherian stage of Germany, which is coeval with the Coniacian and Santonian stages. In magnetostratigraphy, the Coniacian is part of magnetic chronozone C34, the so-called Cretaceous Magnetic Quiet Zone, after a maximum of the global sea level during the early Turonian, the Coniacian was characterized by a gradual fall of the sea level. This cycle is in sequence stratigraphy seen as a first order cycle, during the middle Coniacian a shorter, second order cycle, caused a temporary rise of the sea level on top of the longer first order trend. The following regression separates the Middle from the Upper Coniacian substage, an even shorter third order cycle caused a new transgression during the Late Coniacian. Beginning in the Middle Coniacian, an event occurred in the Atlantic Ocean. The anoxic event lasted till the Middle Santonian and is the longest and last such event during the Cretaceous period, the Coniacian is often subdivided into Lower, Middle and Upper substages. M. & Smith, A. G.2004, A Geologic Time Scale 2004, & Forster, A.2006, Origins and accumulation of organic matter in expanded Albian to Santonian black shale sequences on the Demerara Rise, South American margin, Organic Geochemistry 37, pp 1816–1830
24.
Santonian
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The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and it spans the time between 86.3 ±0.7 mya and 83.6 ±0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian, the Santonian stage was established by French geologist Henri Coquand in 1857. It is named after the city of Saintes in the region of Saintonge, the base of the Santonian stage is defined by the appearance of the inoceramid bivalve Cladoceramus undulatoplicatus. Its top is marked by the extinction of the crinoid Marsupites testudinarius, in 2009, a GSSP for both base and top had not yet been appointed. The Santonian is sometimes subdivided into Lower, Middle and Upper substages, in the Tethys domain the Santonian is coeval with a single ammonite biozone, that of Placenticeras polyopsis. Biostratigraphy based on inoceramids, nannoplankton or forams is more detailed, magnoliopsida Advanced dicotyledons Droseraceae, †Palaeoaldrovanda Gradstein, F. M. & Smith, A. G.2004, A Geologic Time Scale 2004, Cambridge University Press
25.
Campanian
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The Campanian is, in the ICS geologic timescale, the fifth of six ages of the Late Cretaceous epoch. The Campanian spans the time from 83.6 ±0.7 Ma to 72.1 ±0.6 Ma and it is preceded by the Santonian and it is followed by the Maastrichtian. The Campanian was introduced in literature by Henri Coquand in 1857. It is named after the French village of Champagne in the département Charente-Maritime, the original type locality was an outcrop near the village of Aubeterre-sur-Dronne in the same region. Due to changes of the definitions, this section is now part of the Maastrichtian stage. The base of the Campanian stage is laid at the extinction of crinoid species Marsupites testudinarius, a GSSP had not yet been ratified in 2009. One possible candidate is in a section near a dam at Waxahachie, the top of the Campanian is defined as the place in the stratigraphic column were the ammonite Pachydiscus neubergicus first appears. The Campanian is sometimes subdivided into Lower, Middle and Upper subages, in the Tethys domain, the Campanian encompasses six ammonite biozones. In North America, for example, the number of dinosaur genera rises from 4 at the base of the Campanian to 48 in the upper part. This development is referred to as the Campanian Explosion. However, it is not yet if the event is artificial. The generally warm climates and large area covered in shallow sea during the Campanian probably favoured the dinosaurs. In the following Maastrichtian stage, the number of North American dinosaur genera found is 30% less than in the upper Campanian, & Smith, A. G.2004, A Geologic Time Scale 2004, Cambridge University Press. Late Cretaceous oviraptorosaur dinosaurs from Montana, pp. 42–57 in D. H. Tanke and K. Carpenter, Mesozoic Vertebrate Life. Le Loueff, J. Xu, X. Zhao, X. Sahni, A. Gomani,2004, Dinosaur distribution, in, Weishampel, D. B. The Dinosauria, University of California Press, Berkeley, ISBN 0-520-24209-2, pp 517–606
26.
