1.
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
2.
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
3.
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
4.
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
5.
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
6.
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
7.
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
8.
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
9.
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
10.
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
11.
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
12.
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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Paleocene
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The Paleocene or Palaeocene, the old recent, is a geologic epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Paleogene Period in the modern Cenozoic Era, as with many geologic periods, the strata that define the epochs beginning and end are well identified, but the exact ages remain uncertain. The Paleocene Epoch brackets two major events in Earths history and it started with the mass extinction event at the end of the Cretaceous, known as the Cretaceous–Paleogene boundary. This was a marked by the demise of non-avian dinosaurs, giant marine reptiles and much other fauna. The die-off of the dinosaurs left unfilled ecological niches worldwide, the Paleocene ended with the Paleocene–Eocene Thermal Maximum, a geologically brief interval characterized by extreme changes in climate and carbon cycling. The name Paleocene comes from Ancient Greek and refers to the old new fauna that arose during the epoch. The K–Pg boundary that marks the separation between Cretaceous and Paleocene is visible in the record of much of the Earth by a discontinuity in the fossil fauna. There is also evidence of abrupt changes in flora and fauna. There is some evidence that a substantial but very short-lived climatic change may have happened in the early decades of the Paleocene. The end of the Paleocene was also marked by a time of major change, the Paleocene–Eocene Thermal Maximum upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and a major turnover in mammals on land. The Paleocene is divided into three stages, the Danian, the Selandian and the Thanetian, as shown in the table above, additionally, the Paleocene is divided into six Mammal Paleogene zones. The early Paleocene was cooler and dryer than the preceding Cretaceous, in many ways, the Paleocene continued processes that had begun during the late Cretaceous Period. During the Paleocene, the continued to drift toward their present positions. The Laramide orogeny of the late Cretaceous continued to uplift the Rocky Mountains in the American west, africa was heading north towards Europe, slowly closing the Tethys Ocean, and India began its migration to Asia that would lead to a tectonic collision and the formation of the Himalayas. The inland seas in North America and Europe had receded by the beginning of the Paleocene, making way for new land-based flora, warm seas circulated throughout the world, including the poles. The earliest Paleocene featured a low diversity and abundance of marine life, tropical conditions gave rise to abundant marine life, including coral reefs. With the demise of marine reptiles at the end of the Cretaceous, at the end of the Cretaceous, the ammonites and many species of foraminifera became extinct. Marine fauna also came to resemble modern fauna, with only the marine mammals, terrestrial Paleocene strata immediately overlying the K–Pg boundary is in places marked by a fern spike, a bed especially rich in fern fossils
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Common toad
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It is one of a group of closely related animals that are descended from a common ancestral line of toads and which form a species complex. The toad is an animal as it usually lies hidden during the day. It becomes active at dusk and spends the night hunting for the invertebrates on which it feeds and it moves with a slow, ungainly walk or short jumps, and has greyish-brown skin covered with wart-like lumps. Although toads are usually animals, in the breeding season, large numbers of toads converge on certain breeding ponds. Eggs are laid in gelatinous strings in the water and later out into tadpoles. After several months of growth and development, these sprout limbs, the juveniles emerge from the water and remain largely terrestrial for the rest of their lives. The common toad seems to be in decline in part of its range and it is threatened by habitat loss, especially by drainage of its breeding sites, and some toads get killed on the roads as they make their annual migrations. It has long been associated in popular culture and literature with witchcraft, the common toad was first given the name Rana bufo by the Swedish biologist Carl Linnaeus in the 10th edition of Systema Naturae in 1758. In this work, he placed all the frogs and toads in the single genus Rana and it later became apparent that this genus should be divided, and in 1768, the Austrian naturalist Josephus Nicolaus Laurenti placed the common toad in the genus Bufo, naming it Bufo bufo. The toads in this genus are included in the family Bufonidae, various subspecies of B. bufo have been recognized over the years. The Caucasian toad is found in the regions of the Caucasus and was at one time classified as B. b. verrucosissima. It has a genome and differs from B. bufo