1.
Precambrian
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The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon. A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
2.
Cambrian
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The Cambrian Period was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago to the beginning of the Ordovician Period 485.4 mya and its subdivisions, and its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latinised form of Cymru, the Welsh name for Wales, as a result, our understanding of the Cambrian biology surpasses that of some later periods. The rapid diversification of lifeforms in the Cambrian, known as the Cambrian explosion, most of the continents were probably dry and rocky due to a lack of vegetation. Shallow seas flanked the margins of several continents created during the breakup of the supercontinent Pannotia, the seas were relatively warm, and polar ice was absent for much of the period. The United States Federal Geographic Data Committee uses a barred capital C ⟨Є⟩ character similar to the capital letter Ukrainian Ye ⟨Є⟩ to represent the Cambrian Period, the proper Unicode character is U+A792 Ꞓ LATIN CAPITAL LETTER C WITH BAR. Despite the long recognition of its distinction from younger Ordovician Period rocks and older Supereon Precambrian rocks, the base of the Cambrian lies atop a complex assemblage of trace fossils known as the Treptichnus pedum assemblage. Pedum in Namibia, Spain and Newfoundland, and possibly, in the western USA, the stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain. The Cambrian Period followed the Ediacaran Period and was followed by the Ordovician Period, the Cambrian is divided into four epochs and ten ages. Currently only two series and five stages are named and have a GSSP, because the international stratigraphic subdivision is not yet complete, many local subdivisions are still widely used. In some of these subdivisions the Cambrian is divided into three epochs with locally differing names – the Early Cambrian, Middle Cambrian and Furongian, rocks of these epochs are referred to as belonging to the Lower, Middle, or Upper Cambrian. Trilobite zones allow biostratigraphic correlation in the Cambrian, each of the local epochs is divided into several stages. The International Commission on Stratigraphy list the Cambrian period as beginning at 541 million years ago, the lower boundary of the Cambrian was originally held to represent the first appearance of complex life, represented by trilobites. The recognition of small shelly fossils before the first trilobites, and Ediacara biota substantially earlier and this formal designation allowed radiometric dates to be obtained from samples across the globe that corresponded to the base of the Cambrian. Early dates of 570 million years ago quickly gained favour, though the used to obtain this number are now considered to be unsuitable. A more precise date using modern radiometric dating yield a date of 541 ±0.3 million years ago, most continental land was clustered in the Southern Hemisphere at this time, but was drifting north. Large, high-velocity rotational movement of Gondwana appears to have occurred in the Early Cambrian, the sea levels fluctuated somewhat, suggesting there were ice ages, associated with pulses of expansion and contraction of a south polar ice cap. In Baltoscandia a Lower Cambrian transgression transformed large swathes of the Sub-Cambrian peneplain into a epicontinental sea, the Earth was generally cold during the early Cambrian, probably due to the ancient continent of Gondwana covering the South Pole and cutting off polar ocean currents
3.
Ordovician
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The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. Lapworth recognized that the fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods. It received international sanction in 1960, when it was adopted as a period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event considerably increased the diversity of life, fish, the worlds first true vertebrates, continued to evolve, and those with jaws may have first appeared late in the period. Life had yet to diversify on land, about 100 times as many meteorites struck the Earth during the Ordovician compared with today. The Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event and it lasted for about 42 million years and ended with the Ordovician–Silurian extinction event, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary slightly from those found in other sources and this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is highly significant and it correlates well with the occurrence of widespread graptolite, conodont, and trilobite species. The base of the Tremadocian allows scientists to relate these species not only to each other and this makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected an international system of subdivisions. There exist Baltoscandic, British, Siberian, North American, Australian, the Ordovician Period in Britain was traditionally broken into Early, Middle and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, the Floian corresponds to the lower Arenig, the Arenig continues until the early Darriwilian, subsuming the Dapingian. The Llanvirn occupies the rest of the Darriwilian, and terminates with it at the base of the Late Ordovician. The Sandbian represents the first half of the Caradoc, the Caradoc ends in the mid-Katian, during the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole, the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia
4.
Silurian
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The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period,419.2 Mya. As with other periods, the rock beds that define the periods start and end are well identified. The base of the Silurian is set at a major Ordovician-Silurian extinction event when 60% of marine species were wiped out, a significant evolutionary milestone during the Silurian was the diversification of jawed and bony fish. However, terrestrial life would not greatly diversify and affect the landscape until the Devonian, the Silurian system was first identified by British geologist Sir Roderick Impey Murchison, who was examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s. He named the sequences for a Celtic tribe of Wales, the Silures, inspired by his friend Adam Sedgwick and this naming does not indicate any correlation between the occurrence of the Silurian rocks and the land inhabited by the Silures. As it was first identified, the Silurian series when traced farther afield quickly came to overlap Sedgwicks Cambrian sequence, however, charles Lapworth resolved the conflict by defining a new Ordovician system including the contested beds. An early alternative name for the Silurian was Gotlandian after the strata of the Baltic island of Gotland, the French geologist Joachim Barrande, building on Murchisons work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge. He divided the Silurian rocks of Bohemia into eight stages and his interpretation was questioned in 1854 by Edward Forbes, and the later stages of Barrande, F, G and H, have since been shown to be Devonian. Despite these modifications in the groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest fossils. The epoch is named for the town of Llandovery in Carmarthenshire, the Wenlock, which lasted from 433.4 ±1.5 to 427.4 ±2.8 mya, is subdivided into the Sheinwoodian and Homerian ages. It is named after Wenlock Edge in Shropshire, England, during the Wenlock, the oldest known tracheophytes of the genus Cooksonia, appear. The first terrestrial animals also appear in the Wenlock, represented by air-breathing millipedes from Scotland. The Ludlow, lasting from 427.4 ±1.5 to 423 ±2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago, and it is named for the town of Ludlow in Shropshire, England. The Pridoli, lasting from 423 ±1.5 to 419.2 ±2.8 mya, is the final and it is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic. Přídolí is the old name of a field area. The high sea levels of the Silurian and the flat land resulted in a number of island chains. The southern continents remained united during this period, the melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity. The continents of Avalonia, Baltica, and Laurentia drifted together near the equator and this event is the Caledonian orogeny, a spate of mountain building that stretched from New York State through conjoined Europe and Greenland to Norway
5.
Devonian
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The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian,419.2 million years ago, to the beginning of the Carboniferous,358.9 Mya. It is named after Devon, England, where rocks from this period were first studied, the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents, by the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established, Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fish. The first ray-finned and lobe-finned bony fish appeared, while the placodermi began dominating almost every aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral, in the oceans, primitive sharks became more numerous than in the Silurian and Late Ordovician. The first ammonites, species of molluscs, appeared, trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placodermi, and all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, while the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, another common term is Age of the Fishes, referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian, Breconian and Farlovian stages, in the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common. The Devonian Period is formally broken into Early, Middle and Late subdivisions, the rocks corresponding to those epochs are referred to as belonging to the Lower, Middle and Upper parts of the Devonian System. Early Devonian The Early Devonian lasted from 419.2 ±2.8 to 393.3 ±2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ±2.8 to 407.6 ±2.5, and was followed by the Emsian, which lasted until the Middle Devonian began,393. 3±2.7 million years ago. Middle Devonian The Middle Devonian comprised two subdivisions, first the Eifelian, which gave way to the Givetian 387. 7±2.7 million years ago. Late Devonian Finally, the Late Devonian started with the Frasnian,382.7 ±2.8 to 372.2 ±2.5, during which the first forests took shape on land. The first tetrapods appeared in the record in the ensuing Famennian subdivision. This lasted until the end of the Devonian,358. 9±2.5 million years ago, the Devonian was a relatively warm period, and probably lacked any glaciers
6.
Carboniferous
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The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period,298.9 Mya. The name Carboniferous means coal-bearing and derives from the Latin words carbō and ferō, and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the system names to be employed. The Carboniferous is often treated in North America as two periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial life was established by the Carboniferous period. Amphibians were the dominant land vertebrates, of one branch would eventually evolve into amniotes. Arthropods were also common, and many were much larger than those of today. Vast swaths of forest covered the land, which would eventually be laid down, the atmospheric content of oxygen also reached their highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. A major marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred in the middle of the period, the later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. In the United States the Carboniferous is usually broken into Mississippian and Pennsylvanian subperiods, the Silesian is roughly contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, and the Westphalian as the Coal Measures and Pennant Sandstone. There was also a drop in south polar temperatures, southern Gondwanaland was glaciated throughout the period and these conditions apparently had little effect in the deep tropics, where lush swamps, later to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major extinction, one that hit crinoids. This sea level drop and the unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation, the Carboniferous was a time of active mountain-building, as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America, in the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, the Late Carboniferous Pangaea was shaped like an O. There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, which was inside the O in the Carboniferous Pangaea, other minor oceans were shrinking and eventually closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean
7.
