1.
Megaannum
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A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earths axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the globe, four seasons are recognized, spring, summer, autumn. In tropical and subtropical regions several geographical sectors do not present defined seasons, but in the seasonal tropics, a calendar year is an approximation of the number of days of the Earths orbital period as counted in a given calendar. The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a year of 366 days, as do the Julian calendars. For the Gregorian calendar the average length of the year across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a to represent a year of either 365 or 366 days, in English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time, it is defined as 365.25 days of exactly 86400 seconds, totalling exactly 31557600 seconds in the Julian astronomical year. The word year is used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year. Similarly, year can mean the period of any planet, for example. The term can also be used in reference to any long period or cycle, west Saxon ġēar, Anglian ġēr continues Proto-Germanic *jǣran. Cognates are German Jahr, Old High German jār, Old Norse ár and Gothic jer, all the descendants of the Proto-Indo-European noun *yeh₁rom year, season. Cognates also descended from the same Proto-Indo-European noun are Avestan yārǝ year, Greek ὥρα year, season, period of time, Old Church Slavonic jarŭ, Latin annus is from a PIE noun *h₂et-no-, which also yielded Gothic aþn year. Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, the Greek word for year, ἔτος, is cognate with Latin vetus old, from the PIE word *wetos- year, also preserved in this meaning in Sanskrit vat-sa- yearling and vat-sa-ras year. Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc. per annum means each year, anno Domini means in the year of the Lord. No astronomical year has an number of days or lunar months. Financial and scientific calculations often use a 365-day calendar to simplify daily rates, in the Julian calendar, the average length of a year is 365.25 days. In a non-leap year, there are 365 days, in a year there are 366 days
2.
Precambrian
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The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon. A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
3.
Cambrian
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The Cambrian Period was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago to the beginning of the Ordovician Period 485.4 mya and its subdivisions, and its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latinised form of Cymru, the Welsh name for Wales, as a result, our understanding of the Cambrian biology surpasses that of some later periods. The rapid diversification of lifeforms in the Cambrian, known as the Cambrian explosion, most of the continents were probably dry and rocky due to a lack of vegetation. Shallow seas flanked the margins of several continents created during the breakup of the supercontinent Pannotia, the seas were relatively warm, and polar ice was absent for much of the period. The United States Federal Geographic Data Committee uses a barred capital C ⟨Є⟩ character similar to the capital letter Ukrainian Ye ⟨Є⟩ to represent the Cambrian Period, the proper Unicode character is U+A792 Ꞓ LATIN CAPITAL LETTER C WITH BAR. Despite the long recognition of its distinction from younger Ordovician Period rocks and older Supereon Precambrian rocks, the base of the Cambrian lies atop a complex assemblage of trace fossils known as the Treptichnus pedum assemblage. Pedum in Namibia, Spain and Newfoundland, and possibly, in the western USA, the stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain. The Cambrian Period followed the Ediacaran Period and was followed by the Ordovician Period, the Cambrian is divided into four epochs and ten ages. Currently only two series and five stages are named and have a GSSP, because the international stratigraphic subdivision is not yet complete, many local subdivisions are still widely used. In some of these subdivisions the Cambrian is divided into three epochs with locally differing names – the Early Cambrian, Middle Cambrian and Furongian, rocks of these epochs are referred to as belonging to the Lower, Middle, or Upper Cambrian. Trilobite zones allow biostratigraphic correlation in the Cambrian, each of the local epochs is divided into several stages. The International Commission on Stratigraphy list the Cambrian period as beginning at 541 million years ago, the lower boundary of the Cambrian was originally held to represent the first appearance of complex life, represented by trilobites. The recognition of small shelly fossils before the first trilobites, and Ediacara biota substantially earlier and this formal designation allowed radiometric dates to be obtained from samples across the globe that corresponded to the base of the Cambrian. Early dates of 570 million years ago quickly gained favour, though the used to obtain this number are now considered to be unsuitable. A more precise date using modern radiometric dating yield a date of 541 ±0.3 million years ago, most continental land was clustered in the Southern Hemisphere at this time, but was drifting north. Large, high-velocity rotational movement of Gondwana appears to have occurred in the Early Cambrian, the sea levels fluctuated somewhat, suggesting there were ice ages, associated with pulses of expansion and contraction of a south polar ice cap. In Baltoscandia a Lower Cambrian transgression transformed large swathes of the Sub-Cambrian peneplain into a epicontinental sea, the Earth was generally cold during the early Cambrian, probably due to the ancient continent of Gondwana covering the South Pole and cutting off polar ocean currents
4.
Ordovician
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The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. Lapworth recognized that the fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods. It received international sanction in 1960, when it was adopted as a period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event considerably increased the diversity of life, fish, the worlds first true vertebrates, continued to evolve, and those with jaws may have first appeared late in the period. Life had yet to diversify on land, about 100 times as many meteorites struck the Earth during the Ordovician compared with today. The Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event and it lasted for about 42 million years and ended with the Ordovician–Silurian extinction event, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary slightly from those found in other sources and this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is highly significant and it correlates well with the occurrence of widespread graptolite, conodont, and trilobite species. The base of the Tremadocian allows scientists to relate these species not only to each other and this makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected an international system of subdivisions. There exist Baltoscandic, British, Siberian, North American, Australian, the Ordovician Period in Britain was traditionally broken into Early, Middle and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, the Floian corresponds to the lower Arenig, the Arenig continues until the early Darriwilian, subsuming the Dapingian. The Llanvirn occupies the rest of the Darriwilian, and terminates with it at the base of the Late Ordovician. The Sandbian represents the first half of the Caradoc, the Caradoc ends in the mid-Katian, during the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole, the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia
5.
Silurian
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The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period,419.2 Mya. As with other periods, the rock beds that define the periods start and end are well identified. The base of the Silurian is set at a major Ordovician-Silurian extinction event when 60% of marine species were wiped out, a significant evolutionary milestone during the Silurian was the diversification of jawed and bony fish. However, terrestrial life would not greatly diversify and affect the landscape until the Devonian, the Silurian system was first identified by British geologist Sir Roderick Impey Murchison, who was examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s. He named the sequences for a Celtic tribe of Wales, the Silures, inspired by his friend Adam Sedgwick and this naming does not indicate any correlation between the occurrence of the Silurian rocks and the land inhabited by the Silures. As it was first identified, the Silurian series when traced farther afield quickly came to overlap Sedgwicks Cambrian sequence, however, charles Lapworth resolved the conflict by defining a new Ordovician system including the contested beds. An early alternative name for the Silurian was Gotlandian after the strata of the Baltic island of Gotland, the French geologist Joachim Barrande, building on Murchisons work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge. He divided the Silurian rocks of Bohemia into eight stages and his interpretation was questioned in 1854 by Edward Forbes, and the later stages of Barrande, F, G and H, have since been shown to be Devonian. Despite these modifications in the groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest fossils. The epoch is named for the town of Llandovery in Carmarthenshire, the Wenlock, which lasted from 433.4 ±1.5 to 427.4 ±2.8 mya, is subdivided into the Sheinwoodian and Homerian ages. It is named after Wenlock Edge in Shropshire, England, during the Wenlock, the oldest known tracheophytes of the genus Cooksonia, appear. The first terrestrial animals also appear in the Wenlock, represented by air-breathing millipedes from Scotland. The Ludlow, lasting from 427.4 ±1.5 to 423 ±2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago, and it is named for the town of Ludlow in Shropshire, England. The Pridoli, lasting from 423 ±1.5 to 419.2 ±2.8 mya, is the final and it is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic. Přídolí is the old name of a field area. The high sea levels of the Silurian and the flat land resulted in a number of island chains. The southern continents remained united during this period, the melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity. The continents of Avalonia, Baltica, and Laurentia drifted together near the equator and this event is the Caledonian orogeny, a spate of mountain building that stretched from New York State through conjoined Europe and Greenland to Norway
6.
Devonian
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The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian,419.2 million years ago, to the beginning of the Carboniferous,358.9 Mya. It is named after Devon, England, where rocks from this period were first studied, the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents, by the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established, Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fish. The first ray-finned and lobe-finned bony fish appeared, while the placodermi began dominating almost every aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral, in the oceans, primitive sharks became more numerous than in the Silurian and Late Ordovician. The first ammonites, species of molluscs, appeared, trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placodermi, and all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, while the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, another common term is Age of the Fishes, referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian, Breconian and Farlovian stages, in the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common. The Devonian Period is formally broken into Early, Middle and Late subdivisions, the rocks corresponding to those epochs are referred to as belonging to the Lower, Middle and Upper parts of the Devonian System. Early Devonian The Early Devonian lasted from 419.2 ±2.8 to 393.3 ±2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ±2.8 to 407.6 ±2.5, and was followed by the Emsian, which lasted until the Middle Devonian began,393. 3±2.7 million years ago. Middle Devonian The Middle Devonian comprised two subdivisions, first the Eifelian, which gave way to the Givetian 387. 7±2.7 million years ago. Late Devonian Finally, the Late Devonian started with the Frasnian,382.7 ±2.8 to 372.2 ±2.5, during which the first forests took shape on land. The first tetrapods appeared in the record in the ensuing Famennian subdivision. This lasted until the end of the Devonian,358. 9±2.5 million years ago, the Devonian was a relatively warm period, and probably lacked any glaciers
7.
Carboniferous
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The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period,298.9 Mya. The name Carboniferous means coal-bearing and derives from the Latin words carbō and ferō, and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the system names to be employed. The Carboniferous is often treated in North America as two periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial life was established by the Carboniferous period. Amphibians were the dominant land vertebrates, of one branch would eventually evolve into amniotes. Arthropods were also common, and many were much larger than those of today. Vast swaths of forest covered the land, which would eventually be laid down, the atmospheric content of oxygen also reached their highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. A major marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred in the middle of the period, the later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. In the United States the Carboniferous is usually broken into Mississippian and Pennsylvanian subperiods, the Silesian is roughly contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, and the Westphalian as the Coal Measures and Pennant Sandstone. There was also a drop in south polar temperatures, southern Gondwanaland was glaciated throughout the period and these conditions apparently had little effect in the deep tropics, where lush swamps, later to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major extinction, one that hit crinoids. This sea level drop and the unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation, the Carboniferous was a time of active mountain-building, as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America, in the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, the Late Carboniferous Pangaea was shaped like an O. There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, which was inside the O in the Carboniferous Pangaea, other minor oceans were shrinking and eventually closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean
8.