Maastrichtian
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The Maastrichtian is, in the ICS geologic timescale, the latest age of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned the interval from 72.1 to 66 million years ago, the Maastrichtian was preceded by the Campanian and succeeded by the Danian. At the end of period, there was a mass extinction known as the Cretaceous–Paleogene extinction event. At this extinction event, many commonly recognized groups such as dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser-known groups. The cause of the extinction is most commonly linked to an asteroid about 10 kilometres wide colliding with Earth at the end of the Cretaceous. The Maastrichtian was introduced into scientific literature by Belgian geologist André Hubert Dumont in 1849 and these strata are now classified as the Maastricht Formation - both formation and stage derive their names from the city. The Maastricht Formation is known for its fossils from this age, most notably those of the giant sea reptile Mosasaurus, the base of the Maastrichtian stage is at the first appearance of ammonite species Pachydiscus neubergicus. At the original type locality near Maastricht, the record was later found to be incomplete. A reference profile for the base was then appointed in a section along the Ardour river called Grande Carrière, the Maastrichtian is commonly subdivided into two substages and three ammonite biozones. The following are summaries of the characteristics of specific Maastrichtian aged formations, the Bearpaw Formation, also called the Bearpaw Shale, is a sedimentary rock formation found in northwestern North America. It is exposed in the U. S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, east of the Rocky Mountains. It overlies the older Two Medicine, Judith River and Dinosaur Park Formations, and is in turn overlain by the Horseshoe Canyon Formation in Canada, to the east and south it blends into the Pierre Shale. Other fossils found in this include many types of shellfish, bony fish, sharks, rays, birds. The occasional dinosaur remains have also discovered, presumably from carcasses washed out to sea. The Hell Creek Formation is an intensely studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The Hell Creek Formation occurs in badlands of eastern Montana and portions of North Dakota, South Dakota, in Montana, the Hell Creek Formation overlies the Fox Hills Formation and is the uppermost formation of the Cretaceous period. The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230 m in depth and it is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales. There are a variety of environments, which have yielded a diversity of fossil material, the Horseshoe Canyon Formation outcrops extensively in the area of Drumheller, Alberta, as well as further north along the Red Deer River near Trochu, and also in the city of Edmonton
27.
Myr
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The Malaysian ringgit is the currency of Malaysia. It is divided into 100 sen, the ringgit is issued by the Bank Negara Malaysia. In modern usage ringgit is used almost solely for the currency, to differentiate between the three currencies, the Malaysian currency is referred to as Ringgit Malaysia, hence the official abbreviation and currency symbol RM. Internationally, the ISO4217 currency code for Malaysian ringgit is MYR, the Malay names ringgit and sen were officially adopted as the sole official names in August 1975. Previously they had been known officially as dollars and cents in English and ringgit and sen in Malay, in the northern states of Peninsular Malaysia, denominations of 10 sen are called kupang in Malay, e. g.50 sen is 5 kupang. On 12 June 1967, the Malaysian dollar, issued by the new bank, Bank Negara Malaysia, replaced the Malaya. The new currency retained all denominations of its predecessor except the $10,000 denomination, and also brought over the colour schemes of the old dollar. In November 1967, five months after the introduction of the Malaysian dollar and this ended on 8 May 1973, when the Malaysian government withdrew from the agreement. The Monetary Authority of Singapore and the Brunei Currency and Monetary Board still maintain the interchangeability of their two currencies, as of 2009, in 1993, the currency symbol RM was introduced to replace the use of the dollar sign $. US$130 and RM1,000 worth of US$260. Despite these measures, the ringgit lost 50% of its value against the US dollar between 1997 and 1998, and suffered general depreciation against other currencies between December 2001 and January 2005. As of 4 September 2008, the ringgit has yet to regain its value circa 2001 against the Singapore dollar, the euro, the Australian dollar, and the British pound. On 21 July 2005, Bank Negara announced the end of the peg to the US dollar immediately after Chinas announcement of the end of the peg to the US dollar. According to Bank Negara, Malaysia allows the ringgit to operate in a float against several major currencies. Following the end of the peg, the ringgit appreciated to as high as 3.16 to the US dollar in April 2008. The ringgit had also enjoyed a period of appreciation against the Hong Kong dollar, the initial stability of the ringgit in the late-2000s had led to considerations to reintroduce the currency to foreign trading. As a result, the US dollar appreciated significantly to close at 3.43 to the MYR as of 4 September 2008, while other major currencies, including the renminbi and Hong Kong dollar, followed suit. The ringgit spiked at 3.73 to the US dollar by March 2009, before recovering to 3.00 to the US dollar by mid-2011. The first series of sen coins were introduced in 1967 in denominations of 1 sen,5 sen,10 sen,20 sen,50 sen, followed by the introduction of the 1 ringgit coin in 1971
28.