morphologically and is now accepted as Bufo verrucosissimus. The spiny toad was classified as B. b. spinosus and it is found in the Mediterranean area and grows to a larger size and has a spinier skin than its more northern counterparts with which it intergrades. It is now accepted as Bufo spinosus, the Gredos toad, B. b. gredosicola, is restricted to the Sierra de Gredos, a mountain range in central Spain. It has exceptionally large paratoid glands and its colour tends to be blotched rather than uniform and it is now considered to be a synonym of Bufo spinosus. B. bufo is part of a complex, a group of closely related species which cannot be clearly demarcated. Several modern species are believed to form an ancient group of related taxa from preglacial times and these are the spiny toad, the Caucasian toad and the Japanese common toad. The European common toad seems to have more recently
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Atelopus franciscus
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Atelopus franciscus, the Central Coast stubfoot toad, is a species of toad in the family Bufonidae, endemic to the central coastal region of French Guiana. It is a common, diurnal species found near fast-flowing small streams. Many authors have suggested this taxon might be a synonym of Atelopus flavescens and it is threatened by habitat loss To attract females and to defend their territories, males of A. franciscus use advertisement calls, not visual displays as typical for Atelopus. This is somewhat unexpected, given their environment is noisy and males must acoustically compete with males of other frog species. Moreover, this species lacks a vocal sac, so can only produce low-intensity calls that propagate short distances. It also lacks external tympana and could be considered anatomically deaf, nevertheless, it has a well-developed inner ear and has been shown to respond acoustically to the calls of conspecifics in the field. Male territories are closely spaced, only 2–4 m apart on average, eggs are laid in the water
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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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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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Neobatrachia
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The Neobatrachia are a suborder of the Anura, the order of frogs and toads. This suborder is the most advanced and apomorphic of the three anuran orders alive today, hence its name, which means new frogs. It is also by far the largest of the three, its more than 5,000 different species make up over 96% of all living anurans. Neobatrachia are usually sorted into five superfamilies, but this division is also controversial, in addition, several families have been revealed to be paraphyletic and consequently split up to make them correspond to clades and thus be natural, evolutionary groups. This has approximately doubled the number of presently recognized neobatrachian families, mitochondrial phylogeny of Anura, A case study of congruent phylogenetic reconstruction using amino acid and nucleotide characters. Hoegg, Simone, Miguel Vences, Henner Brinkmann, Axel Meyer, phylogeny and comparative substitution rates of frogs inferred from sequences of three nuclear genes. San Mauro, Diego, Miguel Vences, Marina Alcobendas, Rafael Zardoya, initial diversification of living amphibians predated the breakup of Pangaea
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John Edward Gray
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John Edward Gray, FRS was a British zoologist. He was the brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray. Gray was Keeper of Zoology at the British Museum in London from 1840 until Christmas 1874 and he published several catalogues of the museum collections that included comprehensive discussions of animal groups as well as descriptions of new species. He improved the zoological collections to make them amongst the best in the world, Gray was born in Walsall, but his family soon moved to London, where Gray studied medicine. He assisted his father in writing The Natural Arrangement of British Plants, after being blackballed by the Linnean Society he turned his interest from botany to zoology. He began his career by volunteering to collect insects for the British Museum at age 15. He officially joined the Zoological Department in 1824 to help John George Children catalog the reptile collection, in 1840 he took over from Children as Keeper of Zoology, which he continued for 35 years, publishing well over 1000 papers. He named many species, genera, subfamilies, and families. During this period he collaborated with Benjamin Waterhouse Hawkins, the natural history artist. Knowsley Park, near Liverpool, had been founded by Edward Stanley, Gray married Maria Emma Smith in 1826. She helped him with his work, especially with her drawings. In 1833, he was a founder of what became the Royal Entomological Society of London, during his fifty years employed at the British Museum Gray wrote nearly 500 papers, including many descriptions of species new to science. He was also active in malacology, the study of molluscs, on his death he was buried at St Marys Church, Lewisham. 1821, On the natural arrangement of Vertebrose Animals,1824, A revision of the family Equidae. 1824, On the natural arrangement of the pulmonobranchous Mollusca, annals of Philosophy, new series 8, 107–109. 1825, A list and description of species of shells not taken notice of by Lamarck. 1825, An outline of an attempt at the disposition of the Mammalia into tribes and families with a list of the genera apparently appertaining to each tribe, narrative of a Survey of the Intertropical and Western Coasts of Australia. Performed between the years 1818 and 1822, with an Appendix, containing various subjects relating to hydrography and natural history