Permian
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The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era, the following Triassic Period belongs to the Mesozoic Era, the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the groups of the mammals, turtles, lepidosaurs. The world at the time was dominated by two known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior, amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earths history, in which nearly 90% of marine species and it would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian-Triassic extinction event was protracted, on land, the term Permian was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil, the region now lies in the Perm Krai of Russia. This could have in part caused the extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms. During the Permian, all the Earths major landmasses were collected into a supercontinent known as Pangaea. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, a new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmass interiors experience climates with extreme variations of heat and cold, deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian, the climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an Ice Age, glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continents interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles, Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. By the close of the Permian, trilobites and a host of other groups became extinct. Terrestrial life in the Permian included diverse plants, fungi, arthropods, the period saw a massive desert covering the interior of Pangaea
9.
Triassic
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The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period 252.17 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era, both the start and end of the period are marked by major extinction events. Therapsids and archosaurs were the terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic, the vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, however, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another mass extinction, the Triassic-Jurassic extinction event. The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, from the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed. Later in the mid-Triassic a similar sea penetrated along the equator from the west, the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates, thus, the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans. At the beginning of the Mesozoic Era, Africa was joined with Earths other continents in Pangaea, Africa shared the supercontinents relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are common in the south than north. The time boundary separating the Permian and Triassic marks the advent of an event with global impact. At Paleorrota geopark, located in Rio Grande do Sul, Brazil, in these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. Pangaeas large size limited the effect of the global ocean, its continental climate was highly seasonal, with very hot summers. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, the best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. On land, the vascular plants included the lycophytes, the dominant cycadophytes, ginkgophyta, ferns, horsetails
10.
Jurassic
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The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic, Middle, and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, Middle, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, India, South America, Japan, Australasia. As the Jurassic proceeded, larger and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are also poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
11.
Cretaceous
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The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 Mya. It is the last period of the Mesozoic Era, the Cretaceous Period is usually abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists, during this time, new groups of mammals and birds, as well as flowering plants, appeared. The Cretaceous ended with a mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, the name Cretaceous was derived from Latin creta, meaning chalk. The Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series, in older literature the Cretaceous is sometimes divided into three series, Neocomian, Gallic and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide, in many parts of the world, alternative local subdivisions are still in use. As with other geologic periods, the rock beds of the Cretaceous are well identified. No great extinction or burst of diversity separates the Cretaceous from the Jurassic and this layer has been dated at 66.043 Ma. A140 Ma age for the Jurassic-Cretaceous boundary instead of the usually accepted 145 Ma was proposed in 2014 based on a study of Vaca Muerta Formation in Neuquén Basin. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a first step toward formally changing the age in the International Union of Geological Sciences, due to the high sea level there was extensive space for such sedimentation. Because of the young age and great thickness of the system. Chalk is a type characteristic for the Cretaceous. It consists of coccoliths, microscopically small calcite skeletons of coccolithophores, the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not easily consolidated and the Chalk Group still consists of sediments in many places. The group also has other limestones and arenites, among the fossils it contains are sea urchins, belemnites, ammonites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls
12.
Paleogene
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The Paleogene is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 million years ago to the beginning of the Neogene Period 23.03 Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon and this period consists of the Paleocene, Eocene and Oligocene epochs. The terms Paleogene System and lower Tertiary System are applied to the rocks deposited during the Paleogene Period. By dividing the Tertiary Period into two periods instead of directly into five epochs, the periods are more comparable to the duration of periods of the preceding Mesozoic and Paleozoic Eras. The trend was caused by the formation of the Antarctic Circumpolar Current. During the Paleogene, the continued to drift closer to their current positions. India was in the process of colliding with Asia, subsequently forming the Himalayas, the Atlantic Ocean continued to widen by a few centimeters each year. Africa was moving north to meet with Europe and form the Mediterranean, inland seas retreated from North America early in the period. Australia had also separated from Antarctica and was drifting towards Southeast Asia, mammals began a rapid diversification during this period. Some of these mammals would evolve into forms that would dominate the land, while others would become capable of living in marine, specialized terrestrial. Those that took to the oceans became modern cetaceans, while those that took to the trees became primates, the group to which humans belong. Birds, which were well established by the end of the Cretaceous. In comparison to birds and mammals, most other branches of life remained unchanged during this period. As the Earth cooled, tropical plants became less numerous and were now restricted to equatorial regions, deciduous plants, which could survive through the seasonal climates the world was now experiencing, became more common. The Paleogene is notable in the context of offshore oil drilling, and especially in Gulf of Mexico oil exploration and these rock formations represent the current cutting edge of deep-water oil discovery. Lower Tertiary explorations to date include, Kaskida Oil Field Tiber Oil Field Jack 2 Paleogene Microfossils, 180+ images of Foraminifera
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Neogene
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The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene, some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. During this period, mammals and birds continued to evolve into modern forms. Early hominids, the ancestors of humans, appeared in Africa near the end of the period, some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the ocean currents from the Pacific to the Atlantic ocean. The global climate cooled considerably over the course of the Neogene, the terms Neogene System and upper Tertiary System describe the rocks deposited during the Neogene Period. The continents in the Neogene were very close to their current positions, the Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas, sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America. The global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, and by the end of the period the first of a series of glaciations of the current Ice Age began, marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the part of the period. Mammals and birds continued to be the dominant terrestrial vertebrates, the first hominids, the ancestors of humans, appeared in Africa and spread into Eurasia. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones, grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. The Neogene traditionally ended at the end of the Pliocene Epoch, just before the definition of the beginning of the Quaternary Period. However, there was a movement amongst geologists to also include ongoing geological time in the Neogene, by dividing the Cenozoic Era into three periods instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras. The International Commission on Stratigraphy once proposed that the Quaternary be considered a sub-era of the Neogene, with a date of 2.58 Ma. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene epochs, thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. Digital Atlas of Neogene Life for the Southeastern United States — by San Jose State University via Web Archive
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Pleistocene
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The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the worlds most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period, the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, all of these stages were defined in southern Europe. In addition to this subdivision, various regional subdivisions are often used. Charles Lyell introduced the term pleistocene in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today and this distinguished it from the older Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. The Pleistocene has been dated from 2.588 million to 11,700 years before present and it covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9640 BC, the IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75°06 N 42°18 W, the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils, Discoaster pentaradiatus, the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the date of the Pleistocene to 2.58 Ma. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places and it is estimated that, at maximum glacial extent, 30% of the Earths surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the sheet, a few hundred kilometres in North America. The mean annual temperature at the edge of the ice was −6 °C, during interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global, antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap, there were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one, the Cordilleran ice sheet covered the North American northwest, the east was covered by the Laurentide
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Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
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Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
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Chordate
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Chordates are deuterostomes, as during the embryo development stage the anus forms before the mouth. They are also bilaterally symmetric coelomates, in the case of vertebrate chordates, the notochord is usually replaced by a vertebral column during development, and they may have body plans organized via segmentation. There are also additional extinct taxa, the Vertebrata are sometimes considered as a subgroup of the clade Craniata, consisting of chordates with a skull, the Craniata and Tunicata compose the clade Olfactores. Of the more than 65,000 living species of chordates, the worlds largest and fastest animals, the blue whale and peregrine falcon respectively, are chordates, as are humans. Fossil chordates are known from at least as early as the Cambrian explosion, Hemichordata, which includes the acorn worms, has been presented as a fourth chordate subphylum, but it now is usually treated as a separate phylum. The Hemichordata, along with the Echinodermata, form the Ambulacraria, the Chordata and Ambulacraria form the superphylum Deuterostomia, composed of the deuterostomes. Attempts to work out the relationships of the chordates have produced several hypotheses. All of the earliest chordate fossils have found in the Early Cambrian Chengjiang fauna. Because the fossil record of early chordates is poor, only molecular phylogenetics offers a prospect of dating their emergence. However, the use of molecular phylogenetics for dating evolutionary transitions is controversial and it has also proved difficult to produce a detailed classification within the living chordates. Attempts to produce family trees shows that many of the traditional classes are paraphyletic. While this has been known since the 19th century, an insistence on only monophyletic taxa has resulted in vertebrate classification being in a state of flux. Although the name Chordata is attributed to William Bateson, it was already in prevalent use by 1880, ernst Haeckel described a taxon comprising tunicates, cephalochordates, and vertebrates in 1866. Though he used the German vernacular form, it is allowed under the ICZN code because of its subsequent latinization, among the vertebrate sub-group of chordates the notochord develops into the spine, and in wholly aquatic species this helps the animal to swim by flexing its tail. In fish and other vertebrates, this develops into the spinal cord, the pharynx is the part of the throat immediately behind the mouth. In fish, the slits are modified to form gills, a muscular tail that extends backwards behind the anus. This is a groove in the wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus and it also stores iodine, and may be a precursor of the vertebrate thyroid gland
