1.
Early Triassic
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The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 252.17 Ma and 247.2 Ma, rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era and is divided into the Induan and Olenekian ages, the Lower Triassic series is coeval with the Scythian stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein, the Permian-Triassic extinction event spawned the Triassic period. The massive extinctions that ended the Permian period and Paleozoic era caused extreme hardships for the surviving species, many types of corals, brachiopods, molluscs, echinoderms, and other invertebrates had completely disappeared. The most common Early Triassic hard-shelled marine invertebrates were bivalves, gastropods, ammonites, echinoids, the most common land vertebrate was the small herbivorous synapsid Lystrosaurus. Early Triassic faunas lacked biodiversity and were relatively homogenous throughout the epoch due to the effects of the extinction, the climate during the Early Triassic epoch was generally arid, rainless and dry and deserts were widespread, however the poles possessed a temperate climate. Until recently the existence of an event about 3 million years following the end-Permian extinctions was not recognised. Large and mobile species disappeared from the tropics, and amongst the species such as molluscs only the ones that could cope with the heat survived. On land the tropics were practically devoid of life, big, active animals only returned to the tropics, and plants recolonised on land when temperatures returned to normal around 247 million years ago. Geologic time scale GeoWhen Database - Early Triassic Palaeos scotese
2.
Megaannum
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A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earths axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the globe, four seasons are recognized, spring, summer, autumn. In tropical and subtropical regions several geographical sectors do not present defined seasons, but in the seasonal tropics, a calendar year is an approximation of the number of days of the Earths orbital period as counted in a given calendar. The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a year of 366 days, as do the Julian calendars. For the Gregorian calendar the average length of the year across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a to represent a year of either 365 or 366 days, in English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time, it is defined as 365.25 days of exactly 86400 seconds, totalling exactly 31557600 seconds in the Julian astronomical year. The word year is used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year. Similarly, year can mean the period of any planet, for example. The term can also be used in reference to any long period or cycle, west Saxon ġēar, Anglian ġēr continues Proto-Germanic *jǣran. Cognates are German Jahr, Old High German jār, Old Norse ár and Gothic jer, all the descendants of the Proto-Indo-European noun *yeh₁rom year, season. Cognates also descended from the same Proto-Indo-European noun are Avestan yārǝ year, Greek ὥρα year, season, period of time, Old Church Slavonic jarŭ, Latin annus is from a PIE noun *h₂et-no-, which also yielded Gothic aþn year. Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, the Greek word for year, ἔτος, is cognate with Latin vetus old, from the PIE word *wetos- year, also preserved in this meaning in Sanskrit vat-sa- yearling and vat-sa-ras year. Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc. per annum means each year, anno Domini means in the year of the Lord. No astronomical year has an number of days or lunar months. Financial and scientific calculations often use a 365-day calendar to simplify daily rates, in the Julian calendar, the average length of a year is 365.25 days. In a non-leap year, there are 365 days, in a year there are 366 days
3.
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
4.
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
5.
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
6.
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
7.
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
8.
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
9.
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
10.
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
11.
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
12.