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Family (biology)
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In biological classification, family is one of the eight major taxonomic ranks, it is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks above the rank of genus. In vernacular usage, a family may be named one of its common members, for example, walnuts and hickory trees belong to the family Juglandaceae. What does or does not belong to a family—or whether a family should be recognized at all—are proposed and determined by practicing taxonomists. There are no rules for describing or recognizing a family. Taxonomists often take different positions about descriptions of taxa, and there may be no broad consensus across the community for some time. Some described taxa are accepted broadly and quickly, but others only rarely, if at all, the naming of families is codified by various international codes. In zoological nomenclature, the names of animals end with the suffix -idae. The concept of rank at time was not yet settled, and in the preface to the Prodromus Magnol spoke of uniting his families into larger genera. Carolus Linnaeus used the word familia in his Philosophia botanica to denote groups of plants, trees, herbs, ferns, palms. He used this term only in the section of the book. In zoology, the family as an intermediate between order and genus was introduced by Pierre André Latreille in his Précis des caractères génériques des insectes. He used families in some but not in all his orders of insects, families can be used for evolutionary, palaeontological and generic studies because they are more stable than lower taxonomic levels such as genera and species
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Toad
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Toad is a common name applied to certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and parotoid glands. In scientific taxonomy, toads are found in the families Bufonidae, Bombinatoridae, Discoglossidae, Pelobatidae, Rhinophrynidae, Scaphiopodidae, usually the largest of the bumps on the skin of a toad are those that cover the parotoid glands. The bumps are commonly called warts, but they have nothing to do with infectious warts, being fixed in size, present on healthy specimens, frogs travel from non-breeding areas to breeding areas of ponds and lakes. Bogert suggests that the call of the toads is the most important cue used by toads in the homing to ponds, toads, like many amphibians, exhibit breeding site fidelity. Individual Bufo americanus toads return to their natal ponds to breed where they are likely to encounter siblings as potential mates, although inbred examples within a species is possible, siblings rarely mate. Toads recognize and actively avoid mating with close kin, advertisement vocalizations given by males appear to serve as cues by which females recognize kin. Kin recognition thus allows avoidance of inbreeding and consequent inbreeding depression, in Kenneth Grahames 1908 novel The Wind in the Willows, Mr. Toad is a likeable and popular, if selfish and narcissistic, comic character. Mr. Toad reappears as the character in A. A. Milnes 1929 play Toad of Toad Hall. In Chinese culture, the Money Toad Jin Chan appears as a Feng Shui charm for prosperity. There is no definitive collective noun for toads, and like most collective nouns, true toad Common toad Chisholm, Hugh, ed. Toad
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Atelopus
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Atelopus is a large genus of true toads, commonly known as harlequin toads or stubfoot toads, from Central and South America, ranging as far north as Costa Rica and as far south as Bolivia. Atelopus species are small, generally brightly colored, and diurnal, most species are associated with mid-to-high elevation streams. This genus has greatly affected by amphibian declines, and many species are now considered endangered. While threatened by loss, pollution, and introduced species. New Atelopus species are discovered with some regularity, and many new species have been described in the last decade, leeanne Alonso from Conservation International, the organisation that led the expedition, said this frog may be threatened by illegal gold mining. It was described as a new subspecies of Atelopus hoogmoedi, named A. h. nassaui in 2012, Atelopus at the Encyclopedia of Life Atelopus. com - Fighting to Survive Ranas Arlequines Bufonidae
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Bufo