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Mammal
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Mammals are any vertebrates within the class Mammalia, a clade of endothermic amniotes distinguished from reptiles by the possession of a neocortex, hair, three middle ear bones and mammary glands. All female mammals nurse their young with milk, secreted from the mammary glands, Mammals include the largest animals on the planet, the great whales. The basic body type is a quadruped, but some mammals are adapted for life at sea, in the air, in trees. The largest group of mammals, the placentals, have a placenta, Mammals range in size from the 30–40 mm bumblebee bat to the 30-meter blue whale. With the exception of the five species of monotreme, all modern mammals give birth to live young, most mammals, including the six most species-rich orders, belong to the placental group. The largest orders are the rodents, bats and Soricomorpha, the next three biggest orders, depending on the biological classification scheme used, are the Primates, the Cetartiodactyla, and the Carnivora. Living mammals are divided into the Yinotheria and Theriiformes There are around 5450 species of mammal, in some classifications, extant mammals are divided into two subclasses, the Prototheria, that is, the order Monotremata, and the Theria, or the infraclasses Metatheria and Eutheria. The marsupials constitute the group of the Metatheria, and include all living metatherians as well as many extinct ones. Much of the changes reflect the advances of cladistic analysis and molecular genetics, findings from molecular genetics, for example, have prompted adopting new groups, such as the Afrotheria, and abandoning traditional groups, such as the Insectivora. The mammals represent the only living Synapsida, which together with the Sauropsida form the Amniota clade, the early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period, this group diverged from the line that led to todays reptiles. Some mammals are intelligent, with some possessing large brains, self-awareness, Mammals can communicate and vocalize in several different ways, including the production of ultrasound, scent-marking, alarm signals, singing, and echolocation. Mammals can organize themselves into fission-fusion societies, harems, and hierarchies, most mammals are polygynous, but some can be monogamous or polyandrous. They provided, and continue to provide, power for transport and agriculture, as well as commodities such as meat, dairy products, wool. Mammals are hunted or raced for sport, and are used as model organisms in science, Mammals have been depicted in art since Palaeolithic times, and appear in literature, film, mythology, and religion. Defaunation of mammals is primarily driven by anthropogenic factors, such as poaching and habitat destruction, Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is accepted, McKenna & Bell and Wilson & Reader provide useful recent compendiums. Though field work gradually made Simpsons classification outdated, it remains the closest thing to a classification of mammals
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Primate
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A primate is a mammal of the order Primates. In taxonomy, primates include two distinct lineages, strepsirrhines and haplorhines, Primates arose from ancestors that lived in the trees of tropical forests, many primate characteristics represent adaptations to life in this challenging three-dimensional environment. Most primate species remain at least partly arboreal, with the exception of humans, who inhabit every continent except for Antarctica, most primates live in tropical or subtropical regions of the Americas, Africa and Asia. Based on fossil evidence, the earliest known true primates, represented by the genus Teilhardina, an early close primate relative known from abundant remains is the Late Paleocene Plesiadapis, c. Molecular clock studies suggest that the branch may be even older. The order Primates was traditionally divided into two groupings, prosimians and anthropoids. Prosimians have characteristics more like those of the earliest primates, and include the lemurs of Madagascar, lorisoids, simians include monkeys, apes and hominins. Simians are divided into two groups, catarrhine monkeys and apes of Africa and Southeast Asia and platyrrhine or New World monkeys of South, catarrhines consist of Old World monkeys, gibbons and great apes, New World monkeys include the capuchin, howler and squirrel monkeys. Humans are the only extant catarrhines to have spread successfully outside of Africa, South Asia, New primate species are still being discovered. More than 25 species were described in the decade of the 2000s. Considered generalist mammals, primates exhibit a range of characteristics. Some primates are primarily terrestrial rather than arboreal, but all species possess adaptations for climbing trees, locomotion techniques used include leaping from tree to tree, walking on two or four limbs, knuckle-walking, and swinging between branches of trees. Primates are characterized by large brains relative to other mammals, as well as a reliance on stereoscopic vision at the expense of smell. These features are developed in monkeys and apes and noticeably less so in lorises. Three-color vision has developed in some primates, most also have opposable thumbs and some have prehensile tails. Many species are dimorphic, differences include body mass, canine tooth size. Primates have slower rates of development than other similarly sized mammals and reach maturity later, depending on the species, adults may live in solitude, in mated pairs, or in groups of up to hundreds of members. The relationships among the different groups of primates were not clearly understood until relatively recently, for example, ape has been used either as an alternative for monkey or for any tailless, relatively human-like primate
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Haplorhini
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Haplorrhini is a clade containing the tarsiers and the simians. The name is also spelt Haplorrhini, the simians include catarrhines, and the platyrrhines. The extinct omomyids, which are considered to be the most basal haplorhines, are believed to be closely related to the tarsiers than to other haplorhines. Haplorhines share a number of derived features that distinguish them from the strepsirrhine wet-nosed primates, the haplorhine upper lip, which has replaced the ancestral rhinarium found in strepsirrhines, is not directly connected to their nose or gum, allowing a large range of facial expressions. Their brain-to-body mass ratio is greater than the strepsirrhines. Haplorhines have a plate, unlike the postorbital bar found in strepsirrhines. All anthropoids have a uterus, tarsiers have a bicornate uterus like the strepsirrhines. Most species typically have single births, although twins and triplets are common for marmosets, despite similar gestation periods, haplorhine newborns are relatively much larger than strepsirrhine newborns, but have a longer dependence period on their mother. This difference in size and dependence is credited to the complexity of their behavior. The taxonomic name Haplorhini derives from the Ancient Greek haploûs and rhinos and it refers to the lack of a rhinarium or wet nose, which is found in many mammals, including strepsirrhine primates. Haplorhini and its sister clade, Strepsirrhini, diverged about 65 million years ago, the fossil Archicebus may be similar to the most recent common ancestor at this time. The other major clade within Haplorhini, the simians, is divided into two parvorders, Platyrrhini and Catarrhini, the New World monkeys split from catarrhines about 40 mya, while the apes diverged from Old World monkeys about 25 mya. The available fossil evidence indicates both the hominoid and cercopithecoid clades originated in Africa. The following is the listing of the living families, and their placement in the Order Primates, ORDER PRIMATES Suborder Strepsirrhini, lemurs, lorises
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Simian
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The simians are the monkeys, cladistically including the apes, the New World monkeys or platyrrhines, and the catarrhine clade consisting of the Old World monkeys and apes. The simian line and the line diverged about 60 million years ago. Forty million years ago, simians from Africa colonized South America, the remaining simians split 25 million years ago into apes and Old World monkeys. Under modern classification, the tarsiers and simians are grouped under the suborder Haplorhini while the strepsirrhines are placed in suborder Strepsirrhini, in anthropoidea, evidences indicate that the Old and the New World primates went through parallel evolution. Primatology, paleoanthropology, and other related fields are split on their usage of the synonymous infraorder names, Simiiformes and Anthropoidea. According to Robert Hoffstetter, the term Simiiformes has priority over Anthropoidea because of the taxonomic term Simii by van der Hoeven, from which it is constructed, dates to 1833. In contrast, Anthropoidea by Mivart dates to 1864, while Simiiformes by Haeckel dates to 1866, Hoffstetter also argued that Simiiformes is also constructed like a proper infraorder name, whereas Anthropoidea ends in -oidea, which is reserved for superfamilies. He also noted that Anthropoidea is too easily confused with anthropoïdes, the simians are split into three distinct groups. The New World monkeys in parvorder Platyrrhini split from the rest of the line about 40 mya. This group split about 25 mya between the Old World monkeys and the apes
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Hominidae
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Several revisions in classifying the great apes have caused the use of the term hominid to vary over time. Its original meaning referred only to humans and their closest non-extant relatives and that restrictive meaning has now been largely assumed by the term hominin, which comprises all members of the human clade after the split from the chimpanzees. The current, 21st-century meaning of hominid includes all the great apes including humans, the most recent common ancestor of all Hominidae lived roughly 14 million years ago, when the ancestors of the orangutans speciated from the ancestral line of the other three genera. Those ancestors of the family Hominidae had already speciated from the family Hylobatidae, in the early Miocene, about 22 million years ago, there were many species of arboreally adapted primitive catarrhines from East Africa, the variety suggests a long history of prior diversification. Fossils at 20 million years ago include fragments attributed to Victoriapithecus, the most recent of these far-flung Miocene apes is Oreopithecus, from the fossil-rich coal beds in northern Italy and dated to 9 million years ago. Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by Nakalipithecus fossils found in Kenya and Ouranopithecus found in Greece. Molecular evidence suggests that between 8 and 4 million years ago, first the gorillas, and then the split off from the line leading to the humans. Human DNA is approximately 98. 4% identical to that of chimpanzees when comparing single nucleotide polymorphisms, the earliest fossils argued by some to belong to the human lineage are Sahelanthropus tchadensis and Orrorin tugenensis, followed by Ardipithecus, with species Ar. kadabba and Ar. ramidus. The classification of the apes has been revised several times in the last few decades. The original meaning of the referred to only humans and their closest relatives—what is now the modern meaning of the term hominin. And the meaning of the taxon Hominidae changed gradually, leading to a different usage of hominid that today all the great apes including humans. A hominid is a member of the family Hominidae, the apes, orangutans, gorillas, chimpanzees. A hominine is a member of the subfamily Homininae, gorillas, chimpanzees, a hominin is a member of the tribe Hominini, Chimpanzees and humans. A homininan is a member of the subtribe Hominina of the tribe Hominini, a human is a member of the genus Homo, of which Homo sapiens is the only extant species, and within that Homo sapiens sapiens is the only surviving subspecies. For each clade it is indicated approximately when newer extant clades emerged, some texts will refer to Homonini as the Hominina branch. Many scientists, including paleoanthropologists, continue to use the term hominid to mean humans, as mentioned, Hominidae was originally the name given to the family of humans and their close relatives, with the other great apes all being placed in a separate family, the Pongidae. However, that eventually made Pongidae paraphyletic because at least one great ape species proved to be more closely related to humans than to other great apes. Most taxonomists today encourage monophyletic groups—this would require, in this case, thus, many biologists now assign Pongo to the family Hominidae
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Homininae