Permian
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The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era, the following Triassic Period belongs to the Mesozoic Era, the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the groups of the mammals, turtles, lepidosaurs. The world at the time was dominated by two known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior, amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earths history, in which nearly 90% of marine species and it would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian-Triassic extinction event was protracted, on land, the term Permian was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil, the region now lies in the Perm Krai of Russia. This could have in part caused the extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms. During the Permian, all the Earths major landmasses were collected into a supercontinent known as Pangaea. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, a new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmass interiors experience climates with extreme variations of heat and cold, deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian, the climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an Ice Age, glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continents interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles, Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. By the close of the Permian, trilobites and a host of other groups became extinct. Terrestrial life in the Permian included diverse plants, fungi, arthropods, the period saw a massive desert covering the interior of Pangaea
8.
Triassic
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The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period 252.17 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era, both the start and end of the period are marked by major extinction events. Therapsids and archosaurs were the terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic, the vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, however, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another mass extinction, the Triassic-Jurassic extinction event. The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, from the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed. Later in the mid-Triassic a similar sea penetrated along the equator from the west, the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates, thus, the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans. At the beginning of the Mesozoic Era, Africa was joined with Earths other continents in Pangaea, Africa shared the supercontinents relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are common in the south than north. The time boundary separating the Permian and Triassic marks the advent of an event with global impact. At Paleorrota geopark, located in Rio Grande do Sul, Brazil, in these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. Pangaeas large size limited the effect of the global ocean, its continental climate was highly seasonal, with very hot summers. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, the best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. On land, the vascular plants included the lycophytes, the dominant cycadophytes, ginkgophyta, ferns, horsetails
9.
Jurassic
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The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic, Middle, and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, Middle, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, India, South America, Japan, Australasia. As the Jurassic proceeded, larger and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are also poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
10.
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
11.
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
12.
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
13.
Pacific black duck
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It is usually called the grey duck in New Zealand, where it is also known by its Maori name, pārera. This sociable duck is found in a variety of habitats, and its nesting habits are much like those of the mallard. It feeds by upending, like other Anas ducks and it has a dark body, and a paler head with a dark crown and facial stripes. In flight, it shows a green speculum and pale underwing, the size range is 54–61 cm, males tend to be larger than females, and some island forms are smaller and darker than the main populations. It is not resident on the Marianas islands, but sometimes occurs there during migration, the now extinct Mariana mallard was probably originally derived from hybrids between this species and the mallard, which came to the islands during migration and settled down there. Rhymer et al. say their data points to the loss of identity of the grey duck as a separate species in New Zealand. Heather, Barrie D. & Robertson, Hugh A, the Field Guide to the Birds of New Zealand. BirdLife Species Factsheet Parera, the grey duck Australian Museum fact sheet
14.
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
15.
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
16.
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
17.
Bird
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Birds, a subgroup of Reptiles, are the last living examples of Dinosaurs. Birds live worldwide and range in size from the 5 cm bee hummingbird to the 2.75 m ostrich. They rank as the class of tetrapods with the most living species, at ten thousand. Birds are the closest living relatives of crocodilians, the fossil record indicates that birds evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago, Birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Birds have wings which are more or less developed depending on the species, the digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have evolved for swimming. Many species annually migrate great distances, Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of species are socially monogamous, usually for one breeding season at a time, sometimes for years. Other species have breeding systems that are polygynous or, rarely, Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents, most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilised, songbirds, parrots, and other species are popular as pets. Guano is harvested for use as a fertiliser, Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry, the first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae. Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system currently in use, Birds are categorised as the biological class Aves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda, Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria
18.
Anseriformes
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In fact, these living species are all included in Anatidae except for the three screamers and the magpie goose. All species in the order are highly adapted for an aquatic existence at the water surface, the males, except for the screamers, also have a penis, a trait that has disappeared in Neoaves. All are web-footed for efficient swimming, the earliest known Anseriform is the recently discovered Vegavis, which lived during the Cretaceous period. It is thought that the Anseriformes originated when the original Galloanserae split into the two main lineages, the extinct dromornithids may possibly represent early offshoots of the anseriform line, if they arent stem-Galliformes instead, and so maybe Gastornis. The ancestors of the Anseriformes developed the characteristic bill structure that they still share, the prehistoric wading presbyornithids were even more bizarre. The Anseriformes and the Galliformes are the most primitive neognathous birds, Anatidae systematics, especially regarding placement of some odd genera in the dabbling ducks or shelducks, is not fully resolved. See the Anatidae article for information, and for alternate taxonomic approaches. Some unusual groups, such as the extinct Gastornithidae and Dromornithidae, are found to be at the base of the Anseriformes family tree. Anatidae is traditionally divided into subfamilies Anatinae and Anserinae, the Anatinae consists of tribes Anatini, Aythyini, Mergini and Tadornini. The higher-order classification below follows a phylogenetic analysis performed by Angolin,2007, Mikkos Phylogeny Archive, the clade Somaterini has a single genus Somateria. List of Anseriformes by population Agnolin, F. Brontornis burmeisteri Moreno & Mercerat, un Anseriformes gigante del Mioceno Medio de Patagonia, revista del Museo Argentino de Ciencias Naturales. Clarke, J. A. Tambussi, C. P. Noriega, erickson, G. M. & Ketcham, R. A. Definitive fossil evidence for the extant avian radiation in the Cretaceous, & Zusi, R. L. Higher-order phylogeny of modern birds based on comparative anatomy. Zoological Journal of the Linnen Society, murray, P. F. & Vickers-Rich, P. Magnificent Mihirungs, The Colossal Flightless Birds of the Australian Dreamtime
19.
Anatidae
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The Anatidae are the biological family of birds that includes ducks, geese, and swans. The family has a distribution, occurring on all the worlds continents. These birds are adapted for swimming, floating on the water surface, the family contains around 146 species in 40 genera. They are generally herbivorous, and are monogamous breeders, a number of species undertake annual migrations. A few species have been domesticated for agriculture, and many others are hunted for food, five species have become extinct since 1600, and many more are threatened with extinction. The ducks, geese, and swans are small- to large-sized birds with a broad, diving species vary from this in being rounder. Extant species range in size from the cotton pygmy goose, at as little as 26.5 cm and 164 g, to the trumpeter swan, the wings are short and pointed, and supported by strong wing muscles that generate rapid beats in flight. They typically have long necks, although varies in degree between species. The legs are short, strong, and set far to the back of the body, combined with their body shape, this can make some species awkward on land, but they are stronger walkers than other marine and water birds such as grebes or petrels. They typically have webbed feet, though a few such as the Nene have secondarily lost their webbing. The bills are made of keratin with a thin and sensitive layer of skin on top. For most species, the shape of the bill tends to be flattened to a greater or lesser extent. These contain serrated lamellae which are well defined in the filter-feeding species. Their feathers are excellent at shedding water due to special oils, many of the ducks display sexual dimorphism, with the males being more brightly coloured than the females. The swans, geese, and whistling-ducks lack sexually dimorphic plumage, anatids are vocal birds, producing a range of quacks, honks, squeaks, and trumpeting sounds, depending on species, the female often has a deeper voice than the male. Anatids are generally herbivorous as adults, feeding on various water-plants, although some also eat fish, molluscs. One group, the mergansers, are primarily piscivorous, and have serrated bills to help catch fish. In a number of species, the young include a proportion of invertebrates in their diets
20.