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Bufo is a large genus of about 150 species of true toads in the amphibian family Bufonidae. Bufo is a Latin word for toad, true toads have in common stocky figures and short legs, which make them relatively poor jumpers. As with all members of the family Bufonidae, they lack a tail and teeth and their dry skin is thick and warty. Behind their eyes, Bufo species have structures, the parotoid glands. These glands distinguish the true toads from all other tailless amphibians and they secrete a fatty, white poisonous substance which acts as a deterrent to predators. Ordinary, handling of toads is not dangerous, and does not cause warts in contradiction to folk beliefs, the poison of most if not all toads contains bufotoxin, the poison of the Colorado River toad is a potent hallucinogen containing 5-MeO-DMT and bufotenin. The poisons psychoactive effects are said to have known to pre-Columbian Native Americans. Toads can also inflate their bodies when threatened, males are usually smaller than females and possess a Bidders organ, an incomplete ovary. The adult male of many shows a dark throat. Breeding males have dark nuptial pads on their thumbs and this is a truly cosmopolitan genus, able to live under adverse conditions, and occurring around the world except in the Arctic and Antarctic, Madagascar, Australia, and New Guinea and Oceania. Two species are found in the British Isles, the toad. The former is found almost everywhere in Great Britain, but not in Ireland and it is further remarkable for the very loud croak of the males, produced by a large vocal bladder on the throat which, when inflated, is larger than the head. Several species of Bufo toads produce poison with psychoactive properties, the poison of one species contains both 5-MeO-DMT and bufotenin, while some others contain only bufotenin. Instead, the relationships between the different species are formalized by categorizing them into subgenera, such as Anaxyrus and Rhinella, Bufo is a large group, and it is usually divided into several subgenera. Frost et al. removed most of the species of former Bufo to other genera, however, other authors continue to recognize these subgroups of Bufo as subgenera. Rhinella is composed of a combination of Rhamphophryne and Chaunus, Rhinella is recognized as a distinct genus by some, although other herpetologists disagree and maintain these species as a subgenus within Bufo. Here the species of Rhinella are treated in a separate page, some authors recognize the Genus, Anaxyrus, as a subgenus of the Genus, Bufo. Anaxyrus contains 22 species found in North and Central America including the common American toad, composed of 12 species, this subgenus is found in temperate Eurasia and Japan south to North Africa, the Middle East, northeastern Myanmar, and northern Vietnam
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Australia
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Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the worlds sixth-largest country by total area, the neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north, the Solomon Islands and Vanuatu to the north-east, and New Zealand to the south-east. Australias capital is Canberra, and its largest urban area is Sydney, for about 50,000 years before the first British settlement in the late 18th century, Australia was inhabited by indigenous Australians, who spoke languages classifiable into roughly 250 groups. The population grew steadily in subsequent decades, and by the 1850s most of the continent had been explored, on 1 January 1901, the six colonies federated, forming the Commonwealth of Australia. Australia has since maintained a liberal democratic political system that functions as a federal parliamentary constitutional monarchy comprising six states. The population of 24 million is highly urbanised and heavily concentrated on the eastern seaboard, Australia has the worlds 13th-largest economy and ninth-highest per capita income. With the second-highest human development index globally, the country highly in quality of life, health, education, economic freedom. The name Australia is derived from the Latin Terra Australis a name used for putative lands in the southern hemisphere since ancient times, the Dutch adjectival form Australische was used in a Dutch book in Batavia in 1638, to refer to the newly discovered lands to the south. On 12 December 1817, Macquarie recommended to the Colonial Office that it be formally adopted, in 1824, the Admiralty agreed that the continent should be known officially as Australia. The first official published use of the term Australia came with the 1830 publication of The Australia Directory and these first inhabitants may have been ancestors of modern Indigenous Australians. The Torres Strait Islanders, ethnically Melanesian, were originally horticulturists, the northern coasts and waters of Australia were visited sporadically by fishermen from Maritime Southeast Asia. The first recorded European sighting of the Australian mainland, and the first recorded European landfall on the Australian continent, are attributed to the Dutch. The first ship and crew to chart the Australian coast and meet with Aboriginal people was the Duyfken captained by Dutch navigator, Willem Janszoon. He sighted the coast of Cape York Peninsula in early 1606, the Dutch charted the whole of the western and northern coastlines and named the island continent New Holland during the 17th century, but made no attempt at settlement. William Dampier, an English explorer and privateer, landed on the north-west coast of New Holland in 1688, in 1770, James Cook sailed along and mapped the east coast, which he named New South Wales and claimed for Great Britain. The first settlement led to the foundation of Sydney, and the exploration, a British settlement was established in Van Diemens Land, now known as Tasmania, in 1803, and it became a separate colony in 1825. The United Kingdom formally claimed the part of Western Australia in 1828. Separate colonies were carved from parts of New South Wales, South Australia in 1836, Victoria in 1851, the Northern Territory was founded in 1911 when it was excised from South Australia