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Homininae is a subfamily of Hominidae. It includes two tribes, with their extant as well as species, the Hominini tribe. It comprises all hominids that arose after orangutans split from the line of great apes, the Homininae cladogram has three main branches, which lead to gorillas, and to humans and chimpanzees via the tribe Hominini and subtribes Hominina and Panina. There are two living species of Panina and two living species of gorillas, but only one extant human species, traces of hypothetical Homo species, including Homo floresiensis and Homo denisova, have been found with dates as recent as 12,000 years ago. Organisms in this class are described as hominine or hominines, until 1980, the family Hominidae meant humans only, the non-human great apes were assigned to the family Pongidae. The subfamily Homininae can be subdivided into three branches, the tribe Gorillini, and the tribe Hominini with subtribes Panina and Hominina. Their existence suggests that the Homininae tribes diverged not earlier than about 8 million years ago, today, chimpanzees and gorillas live in tropical forests with acid soils that rarely preserve fossils. This shows that some chimpanzees lived close to Homo at the time, australopithecus and early Paranthropus may have been bipedal. Very early hominins such as Ardipithecus ramidus may have possessed a type of bipedalism. It is proposed that they evolved from H. erectus as a case of insular dwarfism, in spite of their smaller brain, there is evidence that H. floresiensis used fire and made stone tools at least as sophisticated as those of their proposed ancestors H. erectus. In this case, it seems that for intelligence, the structure of the brain is more important than its size, sexuality is related to family structure and partly shapes it. The involvement of fathers in education is unique to humans. Concealed ovulation and menopause in women both also occur in a few other primates however, but are uncommon in other species, testis and penis size seems to be related to family structure, monogamy or promiscuity, or harem, in humans, chimpanzees or gorillas, respectively. The levels of sexual dimorphism are seen as a marker of sexual selection. Concealed ovulation means that the phase of fertility is not detectable in women, women can be partly aware of their ovulation along the menstrual phases, but men are essentially unable to detect ovulation in women. Menopause also occurs in rhesus monkeys, and possibly in chimpanzees, chimpanzee-human last common ancestor List of human evolution fossils Human Timeline – Smithsonian, National Museum of Natural History
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Hominini
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Members of the human clade, that is, the Hominina, including Homo and those species of the australopithecines that arose after the split from the chimpanzees, are called homininans. Not all homininans are directly related to the emergence of early Homo and this is a modern cladogram, For each clade, the cladogram above shows approximately when newer extant clades emerged. Some texts refer to Homonini as the Hominina branch, the subtribe Hominina is the human branch, that is, it contains only the genus Homo. Researchers proposed the taxon Hominini on the basis that the least similar species of a trichotomy should be separated from the other two. The common chimpanzee and the bonobo of the genus Pan are the closest living relatives to humans. All the extinct genera listed to the right are ancestral to, or offshoots of, however, both Orrorin and Sahelanthropus existed around the time of the split, and so may be ancestral to both Pan and Homo. In the proposal of Mann and Weiss, the tribe Hominini includes Pan as well as Homo, Homo and all bipedal apes are referred to the subtribe Hominina, while Pan is assigned to the subtribe Panina. Wood discusses the different views of this taxonomy, the assumption of late hybridization was in particular based on the similarity of the X chromosome in humans and chimpanzees, suggesting a divergence as late as some 4 million years ago. Sahelanthropus tchadensis is an extinct species that lived seven million years ago. Human Timeline – Smithsonian, National Museum of Natural History
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Australopithecus
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Australopithecus is an extinct genus of hominins. During that time, a number of australopithecine species emerged, including Australopithecus afarensis, A. africanus, A. anamensis, A. bahrelghazali, A. deyiremeda, A. garhi, and A. sediba. For some hominid species of time, such as A. robustus and A. boisei. If so, they would be considered robust australopiths, while the others would be gracile australopiths, however, if these species do constitute their own genus, they may be given their own name, Paranthropus. Australopithecus species played a significant part in human evolution, the genus Homo being derived from Australopithecus at some time after three years ago. Among other things, they were the first hominids to show the presence of a gene that causes increased length and ability of neurons in the brain, the duplicated SRGAP2 gene. One of the species eventually became the Homo genus in Africa around two million years ago, and eventually modern humans, H. sapiens sapiens. Gracile australopiths shared several traits with modern apes and humans, and were widespread throughout Eastern and Northern Africa around 3.5 million years ago, the earliest evidence of fundamentally bipedal hominids can be observed at the site of Laetoli in Tanzania. This site contains hominid footprints that are similar to those of modern humans and have been dated to as old as 3.6 million years. The footprints have generally classified as australopith because that is the only form of prehuman known to have existed in that region at that time. Australopithecus anamensis, A. afarensis, and A. africanus are among the most famous of the extinct hominins, a. africanus was once considered to be ancestral to the genus Homo. However, fossils assigned to the genus Homo have been found that are older than A. africanus, thus, the genus Homo either split off from the genus Australopithecus at an earlier date, or both developed from a yet possibly unknown common ancestor independently. According to the Chimpanzee Genome Project, the human and chimpanzee lineages diverged from a common ancestor about five to six years ago. Sahelanthropus tchadensis, commonly called Toumai, is seven million years old. One theory suggests that the human and chimpanzee lineages diverged somewhat at first, the brains of most species of Australopithecus were roughly 35% of the size of a modern human brain. Most species of Australopithecus were diminutive and gracile, usually standing 1.2 to 1.4 m tall, in several variations is a considerable degree of sexual dimorphism, males being larger than females. According to one scholar, A. Furthermore, thermoregulatory models suggest that Australopithecus species were fully covered, more like chimpanzees and bonobos. Modern humans do not appear to display the same degree of sexual dimorphism as Australopithecus did, in modern populations, males are on average a mere 15% larger than females, while in Australopithecus, males could be up to 50% larger than females
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Binomial nomenclature
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Such a name is called a binomial name, a binomen, binominal name or a scientific name, more informally it is also called a Latin name. The first part of the name identifies the genus to which the species belongs, for example, humans belong to the genus Homo and within this genus to the species Homo sapiens. The formal introduction of system of naming species is credited to Carl Linnaeus. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus. Although the general principles underlying binomial nomenclature are common to these two codes, there are differences, both in the terminology they use and in their precise rules. Similarly, both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a name is usually given, at least when it is first mentioned. In zoology Patella vulgata Linnaeus,1758, the original name given by Linnaeus was Fringilla domestica, the parentheses indicate that the species is now considered to belong in a different genus. The ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, in botany Amaranthus retroflexus L. – L. is the standard abbreviation used in botany for Linnaeus. – Linnaeus first named this bluebell species Scilla italica, Rothmaler transferred it to the genus Hyacinthoides, the ICN does not require that the dates of either publication be specified. Prior to the adoption of the binomial system of naming species. Together they formed a system of polynomial nomenclature and these names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description, such polynomial names may sometimes look like binomials, but are significantly different. For example, Gerards herbal describes various kinds of spiderwort, The first is called Phalangium ramosum, Branched Spiderwort, is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia. The Latin phrases are short descriptions, rather than identifying labels, the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné. It was in his 1753 Species Plantarum that he first began using a one-word trivial name together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as an epithet or specific name
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Lee Rogers Berger
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Lee Rogers Berger is an American-born South African paleoanthropologist and National Geographic Explorer-in-Residence. Berger is known not only for his discoveries, but also for his public persona in paleoanthropology. He makes hundreds of talks per year, and has had a relationship with National Geographic for many years, appearing in several of their shows. Berger was born in Shawnee Mission, Kansas in 1965, but was raised outside of Sylvania, Georgia in the United States, as a youth, Berger was active in the Boy Scouts, Future Farmers of America, and president of Georgia 4-H. In 1984, Berger was named Georgias Youth Conservationist of the Year for his work in conserving the threatened gopher tortoise and he is a Distinguished Eagle Scout, and received the Boy Scouts of America Honor Medal for saving a life in 1987. He graduated from Georgia Southern University in 1989 with a degree in anthropology/archaeology, in 1991, he began his long term work at the Gladysvale site. This marked the year that his team discovered the first early hominin remains from the site. In 1993, he was appointed to the position of officer in the Paleo-Anthropology Research Unit at Wits. He became a research fellow and research officer at the University of the Witwatersrand in 1995. He has been the leader of the Palaeoanthropology Research Group and has taken charge of fossil hominin excavations, including Sterkfontein, Swartkrans, in 2004, he was promoted to Reader in Human Evolution and the Public Understanding of Science. He is presently a professor in the same topic at the Evolutionary Studies Institute. Berger served as Executive Officer of the Palaeo-Anthropological Scientific Trust from 1994 to 2001, Berger served on the committee for successful application for World Heritage Site Status for the UNESCO Sterkfontein, Swartkans, Kromdraai, and Environs site. He also served on the Makapansgat site development committee, as well as the committee for both Makapansgat and Taungs application for World Heritage site status and he was also a founding Trustee of the Jane Goodall Trust South Africa. Berger served with the Royal Society of South Africa, Northern Branch and he also served on the Fulbright Commission, South Africa, chairing it in 2005, and chairing its Program Review Committee from 2002 to 2004. Berger is a Fellow of the Royal Society of South Africa, Berger was lead author of a controversial report of the discovery of what he and colleagues claimed were small-bodied humans in Palau, Micronesia in 2006. Fitzpatrick, Greg C. and ad hominem assault, and brings little new data to bear on the question of body size, john Hawks, the paleoanthropologist who edited the original Palau article for PLoS ONE, has replied in part to some of the dissenting researchers claims. In August 2008, 9-year-old Matthew Berger, the son of Lee Rogers Berger, found a clavicle, subsequent excavation, headed by Berger, led to the discovery of numerous bones nearby that dated back nearly two million years. The finding was particularly promising because it revealed a previously unknown transitional species between the more ape-like australopithecines and the more human-like Homo habilis
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Malapa Fossil Site, Cradle of Humankind
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It is situated within the Cradle of Humankind World Heritage Site. At the beginning of project, there were approximately 130 known cave sites in the region. Included in this were more than 25 fossil sites that had been unknown to science, Berger brought in geologist Paul Dirks, at that time Head of the School of GeoSciences at the University of the Witwatersrand, to lead the geological aspects of this exploratory project. On 1 August he dropped off Prof. Dirks to map the recognized cave system and proceeded into the area with his dog Tau. Almost immediately he discovered a fossil site that was unknown to science. On 15 August, Prof. Berger returned to the site with his student, Dr. Job Kibii. Within minutes, Matthew had discovered the first remains of human ancestors - a clavicle. On the opposite side of the block Prof. Berger quickly discovered a jawbone with a tooth of a hominid. The find would soon be prepared and identified as part of a skeleton of a juvenile hominid. On 4 September 2008, Berger returned to the site more than a dozen colleagues where Berger discovered a second partial skeleton of an adult female. Over 200 elements have been recovered to date, the partial skeletons are initially described in two papers in the journal Science by Berger and colleagues as a new species of early human ancestor called Australopithecus sediba. The species has long arms, like an ape, short powerful hands, the skeletons are found among the articulated skeletons of a sabre-toothed cat, antelopes and even mice and hares. It is not known how these skeletons came to be in this pool, no carnivores or scavengers reached their bodies. The fossil was dated using a combination of palaeomagnetism and uranium-lead dating by Andy Herries, Robyn Pickering, u-Pb dating of the underlying flowstone indicates that the fossils are not older than 2.0 Ma. The occurrence of species of animal became extinct at ~1.5 Ma indicate the deposit is not younger than 1.5 Ma. In 2011 a more accurate date of the fossils was established when a capping flowstone was too old to enable the normal polarity deposits to date to the Olduvai event. The deposits were instead correlated to a year long period centred at around 1.977 Ma. List of fossil sites Free Images and resources about Australopithecus sediba and Malapa for Educators and Students
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Cradle of Humankind