William Elford Leach
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William Elford Leach, MD, FRS was an English zoologist and marine biologist. Elford Leach was born at Hoe Gate, Plymouth, the son of an attorney, at the age of twelve he began a medical apprenticeship at the Devonshire and Exeter Hospital, studying anatomy and chemistry. By this time he was already collecting marine animals from Plymouth Sound, at seventeen he began studying medicine at St Bartholomews Hospital in London, finishing his training at the University of Edinburgh before graduating MD from the University of St Andrews. Here he threw himself into the task of reorganising and modernising these collections, in 1815, he published the first bibliography of entomology in Brewsters Edinburgh Encyclopedia. He also worked and published on other invertebrates, amphibians, reptiles, mammals, and was the naturalist who separated the centipedes and millipedes from the insects, giving them their own group, the Myriapoda. In his day he was the leading expert on the Crustacea and was in contact with scientists in the United States. In 1816 he was elected a Fellow of the Royal Society at the age of 25, however, in 1821 he suffered a nervous breakdown due to overwork and became unable to continue his researches. He resigned from the museum in March 1822 and his elder sister Jane took him to continental Europe to convalesce and they lived in Italy and Malta and he died from cholera in San Sebastiano Curone, near Tortona, north of Genoa on 25 August 1836. He was one of the most laborious and successful, as well as one of the most universal, in Britain zoologists remained committed to the system of animal classification introduced by Linnaeus in the middle of the 18th century. This was a tool but its principles led to artificial groupings of species when creating larger groups such as genera. For example, Linnaeus had called all animals encased in an outer skeleton. The grouping does separate animals with hard outer skeletons from jellyfish, worms, snails, vertebrates, etc. in continental Europe in the late 18th century naturalists began to revise the way they grouped species. They used an array of characters, not just one or two, and began to discern groups of species that physically resembled one another, lived in similar ways. They created new genera to house these coherent groups and referred to these as natural genera and they named this approach the natural method or natural system of classification. Unlike many of his countrymen, Leach was aware of developments across the English Channel. He read the French literature and, despite the war with France and he applied the new principles to his own research and brought them to the attention of other British zoologists through his publications. Between the years 1813 and 1830 he produced more than 130 scientific articles, by applying the natural method in these works he created more than 380 new genera, many of which have stood the test of time and remain valid today. In 1834, at the meeting of the British Association for the Advancement of Science, Leonard Jenyns reported on The Recent Progress
21.
Type species
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A similar concept is used for suprageneric groups called a type genus. In botanical nomenclature, these terms have no standing under the code of nomenclature. In botany, the type of a name is a specimen which is also the type of a species name. The species name that has that type can also be referred to as the type of the genus name, names of genus and family ranks, the various subdivisions of those ranks, and some higher-rank names based on genus names, have such types. In bacteriology, a species is assigned for each genus. Every named genus or subgenus in zoology, whether or not currently recognized as valid, is associated with a type species. In practice, however, there is a backlog of untypified names defined in older publications when it was not required to specify a type, a type species is both a concept and a practical system that is used in the classification and nomenclature of animals. The type species represents the species and thus definition for a particular genus name. In the Glossary, type species is defined as The nominal species that is the type of a nominal genus or subgenus. The type species permanently attaches a formal name to a genus by providing just one species within that genus to which the name is permanently linked. The species name in turn is fixed, in theory, to a type specimen, for example, the type species for the land snail genus Monacha is Monacha cartusiana. That genus is placed within the family Hygromiidae. The type genus for that family is the genus Hygromia, the concept of the type species in zoology was introduced by Pierre André Latreille. The International Code of Zoological Nomenclature states that the name of the type species should always be cited. It gives an example in Article 67.1, Astacus marinus Fabricius,1775 was later designated as the type species of the genus Homarus, thus giving it the name Homarus marinus. However, the species of Homarus should always be cited using its original name. 3, the type of the genus name Elodes is quoted as the type of the species name Hypericum aegypticum, Glossary of scientific naming Genetypes – genetic sequence data from type specimens. Holotype Paratype Principle of Typification Type Type genus
22.
Mallard
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This duck belongs to the subfamily Anatinae of the waterfowl family Anatidae. The male birds have a green head and are grey on wings and belly. Both sexes have an area of white-bordered black speculum feathers which commonly also include iridescent blue feathers especially among males, mallards live in wetlands, eat water plants and small animals, and are social animals preferring to congregate in groups or flocks of varying sizes. This species is the ancestor of most breeds of domesticated ducks. The mallard was one of the bird species originally described by Carl Linnaeus in his 18th-century work Systema Naturae. The scientific name is from Latin Anas, duck and Ancient Greek platyrhynchus, Mallard originally referred to any wild drake and it is sometimes still used this way. It was derived from the Old French malart or mallart for wild drake and it may be related to an Old High German masculine proper name Madelhart, clues lying in the alternate English forms maudelard or mawdelard. Masle has also proposed as an influence. This is quite unusual among such different species, and apparently is because the mallard evolved very rapidly and recently, the distinct lineages of this radiation are usually kept separate due to non-overlapping ranges and behavioural cues, but are still not fully genetically incompatible. Mallards and their domesticated conspecifics are also fully interfertile, the genome of Anas platyrhynchos was sequenced in 2013. Mallards appear to be closer to their Indo-Pacific relatives than to their American ones judging from biogeography, the large ice age palaeosubspecies which made up at least the European and west Asian populations during the Pleistocene has been named Anas platyrhynchos palaeoboschas. In their mitochondrial DNA, mallards are differentiated between North America and Eurasia, however, in the nuclear genome there is a lack of genetic structure. Haplotypes typical of American mallard relatives and spotbills can be found in mallards around the Bering Sea, the Aleutian Islands hold a population of mallards that appear to be evolving towards a subspecies, as gene flow with other populations is very limited. The size of the mallard varies clinally, and birds from Greenland and they are sometimes separated as subspecies, the Greenland mallard. The mallard is a waterfowl species although it is often slightly heavier than most other dabbling ducks. It is 50–65 cm long, has a wingspan of 81–98 cm, and weighs 0. 72–1.58 kg. Among standard measurements, the chord is 25.7 to 30.6 cm, the bill is 4.4 to 6.1 cm. The breeding male mallard is unmistakable, with a glossy bottle-green head and white collar which demarcates the head from the purple-tinged brown breast, grey wings
23.
Carl Linnaeus
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Carl Linnaeus, also known after his ennoblement as Carl von Linné, was a Swedish botanist, physician, and zoologist, who formalised the modern system of naming organisms called binomial nomenclature. He is known by the father of modern taxonomy. Many of his writings were in Latin, and his name is rendered in Latin as Carolus Linnæus, Linnaeus was born in the countryside of Småland, in southern Sweden. He received most of his education at Uppsala University. He lived abroad between 1735 and 1738, where he studied and also published a first edition of his Systema Naturae in the Netherlands and he then returned to Sweden, where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on journeys through Sweden to find and classify plants. In the 1750s and 1760s, he continued to collect and classify animals, plants, and minerals, at the time of his death, he was one of the most acclaimed scientists in Europe. The philosopher Jean-Jacques Rousseau sent him the message, Tell him I know no man on earth. The German writer Johann Wolfgang von Goethe wrote, With the exception of Shakespeare and Spinoza, Swedish author August Strindberg wrote, Linnaeus was in reality a poet who happened to become a naturalist. Among other compliments, Linnaeus has been called Princeps botanicorum, The Pliny of the North and he is also considered as one of the founders of modern ecology. In botany, the abbreviation used to indicate Linnaeus as the authority for species names is L. In older publications, sometimes the abbreviation Linn. is found, Linnæus was born in the village of Råshult in Småland, Sweden, on 23 May 1707. He was the first child of Nicolaus Ingemarsson and Christina Brodersonia and his siblings were Anna Maria Linnæa, Sofia Juliana Linnæa, Samuel Linnæus, and Emerentia Linnæa. One of a line of peasants and priests, Nils was an amateur botanist, a Lutheran minister. Christina was the daughter of the rector of Stenbrohult, Samuel Brodersonius, a year after Linnæus birth, his grandfather Samuel Brodersonius died, and his father Nils became the rector of Stenbrohult. The family moved into the rectory from the curates house, even in his early years, Linnæus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which calmed him. Nils spent much time in his garden and often showed flowers to Linnaeus, soon Linnæus was given his own patch of earth where he could grow plants
24.