Mesozoic Era
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The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. This Era is also called from a paleobotanist view the Age of Conifers, Mesozoic means middle life, deriving from the Greek prefix meso-/μεσο- for between and zōon/ζῷον meaning animal or living being. It is one of three eras of the Phanerozoic Eon, preceded by the Paleozoic and succeeded by the Cenozoic. The era is subdivided into three periods, the Triassic, Jurassic, and Cretaceous, which are further subdivided into a number of epochs. The Mesozoic was a time of significant tectonic, climate and evolutionary activity, the era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions. The climate of the Mesozoic was varied, alternating between warming and cooling periods, overall, however, the Earth was hotter than it is today. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs, the first mammals also appeared during the Mesozoic, but would remain small—less than 15 kg —until the Cenozoic. Following the Paleozoic, the Mesozoic extended roughly 186 million years and this time frame is separated into three geologic periods. It is also known as the Great Dying because it is considered the largest mass extinction in the Earths history, the upper boundary of the Mesozoic is set at the Cretaceous–Paleogene extinction event, which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. Towards the Late Cretaceous large volcanic eruptions are believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs, the Triassic ranges roughly from 252 million to 201 million years ago. The Triassic is a time in Earths history bracketed between the Permian Extinction and the Triassic–Jurassic extinction event, two of the big five, and precedes the Jurassic Period and it has three major epochs, the Early Triassic, the Middle Triassic and the Late Triassic. The Early Triassic was between about 252 million to 247 million years ago and was dominated by deserts as Pangaea had not yet broken up, thus the interior was nothing, the Earth had just witnessed a massive die-off in which 95% of all life became extinct. The most common life on earth were Lystrosaurus, labyrinthodonts. Temnospondyls evolved during this time and would be the dominant predator for much of the Triassic, the Middle Triassic spans roughly from 247 million to 237 million years ago. The Middle Triassic featured the beginnings of the breakup of Pangaea, the ecosystem had recovered from the devastation that was the Great Dying. Algae, sponge, corals, and crustaceans all had recovered, new aquatic reptiles evolved, such as ichthyosaurs and nothosaurs. Meanwhile, on land, pine forests flourished, as did groups of insects like mosquitoes, the first ancient crocodilians evolved, which sparked competition with the large amphibians that had since ruled the freshwater world
29.
German language
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German is a West Germanic language that is mainly spoken in Central Europe. It is the most widely spoken and official language in Germany, Austria, Switzerland, South Tyrol, the German-speaking Community of Belgium and it is also one of the three official languages of Luxembourg. Major languages which are most similar to German include other members of the West Germanic language branch, such as Afrikaans, Dutch, English, Luxembourgish and it is the second most widely spoken Germanic language, after English. One of the languages of the world, German is the first language of about 95 million people worldwide. The German speaking countries are ranked fifth in terms of publication of new books. German derives most of its vocabulary from the Germanic branch of the Indo-European language family, a portion of German words are derived from Latin and Greek, and fewer are borrowed from French and English. With slightly different standardized variants, German is a pluricentric language, like English, German is also notable for its broad spectrum of dialects, with many unique varieties existing in Europe and also other parts of the world. The history of the German language begins with the High German consonant shift during the migration period, when Martin Luther translated the Bible, he based his translation primarily on the standard bureaucratic language used in Saxony, also known as Meißner Deutsch. Copies of Luthers Bible featured a long list of glosses for each region that translated words which were unknown in the region into the regional dialect. Roman Catholics initially rejected Luthers translation, and tried to create their own Catholic standard of the German language – the difference in relation to Protestant German was minimal. It was not until the middle of the 18th century that a widely accepted standard was created, until about 1800, standard German was mainly a written language, in urban northern Germany, the local Low German dialects were spoken. Standard German, which was different, was often learned as a foreign language with uncertain pronunciation. Northern German pronunciation was considered the standard in prescriptive pronunciation guides though, however, German was the language of commerce and government in the Habsburg Empire, which encompassed a large area of Central and Eastern Europe. Until the mid-19th century, it was essentially the language of townspeople throughout most of the Empire and its use indicated that the speaker was a merchant or someone from an urban area, regardless of nationality. Some cities, such as Prague and Budapest, were gradually Germanized in the years after their incorporation into the Habsburg domain, others, such as Pozsony, were originally settled during the Habsburg period, and were primarily German at that time. Prague, Budapest and Bratislava as well as cities like Zagreb, the most comprehensive guide to the vocabulary of the German language is found within the Deutsches Wörterbuch. This dictionary was created by the Brothers Grimm and is composed of 16 parts which were issued between 1852 and 1860, in 1872, grammatical and orthographic rules first appeared in the Duden Handbook. In 1901, the 2nd Orthographical Conference ended with a standardization of the German language in its written form
30.
Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
31.
Sea level
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Mean sea level is an average level of the surface of one or more of Earths oceans from which heights such as elevations may be measured. A common and relatively straightforward mean sea-level standard is the midpoint between a low and mean high tide at a particular location. Sea levels can be affected by factors and are known to have varied greatly over geological time scales. The careful measurement of variations in MSL can offer insights into ongoing climate change, the term above sea level generally refers to above mean sea level. Precise determination of a sea level is a difficult problem because of the many factors that affect sea level. Sea level varies quite a lot on several scales of time and this is because the sea is in constant motion, affected by the tides, wind, atmospheric pressure, local gravitational differences, temperature, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point, for example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. One measures the values of MSL in respect to the land, hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates. In the UK, the Ordnance Datum is the sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the datum was MSL at the Victoria Dock, in Hong Kong, mPD is a surveying term meaning metres above Principal Datum and refers to height of 1. 230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and it is used for a part of continental Europe and main part of Africa as official sea level. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001, height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum. It is also used in aviation, where some heights are recorded and reported with respect to sea level, and in the atmospheric sciences. An alternative is to base height measurements on an ellipsoid of the entire Earth, in aviation, the ellipsoid known as World Geodetic System 84 is increasingly used to define heights, however, differences up to 100 metres exist between this ellipsoid height and mean tidal height. The alternative is to use a vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, the elevation of a mountain denotes the highest point or summit and is typically illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, for one such case, see Amsterdam Airport Schiphol
32.