Cretaceous
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The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 Mya. It is the last period of the Mesozoic Era, the Cretaceous Period is usually abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists, during this time, new groups of mammals and birds, as well as flowering plants, appeared. The Cretaceous ended with a mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, the name Cretaceous was derived from Latin creta, meaning chalk. The Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series, in older literature the Cretaceous is sometimes divided into three series, Neocomian, Gallic and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide, in many parts of the world, alternative local subdivisions are still in use. As with other geologic periods, the rock beds of the Cretaceous are well identified. No great extinction or burst of diversity separates the Cretaceous from the Jurassic and this layer has been dated at 66.043 Ma. A140 Ma age for the Jurassic-Cretaceous boundary instead of the usually accepted 145 Ma was proposed in 2014 based on a study of Vaca Muerta Formation in Neuquén Basin. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a first step toward formally changing the age in the International Union of Geological Sciences, due to the high sea level there was extensive space for such sedimentation. Because of the young age and great thickness of the system. Chalk is a type characteristic for the Cretaceous. It consists of coccoliths, microscopically small calcite skeletons of coccolithophores, the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not easily consolidated and the Chalk Group still consists of sediments in many places. The group also has other limestones and arenites, among the fossils it contains are sea urchins, belemnites, ammonites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls
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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
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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
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Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
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Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
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Chordate
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Chordates are deuterostomes, as during the embryo development stage the anus forms before the mouth. They are also bilaterally symmetric coelomates, in the case of vertebrate chordates, the notochord is usually replaced by a vertebral column during development, and they may have body plans organized via segmentation. There are also additional extinct taxa, the Vertebrata are sometimes considered as a subgroup of the clade Craniata, consisting of chordates with a skull, the Craniata and Tunicata compose the clade Olfactores. Of the more than 65,000 living species of chordates, the worlds largest and fastest animals, the blue whale and peregrine falcon respectively, are chordates, as are humans. Fossil chordates are known from at least as early as the Cambrian explosion, Hemichordata, which includes the acorn worms, has been presented as a fourth chordate subphylum, but it now is usually treated as a separate phylum. The Hemichordata, along with the Echinodermata, form the Ambulacraria, the Chordata and Ambulacraria form the superphylum Deuterostomia, composed of the deuterostomes. Attempts to work out the relationships of the chordates have produced several hypotheses. All of the earliest chordate fossils have found in the Early Cambrian Chengjiang fauna. Because the fossil record of early chordates is poor, only molecular phylogenetics offers a prospect of dating their emergence. However, the use of molecular phylogenetics for dating evolutionary transitions is controversial and it has also proved difficult to produce a detailed classification within the living chordates. Attempts to produce family trees shows that many of the traditional classes are paraphyletic. While this has been known since the 19th century, an insistence on only monophyletic taxa has resulted in vertebrate classification being in a state of flux. Although the name Chordata is attributed to William Bateson, it was already in prevalent use by 1880, ernst Haeckel described a taxon comprising tunicates, cephalochordates, and vertebrates in 1866. Though he used the German vernacular form, it is allowed under the ICZN code because of its subsequent latinization, among the vertebrate sub-group of chordates the notochord develops into the spine, and in wholly aquatic species this helps the animal to swim by flexing its tail. In fish and other vertebrates, this develops into the spinal cord, the pharynx is the part of the throat immediately behind the mouth. In fish, the slits are modified to form gills, a muscular tail that extends backwards behind the anus. This is a groove in the wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus and it also stores iodine, and may be a precursor of the vertebrate thyroid gland
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Amphibian