10th edition of Systema Naturae
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The 10th edition of Systema Naturae is a book written by Carl Linnaeus and published in two volumes in 1758 and 1759, which marks the starting point of zoological nomenclature. In it, Linnaeus introduced binomial nomenclature for animals, something he had already done for plants in his 1753 publication of Species Plantarum, before 1758, most biological catalogues had used polynomial names for the taxa included, including earlier editions of Systema Naturae. The first work to consistently apply binomial nomenclature across the kingdom was the 10th edition of Systema Naturae. Names published before that date are unavailable, even if they would otherwise satisfy the rules, during Linnaeus lifetime, Systema Naturae was under continuous revision. The Animal Kingdom, Animals enjoy sensation by means of an organization, animated by a medullary substance, perception by nerves. They have members for the different purposes of life, organs for their different senses and they all originate from an egg. Their external and internal structure, their anatomy, habits, instincts. The list has been broken down into the six classes Linnaeus described for animals, Mammalia, Aves, Amphibia, Pisces, Insecta. These classes were created by studying the internal anatomy, as seen in his key. Warm, red blood Viviparous, Mammalia Oviparous, Aves Heart with 1 auricle,1 ventricle, cold, red blood Lungs voluntary, Amphibia External gills, Pisces Heart with 1 auricle,0 ventricles. Linnaeus described mammals as, Animals that suckle their young by means of lactiferous teats, in external and internal structure they resemble man, most of them are quadrupeds, and with man, their natural enemy, inhabit the surface of the Earth. The largest, though fewest in number, inhabit the ocean and they are areal, vocal, swift and light, and destitute of external ears, lips, teeth, scrotum, womb, bladder, epiglottis, corpus callosum and its arch, and diaphragm. They breathe by means of gills, which are united by a bony arch, swim by means of radiate fins. Many of them are without a head, and most of them without feet. They are principally distinguished by their tentacles, by the Ancients they were not improperly called imperfect animals, as being destitute of ears, nose, head, eyes and legs, and are therefore totally distinct from Insects. In addition to repeating the species he had listed in his Species Plantarum. The species from Species Plantarum were numbered sequentially, while the new species were labelled with letters, new plant species described in the 10th edition of Systema Naturae include, The original 1758 Systema Naturae Linnaeus 1758 Classification of Animals on the Taxonomicon
25.
Genus
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A genus is a taxonomic rank used in the biological classification of living and fossil organisms in biology. In the hierarchy of classification, genus comes above species. In binomial nomenclature, the name forms the first part of the binomial species name for each species within the genus. Felis catus and Felis silvestris are two species within the genus Felis, Felis is a genus within the family Felidae. The composition of a genus is determined by a taxonomist, the standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. Moreover, genera should be composed of units of the same kind as other genera. The term comes from the Latin genus, a noun form cognate with gignere, linnaeus popularized its use in his 1753 Species Plantarum, but the French botanist Joseph Pitton de Tournefort is considered the founder of the modern concept of genera. The scientific name of a genus may be called the name or generic epithet. It plays a role in binomial nomenclature, the system of naming organisms. The rules for the names of organisms are laid down in the Nomenclature Codes. The standard way of scientifically describing species and other lower-ranked taxa is by binomial nomenclature, the generic name forms its first half. For example, the gray wolfs binomial name is Canis lupus, with Canis being the name shared by the wolfs close relatives. The specific name is written in lower-case and may be followed by names in zoology or a variety of infraspecific names in botany. Especially with these names, when the generic name is known from context. Because animals are typically only grouped within subspecies, it is written as a trinomen with a third name. Dog breeds, meanwhile, are not scientifically distinguished, there are several divisions of plant species and therefore their infraspecific names generally include contractions explaining the relation. For example, the genus Hibiscus includes hundreds of other species apart from the Rose of Sharon or common garden hibiscus, Rose of Sharon doesnt have subspecies but has cultivars that carry desired traits, such as the bright white H. syriaca Diana. Hawaiian hibiscus, meanwhile, includes several separate species, since not all botanists agree on the divisions or names between species, it is common to specify the source of the name using author abbreviations
26.
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
27.
Swan
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Swans are birds of the family Anatidae within the genus Cygnus. The swans close relatives include the geese and ducks, Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a subfamily, Cygninae. There are six or seven species of swan in the genus Cygnus, in there is another species known as the coscoroba swan. Swans usually mate for life, though divorce does sometimes occur, particularly following nesting failure, and if a mate dies, the number of eggs in each clutch ranges from three to eight. The English word swan, akin to the German Schwan, Dutch zwaan, an adult male is a cob, from Middle English cobbe, an adult female is a pen. Swans are the largest extant members of the waterfowl family Anatidae, the largest species, including the mute swan, trumpeter swan, and whooper swan, can reach a length of over 1.5 m and weigh over 15 kg. Their wingspans can be over 3.1 m, compared to the closely related geese, they are much larger and have proportionally larger feet and necks. Adults also have a patch of unfeathered skin between the eyes and bill, the sexes are alike in plumage, but males are generally bigger and heavier than females. The Northern Hemisphere species of swan have pure white plumage but the Southern Hemisphere species are mixed black, the Australian black swan is completely black except for the white flight feathers on its wings, the chicks of black swans are light grey. The South American black-necked swan has a body with a black neck. The legs of swans are normally a dark grey colour. Bill colour varies, the four species have black bills with varying amounts of yellow. The mute swan and black-necked swan have lumps at the base of their bills on the upper mandible, Swans are generally found in temperate environments, rarely occurring in the tropics. A group of swans is called a bevy or a wedge in flight, four species occur in the Northern Hemisphere, one species is found in Australia and New Zealand and one species is distributed in southern South America. They are absent from tropical Asia, Central America, northern South America, one species, the mute swan, has been introduced to North America, Australia and New Zealand. Several species are migratory, either wholly or partly so, the mute swan is a partial migrant, being resident over areas of Western Europe but wholly migratory in Eastern Europe and Asia. The whooper swan and tundra swan are wholly migratory, and the swans are almost entirely migratory
28.
Goose
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Geese are waterfowl belonging to the tribe Anserini of the family Anatidae. This tribe comprises the genera Anser, Branta and Chen, some other birds, mostly related to the shelducks, have goose as part of their names. More distantly related members of the family Anatidae are swans, most of which are larger than true geese, and ducks, the word goose is a direct descendent of Proto-Indo-European root, *ghans-. In Germanic languages, the root gave Old English gōs with the plural gēs and gandres, Frisian goes, gies and guoske, New High German Gans, Gänse, and Ganter, and Old Norse gās. The term goose applies to the female in particular, while applies to the male in particular. Young birds before fledging are called goslings, the collective noun for a group of geese on the ground is a gaggle, when in flight, they are called a skein, a team, or a wedge, when flying close together, they are called a plump. The three living genera of true geese are, Anser, grey geese, including the goose, and domestic geese, Chen, white geese. Either these or, more probably, the goose-like Coscoroba swan is the closest living relative of the true geese, the aptly named Anser atavus from some 12 million years ago had even more plesiomorphies in common with swans. In addition, some birds are known from subfossil remains found on the Hawaiian Islands. Geese are monogamous, living in permanent pairs throughout the year, however, unlike most other permanently monogamous animals, paired geese are more dominant and feed more, two factors that result in more young. Some mainly Southern Hemisphere birds are called geese, most of which belong to the shelduck subfamily Tadorninae, the blue-winged goose, Cyanochen cyanopterus, and the Cape Barren goose, Cereopsis novaehollandiae, have disputed affinities. They belong to separate ancient lineages that may ally either to the Tadorninae, Anserinae, the three species of small waterfowl in the genus Nettapus are named pygmy geese. They seem to represent another ancient lineage, with affinities to the Cape Barren goose or the spur-winged goose. A genus of prehistorically extinct seaducks, Chendytes, is sometimes called diving-geese due to their large size, the unusual magpie goose is in a family of its own, the Anseranatidae. The northern gannet, a seabird, is known as the Solan goose, although it is a bird unrelated to the true geese. Well-known sayings about geese include, To have a gander is to something in detail. Whats sauce for the goose is sauce for the means that what is appropriate treatment for one person is equally appropriate for someone else. Saying that someones goose is cooked means that they have suffered, or are about to suffer, a wild goose chase is a useless, futile waste of time and effort
29.