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Antarctica
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It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 square kilometres, it is the fifth-largest continent, for comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, bacteria, fungi, plants, protista, vegetation, where it occurs, is tundra. The continent, however, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources. In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north. For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
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Egg
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An egg is the organic vessel containing the zygote in which an animal embryo develops until it can survive on its own, at which point the animal hatches. An egg results from fertilization of an ovum, most arthropods, vertebrates, and mollusks lay eggs, although some do not, such as scorpions and most mammals. Reptile eggs, bird eggs, and monotreme eggs are laid out of water, eggs laid on land or in nests are usually kept within a favorable temperature range while the embryo grows. When the embryo is developed it hatches, i. e. breaks out of the eggs shell. Some embryos have an egg tooth with which to crack, pip. The largest recorded egg is from a shark, and was 30 cm ×14 cm ×9 cm in size. At 1.5 kg and up to 17.8 cm ×14 cm, the bee hummingbird produces the smallest known bird egg, which weighs half of a gram. The eggs laid by some reptiles and most fish can be smaller. Reproductive structures similar to the egg in other kingdoms are termed spores, or in spermatophytes seeds, several major groups of animals typically have readily distinguishable eggs. The most common strategy for fish is known as oviparity. Typically large numbers of eggs are laid at one time and the eggs are left to develop without parental care. When the larvae hatch from the egg, they carry the remains of the yolk in a yolk sac which continues to nourish the larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a point after which they must learn how to hunt. A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized, however the larvae still grow inside the egg consuming the eggs yolk and without any direct nourishment from the mother. The mother then gives birth to relatively mature young, in certain instances, the physically most developed offspring will devour its smaller siblings for further nutrition while still within the mothers body. This is known as intrauterine cannibalism, the eggs of fish and amphibians are jellylike. Cartilagenous fish eggs are fertilized internally and exhibit a variety of both internal and external embryonic development. Most fish species spawn eggs that are fertilized externally, typically with the male inseminating the eggs after the female lays them and these eggs do not have a shell and would dry out in the air
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Tadpole
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A tadpole is the larval stage in the life cycle of an amphibian, particularly that of a frog or toad. They are usually wholly aquatic, though some species have tadpoles that are terrestrial, when first hatched from the egg they have a more or less globular body, a laterally compressed tail and internal or external gills. As they grow they undergo metamorphosis, during which process they grow limbs, develop lungs, most tadpoles are herbivorous and during metamorphosis the mouth and internal organs are rearranged to prepare for an adult carnivorous lifestyle. Having no hard parts, it might be expected that fossil tadpoles would not exist, however, traces of biofilms have been preserved and fossil tadpoles have been found dating back to the Miocene. Tadpoles are eaten in parts of the world and are mentioned in folk tales. The name tadpole is from Middle English taddepol, made up of the elements tadde, toad, similarly, pollywog / polliwog is from Middle English polwygle, made up of the same pol, head, and wiglen, to wiggle. Tadpoles are young amphibians that live in the water, though a few tadpoles are semi-terrestrial and terrestrial. During the tadpole stage of the life cycle, most respire by means of autonomous external or internal gills. They do not usually have arms or legs until the transition to adulthood, as a tadpole matures, it most commonly metamorphosizes by gradually growing limbs and then outwardly absorbing its tail by apoptosis. Lungs develop around the time of leg development, and tadpoles late in development will often be found near the surface of the water, where they breathe air. During the final stages of external metamorphosis, the mouth changes from a small. The intestines shorten to accommodate the new diet, most tadpoles are herbivorous, subsisting on algae and plants. Some species are omnivorous, eating detritus and, when available, tadpoles vary greatly in size, both during their development and between species. For example, in a family, Megophryidae, length of late-stage tadpoles varies between 33 millimetres and 106 millimetres. The tadpoles of Pseudis paradoxa grow to 25 centimetres, the largest of any frog, despite their soft-bodied nature and lack of mineralised hard parts, fossil tadpoles have been recovered from Upper Miocene strata. They are preserved by virtue of biofilms, with more robust structures preserved as a carbon film, in Miocene fossils from Libros, Spain, the brain case is preserved in calcium carbonate, and the nerve cord in calcium phosphate. Other parts of the tadpoles bodies exist as organic remains and bacterial biofilms, tadpole remains with telltale external gills are also known from several of the Labyrinthodont groups. Some tadpoles are used as food, tadpoles of megophryid frog Oreolalax rhodostigmatus are particularly large, more than 10 cm in length, and are collected for human consumption in China