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The Cradle of Humankind is a paleoanthropological site about 50 kilometres northwest of Johannesburg, South Africa in the Gauteng province. Declared a World Heritage Site by UNESCO in 1999, the site currently occupies 47,000 hectares, the registered name of the site in the list of World Heritage Sites is Fossil Hominid Sites of South Africa. The Sterkfontein Caves contain the discovery of a 2. 3-million-year-old fossil Australopithecus africanus, found in 1947 by Robert Broom, Sterkfontein alone has produced more than a third of early hominid fossils ever found prior to 2010. The Dinaledi Chamber contains over 1500 H. naledi fossils, the most extensive discovery of a hominid species ever found in Africa. The name Cradle of Humankind reflects the fact that the site has produced a number of hominin fossils ever found. In 1935, Robert Broom found the first ape-man fossils at Sterkfontein, in 1938, a young schoolboy, Gert Terrblanche, brought Raymond Dart fragments of a skull from nearby Kromdraai which later were identified as Paranthropus robustus. Also in 1938, a single tooth was found at the Coopers site between Kromdraai and Sterkfontein. In 1948, the Camp-Peabody Expedition from the United States worked at Bolts Farm and Gladysvale looking for fossil hominids, later in 1948, Robert Broom identified the first hominid remains from Swartkrans cave. Brain began working at sites in the Cradle, including Coopers Cave and he soon would initiate his three-decade work at Swartkrans cave, it would result in the recovery of the second-largest sample of hominid remains from the Cradle. The oldest controlled use of fire by Homo erectus was discovered at Swartkrans. In 1966, Phillip Tobias began his excavations of Sterkfontein which are continuing and are the longest continuously running fossil excavations in the world. In 1994, Andre Keyser discovered fossil hominids at the site of Drimolen, in 1997, Kevin Kuykendall and Colin Menter of the University of the Witwatersrand found two fossil hominid teeth at the site of Gondolin. Also in 1997, the near-complete Australopithecus skeleton of Little Foot, in 2001, Steve Churchill of Duke University and Lee Berger found early modern human remains at Plovers Lake. Also in 2001, the first hominid fossils and stone tools were discovered in-situ at Coopers, in 2008, Lee Berger discovered the partial remains of two hominids in the Malapa Fossil Site that lived between 1.78 and 1.95 million years ago. Cavers Rick Hunter and Steven Tucker discovered hominid fossils in an unexplored area of the Rising Star/Westminster Cave System assigned site designation UW-101. In November 2013, Lee Berger led a joint expedition of the University of the Witwatersrand, the site is still in the process of being dated. In the last days of the Rising Star Expedition, cavers Rick Hunter, preliminary excavations at this site, designated UW-102, have begun and yielded complete hominid fossil material of its own. It is unknown what the relationship of sites 101 and 102 is, hominids may have lived all over Africa, but their remains are found only at sites where conditions allowed for the formation and preservation of fossils
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World Heritage Site
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A World Heritage Site is a landmark which has been officially recognized by the United Nations, specifically by the United Nations Educational, Scientific and Cultural Organization. Sites are selected on the basis of having cultural, historical, scientific or some form of significance. UNESCO regards these sites as being important to the interests of humanity. The programme catalogues, names, and conserves sites of outstanding cultural or natural importance to the common culture, under certain conditions, listed sites can obtain funds from the World Heritage Fund. The program was founded with the Convention Concerning the Protection of the Worlds Cultural and Natural Heritage, since then,192 state parties have ratified the convention, making it one of the most adhered to international instruments. As of July 2016,1052 sites are listed,814 cultural,203 natural, in 1959, the governments of Egypt and Sudan requested UNESCO to assist their countries to protect and rescue the endangered monuments and sites. In 1960, the Director-General of UNESCO launched an appeal to the Member States for an International Campaign to Save the Monuments of Nubia, the campaign, which ended in 1980, was considered a success. The project cost $80 million, about $40 million of which was collected from 50 countries, the projects success led to other safeguarding campaigns, saving Venice and its lagoon in Italy, the ruins of Mohenjo-daro in Pakistan, and the Borobodur Temple Compounds in Indonesia. UNESCO then initiated, with the International Council on Monuments and Sites, the United States initiated the idea of cultural conservation with nature conservation. The International Union for Conservation of Nature developed similar proposals in 1968, the Convention came into force on 17 December 1975. As of June 2016, it has been ratified by 192 states, including 188 UN member states plus the Cook Islands, the Holy See, Niue, a country must first list its significant cultural and natural sites, the result is called the Tentative List. A country may not nominate sites that have not been first included on the Tentative List, next, it can place sites selected from that list into a Nomination File. The Nomination File is evaluated by the International Council on Monuments and Sites and these bodies then make their recommendations to the World Heritage Committee. There are ten selection criteria – a site must meet at least one of them to be included on the list, up to 2004, there were six criteria for cultural heritage and four criteria for natural heritage. In 2005, this was modified so there is now only one set of ten criteria. Nominated sites must be of outstanding value and meet at least one of the ten criteria. Thus, the Geneva Convention treaty promulgates, Article 53, PROTECTION OF CULTURAL OBJECTS AND OF PLACES OF WORSHIP. There are 1,052 World Heritage Sites located in 165 States Party, of these,814 are cultural,203 are natural and 35 are mixed properties
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South Africa
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South Africa, officially the Republic of South Africa, is the southernmost country in Africa. South Africa is the 25th-largest country in the world by land area and it is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Sub-Saharan African ancestry, divided among a variety of ethnic groups speaking different Bantu languages, the remaining population consists of Africas largest communities of European, Asian, and multiracial ancestry. South Africa is a multiethnic society encompassing a variety of cultures, languages. Its pluralistic makeup is reflected in the recognition of 11 official languages. The country is one of the few in Africa never to have had a coup détat, however, the vast majority of black South Africans were not enfranchised until 1994. During the 20th century, the black majority sought to recover its rights from the dominant white minority, with this struggle playing a role in the countrys recent history. The National Party imposed apartheid in 1948, institutionalising previous racial segregation, since 1994, all ethnic and linguistic groups have held political representation in the countrys democracy, which comprises a parliamentary republic and nine provinces. South Africa is often referred to as the Rainbow Nation to describe the multicultural diversity. The World Bank classifies South Africa as an economy. Its economy is the second-largest in Africa, and the 34th-largest in the world, in terms of purchasing power parity, South Africa has the seventh-highest per capita income in Africa. However, poverty and inequality remain widespread, with about a quarter of the population unemployed, nevertheless, South Africa has been identified as a middle power in international affairs, and maintains significant regional influence. The name South Africa is derived from the geographic location at the southern tip of Africa. Upon formation the country was named the Union of South Africa in English, since 1961 the long form name in English has been the Republic of South Africa. In Dutch the country was named Republiek van Zuid-Afrika, replaced in 1983 by the Afrikaans Republiek van Suid-Afrika, since 1994 the Republic has had an official name in each of its 11 official languages. Mzansi, derived from the Xhosa noun umzantsi meaning south, is a name for South Africa. South Africa contains some of the oldest archaeological and human fossil sites in the world, extensive fossil remains have been recovered from a series of caves in Gauteng Province. The area is a UNESCO World Heritage site and has termed the Cradle of Humankind
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Holotype
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A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, under the International Code of Zoological Nomenclature, a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants and ICZN the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly Lycaeides idas longinus is a specimen of that species. An isotype is a duplicate of the holotype and is made for plants. A holotype is not necessarily typical of that taxon, although ideally it should be, sometimes just a fragment of an organism is the holotype, particularly in the case of a fossil. For example, the holotype of Pelorosaurus humerocristatus, a herbivorous dinosaur from the early Jurassic period, is a fossil leg bone stored at the Natural History Museum in London. Even if a specimen is subsequently found, the holotype is not superseded. Under the ICN, an additional and clarifying type could be designated, an epitype under Article 9.8, a conserved type is sometimes used to correct a problem with a name which has been misapplied, this specimen replaces the original holotype. In the absence of a holotype, another type may be selected, out of a range of different kinds of type, depending on the case, a lectotype or a neotype. For example, in both the ICN and the ICZN a neotype is a type that was appointed in the absence of the original holotype. This made the name Parasuchus hislopi a nomen dubium, texan paleontologist Sankar Chatterjee proposed that a new type specimen, a complete skeleton, be designated. The International Commission on Zoological Nomenclature considered the case and agreed to replace the type specimen with the proposed neotype. Type Allotype Paratype Type species Genetypes- genetic sequence data from type specimens, BOA Photographs of type specimens of Neotropical Rhopalocera
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Paratype
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In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype. Often there is more than one paratype, paratypes are usually held in museum research collections. The exact meaning of the term paratype when it is used in zoology is not the same as the meaning when it is used in botany, in both cases however, this term is used in conjunction with holotype. In zoological nomenclature, a paratype is officially defined as Each specimen of a series other than the holotype. In turn, this relies on the definition of a type series. Thus, in a series of five specimens, if one is the holotype. A paratype may originate from a different locality than the holotype, a paratype cannot become a lectotype, though it is eligible for designation as a neotype. Apart from species exhibiting sexual dimorphism, relatively few authors take the trouble to designate such a specimen. It is not uncommon for an allotype to be a member of a different species from the holotype. In botanical nomenclature, a paratype is a specimen cited in the description that may not have been said to be a type. It is not the holotype nor an isotype, if no types were specified, then all specimens cited are syntypes. If more than one specimen was cited as the type, then they are all syntypes, the author may choose to designate paratypes that could help subsequent botanists to know what collections were examined and considered part of the same taxon. Another specimen that shows different characteristics of the species from those shown by the holotype might be listed as a paratype. For example, a specimen from the same tree taken at a different time of year, or if the holotype is of one sex, like other types, a paratype may be specified for taxa at the rank of family or below. A paratype may be designated as a lectotype if no holotype, isotype, syntype, biological type Scientific name Binomial nomenclature
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Science (journal)
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Science, also widely referred to as Science Magazine, is the peer-reviewed academic journal of the American Association for the Advancement of Science and one of the worlds top academic journals. It was first published in 1880, is circulated weekly and has a print subscriber base of around 130,000. Because institutional subscriptions and online access serve an audience, its estimated readership is 570,400 people. Unlike most scientific journals, which focus on a field, Science. According to the Journal Citation Reports, Sciences 2015 impact factor was 34.661, although it is the journal of the AAAS, membership in the AAAS is not required to publish in Science. Papers are accepted from authors around the world, competition to publish in Science is very intense, as an article published in such a highly cited journal can lead to attention and career advancement for the authors. Fewer than 7% of articles submitted are accepted for publication, Science is based in Washington, D. C. United States, with an office in Cambridge, England. Science was founded by New York journalist John Michels in 1880 with financial support from Thomas Edison, however, the journal never gained enough subscribers to succeed and ended publication in March 1882. Entomologist Samuel H. Scudder resurrected the journal one year later and had some success while covering the meetings of prominent American scientific societies, however, by 1894, Science was again in financial difficulty and was sold to psychologist James McKeen Cattell for $500. In an agreement worked out by Cattell and AAAS secretary Leland O. Howard, after Cattell died in 1944, the ownership of the journal was transferred to the AAAS. After Cattells death in 1944, the journal lacked a consistent editorial presence until Graham DuShane became editor in 1956. In 1958, under DuShanes leadership, Science absorbed The Scientific Monthly, physicist Philip Abelson, a co-discoverer of neptunium, served as editor from 1962 to 1984. Under Abelson the efficiency of the process was improved and the publication practices were brought up to date. During this time, papers on the Apollo program missions and some of the earliest reports on AIDS were published, biochemist Daniel E. Koshland, Jr. served as editor from 1985 until 1995. From 1995 until 2000, neuroscientist Floyd E. Bloom held that position, biologist Donald Kennedy became the editor of Science in 2000. Biochemist Bruce Alberts took his place in March 2008, geophysicist Marcia McNutt became editor-in-chief in June 2013. During her tenure the family of journals expanded to include Science Robotics and Science Immunology, jeremy M. Berg became editor-in-chief on July 1,2016