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Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. They inhabit a variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, the young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a respiratory surface and some small terrestrial salamanders and frogs lack lungs. They are superficially similar to lizards but, along with mammals and birds, reptiles are amniotes, the earliest amphibians evolved in the Devonian period from sarcopterygian fish with lungs and bony-limbed fins, features that were helpful in adapting to dry land. They diversified and became dominant during the Carboniferous and Permian periods, over time, amphibians shrank in size and decreased in diversity, leaving only the modern subclass Lissamphibia. The three modern orders of amphibians are Anura, Urodela, and Apoda, the number of known amphibian species is approximately 7,000, of which nearly 90% are frogs. The smallest amphibian in the world is a frog from New Guinea with a length of just 7.7 mm. The largest living amphibian is the 1.8 m Chinese giant salamander, the study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology. The word amphibian is derived from the Ancient Greek term ἀμφίβιος, the term was initially used as a general adjective for animals that could live on land or in water, including seals and otters. Traditionally, the class Amphibia includes all tetrapod vertebrates that are not amniotes, the numbers of species cited above follows Frost and the total number of known amphibian species is over 7,000, of which nearly 90% are frogs. With the phylogenetic classification, the taxon Labyrinthodontia has been discarded as it is a group without unique defining features apart from shared primitive characteristics. Classification varies according to the phylogeny of the author and whether they use a stem-based or a node-based classification. The phylogeny of Paleozoic amphibians is uncertain, and Lissamphibia may possibly fall within groups, like the Temnospondyli or the Lepospondyli. If the common ancestor of amphibians and amniotes is included in Amphibia, all modern amphibians are included in the subclass Lissamphibia, which is usually considered a clade, a group of species that have evolved from a common ancestor. The three modern orders are Anura, Caudata, and Gymnophiona, although the fossils of several older proto-frogs with primitive characteristics are known, the oldest true frog is Prosalirus bitis, from the Early Jurassic Kayenta Formation of Arizona. It is anatomically similar to modern frogs. The oldest known caecilian is another Early Jurassic species, Eocaecilia micropodia, the earliest salamander is Beiyanerpeton jianpingensis from the Late Jurassic of northeastern China
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Binomial nomenclature
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Such a name is called a binomial name, a binomen, binominal name or a scientific name, more informally it is also called a Latin name. The first part of the name identifies the genus to which the species belongs, for example, humans belong to the genus Homo and within this genus to the species Homo sapiens. The formal introduction of system of naming species is credited to Carl Linnaeus. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus. Although the general principles underlying binomial nomenclature are common to these two codes, there are differences, both in the terminology they use and in their precise rules. Similarly, both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a name is usually given, at least when it is first mentioned. In zoology Patella vulgata Linnaeus,1758, the original name given by Linnaeus was Fringilla domestica, the parentheses indicate that the species is now considered to belong in a different genus. The ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, in botany Amaranthus retroflexus L. – L. is the standard abbreviation used in botany for Linnaeus. – Linnaeus first named this bluebell species Scilla italica, Rothmaler transferred it to the genus Hyacinthoides, the ICN does not require that the dates of either publication be specified. Prior to the adoption of the binomial system of naming species. Together they formed a system of polynomial nomenclature and these names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description, such polynomial names may sometimes look like binomials, but are significantly different. For example, Gerards herbal describes various kinds of spiderwort, The first is called Phalangium ramosum, Branched Spiderwort, is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia. The Latin phrases are short descriptions, rather than identifying labels, the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné. It was in his 1753 Species Plantarum that he first began using a one-word trivial name together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as an epithet or specific name
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Salientia
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The oldest fossil proto-frog appeared in the early Triassic of Madagascar, but molecular clock dating suggests their origins may extend further back to the Permian,265 million years ago. Very few fossils of early salientians have been found, which makes defining the characteristics of the group, the early proto-frogs developed from temnospondylid ancestors in which some of the elements of their vertebrae remained separate. The structure of the pelvis and hind limb was probably developed for swimming rather than jumping. From the structure of the vertebrae, the group not to be monophyletic. The evolution of salientians seems to have rapid and radiative. The essential features of recent groupings seem to have been established during the Mesozoic or early Tertiary, the origins and evolutionary relationships between the three main groups of amphibians are hotly debated. This would help account for the scarcity of amphibian fossils from the period before the groups split. The neobatrachians seemed to have originated in Africa/India, the salamanders in East Asia, other researchers, while agreeing with the main thrust of this study, questioned the choice of calibration points used to synchronise the