Duck
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Duck is the common name for a large number of species in the waterfowl family Anatidae, which also includes swans and geese. The ducks are divided among several subfamilies in the family Anatidae, they do not represent a group but a form taxon, since swans. Ducks are mostly birds, mostly smaller than the swans and geese. Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes, gallinules and this word replaced Old English ened/ænid duck, possibly to avoid confusion with other Old English words, like ende end with similar forms. Other Germanic languages still have similar words for duck, for example, Dutch eend duck, the word ened/ænid was inherited from Proto-Indo-European, compare, Latin anas duck, Lithuanian ántis duck, Ancient Greek nēssa/nētta duck, and Sanskrit ātí water bird, among others. A duckling is a duck in downy plumage or baby duck. A male duck is called a drake and the female is called a duck, the overall body plan of ducks is elongated and broad, and the ducks are also relatively long-necked, albeit not as long-necked as the geese and swans. The body shape of diving ducks varies somewhat from this in being more rounded, the bill is usually broad and contains serrated lamellae, which are particularly well defined in the filter-feeding species. In the case of some fishing species the bill is long, the scaled legs are strong and well developed, and generally set far back on the body, more so in the highly aquatic species. The wings are strong and are generally short and pointed. Three species of duck are almost flightless, however. Many species of duck are temporarily flightless while moulting, they seek out protected habitat with good food supplies during this period, the drakes of northern species often have extravagant plumage, but that is moulted in summer to give a more female-like appearance, the eclipse plumage. The plumage of birds generally resembles that of the female. Over the course of evolution, female ducks have evolved to have a corkscrew shaped vagina to prevent rape, Ducks exploit a variety of food sources such as grasses, aquatic plants, fish, insects, small amphibians, worms, and small molluscs. Dabbling ducks feed on the surface of water or on land, along the edge of the beak there is a comb-like structure called a pecten. This strains the water squirting from the side of the beak, the pecten is also used to preen feathers and to hold slippery food items. Diving ducks and sea ducks forage deep underwater, to be able to submerge more easily, the diving ducks are heavier than dabbling ducks, and therefore have more difficulty taking off to fly. A few specialized species such as the mergansers are adapted to catch, to avoid injury when digging into sediment it has no cere, but the nostrils come out through hard horn
30.
Moa-nalo
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The moa-nalo are a group of extinct aberrant, goose-like ducks that lived on the larger Hawaiian Islands, except Hawaiʻi itself, in the Pacific. They were the major herbivores on most of islands for the last 3 million years or so. Subsequently, bones were found on Maui, Oʻahu, and Lānaʻi, in tubes, lake beds. All species were flightless and large, with a mass of 4–7.5 kg. Some moa-nalo fossils have found to contain traces of mitochondrial DNA which were compared to living duck species in order to establish their place in the duck family. There they increased in size, but must have retained the ability to fly until they had spread to the newer islands, the unusual shape and size of the moa-nalo can be attributed to their role in the ecology of prehistoric Hawaiʻi. This conclusion is backed up by the shapes of their beaks and this indicates they were the principal browsers on the island. The moa-nalo themselves filled the niche of herbivore usually filled by such as goats and deer, or the giant tortoises of Galápagos. This has implications for the ecology of Hawaiian Islands today, as a group of species have been lost. Like island taxa from Mauritius, New Zealand and Polynesia, they were unused to mammals and were taken by hunters or the animals that were introduced and became feral. The diet and ecology of Hawaiis extinct flightless waterfowl, evidence from coprolites, relationships of the extinct moa-nalos, flightless Hawaiian waterfowl, based on ancient DNA. Slikas, Beth, Hawaiian Birds, Lessons from a Rediscovered Avifauna
31.
Cladistics
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Therefore, members of a group are assumed to share a common history and are considered to be closely related. The techniques and nomenclature of cladistics have been applied to other disciplines, Cladistics in the original sense refers to a particular set of methods used in phylogenetic analysis, although it is now sometimes used to refer to the whole field. What is now called the cladistic method appeared as early as 1901 with a work by Peter Chalmers Mitchell for birds and subsequently by Robert John Tillyard in 1921, Hennig referred to his own approach as phylogenetic systematics. Phenetics was championed at this time by the numerical taxonomists Peter Sneath and Robert Sokal, originally conceived, if only in essence, by Willi Hennig in a book published in 1950, cladistics did not flourish until its translation into English in 1966. Today, cladistics is the most popular method for constructing phylogenies from morphological, unlike phenetics, cladistics is specifically aimed at reconstructing evolutionary histories. The way for computational phylogenetics was paved by phenetics, a set of commonly used from the 1950s to 1980s. Phenetics did not try to reconstruct phylogenetic trees, rather, it tried to build dendrograms from similarity data, the cladistic method interprets each character state transformation implied by the distribution of shared character states among taxa as a potential piece of evidence for grouping. The outcome of an analysis is a cladogram – a tree-shaped diagram that is interpreted to represent the best hypothesis of phylogenetic relationships. Cladists contend that these models are unjustified, every cladogram is based on a particular dataset analyzed with a particular method. Different datasets and different methods, not to mention violations of the mentioned assumptions, only scientific investigation can show which is more likely to be correct. Since the cladograms provide competing accounts of events, at most one of them is correct. Within the primates, all anthropoids are hypothesized to have had a common ancestor all of whose descendants were anthropoids, the prosimians, on the other hand, form a paraphyletic taxon. When two or more taxa that are not nested within each other share a plesiomorphy, it is a symplesiomorphy, symplesiomorphies do not mean that the taxa that exhibit that character state are necessarily closely related. For example, Reptilia is traditionally characterized by being cold-blooded, whereas birds are warm-blooded, an apomorphy or derived state is an innovation. It can thus be used to diagnose a clade – or even to help define a clade name in phylogenetic nomenclature, features that are derived in individual taxa are called autapomorphies. Autapomorphies express nothing about relationships among groups, clades are identified by synapomorphies, for example, the possession of digits that are homologous with those of Homo sapiens is a synapomorphy within the vertebrates. The tetrapods can be singled out as consisting of the first vertebrate with such digits homologous to those of Homo sapiens together with all descendants of this vertebrate and it is therefore inferred to have evolved by convergence or reversal. Both mammals and birds are able to maintain a constant body temperature
32.
Systematics
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Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees, phylogenies have two components, branching order and branch length. Phylogenetic trees of species and higher taxa are used to study the evolution of traits, Systematics, in other words, is used to understand the evolutionary history of life on Earth. John Lindley provided a definition of systematics in 1830, although he wrote of systematic botany rather than using the term systematics. This is a field with a history that in recent years has experienced a notable renaissance. Part of the material has to do with evolutionary areas. Taxonomy is that part of Systematics concerned with topics to above, however, in modern usage, they can all be considered synonyms of each other. For example, Websters 9th New Collegiate Dictionary of 1987 treats classification, taxonomy, according to this work the terms originated in 1790, c. Europeans tend to use the terms systematics and biosystematics for the field of the study of biodiversity as a whole, all of these biological disciplines can deal both with extinct and with extant organisms. Scientific classifications are aids in recording and reporting information to other scientists, the systematist, a scientist who specializes in systematics, must, therefore, be able to use existing classification systems, or at least know them well enough to skilfully justify not using them. Phenetics was an attempt to determine the relationships of organisms through a measure of overall similarity, from the late-20th century onwards, it was superseded by cladistics, which rejects plesiomorphies in attempting to resolve the phylogeny of Earths various organisms through time. Todays systematists generally make use of molecular biology and of computer programs to study organisms. Taxonomic characters are the attributes that can be used to provide the evidence from which relationships between taxa are inferred. Adaptation, or evolutionary mechanisms Scientific classification and Taxonomy - the result of research in systematics Schuh, Randall T. biological Systematics, Principles and Applications, 2nd edn. ISBN 978-0-8014-4799-0 Simpson, Michael G.2005, ISBN 978-0-12-644460-5 Society of Australian Systematic Biologists Society of Systematic Biologists Willi Hennig Society
33.
Tribe (biology)
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In biology, a tribe is a taxonomic rank above genus, but below family and subfamily. It is sometimes subdivided into subtribes, in zoology, some examples include the tribes Caprini, Hominini, Bombini, and Thunnini. The standard ending for the name of a tribe is -ini. The tribe Hominini is divided into subtribes by some scientists, subtribe Hominina then comprises humans, the standard ending for the name of a zoological subtribe is -ina. In botany, examples include the tribes Acalypheae and Hyacintheae, the standard ending for the name of a botanical tribe is -eae. The tribe Hyacintheae is divided into subtribes, including the subtribe Massoniinae, the standard ending for the name of a botanical subtribe is -inae. In bacteriology, the form of names is as in botany, e. g. Pseudomonadeae
34.