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Nectophrynoides
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Nectophrynoides is a genus of true toads. They are endemic to Eastern Arc forests and wetlands in Tanzania, Species of the genus are ovoviviparous, fertilization is internal, and the females give birth to fully developed, small toadlets. Together with the West Africa Nimbaphrynoides and Limnonectes larvaepartus, they are the only frogs/toads in the world that do not lay eggs, the Ethiopian Altiphrynoides, which lay eggs, were also part of Nectophrynoides in the past. Amphibian Species of the World, an Online Reference, american Museum of Natural History, New York, USA. Nectophrynoides accessdate=2008-04-14 Data related to Nectophrynoides at Wikispecies Media related to Nectophrynoides at Wikimedia Commons
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Parotoid gland
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The parotoid gland is an external skin gland on the back, neck, and shoulder of toads and some frogs and salamanders. It secretes a milky alkaloid substance to deter predators, the substance, bufotoxin, acts as a neurotoxin. The cell layers have interlocking microvilli, the inner layer was hypothesised to be involved in venom formation and release. The study noted that the structure of the glands of the Colorado River toad is very different from the structure of the same glands in the cane toad. There is extensive blood supply to the glands to deliver cholesterol. The vague similarity in appearance, however, is the reason behind the belief that touching a toad causes warts
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Alkaloid
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Alkaloids are a group of naturally occurring chemical compounds that mostly contain basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties, some synthetic compounds of similar structure are also termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other such as chlorine, bromine. Alkaloids are produced by a variety of organisms including bacteria, fungi, plants. They can be purified from crude extracts of these organisms by acid-base extraction, many have found use in traditional or modern medicine, or as starting points for drug discovery. Other alkaloids possess psychotropic and stimulant activities, and have used in entheogenic rituals or as recreational drugs. Although alkaloids act on a diversity of systems in humans and other animals. The boundary between alkaloids and other nitrogen-containing natural compounds is not clear-cut, Compounds like amino acid peptides, proteins, nucleotides, nucleic acid, amines, and antibiotics are usually not called alkaloids. Natural compounds containing nitrogen in the position are usually classified as amines rather than as alkaloids. Some authors, however, consider alkaloids a special case of amines, the name alkaloids was introduced in 1819 by the German chemist Carl Friedrich Wilhelm Meißner, and is derived from late Latin root Latin, alkali and the suffix Greek, -οειδής – like. However, the term came into use only after the publication of a review article by Oscar Jacobsen in the chemical dictionary of Albert Ladenburg in the 1880s. There is no method of naming alkaloids. Many individual names are formed by adding the suffix ine to the species or genus name, for example, atropine is isolated from the plant Atropa belladonna, strychnine is obtained from the seed of Strychnine tree. If several alkaloids are extracted from one plant then their names often contain suffixes idine, anine, aline, inine etc. There are also at least 86 alkaloids whose names contain the root vin because they are extracted from plants such as Vinca rosea. Alkaloid-containing plants have been used by humans since ancient times for therapeutic, for example, medicinal plants have been known in the Mesopotamia at least around 2000 BC. The Odyssey of Homer referred to a given to Helen by the Egyptian queen. It is believed that the gift was an opium-containing drug, a Chinese book on houseplants written in 1st–3rd centuries BC mentioned a medical use of Ephedra and opium poppies
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Cane toad
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It is a member of the genus Rhinella, but was formerly in the genus Bufo, which includes many different true toad species found throughout Central and South America. The cane toad is a breeder, females lay single-clump spawns with thousands of eggs. Its reproductive success is partly because of feeding, it has a diet, unusual among anurans. Adults average 10–15 cm in length, the largest recorded specimen had a snout-vent length of 24 cm, the cane toad is an old species. A fossil toad from the La Venta fauna of the late Miocene of Colombia is indistinguishable from modern cane toads from northern South America and it was discovered in a floodplain deposit, which suggests the R. marina habitat preferences have long been for open areas. The cane toad has poison glands, and the tadpoles are toxic to most animals if ingested. Because of its voracious appetite, the toad has been introduced to many regions of the Pacific. The species derives its name from its use