data. They proposed that the date of lissamphibian diversification be put in the Permian, rather less than 300 million years ago, the study postulated the Lissamphibia originated no earlier than the late Carboniferous, some 290 to 305 million years ago. The split between Anura and Caudata was estimated as taking place 292 million years ago, rather later than most molecular studies suggest, in 2008, Gerobatrachus hottoni, a temnospondyl with many frog- and salamander-like characteristics, was discovered in Texas. However, others have suggested that Gerobatrachus hottoni was only a dissorophoid temnospondyl unrelated to extant amphibians, the skull of Triadobatrachus is frog-like, being broad with large eye sockets, but the fossil has features diverging from modern frogs. These include a body with more vertebrae. The tail has separate vertebrae, unlike the fused urostyle or coccyx found in modern frogs, the tibia and fibula bones are also separate, making it probable that Triadobatrachus was not an efficient leaper. The Salientia are a group including modern frogs in the order Anura. The earliest salientian yet discovered is Triadobatrachus massinoti, known from a fossil specimen found in Madagascar. It dates back to the Early Triassic, about 250 million years ago and it had many frog-like features, but had 14 presacral vertebrae, while modern frogs have nine or 10. Previous fossil amphibians had many more vertebrae than this and T. massinoti provides a missing link between salamanders and frogs. Czatkobatrachus is another proto-frog with some similar to Triadobatrachus
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Frog
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A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura. The oldest fossil proto-frog appeared in the early Triassic of Madagascar, Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforests. There are approximately 4,800 recorded species, accounting for over 85% of extant amphibian species and they are also one of the five most diverse vertebrate orders. The body plan of a frog is generally characterized by a stout body, protruding eyes, cleft tongue, limbs folded underneath. Besides living in water and on dry land, the adults of some species are adapted for living underground or in trees. The skin of the frog is glandular, with secretions ranging from distasteful to toxic, Frogs skins vary in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to advertise toxicity and warn off predators. Frogs typically lay their eggs in water, the eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets, the life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage, adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on fruit. Frogs are extremely efficient at converting what they eat into body mass and they are an important food source for predators and part of the food web dynamics of many of the worlds ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they live in moist places or have special adaptations to deal with dry habitats. Frogs are valued as food by humans and also have many roles in literature, symbolism. Frog populations have declined significantly since the 1950s, more than one third of species are considered to be threatened with extinction and over one hundred and twenty are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and a fungal disease. Conservation biologists are working to understand the causes of these problems, the name frog derives from Old English frogga, abbreviated to frox, forsc, and frosc, probably deriving from Proto-Indo-European preu = to jump. About 88% of amphibian species are classified in the order Anura and these include around 4,810 species in 33 families, of which the Leptodactylidae, Hylidae and Ranidae are the richest in species. The use of the common frog and toad has no taxonomic justification. From a classification perspective, all members of the order Anura are frogs, there are numerous exceptions to this rule
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Transitional fossil
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A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. This is especially important where the descendant group is sharply differentiated by gross anatomy and these fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation. Because of the incompleteness of the record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. Therefore, it cannot be assumed that transitional fossils are direct ancestors of more recent groups, in 1859, when Charles Darwins On the Origin of Species was first published, the fossil record was poorly known. Indeed, Archaeopteryx was discovered just two later, in 1861, and represents a classic transitional form between dinosaurs and birds. Many more transitional fossils have been discovered since then, and there is now abundant evidence of how all classes of vertebrates are related, specific examples include humans and other primates, tetrapods and fish, and birds and dinosaurs. The term missing link has been used extensively in popular writings on evolution to refer to a perceived gap in the hominid evolutionary record. It is most commonly used to refer to any new transitional fossil finds, scientists, however, do not use the term, as it refers to a pre-evolutionary view of nature. Transitional forms are seen as falling between the groups in terms of anatomy, having a mixture of characteristics from inside and outside the newly branched clade. With the establishment of cladistics in the 1990s, relationships commonly came to be expressed in cladograms that illustrate the branching of the lineages in stick-like figures. The different so-called natural or monophyletic groups form nested units, while in traditional