Salvadori's teal
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The Salvadoris teal or Salvadoris duck is a species of bird endemic to New Guinea. It is placed in the monotypic genus Salvadorina and it has a dark brown head and neck, and its body is barred and spotted dark brown and off white, with orange legs and a yellow bill. It is a inhabitant of fast-flowing highland streams and lakes. It locates its nest near water, and lays 2 to 4 eggs in the dry season, the IUCN has listed the bird as vulnerable, and the total population may be slowly declining. When Walter Rothschild and Ernst Hartert first described Salvadoris teal in 1894, initially, it was generally placed with South Americas torrent duck and New Zealands blue duck — two species of similar ecological niches — in a tribe called Merganettini. In the 1940s, Ernst Mayr moved the species to the dabbling duck genus Anas, all or some of these species may actually be surviving lineages of an ancient Gondwanan radiation of waterfowl. The ducks common and genus names both commemorate 18th-century Italian ornithologist Tommaso Salvadori, the species name waigiuensis refers to Waigeo, an island near New Guinea. Measuring 38–43 cm in length, with a wingspan of 56–71 cm, the sexes are similar in plumage, with males averaging slightly larger than females. Resident at elevations ranging from 500 to 4,000 m, Salvadoris teal prefers swiftly flowing rivers and streams, Salvadoris teal is an omnivore, and feeds by both dabbling and diving. It eats plants and insects, and possibly small fish and it locates its nest near water, and lays 2 to 4 eggs in the dry season. The International Union for the Conservation of Nature has listed Salvadoris teal as vulnerable, the total world population, currently estimated to be between 2,500 and 9,999 mature individuals, is thought to be declining at a moderate rate. Hunting, habitat degradation and predation by dogs are among the threats this species faces, beehler, Bruce M. Pratt, Thane K. & Zimmerman, Dale A. The Helm Dictionary of Scientific Names, sraml, M. Christidis, L. Easteal, S. Horn, P. & Collet, C. Australian Journal of Zoology 44, 47-58
35.
Pink-eared duck
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The pink-eared duck is a species of duck found in Australia. It has a large spatulate bill like the Australasian shoveler, but is smaller at 38–40 cm length and its brown back and crown, black and white barred sides and black eye patches on its otherwise white face make this bird unmistakable. Juveniles are slightly duller, but otherwise all plumages are similar, the Pink-eared duck was first described by the English ornithologist John Latham in 1801 under the binomial name Anas membranacea. It is the only living member of the genus Malacorhynchus, a closely related and this peculiar duck may be most closely related to the shelducks but its relationships are enigmatic. It may be closer to the duck and the stiff-tails and, formerly placed in the paraphyletic perching ducks. This species is the member of the order Anseriformes known to have carotenoid pigments in its feathers. The pink-eared duck was reportedly known as the New Holland duck by early colonists in Western Australia, widely distributed throughout Australia and highly mobile, these ducks can appear anywhere there is standing water, especially in dry inland regions, where annual rainfall rarely exceeds 15 in. They are dependent on plankton, as well as crustaceans, mollusks and their bill is well designed for straining minute organisms, with pliable mandibular flaps that channel water in a manner that allow the ducks to filter algae and other plankton efficiently. They also feed by vortexing, in which two ducks spin about a point with the head of one opposite the tail of the other. Nesting is stimulated by the drying and filling of pools that promote increased levels of organic material, in good years, large numbers of pink-eared ducks concentrate in shallow flood plains. However, when conditions do not meet specifications, reproduction may be completely curtailed, sraml, M. Christidis, L. Easteal, S. Horn, P. & Collet, C. Australian Journal of Zoology 44, 47-58, the Illustrated Dictionary of Australian Birds by Common Name
36.
Marbled duck
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The marbled duck, or marbled teal, is a medium-sized duck. It used to be included among the dabbling ducks, but is now classed as a diving duck, the scientific name, Marmaronetta angustirostris, comes from the Greek marmaros, marbled and netta, a duck, and Latin angustus, narrow or small and rostris billed. This duck formerly bred in large numbers in the Mediterranean region and its breeding habitat is lowland where they lay their eggs in long grass or in high trees. They may lay 7 to 10 cream eggs and they are common in private collections but are a nervous and flighty bird. In some areas birds disperse from the grounds, and have been encountered in the winter period in the Sahel zone. These are gregarious birds, at times even when nesting, outside the breeding season flocks are often small, although large wintering flocks have been reported in some areas. The largest winter concentration known is in Khuzestan, Iran, in 2011, a group of Iraqi ornithologists counted a single flock of the rare marbled teal on the lakes of the Iraqi marshes, numbering at least 40,000 birds. The marbled duck is approximately 39–42 cm long, adults are a pale sandy-brown colour, diffusely blotched off-white, with a dark eye-patch and shaggy head. Juveniles are similar but with more off-white blotches, in flight, the wings look pale without a marked pattern, and no speculum on the secondaries. These birds feed mainly in water by dabbling or up-ending. Little is known of their diet and this bird is considered vulnerable due to a reduction in population caused by habitat destruction and hunting. It is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds applies, Marmaronetta angustirostris in the Flickr, Field Guide Birds of the World Marbled duck media at ARKive BirdLife species factsheet for Marmaronetta angustirostris Marmaronetta angustirostris. Marbled teal photo gallery at VIREO Interactive range map of Marmaronetta angustirostris at IUCN Red List maps Audio recordings of Marbled duck on Xeno-canto
37.
Bird migration
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Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Migration carries high costs in predation and mortality, including from hunting by humans and it occurs mainly in the northern hemisphere, where birds are funnelled on to specific routes by natural barriers such as the Mediterranean Sea or the Caribbean Sea. More recently, Johannes Leche began recording dates of arrivals of spring migrants in Finland in 1749, threats to migratory birds have grown with habitat destruction especially of stopover and wintering sites, as well as structures such as power lines and wind farms. The Arctic tern holds the long-distance migration record for birds, travelling between Arctic breeding grounds and the Antarctic each year, shorter migrations are common, including altitudinal migrations on mountains such as the Andes and Himalayas. The timing of migration seems to be controlled primarily by changes in day length, migrating birds navigate using celestial cues from the sun and stars, the earths magnetic field, and probably also mental maps. Records of bird migration were made as much as 3,000 years ago by the Ancient Greek writers Hesiod, Homer, Herodotus and Aristotle. The Bible also notes migrations, as in the Book of Job, the author of Jeremiah wrote, Even the stork in the heavens knows its seasons, and the turtle dove, the swift and the crane keep the time of their arrival. Aristotle noted that cranes traveled from the steppes of Scythia to marshes at the headwaters of the Nile, pliny the Elder, in his Historia Naturalis, repeats Aristotles observations. Aristotle however suggested that swallows and other birds hibernated and this belief persisted as late as 1878, when Elliott Coues listed the titles of no less than 182 papers dealing with the hibernation of swallows. It was not until the end of the century that migration as an explanation for the winter disappearance of birds from northern climes was accepted. Bewick then describes an experiment which succeeded in keeping alive in Britain for several years. He concludes, These experiments have since been confirmed by. Migration is the seasonal movement, often north and south. Bird movements include those made in response to changes in food availability, habitat, sometimes, journeys are not termed true migration because they are irregular or in only one direction. Migration is marked by its annual seasonality, non-migratory birds are said to be resident or sedentary. Approximately 1800 of the worlds 10,000 bird species are long-distance migrants, many bird populations migrate long distances along a flyway. The most common pattern involves flying north in the spring to breed in the temperate or Arctic summer, of course, in the southern hemisphere the directions are reversed, but there is less land area in the far south to support long-distance migration. The primary motivation for migration appears to be food, for example, also, the longer days of the northern summer provide extended time for breeding birds to feed their young
38.
Shelduck
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The shelducks are a group of larger often semi-terrestrial waterfowl, which can be seen as intermediate between geese and ducks. They are mid-sized Old World waterfowl and their diet consists of small shore animals as well as grasses and other plants. They were originally known as sheldrakes, which remained the most common name until the late 19th century, the word is still sometimes used to refer to a male shelduck and can also occasionally refer to the canvasback of North America. The genus name comes from the French name Tadorne for the common shelduck and it may originally derive from Celtic roots meaning pied waterfowl, essentially the same as the English shelduck. The namesake genus of the Tadorninae, Tadorna is very close to the Egyptian goose and its relatives from the Madagascar region. They have even proposed to be referable to the common shelduck. Based on the Taxonomy in Flux from John Boyds website
39.