against the cane beetle. The cane toad is now considered a pest and a species in many of its introduced regions, of particular concern is its toxic skin. Cane toads are particularly dangerous to dogs, originally, the cane toads were used to eradicate pests from sugarcane, giving rise to their common name. The cane toad has many common names, including giant toad and marine toad, the former refers to its size. It was one of many species described by Linnaeus in his 18th-century work Systema Naturae, Linnaeus based the specific epithet marina on an illustration by Dutch zoologist Albertus Seba, who mistakenly believed the cane toad to inhabit both terrestrial and marine environments. Other common names include giant neotropical toad, Dominican toad, giant marine toad, in Trinidadian English, they are commonly called crapaud, the French word for toad. The genus Rhinella is considered to constitute a genus of its own. In Australia, the adults may be confused with large native frogs from the genera Limnodynastes, Cyclorana and these species can be distinguished from the cane toad by the absence of large parotoid glands behind their eyes and the lack of a ridge between the nostril and the eye. Juvenile cane toads may be confused with species of the Uperoleia genus, in the United States, the cane toad closely resembles many bufonid species. In particular, it could be confused with the southern toad, the cane toad is very large, the females are significantly longer than males, reaching an average length of 10–15 cm, with a maximum of 24 cm. Larger toads tend to be found in areas of population density
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Colorado River toad
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The Colorado River toad, also known as the Sonoran Desert toad, is a psychoactive toad found in northern Mexico and the southwestern United States. Its toxin, as an exudate of glands within the skin, contains 5-MeO-DMT, the Colorado River toad can grow to about 190 millimetres long and is the largest toad in the United States apart from the non-native cane toad. It has a smooth, leathery skin and is green or mottled brown in color. Just behind the large eye with horizontal pupil is a bulging kidney-shaped parotoid gland. Below this is a large pale green area which is the tympanum or ear drum. By the corner of the mouth there is a white wart, all these glands produce toxic secretions. Dogs that have attacked toads have been paralyzed or even killed. Raccoons have learned to pull a toad away from a pond by the leg, turn it on its back and start feeding on its belly. Unlike other vertebrates, this amphibian obtains water mostly by osmotic absorption across their abdomen, toads in the family bufonidae have a region of skin known as the seat patch, which extends from mid abdomen to the hind legs and is specialized for rapid rehydration. Most of the rehydration is done through absorption of water from small pools or wet objects, the Colorado River toad is found in the lower Colorado River and the Gila River catchment areas, in southeastern California, New Mexico, Mexico and much of southern Arizona. It lives in desert and semiarid areas throughout its range. It is semiaquatic and is found in streams, near springs, in canals and drainage ditches. The Bufo alvarius is known to breed in water bodies and as a result. It often makes its home in rodent burrows and is nocturnal and its call is described as, a weak, low-pitched toot, lasting less than a second. Bufo alvarius is sympatric with the spadefoot toad, Great Plains toad, red-spotted toad, like many other toads, they are active foragers and feed on invertebrates, lizards, small mammals, and amphibians. The most active season for toads is May–September, due to greater rainfalls. The age of B. alvarius ranges from 2 to 4 years within a population at Adobe Dam in Maricopa County, Arizona, the taxonomic affinities of B. alvarius remain unclear, but immunologically, it is equally close to the boreas and valliceps groups. The breeding season starts in May, when the season begins
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Recreational drug use
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Recreational drug use is the use of a psychoactive drug to alter ones mental state in a way that modifies emotions, perceptions, and feelings for recreational purposes. When a substance enters the body, it brings on an intoxicating effect. Generally, people use drugs that fall into three categories, depressants, stimulants, and psychedelic drugs. In popular usage, it is considered to be a tolerated social behaviour rather than a serious medical condition such as self-medication. The substances classified as controlled and illegal drugs vary by country, in 2009 it was estimated that about 3% to 6% of people aged 15 to 65 had used illegal drugs at least once. International and domestic law enforcement agencies are perpetually occupied with interdiction efforts against illegal use, manufacture. Many researchers have explored the etiology of recreational drug use, there has not been agreement around any one single cause. Instead, experts tend to apply the biopsychosocial model, any number of these factors are likely to influence an individual’s drug use as they are not mutually exclusive. Regardless of genetics, mental health or traumatic experiences, social factors play a role in exposure to and availability of certain types of drugs. According to addiction researcher Martin A. Plant, many go through a period of self-redefinition before initiating recreational drug