Inland sea (geology)
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An inland sea is a shallow sea that covers central areas of continents during periods of high sea level that result in marine transgressions. In modern times, continents stand high, eustatic sea levels are low, modern examples might also include the recently reflooded Persian Gulf, and the South China Sea that presently covers the Sunda Shelf. At various times in the geologic past, inland seas have been greater in extent, a vast inland sea, the Western Interior Seaway, extended from the Gulf of Mexico deep into present-day Canada during the Cretaceous. At the same time, much of the low plains of modern-day northern France and northern Germany were inundated by an inland sea, where the chalk was deposited that gave the Cretaceous Period its name. The Amazon, originally emptying into the Pacific, as South America rifted from Africa, a great inland sea developed, at times draining north through what is now Venezuela before finding its present eastward outlet into the South Atlantic. Gradually this inland sea became a vast freshwater lake and wetlands where sediment flattened its profiles and the marine inhabitants adapted to life in freshwater. Over 20 species of stingray, most closely related to those found in the Pacific Ocean, can be today in the freshwaters of the Amazon. In 2005 fossilized remains of a giant crocodilian, estimated to have been 46 ft in length, were discovered in the northern rainforest of Amazonian Peru. In Australia the promise of a sea is often said to have been one of the prime motives of inland exploration during the 1820s and 1830s. Also in Australia, the Eromanga Sea existed during the Cretaceous Period and it covered large swaths of the eastern half of the continent. The Baltic Sea is an inland sea, arguably the largest body of brackish water in the world. It occupies a basin formed by glacial erosion, hudson Bay, including James Bay at its southern end, reach within the North American continent from Baffin Island in the north to Quebec and Ontario in the south. Endorheic basin Mediterranean sea Marginal sea Geology Project - Inland Sea Movement Through Time
33.
Extinct
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In biology and ecology, extinction is the end of an organism or of a group of organisms, normally a species. The moment of extinction is considered to be the death of the last individual of the species, although the capacity to breed. Because a species range may be very large, determining this moment is difficult. This difficulty leads to such as Lazarus taxa, where a species presumed extinct abruptly reappears after a period of apparent absence. More than 99 percent of all species, amounting to five billion species. Estimates on the number of Earths current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described, the relationship between animals and their ecological niches has been firmly established. Mass extinctions are relatively rare events, however, isolated extinctions are quite common, only recently have extinctions been recorded and scientists have become alarmed at the current high rate of extinctions. Most species that become extinct are never scientifically documented, some scientists estimate that up to half of presently existing plant and animal species may become extinct by 2100. A dagger symbol next to a name is often used to indicate its extinction. A species is extinct when the last existing member dies, Extinction therefore becomes a certainty when there are no surviving individuals that can reproduce and create a new generation. Pinpointing the extinction of a species requires a definition of that species. If it is to be declared extinct, the species in question must be distinguishable from any ancestor or daughter species. Extinction of a plays a key role in the punctuated equilibrium hypothesis of Stephen Jay Gould. In ecology, extinction is often used informally to refer to local extinction, in which a species ceases to exist in the area of study. This phenomenon is known as extirpation. Local extinctions may be followed by a replacement of the species taken from other locations, species which are not extinct are termed extant. Those that are extant but threatened by extinction are referred to as threatened or endangered species, currently an important aspect of extinction is human attempts to preserve critically endangered species
34.
Marine reptile
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Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semi-aquatic life in a marine environment. The earliest marine reptiles arose in the Permian period during the Paleozoic era, various types of marine gavialid crocodilians remained widespread as recently as the Late Miocene. Others, such as sea turtles and saltwater crocodiles, return to shore to lay their eggs, some marine reptiles also occasionally rest and bask on land. Sea turtles are largely solitary animals, though some do form large, although only seven turtle species are truly marine, many more live dwell in brackish waters. Sea snakes, the most abundant of the reptiles, there are over 60 different species of sea snakes. They inhabit the tropical and subtropical waters of the Indian and Pacific oceans, sea snakes are venomous and their bites have been known to be fatal, though generally they only bite when provoked and often inject only a very small, non-fatal quantity of venom. Sea snakes are distinguished from terrestrial snakes by a flattened tail. Marine iguana, marine iguanas live only on the Galapagos Islands and are not fully adapted to marine life, saltwater crocodiles dispose of excess salt in their bodies through specialized salt glands. These animals are the largest species of crocodiles, also making them the largest of the reptiles—they can grow up to six meters in length, most species of marine reptiles are considered endangered to some degree. Saltwater crocodiles are at low risk for extinction, list of marine reptiles Salt gland
35.
