The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic 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, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. 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 been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A 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 Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase 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 and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 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 2400–2100 Ma. 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 of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
In the fields of horticulture and botany, the term deciduous means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves in the autumn. The term deciduous means "the dropping of a part, no longer needed" and the "falling away after its purpose is finished". In plants, it is the result of natural processes. "Deciduous" has a similar meaning when referring to animal parts, such as deciduous antlers in deer, deciduous teeth in some mammals. Wood from deciduous trees is used in a variety of ways in several industries including lumber for furniture and flooring, bowling pins and baseball bats and furniture, cabinets and paneling. In botany and horticulture, deciduous plants, including trees and herbaceous perennials, are those that lose all of their leaves for part of the year; this process is called abscission. In some cases leaf loss coincides with winter -- namely in polar climates. In other parts of the world, including tropical and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall.
The converse of deciduous is evergreen, where foliage is shed on a different schedule from deciduous trees, therefore appearing to remain green year round. Plants that are intermediate may be called semi-deciduous. Other plants are semi-evergreen and lose their leaves before the next growing season, retaining some during winter or dry periods; some trees, including a few species of oak, have desiccated leaves that remain on the tree through winter. Many deciduous plants flower during the period when they are leafless, as this increases the effectiveness of pollination; the absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, result in water stress on the plant. There is much less branch and trunk breakage from glaze ice storms when leafless, plants can reduce water loss due to the reduction in availability of liquid water during cold winter days.
Leaf drop or abscission involves complex physiological changes within plants. The process of photosynthesis degrades the supply of chlorophylls in foliage; when autumn arrives and the days are shorter or when plants are drought-stressed, deciduous trees decrease chlorophyll pigment production, allowing other pigments present in the leaf to become apparent, resulting in non-green colored foliage. The brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing; these other pigments include carotenoids that are yellow and orange. Anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, when sugars are trapped in the leaves after the process of abscission begins. Parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees fall off without turning the bright colors produced from the accumulation of anthocyanin pigments.
The beginnings of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf; the cells are sensitive to a plant hormone called auxin, produced by the leaf and other parts of the plant. When auxin coming from the leaf is produced at a rate consistent with that from the body of the plant, the cells of the abscission layer remain connected; the elongation of these cells break the connection between the different cell layers, allowing the leaf to break away from the plant. It forms a layer that seals the break, so the plant does not lose sap. A number of deciduous plants remove nitrogen and carbon from the foliage before they are shed and store them in the form of proteins in the vacuoles of parenchyma cells in the roots and the inner bark. In the spring, these proteins are used as a nitrogen source during the growth of new leaves or flowers. Plants with deciduous foliage have advantages and disadvantages compared to plants with evergreen foliage.
Since deciduous plants lose their leaves to conserve water or to better survive winter weather conditions, they must regrow new foliage during the next suitable growing season. Evergreens suffer greater water loss during the winter and they can experience greater predation pressure when small. Losing leaves in winter may reduce damage from insects. Removing leaves reduces cavitation which can damage xylem vessels in plants; this allows deciduous plants to have xylem vessels with larger diameters and therefore a greater rate of transpiration during the summer growth period
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, 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 modern'system' names to be employed, reflects the fact that many coal beds were formed globally during that time; the Carboniferous is treated in North America as two geological periods, the earlier Mississippian and the Pennsylvanian. Terrestrial animal life was well established by the Carboniferous period. Amphibians were the dominant land vertebrates, of which one branch would evolve into amniotes, the first terrestrial vertebrates. Arthropods were very common, many were much larger than those of today. Vast swaths of forest covered the land, which would be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today.
The atmospheric content of oxygen reached its highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. The half of the period experienced glaciations, low sea level, mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change. In the United States the Carboniferous is broken into Mississippian and Pennsylvanian subperiods; the Mississippian is about twice as long as the Pennsylvanian, but due to the large thickness of coal-bearing deposits with Pennsylvanian ages in Europe and North America, the two subperiods were long thought to have been more or less equal in duration. In Europe the Lower Carboniferous sub-system is known as the Dinantian, comprising the Tournaisian and Visean Series, dated at 362.5-332.9 Ma, the Upper Carboniferous sub-system is known as the Silesian, comprising the Namurian and Stephanian Series, dated at 332.9-298.9 Ma.