classification tetrapods and fish are seen as two different groups, phylogenetically tetrapods are considered a branch of fish. Thus, with there is no longer a transition between established groups, and the term transitional fossils is a misnomer. Differentiation occurs within groups, represented as branches in the cladogram, such early representatives of a group are usually termed basal taxa or sister taxa, depending on whether the fossil organism belongs to the daughter clade or not. A source of confusion is the notion that a transitional form between two different taxonomic groups must be an ancestor of one or both groups. The difficulty is exacerbated by the fact one of the goals of evolutionary taxonomy is to identify taxa that were ancestors of other taxa. However, it is almost impossible to be sure that any form represented in the record is a direct ancestor of any other. Archaeopteryx is a genus of theropod dinosaur closely related to the birds, similar in shape to a European magpie, with the largest individuals possibly attaining the size of a raven, Archaeopteryx could grow to about 0.5 metres in length. Despite its small size, broad wings, and inferred ability to fly or glide and these features make Archaeopteryx a clear candidate for a transitional fossil between dinosaurs and birds, making it important in the study both of dinosaurs and of the origin of birds
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Madagascar
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Madagascar, officially the Republic of Madagascar, and previously known as the Malagasy Republic, is an island country in the Indian Ocean, off the coast of Southeast Africa. The nation comprises the island of Madagascar, and numerous smaller peripheral islands, consequently, Madagascar is a biodiversity hotspot, over 90% of its wildlife is found nowhere else on Earth. The islands diverse ecosystems and unique wildlife are threatened by the encroachment of the growing human population. The first archaeological evidence for human foraging on Madagascar dates to 2000 BC, human settlement of Madagascar occurred between 350 BC and AD550 by Austronesian peoples arriving on outrigger canoes from Borneo. These were joined around AD1000 by Bantu migrants crossing the Mozambique Channel from East Africa, other groups continued to settle on Madagascar over time, each one making lasting contributions to Malagasy cultural life. The Malagasy ethnic group is divided into 18 or more sub-groups of which the largest are the Merina of the central highlands. Until the late 18th century, the island of Madagascar was ruled by an assortment of shifting sociopolitical alliances. Beginning in the early 19th century, most of the island was united and ruled as the Kingdom of Madagascar by a series of Merina nobles, the monarchy collapsed in 1897 when the island was absorbed into the French colonial empire, from which the island gained independence in 1960. The autonomous state of Madagascar has since undergone four major constitutional periods, since 1992, the nation has officially been governed as a constitutional democracy from its capital at Antananarivo. However, in an uprising in 2009, president Marc Ravalomanana was made to resign. Constitutional governance was restored in January 2014, when Hery Rajaonarimampianina was named president following a 2013 election deemed fair, Madagascar is a member of the United Nations, the Organisation Internationale de la Francophonie and the Southern African Development Community. Madagascar belongs to the group of least developed countries, according to the United Nations, Malagasy and French are both official languages of the state. The majority of the population adheres to traditional beliefs, Christianity, ecotourism and agriculture, paired with greater investments in education, health, and private enterprise, are key elements of Madagascars development strategy. As of 2017, the economy has been weakened by the 2009-2013 political crisis, in the Malagasy language, the island of Madagascar is called Madagasikara and its people are referred to as Malagasy. The islands appellation Madagascar is not of origin, but rather was popularized in the Middle Ages by Europeans. On St. Laurences Day in 1500, Portuguese explorer Diogo Dias landed on the island, polos name was preferred and popularized on Renaissance maps. At 592,800 square kilometres, Madagascar is the worlds 47th largest country, the country lies mostly between latitudes 12°S and 26°S, and longitudes 43°E and 51°E. Neighboring islands include the French territory of Réunion and the country of Mauritius to the east, as well as the state of Comoros, the nearest mainland state is Mozambique, located to the west
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Vertebra
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The basic configuration of a vertebra varies, the large part is the body, and the central part is the centrum. The upper and lower surfaces of the vertebra body give attachment to the intervertebral discs, the posterior part of a vertebra forms a vertebral arch, in eleven parts, consisting of two pedicles, two laminae, and seven processes. The laminae give attachment to the ligamenta flava, there are vertebral notches formed from the shape of the pedicles, which form the intervertebral foramina when the vertebrae articulate. These foramina are the entry and exit conducts for the spinal nerves, the body of the vertebra and the vertebral arch form the vertebral foramen, the larger, central opening that accommodates the spinal canal, which encloses and protects the spinal cord. Vertebrae articulate with other to give strength and flexibility to the spinal column. Structurally, vertebrae are essentially alike