Diving duck
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The diving ducks, commonly called pochards or scaups, are a category of duck which feed by diving beneath the surface of the water. They are part of Anatidae, the diverse and very large family that includes ducks, geese, the diving ducks are placed in a distinct subfamily, Aythyinae. While morphologically close to the ducks, there are nonetheless some pronounced differences such as in the structure of the trachea. Alternatively, the ducks are placed as a tribe Aythyini in a subfamily Anatidae which would encompass all duck-like birds except the whistling-ducks. Although the group is cosmopolitan, most members are native to the Northern Hemisphere and this group of ducks is so named because its members feed mainly by diving, although in fact the Netta species are reluctant to dive, and feed more like dabbling ducks. These are gregarious ducks, mainly found on water or on estuaries. They are strong fliers, their broad, blunt-tipped wings require faster wing-beats than those of many ducks, Northern species tend to be migratory, southern species do not migrate though the hardhead travels long distances on an irregular basis in response to rainfall. Diving ducks do not walk as well on land as the dabbling ducks, three genera are included in the Aythyini. The probably extinct pink-headed duck, previously treated separately in Rhodonessa, has suggested to belong into Netta. DNA sequence analyses, which would resolve this question, have not been conducted to date for lack of suitable material. It might be a divergence from the dabbling duck lineage. The molecular analysis suggests that the white-winged duck should be placed into a monotypic genus Asarcornis which is fairly close to Aythya
40.
Paraphyletic
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In taxonomy, a group is paraphyletic if it consists of the groups last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—monophyletic subgroups. The group is said to be paraphyletic with respect to the excluded subgroups, the term is commonly used in phylogenetics and in linguistics. The term was coined to apply to well-known taxa like reptiles which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles and all descendants of that all extant reptiles as well as the extinct synapsids—except for mammals. Other commonly recognized paraphyletic groups include fish, monkeys and lizards, if many subgroups are missing from the named group, it is said to be polyparaphyletic. A paraphyletic group cannot be a clade, which is a monophyletic group, groups that include all the descendants of a common ancestor are said to be monophyletic. A paraphyletic group is a group from which one or more subsidiary clades is excluded to form a separate group. Ereshefsky has argued that paraphyletic taxa are the result of anagenesis in the group or groups. For example, dinosaurs are paraphyletic with respect to birds because birds possess many features that dinosaurs lack, a group whose identifying features evolved convergently in two or more lineages is polyphyletic. More broadly, any taxon that is not paraphyletic or monophyletic can be called polyphyletic and these terms were developed during the debates of the 1960s and 70s accompanying the rise of cladistics. The prokaryotes, because they exclude the eukaryotes, a descendant group, bacteria and Archaea are prokaryotes, but archaea and eukaryotes share a common ancestor that is not ancestral to the bacteria. The prokaryote/eukaryote distinction was proposed by Edouard Chatton in 1937 and was accepted after being adopted by Roger Stanier. The botanical code abandoned consideration of bacterial nomenclature in 1975, currently, dicotyledons are paraphyletic because the group excludes monocotyledons. Dicotyledon has not been used as an ICBN classification for decades, phylogenetic analysis indicates that the monocots are a development from a dicot ancestor. Excluding monocots from the dicots makes the latter a paraphyletic group, the order Artiodactyla, because it excludes Cetaceans. In the ICZN Code, the two taxa are orders of equal rank, molecular studies, however, have shown that the Cetacea descend from the Artiodactyl ancestors, although the precise phylogeny within the order remains uncertain. Without the Cetacean descendants the Artiodactyls must be paraphyletic, the class Reptilia as traditionally defined, because it excludes birds and mammals. In the ICZN Code, the three taxa are classes of equal rank, however, mammals hail from the synapsids and birds are descended from the dinosaurs, both of which are reptiles
41.
Tropics
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The tropics are a region of the Earth surrounding the equator. The tropics are also referred to as the zone and the torrid zone. The tropics include all the areas on the Earth where the Sun is at a point directly overhead at least once during the solar year. The tropics are distinguished from the climatic and biomatic regions of Earth, which are the middle latitudes. Tropical is sometimes used in a sense for a tropical climate to mean warm to hot and moist year-round. Many tropical areas have a dry and wet season, the wet season, rainy season or green season, is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls. Areas with wet seasons are disseminated across portions of the tropics and subtropics, under the Köppen climate classification, for tropical climates, a wet season month is defined as a month where average precipitation is 60 millimetres or more. Tropical rainforests technically do not have dry or wet seasons, since their rainfall is distributed through the year. When the wet season occurs during the season, or summer, precipitation falls mainly during the late afternoon. The wet season is a time when air quality improves, freshwater quality improves and vegetation grows significantly, floods cause rivers to overflow their banks, and some animals to retreat to higher ground. Soil nutrients diminish and erosion increases, the incidence of malaria increases in areas where the rainy season coincides with high temperatures. Animals have adaptation and survival strategies for the wetter regime, unfortunately, the previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Regions within the tropics may well not have a tropical climate, there are alpine tundra and snow-capped peaks, including Mauna Kea, Mount Kilimanjaro, and the Andes as far south as the northernmost parts of Chile and Argentina. Under the Köppen climate classification, much of the area within the tropics is classed not as tropical but as dry including the Sahara Desert. Tropical plants and animals are those native to the tropics. Tropical ecosystems may consist of rainforests, dry forests, spiny forests, desert. There are often significant areas of biodiversity, and species present, particularly in rainforests. In biogeography, the tropics are divided into Paleotropics and Neotropics, together, they are sometimes referred to as the Pantropic
42.
Evolution
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Evolution is change in the heritable characteristics of biological populations over successive generations. Evolutionary processes give rise to biodiversity at every level of organisation, including the levels of species, individual organisms. In July 2016, scientists reported identifying a set of 355 genes from the LUCA of all living on Earth. The fossil record includes a progression from early biogenic graphite, to microbial mat fossils, existing patterns of biodiversity have been shaped both by speciation and by extinction. More than 99 percent of all species that lived on Earth are estimated to be extinct. Estimates of Earths current species range from 10 to 14 million, more recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described. In the mid-19th century, Charles Darwin formulated the theory of evolution by natural selection. This teleonomy is the quality whereby the process of natural selection creates and preserves traits that are fitted for the functional roles they perform. The processes by which the changes occur, from one generation to another, are called evolutionary processes or mechanisms, the four most widely recognized evolutionary processes are natural selection, genetic drift, mutation and gene migration. Natural selection and genetic drift sort variation, mutation and gene migration create variation, consequences of selection can include meiotic drive, nonrandom mating and genetic hitchhiking. In the early 20th century the modern evolutionary synthesis integrated classical genetics with Darwins theory of evolution by natural selection through the discipline of population genetics, the importance of natural selection as a cause of evolution was accepted into other branches of biology. Moreover, previously held notions about evolution, such as orthogenesis, evolutionism, evolutionary computation, a sub-field of artificial intelligence, involves the application of Darwinian principles to problems in computer science. The proposal that one type of organism could descend from another type goes back to some of the first pre-Socratic Greek philosophers, such as Anaximander, such proposals survived into Roman times. The poet and philosopher Lucretius followed Empedocles in his masterwork De rerum natura, in contrast to these materialistic views, Aristotelianism considered all natural things as actualisations of fixed natural possibilities, known as forms. This was part of a teleological understanding of nature in which all things have an intended role to play in a divine cosmic order. In the 17th century, the new method of modern science rejected the Aristotelian approach, however, this new approach was slow to take root in the biological sciences, the last bastion of the concept of fixed natural types. The biological classification introduced by Carl Linnaeus in 1735 explicitly recognized the nature of species relationships. Other naturalists of this time speculated on the change of species over time according to natural laws
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Habitat