Ammonites
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Ammonoids are an extinct group of marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs are more related to living coleoids than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species died out during the Cretaceous–Paleogene extinction event, Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geologic time periods. Their fossil shells usually take the form of planispirals, although there were some helically spiraled and nonspiraled forms, the name ammonite, from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams horns. Pliny the Elder called fossils of these animals ammonis cornua because the Egyptian god Ammon was typically depicted wearing rams horns, often the name of an ammonite genus ends in -ceras, which is Greek for horn. The topology of the septa, especially around the rim, results in the various suture patterns found, three major types of suture patterns are found in the Ammonoidea, Goniatitic - numerous undivided lobes and saddles, typically 8 lobes around the conch. This pattern is characteristic of the Paleozoic ammonoids, ceratitic - lobes have subdivided tips, giving them a saw-toothed appearance, and rounded undivided saddles. This suture pattern is characteristic of Triassic ammonoids and appears again in the Cretaceous pseudoceratites, ammonitic - lobes and saddles are much subdivided, subdivisions are usually rounded instead of saw-toothed. Ammonoids of this type are the most important species from a point of view. This suture type is characteristic of Jurassic and Cretaceous ammonoids, the siphuncle in most ammonoids by far is a narrow tubular structure that runs along the outer rim, known as the venter, connecting the chambers of the phragmocone to the body or living chamber. This distinguishes them from living nautiloides and typical Nautilida, the word siphuncle comes from the New Latin siphunculus, meaning little siphon. Originating from within the bactritoid nautiloids, the ammonoid cephalopods first appeared in the Devonian, while nearly all nautiloids show gently curving sutures, the ammonoid suture line is variably folded, forming saddles and lobes. In subsequent taxonomies, these are regarded as orders within the subclass Ammonoidea. Because ammonites and their relatives are extinct, little is known about their way of life. Their soft body parts are rarely preserved in any detail. Nonetheless, much has been worked out by examining ammonoid shells, synchrotron analysis of an aptychophoran ammonite revealed remains of isopod and mollusc larvae in its buccal cavity, indicating at least this kind of ammonite fed on plankton. They may have avoided predation by squirting ink, much like modern cephalopods, the soft body of the creature occupied the largest segments of the shell at the end of the coil. The smaller earlier segments were walled off and the animal could maintain its buoyancy by filling them with gas, thus, the smaller sections of the coil would have floated above the larger sections
36.
Rudists
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The size of these conical forms ranged widely from just a few centimeters to well over a meter in length. The small upper valve could take a variety of interesting forms, including, a flat lid, a low cone, a spiral. The rudists became extinct at the end of the Cretaceous, apparently as a result of the Cretaceous–Paleogene extinction event. It had been thought that this began a decline about 2.5 million years earlier which culminated in complete extinction half a million years before the end of the Cretaceous. However, evidence now suggests that rudists survived until the extinction event. The rudists are, according to different systematic schemes, placed in the orders Hippuritoida or Rudistes, however, rudists were one of the most important constituents of reefs during the Cretaceous Period. During the Cretaceous, rudist reefs were so successful that they drove scleractinian corals out of tropical environments, including shelves that are today the Caribbean. It is likely that their success as reef builders was at least partially due to the environment of the Cretaceous. Because of their porosity, rudist reefs are highly favored oil traps. An Introduction to the Paleontology of Rudist Bivalves, paleos. com, The Aptian Age Johnson, C. 2002, The rise and fall of Rudist reefs, American Scientist, v.90, Rudist Reef at the Smithsonian Ocean Portal More about Rudists
37.
Dinosaur
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Dinosaurs are a diverse group of reptiles of the clade Dinosauria that first appeared during the Triassic. Although the exact origin and timing of the evolution of dinosaurs is the subject of active research and they became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Their dominance continued through the Jurassic and Cretaceous periods and ended when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups 66 million years ago, until the late 20th century, all groups of dinosaurs were believed to be extinct. As such, birds were the dinosaur lineage to survive the mass extinction event. This article deals primarily with non-avian dinosaurs, Dinosaurs are a varied group of animals from taxonomic, morphological and ecological standpoints. Birds, at over 10,000 living species, are the most diverse group of vertebrates besides perciform fish, using fossil evidence, paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both extant species and fossil remains, while dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, evidence suggests that egg laying and nest building are additional traits shared by all dinosaurs.7 meters and heights of 18 meters and were the largest land animals of all time. Still, the idea that dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large. Many dinosaurs were small, Xixianykus, for example, was only about 50 cm long. Through the first half of the 20th century, before birds were recognized to be dinosaurs, most of the community believed dinosaurs to have been sluggish. Most research conducted since the 1970s, however, has indicated that all dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction. The large sizes of some groups, as well as their seemingly monstrous and fantastic nature, have ensured dinosaurs regular appearance in best-selling books and films. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, the term is derived from the Greek words δεινός and σαῦρος. Though the taxonomic name has often interpreted as a reference to dinosaurs teeth, claws. Instead, dinosaurs, like many forms of reptile sub-groups, did not exhibit characteristics which were traditionally regarded as reptilian. Under phylogenetic nomenclature, dinosaurs are usually defined as the group consisting of Triceratops, Neornithes, their most recent common ancestor, Birds are now recognized as being the sole surviving lineage of theropod dinosaurs. In traditional taxonomy, birds were considered a class that had evolved from dinosaurs