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Paleoanthropology
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Hominoids are a primate superfamily, the hominid family is currently considered to comprise both the great ape lineages and human lineages within the hominoid superfamily. The Homininae comprise both the human lineages and the African ape lineages, the term African apes refers only to chimpanzees and gorillas. The terminology of the biological family is currently in flux. The term hominin refers to any genus in the human tribe, since, the great apes were considered the closest relatives of human beings, based on morphological similarity. The science arguably began in the late 19th century when important discoveries occurred that led to the study of human evolution. The discovery of the Neanderthal in Germany, Thomas Huxleys Evidence as to Mans Place in Nature, the modern field of paleoanthropology began in the 19th century with the discovery of Neanderthal man, and with evidence of so-called cave men. Debates between Thomas Huxley and Richard Owen focused on the idea of human evolution, Huxley convincingly illustrated many of the similarities and differences between humans and apes in his 1863 book Evidence as to Mans Place in Nature. By the time Darwin published his own book on the subject, Descent of Man, even many of Darwins original supporters balked at the idea that human beings could have evolved their apparently boundless mental capacities and moral sensibilities through natural selection. Prior to todays general acceptance of Africa as the root of genus Homo, although Schlosser was very cautious, identifying the tooth only as “. Anthropoide g. et sp. indet. ”He was hopeful that future work would discover a new anthropoid in China. Eleven years later, the Swedish geologist Johan Gunnar Andersson was sent to China as a mining advisor and it was he who, in 1918, discovered the sites around Zhoukoudian, a village about 50 kilometers southwest of Beijing. However, because of the nature of the initial finds. Work did not resume until 1921, when the Austrian paleontologist, Otto Zdansky, fresh with his degree from Vienna. Zdansky conducted short-term excavations at Locality 1 in 1921 and 1923, with that done, Zdansky returned to Austria and suspended all fieldwork. News of the fossil hominin teeth delighted the scientific community in Beijing, at the epicenter of excitement was Davidson Black, a Canadian-born anatomist working at Peking Union Medical College. Black shared Andersson’s interest, as well as his view that central Asia was a home for early humankind. The Zhoukoudian Project came into existence in the spring of 1927, being the first institution of its kind, the Cenozoic Laboratory opened up new avenues for the study of paleogeology and paleontology in China. The Laboratory was the precursor of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Science, the first of the major project finds are attributed to the young Swedish paleontologist, Anders Birger Bohlin, then serving as the field advisor at Zhoukoudian. He recovered a left lower molar that Black identified as unmistakably human, the news was at first met with skepticism, and many scholars had reservations that a single tooth was sufficient to justify the naming of a new type of early hominin
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University of the Witwatersrand
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The University of the Witwatersrand, Johannesburg, is a multi-campus South African public research university situated in the northern areas of central Johannesburg. It is more known as Wits University. The university has its roots in the industry, as do Johannesburg. It was desegregated once again prior to the abolition of apartheid in 1990, several of apartheids most provocative critics, of either European or African descent, were one-time students and graduates of the university. The university has an enrolment of 33,711 students as of 2015,65 percent of the universitys total enrolment is for undergraduate study, with the remaining 35 percent being postgraduate. The university was founded in Kimberley in 1896 as the South African School of Mines, eight years later, in 1904, the school was moved to Johannesburg and renamed the Transvaal Technical Institute. The schools name changed yet again in 1906 to Transvaal University College, in 1908, a new campus of the Transvaal University College was established in Pretoria. The Johannesburg and Pretoria campuses separated on 17 May 1910, each becoming a separate institution, in 1920, the school was renamed the University College, Johannesburg. Finally, on 1 March 1922, the University College, Johannesburg, was granted university status after being incorporated as the University of the Witwatersrand. The Johannesburg municipality donated a site in Milner Park, north-west of Braamfontein, to the new institution as its campus and construction began the same year, on 4 October. True to Hofmeyrs words, from the outset Wits was a university with a policy of non-discrimination on racial or any other grounds. Initially, there were six faculties—Arts, Science, Medicine, Engineering, Law and Commerce—37 departments,73 academic staff, and approximately 1,000 students. In 1923, the university began moving into the new campus, slowly vacating its former premises on Ellof Street for the first completed building in Milner Park, in 1925, the Prince of Wales officially opened Central Block. The universitys first library, housed at the time in what was meant to be a construction, was destroyed in a fire on Christmas Eve in 1931. Following this, an appeal was made to the public for ₤80,000 to pay for the construction of a new library, and this resulted in the fairly rapid construction of the William Cullen Library, completed in 1935. During this period, as the Great Depression hit South Africa, nonetheless, it continued to grow at an impressive rate. From a total enrolment of 2,544 students in 1939 and this growth led to accommodation problems, which were temporarily resolved by the construction of wood and galvanised-iron huts in the centre of the campus. During World War II, Wits was involved in South Africas war efforts, the Bernard Price Institute of Geophysical Research was placed under the Union of South Africas defence ministry, and was involved in important research into the use of radar
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Sotho language
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Like all Bantu languages, Sesotho is an agglutinative language, which uses numerous affixes and derivational and inflexional rules to build complete words. Within the Sotho-Tswana group, Sesotho proper is most closely related to Lozi, the Northern Sotho group is geographical, and includes a number of dialects also closely related to Sesotho-Lozi. Tswana is also known as Western Sesotho, Sotho is a tribal suffix, i. e. the name of the Sotho people or Basotho, while Sesotho is the term for the language of the Basotho. Use of Sesotho rather than Sotho language in English has seen increasing use since the 1980s, especially in South African English, the Nguni language Phuthi has been heavily influenced by Sesotho, its speakers have mixed Nguni and Sotho–Tswana ancestry. It seems that it is sometimes treated erroneously as a dialect of Sesotho called Sephuthi, however, Phuthi is mutually unintelligible with standard Sesotho and thus cannot in any sense be termed a dialect of it. These were the first peoples to be called Basotho, before many of their descendants, the situation is even further complicated by various historical factors, such as members of parent clans joining their descendants or various clans calling themselves by the same names. According to the South African National Census of 2011, there were almost four million first language Sesotho speakers recorded in South Africa – approximately eight per cent of the population. Sesotho is also the language spoken by the people of Lesotho. The census fails, to record other South Africans for whom Sesotho is a second or third language, such speakers are found in all major residential areas of Metropolitan Municipalities - such as Johannesburg, and Tshwane - where multilingualism and polylectalism are very high. Sesotho is one of the official languages of South Africa. Sesotho is one of the languages from which the pseudo-language Tsotsitaal is derived. Tsotsitaal is not a language, as it is primarily a unique vocabulary. It is a part of the culture in most Southern Gauteng townships and is the primary language used in Kwaito music. The sound system of Sesotho is unusual in many respects and it has ejective consonants, click consonants, a uvular trill, a relatively large number of affricate consonants, no prenasalised consonants, and a rare form of vowel-height harmony. In total, the language contains some 39 consonantal and 9 vowel phonemes and it also has a large number of complex sound transformations which often change the phones of words due to the influence of other sounds. The most striking properties of Sesotho grammar, and the most important properties which reveal it as a Bantu language, are its noun gender, the grammatical gender system does not encode sex gender, and indeed, Bantu languages in general are not grammatically marked for gender. Another well-known property of the Bantu languages is their agglutinative morphology, additionally, they tend to lack any grammatical case systems, indicating noun roles almost exclusively through word order. Sotho calendar Sotho people South African Translators Association Sesotho Online A gentle introduction to the Sesotho language, weblog on Sesotho Translate. org. za Project translating Free and Open Source Software into South African languages, including Sesotho
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Savanna
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A savanna or savannah is a mixed woodland grassland ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support a herbaceous layer consisting primarily of grasses. Savannas maintain an open canopy despite a high tree density and it is often believed that savannas feature widely spaced, scattered trees. However, in savannas, tree densities are higher and trees are more regularly spaced than in forests. Savanna covers approximately 20% of the Earths land area, the word originally entered English in 1555 as the Latin Zauana, equivalent in the orthography of the times to zavana. Peter Martyr reported it as the name for the plain around Comagre. The accounts are inexact, but this is placed in present-day Madugandí or at points on the nearby Guna Yala coast opposite Ustupo or on Point Mosquitos. These areas are now given over to modern cropland or jungle. The common usage meaning to describe vegetation now conflicts with a simplified yet widespread climatic concept meaning, the divergence has sometimes caused areas such as extensive savannas north and south of the Congo and Amazon Rivers to be excluded from mapped savanna categories. Barrens has been used almost interchangeably with savanna in different parts of North America, sometimes midwestern savanna were described as grassland with trees. Different authors have defined the limits of savanna tree coverage as 5–10%. Two factors common to all environments are rainfall variations from year to year. In the Americas, e. g. in Belize, Central America, savanna vegetation is similar from Mexico to South America, savannas are subject to regular wildfires and the ecosystem appears to be the result of human use of fire. For example, Native Americans created the Pre-Columbian savannas of North America by periodically burning where fire-resistant plants were the dominant species, pine barrens in scattered locations from New Jersey to coastal New England are remnants of these savannas. Aboriginal burning appears to have responsible for the widespread occurrence of savanna in tropical Australia and New Guinea. The maquis shrub savannas of the Mediterranean region were created and maintained by anthropogenic fire. These fires are usually confined to the layer and do little long term damage to mature trees. However, these either kill or suppress tree seedlings, thus preventing the establishment of a continuous tree canopy which would prevent further grass growth
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Fruit