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A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant, or other type of organism. The term typically refers to the zone in which the organism lives and it is the natural environment in which an organism lives, or the physical environment that surrounds a species population. Every organism has certain habitat needs for the conditions in which it will thrive, habitat types include polar, temperate, subtropical and tropical. The terrestrial vegetation type may be forest, steppe, grassland, the word habitat has been in use since about 1755 and derives from the Latin third-person singular present indicative of habitāre, to inhabit, from habēre, to have or to hold. Habitat can be defined as the environment of an organism. It is similar in meaning to a biotope, an area of environmental conditions associated with a particular community of plants. Generally speaking, animal communities are reliant on specific types of plant communities, some plants and animals are generalists, and their habitat requirements are met in a wide range of locations. The small white butterfly for example is found on all the continents of the world apart from Antarctica and its larvae feed on a wide range of Brassicas and various other plant species, and it thrives in any open location with diverse plant associations. Disturbance is important in the creation of biodiverse habitats, in the absence of disturbance, a climax vegetation cover develops that prevents the establishment of other species. Lightning strikes and toppled trees in tropical forests allow species richness to be maintained as pioneering species move in to fill the gaps created. Similarly coastal habitats can become dominated by kelp until the seabed is disturbed by a storm, another cause of disturbance is when an area may be overwhelmed by an invasive introduced species which is not kept under control by natural enemies in its new habitat. Terrestrial habitat types include forests, grasslands, wetlands and deserts, within these broad biomes are more specific habitats with varying climate types, temperature regimes, soils, altitudes and vegetation types. Many of these habitats grade into each other and each one has its own communities of plants. A habitat may suit a particular species well, but its presence or absence at any particular location depends to some extent on chance, on its dispersal abilities, freshwater habitats include rivers, streams, lakes, ponds, marshes and bogs. Although some organisms are found across most of these habitats, the majority have more specific requirements, similarly, aquatic plants can be floating, semi-submerged, submerged or grow in permanently or temporarily saturated soils besides bodies of water. Marine habitats include brackish water, estuaries, bays, the sea, the intertidal zone. Further variations include rock pools, sand banks, mudflats, brackish lagoons, sandy and pebbly beaches, the benthic zone or seabed provides a home for both static organisms, anchored to the substrate, and for a large range of organisms crawling on or burrowing into the surface. A desert is not the kind of habitat that favours the presence of amphibians, with their requirement for water to keep their skins moist, nevertheless, some frogs live in deserts, creating moist habitats underground and hibernating while conditions are adverse
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Brazilian teal
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The Brazilian teal or Brazilian duck is the only duck in the genus Amazonetta. There are two sub-species, A. brasiliensis brasiliensis, the race, found in Brazil, Suriname, Guyana, French Guiana, central Venezuela, eastern Colombia. A. brasiliensis ipecutiri, found in Brazil, Northern Argentina, eastern Bolivia, Uruguay, the ducks are light brown in colour. Drakes distinguish themselves from females in having red beaks and legs, the colour of these limbs is much duller in females. Their preferred habitat is a body of freshwater away from the coast with dense vegetation nearby, Brazilian teal live in pairs or in small groups of up to twenty birds. Both parents look after their hatchlings and they eat seeds, fruits, roots and insect, while ducklings eat only insects. They are plentiful and are listed as of Least Concern, short description and pictures Media related to Amazonetta brasiliensis at Wikimedia Commons
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Mitochondrial DNA
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Mitochondrial DNA is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, adenosine triphosphate. Mitochondrial DNA is only a portion of the DNA in a eukaryotic cell, most of the DNA can be found in the cell nucleus and, in plants and algae. In humans, the 16,569 base pairs of mitochondrial DNA encode for only 37 genes, human mitochondrial DNA was the first significant part of the human genome to be sequenced. In most species, including humans, mtDNA is inherited solely from the mother, since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology. It also permits an examination of the relatedness of populations, and so has become important in anthropology and this theory is called the endosymbiotic theory. Each mitochondrion is estimated to contain 2–10 mtDNA copies, the reasons why mitochondria have retained some genes are debated. Recent analysis of a range of mtDNA genomes suggests that both these features may dictate mitochondrial gene retention. In most multicellular organisms, mtDNA is inherited from the mother, mechanisms for this include simple dilution, degradation of sperm mtDNA in the male genital tract, in the fertilized egg, and, at least in a few organisms, failure of sperm mtDNA to enter the egg. Whatever the mechanism, this single parent pattern of inheritance is found in most animals, most plants. In sexual reproduction, mitochondria are inherited exclusively from the mother. Also, most mitochondria are present at the base of the sperms tail, in 1999 it was reported that paternal sperm mitochondria are marked with ubiquitin to select them for later destruction inside the embryo. Some in vitro techniques, particularly injecting a sperm into an oocyte. The fact that mitochondrial DNA is maternally inherited enables researchers to trace maternal lineage far back in time. This is usually accomplished on human mitochondrial DNA by sequencing the hypervariable control regions, hVR1, for example, consists of about 440 base pairs. These 440 base pairs are then compared to the regions of other individuals to determine maternal lineage. Most often, the comparison is made to the revised Cambridge Reference Sequence, vilà et al. have published studies tracing the matrilineal descent of domestic dogs to wolves. The concept of the Mitochondrial Eve is based on the type of analysis. MtDNA is highly conserved, and its relatively slow mutation rates make it useful for studying the evolutionary relationships—phylogeny—of organisms, biologists can determine and then compare mtDNA sequences among different species and use the comparisons to build an evolutionary tree for the species examined
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Cytochrome b
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Cytochrome b is a protein found in the mitochondria of eukaryotic cells. It functions as part of the transport chain and is the main subunit of transmembrane cytochrome bc1. In the mitochondrion of eukaryotes and in prokaryotes, cytochrome b is a component of respiratory chain complex III — also known as the bc1 complex or ubiquinol-cytochrome c reductase. In plant chloroplasts and cyanobacteria, there is a protein, cytochrome b6. These complexes are involved in transport, the pumping of protons to create a proton-motive force. This proton gradient is used for the generation of ATP and these complexes play a vital role in cells. Cytochrome b/b6 is a membrane protein of approximately 400 amino acid residues that probably has 8 transmembrane segments. In plants and cyanobacteria, cytochrome b6 consists of two subunits encoded by the petB and petD genes, cytochrome b/b6 non-covalently binds two heme groups, known as b562 and b566. Four conserved histidine residues are postulated to be the ligands of the atoms of these two heme groups. Cytochrome b is used as a region of mitochondrial DNA for determining phylogenetic relationships between organisms, due to its sequence variability. It is considered to be most useful in determining relationships within families, mutations in cytochrome b primarily result in exercise intolerance in human patients, though more rare, severe multi-system pathologies have also been reported. Single-point mutations in cytochrome b of Plasmodium falciparum and P. berghei are associated with resistance to the anti-malarial drug atovaquone
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Protein subunit
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In structural biology, a protein subunit is a single protein molecule that assembles with other protein molecules to form a protein complex. Some naturally occurring proteins have a small number of subunits and therefore described as oligomeric. Others may consist from a large number of subunits and therefore described as multimeric, for example microtubules. The subunits of a protein may be identical, homologous or totally dissimilar. In some protein assemblies, one subunit may be a subunit that enzymatically catalyzes a reaction. Although telomerase has telomerase reverse transcriptase as a subunit, regulation is accomplished by factors outside of the protein. An enzyme composed of regulatory and catalytic subunits when assembled is often referred to as a holoenzyme. For example, class I phosphoinositide 3-kinase is composed of a catalytic subunit. One subunit is made of one polypeptide chain, a polypeptide chain has one gene coding for it – meaning that a protein must have one gene for each unique subunit. A subunit is often named with a Greek or Roman letter, for example, ATP synthase has a type of subunit called α. Three of these are present in the ATP synthase molecule, and is therefore designated α3, larger groups of subunits can also the specified, like α3β3-hexamer and c-ring. A subunit vaccine presents an antigen to the system without introducing viral particles. One method of production involves isolation of a protein from a virus. A weakness of this technique is that proteins can be denatured. The recombinant vector that is genomically modified will express the antigen, the antigen is extracted from the vector. Just like the highly successful subunit vaccines, the antigen will be of little to no risk to the patient. Vi capsular polysaccharide vaccine is another subunit vaccine, in this case and it is also called a conjugate vaccine, in which a polysaccharide antigen has been covalently attached to a carrier protein for T-cell-dependent antigen processing. Protein quaternary structure Allostery Cooperativity Monomer Dilip Gore, Reecha Pandit, in silico Identification of Cell Surface Antigens in Neisseria meningitidis
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Media related to Anatinae at Wikimedia Commons