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Mammal
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Mammals are any vertebrates within the class Mammalia, a clade of endothermic amniotes distinguished from reptiles by the possession of a neocortex, hair, three middle ear bones and mammary glands. All female mammals nurse their young with milk, secreted from the mammary glands, Mammals include the largest animals on the planet, the great whales. The basic body type is a quadruped, but some mammals are adapted for life at sea, in the air, in trees. The largest group of mammals, the placentals, have a placenta, Mammals range in size from the 30–40 mm bumblebee bat to the 30-meter blue whale. With the exception of the five species of monotreme, all modern mammals give birth to live young, most mammals, including the six most species-rich orders, belong to the placental group. The largest orders are the rodents, bats and Soricomorpha, the next three biggest orders, depending on the biological classification scheme used, are the Primates, the Cetartiodactyla, and the Carnivora. Living mammals are divided into the Yinotheria and Theriiformes There are around 5450 species of mammal, in some classifications, extant mammals are divided into two subclasses, the Prototheria, that is, the order Monotremata, and the Theria, or the infraclasses Metatheria and Eutheria. The marsupials constitute the group of the Metatheria, and include all living metatherians as well as many extinct ones. Much of the changes reflect the advances of cladistic analysis and molecular genetics, findings from molecular genetics, for example, have prompted adopting new groups, such as the Afrotheria, and abandoning traditional groups, such as the Insectivora. The mammals represent the only living Synapsida, which together with the Sauropsida form the Amniota clade, the early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period, this group diverged from the line that led to todays reptiles. Some mammals are intelligent, with some possessing large brains, self-awareness, Mammals can communicate and vocalize in several different ways, including the production of ultrasound, scent-marking, alarm signals, singing, and echolocation. Mammals can organize themselves into fission-fusion societies, harems, and hierarchies, most mammals are polygynous, but some can be monogamous or polyandrous. They provided, and continue to provide, power for transport and agriculture, as well as commodities such as meat, dairy products, wool. Mammals are hunted or raced for sport, and are used as model organisms in science, Mammals have been depicted in art since Palaeolithic times, and appear in literature, film, mythology, and religion. Defaunation of mammals is primarily driven by anthropogenic factors, such as poaching and habitat destruction, Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is accepted, McKenna & Bell and Wilson & Reader provide useful recent compendiums. Though field work gradually made Simpsons classification outdated, it remains the closest thing to a classification of mammals
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Birds
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Birds live worldwide and range in size from the 5 cm bee hummingbird to the 2.75 m ostrich. They rank as the class of tetrapods with the most living species, at ten thousand. As a subgroup of Reptilia, birds are the closest living relatives of crocodilians, while birds, the fossil record indicates that birds are also the last surviving representatives of dinosauria, having evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago, dNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Palaeogene extinction event which killed off all other dinosaur lineages. Birds, especially those in the continents, survived this event. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period. Birds have wings which are more or less developed depending on the species, the digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have evolved for swimming. Many species annually migrate great distances, Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of species are socially monogamous, usually for one breeding season at a time, sometimes for years. Other species have breeding systems that are polygynous or, rarely, Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents, most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilised, songbirds, parrots, and other species are popular as pets. Guano is harvested for use as a fertiliser, Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry, the first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae. Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system currently in use, Birds are categorised as the biological class Aves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda, Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria
40.
Flowering plants
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The flowering plants, also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 416 families, approx. 13,164 known genera and a total of c.295,383 known species, etymologically, angiosperm means a plant that produces seeds within an enclosure, in other words, a fruiting plant. The term angiosperm comes from the Greek composite word meaning enclosed seeds, the ancestors of flowering plants diverged from gymnosperms in the Triassic Period, during the range 245 to 202 million years ago, and the first flowering plants are known from 160 mya. They diversified extensively during the Lower Cretaceous, became widespread by 120 mya, angiosperms differ from other seed plants in several ways, described in the table. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, the amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms. The vascular bundles of the stem are arranged such that the xylem and phloem form concentric rings, in the dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium, the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Among the monocotyledons, the bundles are more numerous in the stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases, the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species, the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf, occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. There are two kinds of cells produced by flowers. Microspores, which divide to become pollen grains, are the male cells and are borne in the stamens. The female cells called megaspores, which divide to become the egg cell, are contained in the ovule. The flower may consist only of parts, as in willow. Usually, other structures are present and serve to protect the sporophylls, the individual members of these surrounding structures are known as sepals and petals. The outer series is usually green and leaf-like, and functions to protect the rest of the flower, the inner series is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators, attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower
41.