use. They tend to view using drugs as part of a lifestyle that involves belonging to a subculture that they associate with heightened status. Plant says, “From the users point of there are many positive reasons to become part of the milieu of drug taking. The reasons for drug use appear to have as much to do with needs for friendship, pleasure, becoming a drug taker, to many people, is a positive affirmation rather than a negative experience. ”Anthropological research has suggested that humansmay have evolved to counter-exploit plant neurotoxins. The ability to use chemicals to serve the function of endogenous neurotransmitters may have improved survival rates. A typically restrictive prehistoric diet may have emphasised the apparent benefit of consuming psychoactive drugs, severity and type of risks that come with recreational drug use vary widely with the drug in question and the amount being used. There are many factors in the environment and within the user interact with each drug differently. Overall, some studies suggest that alcohol is one of the most dangerous of all drugs, only heroin, crack cocaine. Researcher David Nutt stated that studies showing benefits for moderate alcohol consumption lacked control for the variable of what the subjects were drinking
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Adenomus
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Adenomus is a small genus of true toads, with only two species, endemic to Sri Lanka. Adenomus kandianus was considered as extinct for 133 years, but was rediscovered in October 2009 in the Kandy area, Adenomus are slender toads that lack the supraorbital ridge and have smooth finger edges. The largest species is Adenomus kelaartii where females can attain 50 mm in snout–vent length, there are two species, The species are syntopic in parts of their range, but generally speaking Adenomus kandianus is a lower-altitude species whereas Adenomus kelaartii is a high-altitude species. A third species, Adenomus dasi was recognized in 2015 as being a synonym of Adenomus kandianus, the two show some morphological differences but negligible genetic divergence
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Amietophrynus
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Amietophrynus is a large genus of true toads native to Africa. Originally, all Amietophrynus species were included in the genus Bufo, the genus was split due to large enough taxonomic divergence. Ohler and Dubois showed in 2016 that Sclerophrys capensis Tschudi,1838 is the species as Bufo regularis rangeri Hewitt,1935. Because the former name is older, the implication is that Amietophrynus is a synonym of Sclerophrys. This change is not yet reflected in Wikipedia, grant, T. Faivovich, J. Bain, R. H. Haas, A. Haddad, C. F. B. de Sá, R. O. Channing, A. Wilkinson, M. Donnellan, S. C,2006, The Amphibian Tree of Life, Bulletin of the American Museum of Natural History no. African Amphibians Amphibian Species of the World 5.1 - Amietophrynus
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Anaxyrus
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Anaxyrus is a genus of true toads native to North and Central America. The meaning of the name was not explained by its author, Tschudi. It is speculated to be composed of the Greek anax and urus, or of the privative prefix an- and axyr or ax Frost, D. R. Grant, T. Faivovich, J. N. Bain, R. H. Haas, A. Haddad, C. L. F. B. De Sá, R. O. Channing, A. Wilkinson, M. Donnellan, raxworthy, C. J. Campbell, J. A. Blotto, B. L. Moler, P. Drewes, R. C. Nussbaum, R. A. Lynch, J. D. Green, D. M. Wheeler, bulletin of the American Museum of Natural History. Pauly, G. B, Hillis, D. M. Cannatella, the history of a Nearctic colonization, Molecular phylogenetics and biogeography of the Nearctic toads. Hillis, David M. & Cannatella, David C, taxonomic freedom and the role of official lists of species names
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Ansonia (genus)
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Ansonia is a genus of true toads found in south India, northern Thailand, Malay Peninsula, Tioman Island, Borneo, and Mindanao. These small forest species spawn in streams and have torrent-adapted tadpoles, common name stream toads has been coined for the genus, although individual species are also being referred to as slender toads. There are currently 29 species in genus, eol - Encyclopedia of Life taxon Ansonia at http. ITIS - Integrated Taxonomic Information System on-line database Taxon Ansonia at https, //web. archive. org/web/20160606043808/http, GBIF - Global Biodiversity Information Facility Taxon Ansonia at https, //web. archive. org/web/20080501142231/http, //data. gbif. org, 80/welcome. htm
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Incilius
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Incilius is genus of toads in the true toad family, Bufonidae. They are sometimes known as the Central American toads or Middle American toads and are found in southern USA, Mexico, Central America, taxonomy and systematics of Incilius has seen many recent changes. Current delineation of the genus was achieved by 2011 when both Cranopsis/Ollotis and Crepidius/Crepidophryne had been brought into synonymy with Incilius, however, the monophyly of Incilius is threatened by Incilius bocourti, which might be the sister taxon of Anaxyrus. Another discussion has been the level at which the genus is recognized. However, others have argued that Incilius should be treated as a subgenus of Bufo, there are at present 40 species