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In botany, a fruit is the seed-bearing structure in flowering plants formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate seeds, accordingly, fruits account for a substantial fraction of the worlds agricultural output, and some have acquired extensive cultural and symbolic meanings. On the other hand, in usage, fruit includes many structures that are not commonly called fruits, such as bean pods, corn kernels, tomatoes. The section of a fungus that produces spores is called a fruiting body. Many common terms for seeds and fruit do not correspond to the botanical classifications, however, in botany, a fruit is the ripened ovary or carpel that contains seeds, a nut is a type of fruit and not a seed, and a seed is a ripened ovule. Examples of culinary vegetables and nuts that are botanically fruit include corn, cucurbits, eggplant, legumes, sweet pepper, in addition, some spices, such as allspice and chili pepper, are fruits, botanically speaking. g. Botanically, a grain, such as corn, rice, or wheat, is also a kind of fruit. However, the wall is very thin and is fused to the seed coat. The outer, often edible layer, is the pericarp, formed from the ovary and surrounding the seeds, the pericarp may be described in three layers from outer to inner, the epicarp, mesocarp and endocarp. Fruit that bears a prominent pointed terminal projection is said to be beaked, a fruit results from maturation of one or more flowers, and the gynoecium of the flower forms all or part of the fruit. Inside the ovary/ovaries are one or more ovules where the megagametophyte contains the egg cell, after double fertilization, these ovules will become seeds. The ovules are fertilized in a process starts with pollination. After pollination, a tube grows from the pollen through the stigma into the ovary to the ovule, later the zygote will give rise to the embryo of the seed, and the endosperm mother cell will give rise to endosperm, a nutritive tissue used by the embryo. As the ovules develop into seeds, the ovary begins to ripen and the ovary wall, in some multiseeded fruits, the extent to which the flesh develops is proportional to the number of fertilized ovules. The pericarp is often differentiated into two or three distinct layers called the exocarp, mesocarp, and endocarp, in some fruits, especially simple fruits derived from an inferior ovary, other parts of the flower, fuse with the ovary and ripen with it. In other cases, the sepals, petals and/or stamens and style of the fall off. When such other floral parts are a significant part of the fruit, it is called an accessory fruit, since other parts of the flower may contribute to the structure of the fruit, it is important to study flower structure to understand how a particular fruit forms. There are three modes of fruit development, Apocarpous fruits develop from a single flower having one or more separate carpels
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Forest
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A forest is a large area dominated by trees. Hundreds of more precise definitions of forest are used throughout the world, incorporating factors such as density, tree height, land use, legal standing. According to the widely used Food and Agriculture Organization definition, forests covered four billion hectares or approximately 30 percent of the land area in 2006. Forests are the dominant terrestrial ecosystem of Earth, and are distributed across the globe, Forests account for 75% of the gross primary productivity of the Earths biosphere, and contain 80% of the Earths plant biomass. Forests at different latitudes and elevations form distinctly different ecozones, boreal forests near the poles, tropical forests near the equator, higher elevation areas tend to support forests similar to those at higher latitudes, and amount of precipitation also affects forest composition. Human society and forests influence each other in both positive and negative ways, Forests provide ecosystem services to humans and serve as tourist attractions. Forests can also affect peoples health, human activities, including harvesting forest resources, can negatively affect forest ecosystems. Although forest is a term of common parlance, there is no universally recognised precise definition, there are three broad categories of forest definitions in use, administrative, land use, and land cover. Land use definitions are based upon the purpose that the land serves. For example, a forest may be defined as any land that is used primarily for production of timber, land cover definitions define forests based upon the type and density of vegetation growing on the land. Such definitions typically define a forest as an area growing trees above some threshold and these thresholds are typically the number of trees per area, the area of ground under the tree canopy or the section of land that is occupied by the cross-section of tree trunks. Under such land cover definitions, and area of land only be defined as forest if it is growing trees, areas that fail to meet the land cover definition may be still included under while immature trees are establishing if they are expected to meet the definition at maturity. Under land use definitions, there is variation on where the cutoff points are between a forest, woodland, and savanna. Under some definitions, forests require high levels of tree canopy cover, from 60% to 100%, excluding savannas. Other definitions consider savannas to be a type of forest, the term was not endemic to Romance languages, and cognates in Romance languages, such as Italian foresta, Spanish and Portuguese floresta, etc. are all ultimately borrowings of the French word. The exact origin of Medieval Latin foresta is obscure, uses of the word forest in English to denote any uninhabited area of non-enclosure are now considered archaic. The word was introduced by the Norman rulers of England as a term denoting an uncultivated area legally set aside for hunting by feudal nobility. These hunting forests were not necessarily wooded much, if at all, however, as hunting forests did often include considerable areas of woodland, the word forest eventually came to mean wooded land more generally
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Chimpanzee
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Chimpanzees are one of the two species of the genus Pan, the other being the bonobo. Together with gorillas, they are the only exclusively African species of ape that are currently extant. Native to sub-Saharan Africa, both chimpanzees and bonobos are found in the Congo jungle. In addition, P. troglodytes is divided into four subspecies, based on genome sequencing, the two extant Pan species diverged around one million years ago. The most obvious differences are that chimpanzees are somewhat larger, more aggressive and male-dominated, while the bonobos are more gracile, peaceful and their hair is typically black or brown. Males and females differ in size and appearance, both chimps and bonobos are some of the most social great apes, with social bonds occurring among individuals in large communities. Fruit is the most important component of a diet, however, they will also eat vegetation, bark, honey, insects. They can live over 30 years in both the wild and captivity, Chimpanzees and bonobos are equally humanitys closest living relatives. As such, they are among the largest-brained, and most intelligent of primates, they use a variety of sophisticated tools and construct elaborate sleeping nests each night from branches and they have both been extensively studied for their learning abilities. There may even be distinctive cultures within populations, field studies of Pan troglodytes were pioneered by primatologist Jane Goodall. Both Pan species are considered to be endangered as human activities have caused declines in the populations. Threats to wild populations include poaching, habitat destruction. Several conservation and rehabilitation organisations are dedicated to the survival of Pan species in the wild, the first use of the name chimpanze is recorded in The London Magazine in 1738, glossed as meaning mockman in a language of the Angolans. The spelling chimpanzee is found in a 1758 supplement to Chambers Cyclopædia, the colloquialism chimp was most likely coined some time in the late 1870s. The common chimpanzee was named Simia troglodytes by Johann Friedrich Blumenbach in 1776, the species name troglodytes is a reference to the Troglodytae, an African people described by Greco-Roman geographers. Blumenbach first used it in his De generis humani varietate nativa liber in 1776, the genus name Pan was first introduced by Lorenz Oken in 1816. An alternative Theranthropus was suggested by Brookes 1828 and Chimpansee by Voigt 1831, troglodytes was not available, as it had been given as the name of a genus of wren in 1809. The International Commission on Zoological Nomenclature adopted Pan as the official name of the genus in 1895
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Phytolith
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Phytoliths are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant. These plants take up silica from the soil, whereupon it is deposited within different intracellular and extracellular structures of the plant, Phytoliths come in varying shapes and sizes. Although some use phytolith to refer to all mineral secretions by plants, in contrast, mineralized calcium secretions in cacti are composed of calcium oxalates. There is still debate in the community as to why plants form phytoliths. Studies that have plants in silica-free environments have typically found that plants lacking silica in the environment do not grow well. For example, the stems of plants will collapse when grown in soil lacking silica. In many cases, phytoliths appear to lend structure and support to the plant, much like the spicules in sponges, Phytoliths may also provide plants with protection. These rigid silica structures help to make more difficult to consume and digest. Phytoliths also appear to provide physiologic benefits, experimental studies have shown that the silicon dioxide in phytoliths may help to alleviate the damaging effects of toxic heavy metals, such as aluminum. Finally, calcium oxalates serve as a reserve of carbon dioxide, cacti use these as a reserve for photosynthesis during the day when they close their pores to avoid water loss, baobabs use this property to make their trunks more flame-resistant. According to Dolores Piperno, an expert in the field of phytolith analysis, discovery and exploratory stage, The first report on phytoliths was published by a German botanist named Struve in 1835. During this time another German scientist named Christian Gottfried Ehrenberg was one of the leaders in the field of phytolith analysis and he developed the first classification system for phytoliths, and analyzed soil samples that were sent to him from all around the world. Botanical phase of research, Phytolith structures in plants gained wide recognition and attention throughout Europe, Research on production, taxonomy and morphology exploded. Detailed notes and drawings on plant families that produce silica structures, period of ecological research, First applications of phytolith analysis to paleoecological work, mostly in Australia, the United States, the United Kingdom, and Russia. Classification systems for differentiation within plant families became popular, also for the first time, phytolith data from pottery are used to track history of clay procurement and pottery manufacture. Around the same time, phytolith data are used as a means of vegetation reconstruction among paleoecologists. A much larger collection on phytolith morphology within varying plant families is assembled. First, soluble silica, also called acid, is taken up from the soil when plant roots absorb groundwater
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Dental plaque
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Dental plaque is a biofilm or mass of bacteria that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms tartar and it is commonly found between the teeth, on the front of teeth, behind teeth, on chewing surfaces, along the gumline, or below the gumline cervical margins. Dental plaque is also known as microbial plaque, oral biofilm, dental biofilm, while plaque is commonly associated with oral diseases such as dental caries and periodontal diseases, its formation is a normal process that cannot be prevented. Removal of dental biofilm can prevent the development of caries and gum diseases, plaque control and removal can be achieved with correct tooth brushing and use of interdental aids such as dental floss and interdental brushes. Oral hygiene is important as dental biofilms may become acidic causing demineralization of the teeth or harden into dental calculus, calculus cannot be removed through tooth brushing or with interdental aids, but only through professional cleaning. Dental plaque is a biofilm that attaches to tooth surfaces, restorations, understanding the formation, composition and characteristics of plaque helps in its control. An acquired pellicle is a layer of saliva that is composed of mainly glycoproteins, bacteria then attach to the pellicle layer, form micro-colonies, and mature on the tooth, which can result in oral diseases. The following table provides a detailed explanation of biofilm formation. These bacteria, as well as leukocytes, neutrophils, macrophages, approximately 80–90% of the weight of plaque is water. While 70% of the dry weight is bacteria, the remaining 30% consists of polysaccharides, the bulk of the microorganisms that form the biofilm are Streptococcus mutans and other anaerobes, though the precise composition varies by location in the mouth. Examples of such anaerobes include fusobacterium and actinobacteria, S. mutans and other anaerobes are the initial colonisers of the tooth surface, and play a major role in the establishment of the early biofilm community. These microorganisms are all present in the oral cavity and are normally harmless. Those microorganisms nearest the surface typically obtain energy by fermenting dietary sucrose. The bacterial equilibrium position varies at different stages of formation, below is a summary of the bacteria that may be present during the phases of plaque maturation. It commonly forms in between the teeth, in the pits and grooves of the teeth and along the gums and it is made up of mostly aerobic bacteria, meaning these bacteria need oxygen to survive. As plaque remains on the tooth for a period of time. Subgingival biofilm is plaque that is located under the gums and it occurs after the formation of the supragingival biofilm by a downward growth of the bacteria from above the gums to below. This plaque is made up of anaerobic bacteria, meaning that these bacteria will only survive if there is no oxygen
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Timeline of human evolution
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The timeline of human evolution outlines the major events in the development of the human species, Homo sapiens, and the evolution of our ancestors. It includes brief explanations of some of the species, genera, and this timeline is based on studies from anthropology, paleontology, developmental biology, morphology, and from anatomical and genetic data. It does not address the origin of life, which discussion is provided by abiogenesis, a caution, Other than Mr Haeckels historic and emblematic tree, this article provides no phylogenetics analysis to help portray the complex, nonlinear facts of human evolution. One of several lines of descent, or taxonomic ranking
45.