Mass extinction
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An extinction event is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a change in the diversity. It occurs when the rate of extinction increases with respect to the rate of speciation, Extinction occurs at an uneven rate. Based on the record, the background rate of extinctions on Earth is about two to five taxonomic families of marine animals every million years. Marine fossils are used to measure extinction rates because of their superior fossil record. The Great Oxygenation Event was probably the first major extinction event, since the Cambrian explosion five further major mass extinctions have significantly exceeded the background extinction rate. In addition to the five mass extinctions, there are numerous minor ones as well. Mass extinctions seem to be a mainly Phanerozoic phenomenon, with extinction rates low before large complex organisms arose, estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from the chosen for describing an extinction event as major. In a landmark paper published in 1982, Jack Sepkoski and David M. Raup identified five mass extinctions, the Big Five cannot be so clearly defined, but rather appear to represent the largest of a relatively smooth continuum of extinction events. Cretaceous–Paleogene extinction event,66 Ma at the Cretaceous -Paleogene transition interval, the event formerly called the Cretaceous-Tertiary or K–T extinction or K-T boundary is now officially named the Cretaceous–Paleogene extinction event. About 17% of all families, 50% of all genera and 75% of all species became extinct, in the seas all the ammonites, plesiosaurs and mosasaurs disappeared and the percentage of sessile animals was reduced to about 33%. All non-avian dinosaurs became extinct during that time, the boundary event was severe with a significant amount of variability in the rate of extinction between and among different clades. Mammals and birds, the latter descended from dinosaurs, emerged as dominant large land animals. Triassic–Jurassic extinction event,201.3 Ma at the Triassic-Jurassic transition, about 23% of all families, 48% of all genera and 70% to 75% of all species became extinct. Most non-dinosaurian archosaurs, most therapsids, and most of the amphibians were eliminated. Non-dinosaurian archosaurs continued to dominate aquatic environments, while non-archosaurian diapsids continued to dominate marine environments, the Temnospondyl lineage of large amphibians also survived until the Cretaceous in Australia. Permian–Triassic extinction event,252 Ma at the Permian-Triassic transition, Earths largest extinction killed 57% of all families, 83% of all genera and 90% to 96% of all species
42.
Pterosaur
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Pterosaurs were flying reptiles of the extinct clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous, Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, Early species had long, fully toothed jaws and long tails, while later forms had a highly reduced tail, and some lacked teeth. Many sported furry coats made up of hair-like filaments known as pycnofibers, Pterosaurs spanned a wide range of adult sizes, from the very small anurognathids to the largest known flying creatures of all time, including Quetzalcoatlus and Hatzegopteryx. Pterosaurs are often referred to in the media and by the general public as flying dinosaurs. Like the dinosaurs, and unlike these other reptiles, pterosaurs are more related to birds than to crocodiles or any other living reptile. Pterosaurs are also referred to as pterodactyls, particularly in fiction. Technically, Pterodactyl refers only to members of the genus Pterodactylus, the anatomy of pterosaurs was highly modified from their reptilian ancestors by the adaption to flight. Pterosaur bones were hollow and air-filled, like the bones of birds and they had a keeled breastbone that was developed for the attachment of flight muscles and an enlarged brain that shows specialised features associated with flight. In some later pterosaurs, the backbone over the shoulders fused into a known as a notarium, which served to stiffen the torso during flight. Pterosaur wings were formed by membranes of skin and other tissues, the primary membranes attached to the extremely long fourth finger of each arm and extended along the sides of the body to the ankles. The outer wings were strengthened by closely spaced fibers called actinofibrils, the actinofibrils themselves consisted of three distinct layers in the wing, forming a crisscross pattern when superimposed on one another. The function of the actinofibrils is unknown, as is the material from which they were made. Depending on their composition, they may have been stiffening or strengthening agents in the outer part of the wing. The wing membranes also contained a layer of muscle, fibrous tissue. The pterosaur wing membrane is divided into three basic units, the first, called the propatagium, was the forward-most part of the wing and attached between the wrist and shoulder, creating the leading edge during flight. This membrane may have incorporated the first three fingers of the hand, as evidenced in some specimens, the brachiopatagium was the primary component of the wing, stretching from the highly elongated fourth finger of the hand to the hind limbs. It is generally agreed though that non-pterodactyloid pterosaurs had a broader uro/cruropatagium, a bone unique to pterosaurs, known as the pteroid, connected to the wrist and helped to support a forward membrane between the wrist and shoulder
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Cenozoic