across the species, with the greatest difference seen between an aquatic animal and other vertebrate animals. As such, vertebrates take their name from the vertebrae that compose the vertebral column, each vertebra is an irregular bone. The size of the vertebrae varies according to placement in the column, spinal loading, posture. Along the length of the spine the vertebrae change to different needs related to stress. Every vertebra has a body, which consists of a large anterior middle portion called the centrum, the body is composed of cancellous bone, which is the spongy type of osseous tissue, whose micro-anatomy has been specifically studied within the pedicle bones. This cancellous bone is in turn, covered by a coating of cortical bone. The vertebral arch and processes have thicker coverings of cortical bone, the upper and lower surfaces of the body of the vertebra are flattened and rough in order to give attachment to the intervertebral discs. These surfaces are the vertebral endplates which are in contact with the intervertebral discs. The endplates are formed from a layer of the cancellous bone of the vertebral body. The endplates function to contain the adjacent discs, to spread the applied loads. They also act as an interface for the exchange of water. The vertebral arch is formed by pedicles and laminae, two pedicles extend from the sides of the vertebral body to join the body to the arch. The pedicles are short thick processes that extend, one each side, posteriorly, from the junctions of the posteriolateral surfaces of the centrum
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Skull
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The skull is a bony structure that forms the head of the skeleton in most vertebrates. It supports the structures of the face and provides a cavity for the brain. The skull is composed of two parts, the cranium and the mandible, in the human these two parts are the neurocranium and the viscerocranium or facial skeleton that includes the mandible as its largest bone. The skull forms the anterior most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, in the human these sensory structures are part of the facial skeleton. In some animals such as horned ungulates, the skull also has a function by providing the mount for the horns. The English word skull is probably derived from Old Norse skulle, while the Latin word cranium comes from the Greek root κρανίον, the skull is made up of a number of fused flat bones, and contains many foramina and processes, and several cavities or sinuses. For details and the constituent bones, see neurocranium and viscerocranium, the human skull is the bony structure that forms the head in the human skeleton. It supports the structures of the face and forms a cavity for the brain, like the skulls of other vertebrates, it protects the brain from injury. The skull consists of two parts, of different embryological origin—the neurocranium and the facial skeleton, the neurocranium forms the protective cranial cavity that surrounds and houses the brain and brainstem. The facial skeleton is formed by the supporting the face. Except for the mandible, all of the bones of the skull are joined together by sutures—synarthrodial joints formed by bony ossification, sometimes there can be extra bone pieces within the suture known as wormian bones or sutural bones. The human skull is considered to consist of twenty-two bones—eight cranial bones. In the neurocranium these are the bone, two temporal bones, two parietal bones, the sphenoid, ethmoid and frontal bones. The bones of the skeleton are the vomer, two nasal conchae, two nasal bones, two maxilla, the mandible, two palatine bones, two zygomatic bones, and two lacrimal bones. Some of these bones—the occipital, parietal, frontal, in the neurocranium, and the nasal, lacrimal, the skull also contains sinus cavities and numerous foramina. The sinuses are lined with respiratory epithelium and their known functions are the lessening of the weight of the skull, the aiding of resonance to the voice and the warming and moistening of the air drawn through the nasal cavity. The foramina are openings in the skull, the largest of these is the foramen magnum that allows the passage of the spinal cord as well as nerves and blood vessels. The many processes of the include the mastoid process and the zygomatic process
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Prosalirus
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Prosalirus bitis is the name given to a prehistoric frog found fossilized in Arizona in 1981 by Farish Jenkins. Geographica, Jurassic Frog hops into the book, National Geographic, August 1996. The skeleton has primitive features, but has mostly lost the salamander-like traits of its ancestors and it has a skeleton designed to absorb the force of jumping with its hind legs and tail. It also has long hip bones, long leg bones, and long ankle bones, all similar to modern frogs. The name comes from the Latin verb prosalire, meaning to leap forward and it is thought to have lived during the Early Jurassic epoch 190 million years ago, well before the first known modern frog, Callobatrachus. As of 2009, only three Prosalirus skeletons have been discovered
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Early Jurassic