Ouranopithecus
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Based on O. macedoniensiss dental and facial anatomy, it has been suggested that the Ouranopithecus were actually dryopithecines. However, Ouranopithecines are probably closely related to the Ponginae. It is true that O. macedoniensis shares derived features with some early hominins and it has been suggested that it may be a synonym of Graecopithecus freybergi, although this is widely disputed in the literature. Media related to Ouranopithecus at Wikimedia Commons Human Timeline – Smithsonian, National Museum of Natural History
46.
Sahelanthropus
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Sahelanthropus tchadensis is an extinct homininae species that is dated to about 7 million years ago, during the Miocene epoch, possibly very close to the time of the chimpanzee–human divergence. Few specimens are known, other than the partial skull nicknamed Toumaï, existing fossils include a relatively small cranium named Toumaï, five pieces of jaw, and some teeth, making up a head that has a mixture of derived and primitive features. The braincase, being only 320 cm³ to 380 cm³ in volume, is similar to that of extant chimpanzees and is less than the approximate human volume of 1350 cm³. The teeth, brow ridges, and facial structure differ markedly from those found in Homo sapiens, cranial features show a flatter face, u-shaped dental arcade, small canines, an anterior foramen magnum, and heavy brow ridges. No postcranial remains have been recovered, the only known skull suffered a large amount of distortion during the time of fossilisation and discovery, as the cranium is dorsoventrally flattened, and the right side is depressed. Sahelanthropus tchadensis may have walked on two legs, upon examination of the foramen magnum in the primary study, the lead author speculated that a bipedal gait would not be unreasonable based on basicranial morphology similar to more recent hominins. Further, according to recent information, what might be a femur of a hominid was also discovered near the cranium—but which has not been published nor accounted for. All known material of Sahelanthropus was found between July 2001 and March 2002 at three sites, TM247, TM266, which yielded most of the material, including a cranium and a femur, and TM292. The discoverers claimed that S. tchadensis is the oldest known human ancestor after the split of the line from that of chimpanzees. The bones were found far from most previous hominin fossil finds, however, an Australopithecus bahrelghazali mandible was found in Chad by Mamelbaye Tomalta, Najia and Alain Beauvilain, Michel Brunet and Aladji H. E. With the sexual dimorphism known to have existed in early hominins, Sahelanthropus may represent a common ancestor of humans and chimpanzees, though no consensus has been reached yet by the scientific community. The original placement of species as a human ancestor but not a chimpanzee ancestor would complicate the picture of human phylogeny. Another possibility is that Toumaï is related to humans and chimpanzees, but is the ancestor of neither. Brigitte Senut and Martin Pickford, the discoverers of Orrorin tugenensis, even if this claim is upheld the find would lose none of its significance, because at present, very few chimpanzee or gorilla ancestors have been found anywhere in Africa. Thus if S. tchadensis is a relative of the chimpanzees or gorillas. And S. tchadensis does indicate that the last common ancestor of humans and chimpanzees is unlikely to closely resemble extant chimpanzees, indeed, some researchers consider suggestions that Sahelanthropus is too early to be a human ancestor to have evaporated. Sediment isotope analysis of atoms in the fossil yielded an age of about 7 million years. In fact, Toumaï may have been reburied in the recent past, taphonomic analysis reveals the likelihood of one, perhaps two, burial
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Orrorin
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Orrorin tugenensis is a postulated early species of Homininae, estimated at 6.1 to 5.7 million years and discovered in 2000. It is not confirmed how Orrorin is related to modern humans and its discovery was an argument against the hypothesis that australopithecines are human ancestors, as much as it still remains the most prevalent hypothesis of human evolution as of 2012. The name of genus Orrorin means original man in Tugen, and the name of the only classified species, O. tugenensis, derives from Tugen Hills in Kenya, as of 2007,20 fossils of the species have been found. Orrorin had small teeth relative to its body size and its dentition differs from that found in Australopithecus in that its cheek teeth are smaller and less elongated mesiodistally and from Ardipithecus in that its enamel is thicker. The dentition differs from both species in the presence of a mesial groove on the upper canines. The canines are ape-like but reduced, like those found in Miocene apes, Orrorin had small post-canines and was microdont, like modern humans, whereas robust australopithecines were megadont. In the femur, the head is spherical and rotated anteriorly, the neck is elongated and oval in section, while these suggest that Orrorin was bipedal, the rest of the postcranium indicates it climbed trees. After the fossils were found in 2000, they were held at the Kipsaraman village community museum, since then, according to the Community Museums of Kenya chairman Eustace Kitonga, the fossils are stored at a secret bank vault in Nairobi. The main similarity is that the Orrorin femur is morphologically closer to that of H. sapiens than is Lucys, there is, however, some debate over this point. Other fossils found in the Lukeino Formation show that Orrorin lived in a dry evergreen forest environment, the team that found these fossils in 2000 was led by Brigitte Senut and Martin Pickford from the Muséum national dhistoire naturelle. This date is markedly different from those using the molecular clock approach. Life timeline List of human evolution fossils Martin Pickford Orrorin tugenensis - The Smithsonian Institutions Human Origins Program Human Timeline – Smithsonian, National Museum of Natural History
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Ardipithecus
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Ardipithecus is a genus of an extinct hominine that lived during Late Miocene and Early Pliocene in Afar Depression, Ethiopia. Two fossil species are described in the literature, A. ramidus, which lived about 4.4 million years ago during the early Pliocene, behavioral analysis showed that Ardipithecus could be very similar to chimpanzees, indicating that the early human ancestors were very chimpanzee-like in behaviour. A. ramidus was named in September 1994, the first fossil found was dated to 4.4 million years ago on the basis of its stratigraphic position between two volcanic strata, the basal Gaala Tuff Complex and the Daam Aatu Basaltic Tuff. The name Ardipithecus ramidus stems mostly from the Afar language, in which Ardi means ground/floor, the pithecus portion of the name is from the Greek word for ape. Like most hominids, but unlike all previously recognized hominins, it had a grasping hallux or big toe adapted for locomotion in the trees and it is not confirmed how much other features of its skeleton reflect adaptation to bipedalism on the ground as well. Like later hominins, Ardipithecus had reduced canine teeth, more fragments were recovered in 1994, amounting to 45% of the total skeleton. This fossil was described as a species of Australopithecus, but White. Between 1999 and 2003, a team led by Sileshi Semaw discovered bones. The fossils were dated to between 4.35 and 4.45 million years old, Ardipithecus ramidus had a small brain, measuring between 300 and 350 cm3. Like common chimpanzees, A. ramidus was much more prognathic than modern humans, the size of the upper canine tooth in A. ramidus males was not distinctly different from that of females. The features of the canine in A. ramidus contrast with the sexual dimorphism observed in common chimpanzees. The less pronounced nature of the canine teeth in A. ramidus has been used to infer aspects of the social behavior of the species. In particular, it has used to suggest that the last common ancestor of hominids. This is markedly different from social patterns in common chimpanzees, among which intermale, researchers in a 2009 study said that this condition compromises the living chimpanzee as a behavioral model for the ancestral hominid condition. A. ramidus existed more recently than the most recent common ancestor of humans and chimpanzees, nevertheless, it is in some ways unlike chimpanzees, suggesting that the common ancestor differs from the modern chimpanzee. After the chimpanzee and human lineages diverged, both underwent substantial evolutionary change, chimp feet are specialized for grasping trees, A. ramidus feet are better suited for walking. The canine teeth of A. ramidus are smaller, and equal in size between males and females, which suggests reduced male-to-male conflict, increased pair-bonding, and increased parental investment. Thus, fundamental reproductive and social behavioral changes probably occurred in long before they had enlarged brains and began to use stone tools
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Homo habilis
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Homo habilis is a species of the tribe Hominini, during the Gelasian and early Calabrian stages of the Pleistocene period, which lived between roughly 2.1 and 1.5 million years ago. LD 350-1 is a fossil jawbone fragment discovered in 2013 which has dated to 2.8 million years ago. There has been debate regarding its placement in the genus Homo rather than the genus Australopithecus. The small size and rather primitive attributes have led experts to propose excluding H. habilis from the genus Homo. These were later classified as milk teeth, and therefore considered difficult to link to taxa unlike permanent teeth, however, in 1959, Mary Leakey recovered the cranium of a young adult which had a small brain, large face, tiny canines and massive chewing teeth. H. habilis was short and had long arms compared to modern humans, however. H. habilis had a capacity slightly less than half of the size of modern humans. Despite the ape-like morphology of the bodies, H. habilis remains are accompanied by primitive stone tools. Homo habilis has often thought to be the ancestor of the more gracile and sophisticated Homo ergaster. New findings in 2007 seemed to confirm the view that H. habilis and H. erectus coexisted, an alternative explanation would be that any ancestral relationship from H. habilis to H. erectus would have to have been cladogenetic rather than anagenetic. Its brain size has been shown to range from 550 cm3 to 687 cm3, a virtual reconstruction published in 2015 estimated the endocranial volume at between 729 and 824 ml, larger than any previously published value. H. habilis brain capacity of around 640 cm³ was on average 50% larger than australopithecines and these hominins were smaller than modern humans, on average standing no more than 1.3 m tall. A fragment of fossilized jawbone, dated to around 2.8 million years ago, was discovered in the Ledi-Geraru research area in Afar Regional State in 2013. The fossil is considered the earliest evidence of the Homo genus known to date, the individual in question lived just after a major climate shift in the region, when forests and waterways were rapidly replaced by arid savannah. One set of remains, discovered by Donald Johanson and Tim White in Olduvai Gorge in 1986, included the important upper and lower limbs, specifically the humerus. Their finding stimulated some debate at the time, locomotor affinities of OH62 have been assessed primarily on the basis of its forelimb to hind limb proportions, which are known to be associated with locomotor behavior among living primates. Initial analyses concentrated on comparisons to the Australopithecus afarensis A. L. 288-1, in most dimensions—measured or estimated—the OH62 upper limb remains equaled or exceeded those of A. L. 288-1, while its lower limb remains appeared to be smaller. In this sense, it was more ‘‘primitive than A. L. 288-1, KNM ER1813 is a relatively complete cranium which dates to 1.9 million years old, discovered at Koobi Fora, Kenya by Kamoya Kimeu in 1973
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