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The Cenozoic Era is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and covering the period from 66 million years ago to the present day. The Cenozoic is also known as the Age of Mammals, because of the mammals that dominated, such as Entelodont, Paraceratherium. The extinction of many large groups such as non-avian dinosaurs, Plesiosauria and Pterosauria allowed the mammals and birds to greatly diversify. Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including mammals, birds, reptiles. From a geological perspective, it did not take long for mammals, some flightless birds grew larger than humans. These species are referred to as terror birds, and were formidable predators. Mammals came to occupy almost every available niche, and some also grew very large, the Earths climate had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, and partially offset by the Paleocene-Eocene Thermal Maximum. The continents also began looking roughly familiar at this time and moved into their current positions. The Cenozoic is divided into three periods, the Paleogene, Neogene, and Quaternary, and seven epochs, the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. The common use of epochs during the Cenozoic helps paleontologists better organize, there is also more detailed knowledge of this era than any other because of the relatively young, well-preserved rocks associated with it. The Paleogene spans from the extinction of dinosaurs,66 million years ago. It features three epochs, the Paleocene, Eocene and Oligocene, the Paleocene ranged from 66 million to 56 million years ago. The Paleocene is a point between the devastation that is the K-T extinction, to the rich jungles environment that is the Early Eocene. The Early Paleocene saw the recovery of the earth, the continents began to take their modern shape, but all the continents and subcontinent India were separated from each other. Afro-Eurasia was separated by the Tethys Sea, and the Americas were separated by the strait of Panama and this epoch featured a general warming trend, with jungles eventually reaching the poles. The oceans were dominated by sharks as the large reptiles that had once ruled became extinct, archaic mammals filled the world such as creodonts and early primates that evolved during the Mesozoic, and as a result, there was nothing over 10 kilograms. The Eocene Epoch ranged from 56 million years to 33.9 million years ago, in the Early-Eocene, life was small and lived in cramped jungles, much like the Paleocene. There was nothing over the weight of 10 kilograms, among them were early primates, whales and horses along with many other early forms of mammals
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Jean Baptiste Julien d'Omalius d'Halloy
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Jean Baptiste Julien dOmalius dHalloy was a Belgian geologist. Born in Liège, he was the son of an ancient and noble family. After completing his studies in his home town he was sent to Paris in 1801 by his parents to avail himself of the social. A lively interest, however, in geology awakened by the works of Buffon, directed his steps to the museums and he visited Paris again in 1803 and 1805, and during these periods attended the lectures of Fourcroy, Lacépède, and Georges Cuvier. His homeward journeys were made the occasion of a geological expedition through northern France. As early as 1808 he communicated to the Journal des Mines a paper entitled Essai sur la geologie du Nord de la France and he thus conceived the project of making a series of surveys throughout the whole country. This was furthered by a commission to execute a geological map of the empire which brought with it exemption from military duty and he devoted himself energetically to the work and by 1813 had traversed over 15,500 miles in France and portions of Italy. His family had, however, but little sympathy with his geological activity, the map which he had made of France and the neighbouring territories was not published until 1822 and served as a basis for the more detailed surveys of Armand Dufrénoy and Elie de Beaumont. After having served as sous-intendant of the arrondissement of Dinant and general secretary of the province of Liège and he held this office until after the Revolution of 1830. He was elected a member of the Belgian Senate in 1848, became its vice-president in 1851, was made a member of the Academy of Brussels in 1816 and this included dHalloy – In 1846 the veteran geologist M. J. In his later years he gave attention to questions of ethnology. His death was hastened by the exertions of an expedition undertaken alone in his ninety-first year. He died in Brussels on January 15,1875, Halloy was one of the pioneers of modern geology, and in particular laid the foundation of geological knowledge over wide areas. He made important studies in the Carboniferous districts of Belgium and the Rhine provinces and he was a practical Catholic during his long and active life, and was characterized by his loyalty and devotion to the Church. He insisted on the harmony between faith and science, making this the subject of his oration on the occasion of the jubilee of the Belgian Academy in 1866. In this last book, Halloy established a classification according to skin colour. He was an member of the Belgian Academy of Sciences from 1816. He was likewise president of the Geological Society of France in 1852 and he studied also in detail the Tertiary deposits of the Paris Basin, and ascertained the extent of the Cretaceous and some of the older strata, which he for the first time clearly depicted on a map
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Stratum
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In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers. The stratum is the unit in a stratigraphic column and forms the basis of the study of stratigraphy. Each layer is one of a number of parallel layers that lie one upon another. They may extend over hundreds of thousands of kilometers of the Earths surface. Strata are typically seen as bands of different colored or differently structured material exposed in cliffs, road cuts, quarries, individual bands may vary in thickness from a few millimeters to a kilometer or more. Each band represents a mode of deposition, river silt, beach sand, coal swamp, sand dune, lava bed. Geologists study rock strata and categorize them by the material of beds, each distinct layer is typically assigned to the name of sheet, usually based on a town, river, mountain, or region where the formation is exposed and available for study. For example, the Burgess Shale is an exposure of dark, occasionally fossiliferous. Slight distinctions in material in a formation may be described as members, formations are collected into groups while groups may be collected into supergroups. Archaeological horizon Geologic formation Geologic map Geologic unit Law of superposition Bed GeoWhen Database
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"Cretaceous System". Encyclopædia Britannica. 7 (11th ed.). 1911. pp. 414–418.
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