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The Early Jurassic epoch is the earliest of three epochs of the Jurassic period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event,201.3 Ma, certain rocks of marine origin of this age in Europe are called Lias and that name was used for the period, as well, in 19th century geology. In southern Germany rocks of this age are called Black Jurassic, there are extensive Liassic outcrops around the coast of the United Kingdom, in particular in Glamorgan, North Yorkshire and Dorset. The Jurassic Coast of Dorset is often associated with the work of Mary Anning of Lyme Regis. The facies of the Lower Jurassic in this area are predominantly of clays, thin limestones and siltstones, Lias Group strata form imposing cliffs on the Vale of Glamorgan coast, in southern Wales. There has been debate over the actual base of the Hettangian stage. If this biostratigraphical indicator is used, then technically the Lias Group—a lithostratigraphical division—spans the Jurassic / Triassic boundary, during this period, ammonoids, which had almost died out at the end-of-Triassic extinction, radiated out into a huge diversity of new forms with complex suture patterns. Ammonites evolved so rapidly, and their shells are so often preserved, there were several distinct waves of ammonite evolution in Europe alone. The Early Jurassic was an important time in the evolution of the marine reptiles, all these plesiosaurs had medium-sized necks and large heads. In the Toarcian, at the end of the Early Jurassic, accompanying them as small carnivores were the sphenosuchian and protosuchid crocodilians. In the air, new types of pterosaurs replaced those that had died out at the end of the Triassic, but in the undergrowth were various types of early mammals, as well as tritylodont mammal-like reptiles, lizard-like sphenodonts, and early Lissamphibians. Late Triassic Toarcian turnover Davies, A. M, an Introduction to Palaeontology, Thomas Murby & Co. Geology of The Dorset Coast, The Geologists Association, simms, M. J. Chidlaw, N. Morton, N. and Page, K. N. British Lower Jurassic Stratigraphy, Geological Conservation Review Series, No,30, Joint Nature Conservation Committee, Peterborough. Early Jurassic Period – The Lias epoch, informative lecture notes by Dr. Paul Olsen
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International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
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Wikidata
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Wikidata is a collaboratively edited knowledge base operated by the Wikimedia Foundation. It is intended to provide a source of data which can be used by Wikimedia projects such as Wikipedia. This is similar to the way Wikimedia Commons provides storage for files and access to those files for all Wikimedia projects. Wikidata is powered by the software Wikibase, Wikidata is a document-oriented database, focused on items. Each item represents a topic and is identified by a number, prefixed with the letter Q—for example. This enables the basic information required to identify the topic the item covers to be translated without favouring any language, information is added to items by creating statements. Statements take the form of pairs, with each statement consisting of a property. The creation of the project was funded by donations from the Allen Institute for Artificial Intelligence, the Gordon and Betty Moore Foundation, at this time, only the first phase was available. Historically, a Wikipedia article would include a list of links, being links to articles on the same topic in other editions of Wikipedia. Initially, Wikidata was a repository of interlanguage links. No Wikipedia language editions were able to access Wikidata, so they needed to continue to maintain their own lists of interlanguage links, on 14 January 2013, the Hungarian Wikipedia became the first to enable the provision of interlanguage links via Wikidata. This functionality was extended to the Hebrew and Italian Wikipedias on 30 January, to the English Wikipedia on 13 February, on 23 September 2013, phase 1 went live on Wikimedia Commons. The first aspects of the second phase were deployed on 4 February 2013, the values were initially limited to two data types, with more data types to follow later. The first new type, string, was deployed on 6 March, the ability of the various language editions of Wikipedia to access data added to Wikidata as part of phase two was rolled out progressively between 27 March and 25 April 2013. On 16 September 2015, Wikidata began allowing so-called arbitrary access, for example, in the past the article about Berlin you could not access data about Germany, but with arbitrary access it could. On 27 April 2016 arbitrary access was activated on Wikimedia Commons, phase 3 will involve database querying and the creation of lists based on data stored on Wikidata. As of October 2016 two tools for querying Wikidata were available, AutoList and PetScan, additionally to a public SPARQL endpoint, there is concern that the project is being influenced by lobbying companies, PR professionals and search engine optimizers. As of December 2015, according to Wikimedia statistics, half of the information in Wikidata is unsourced, another 30% is labeled as having come from Wikipedia, but with no indication as to which article
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Global Biodiversity Information Facility
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The Global Biodiversity Information Facility is an international organisation that focuses on making scientific data on biodiversity available via the Internet using web services. The data are provided by institutions from around the world. Data available through the GBIF portal are primarily distribution data on plants, animals, fungi, and microbes for the world, the mission of the Global Biodiversity information Facility is to facilitate free and open access to biodiversity data worldwide to underpin sustainable development. ABCD Schema Atlas of Living Australia Darwin Core Global biodiversity Pacific Biodiversity Information Forum GBIF website Short description of GBIF