The Silesian is 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, the Westphalian as the Coal Measures and Pennant Sandstone; the International Commission on Stratigraphy faunal stages from youngest to oldest, together with some of their regional subdivisions, are: A global drop in sea level at the end of the Devonian reversed early in the Carboniferous. There was a drop in south polar temperatures; these conditions had little effect in the deep tropics, where lush swamps to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major marine extinction, one that hit crinoids and ammonites hard; this sea level drop and the associated 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; this continental collision resulted in the Hercynian orogeny in Europe, the Alleghenian orogeny in 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, South China continents were still separated from Laurasia; the Late Carboniferous Pangaea was shaped like an "O." There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, inside the "O" in the Carboniferous Pangaea. Other minor oceans were shrinking and closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean. Average global temperatures in the Early Carboniferous Period were high: 20 °C.
However, cooling during the Middle Carboniferous reduced average global temperatures to about 12 °C. Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical climate. Glaciations in Gondwana, triggered by Gondwana's southward movement, continued into the Permian and because of the lack of clear markers and breaks, the deposits of this glacial period are referred to as Permo-Carboniferous in age; the cooling and drying of the climate led to the Carboniferous Rainforest Collapse during the late Carboniferous. Tropical rainforests fragmented and were devastated by climate change. Carboniferous rocks in Europe and eastern North America consist of a repeated sequence of limestone, sandstone and coal beds. In North America, the early Carboniferous is marine
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 longest period of the Phanerozoic Eon; the Cretaceous Period is 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 and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared; the Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs and large marine reptiles died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
The Cretaceous as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk, found in the upper Cretaceous of Western Europe. The name Cretaceous was derived from Latin creta; 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 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 older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is defined, being placed at an iridium-rich layer found worldwide, believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico.
This layer has been dated at 66.043 Ma. A 140 Ma age for the Jurassic-Cretaceous boundary instead of the accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. 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. From youngest to oldest, the subdivisions of the Cretaceous period are: Late Cretaceous Maastrichtian – Campanian – Santonian – Coniacian – Turonian – Cenomanian – Early Cretaceous Albian – Aptian – Barremian – Hauterivian – Valanginian – Berriasian – The high sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms; the Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type, formed under warm, shallow marine circumstances.
Due to the high sea level, there was extensive space for such sedimentation. Because of the young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. Chalk is a rock type characteristic for the Cretaceous, it consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas. In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast; 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 consolidated and the Chalk Group still consists of loose sediments in many places; the group has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is a marine system consisting of competent limestone beds or incompetent marls.
Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean. Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed. Half the worlds petroleum reserves were laid down at this time in the anoxic conditions of what would become the Persian Gulf and the Gulf of Mexico. In many places around the world, dark anoxic shales were formed during this interval; these shales are an important source rock for oil and gas, for example in the subsurface of the North Sea. During th
Philippe Pinel was a French physician, instrumental in the development of a more humane psychological approach to the custody and care of psychiatric patients, referred to today as moral therapy. He made notable contributions to the classification of mental disorders and has been described by some as "the father of modern psychiatry". An 1809 description of a case that Pinel recorded in the second edition of his textbook on insanity is regarded by some as the earliest evidence for the existence of the form of mental disorder known as dementia praecox or schizophrenia, although Emil Kraepelin is accredited with its first conceptualisation. Pinel was born in the South of France, in the modern department of Tarn, he was the nephew of physicians. After receiving a degree from the faculty of medicine in Toulouse, he studied an additional four years at the Faculty of Medicine of Montpellier, he arrived in Paris in 1778. He spent fifteen years earning his living as a writer and editor because the restrictive regulations of the old regime prevented him from practicing medicine in Paris.
The faculty did not recognize a degree from a provincial university like Toulouse. He failed twice in a competition. In the second competition, the jury stressed his ‘painful’ mediocrity in all areas of medical knowledge, an assessment so grossly incompatible with his intellectual accomplishments that political motives have been suggested. Discouraged, Pinel considered emigrating to America. In 1784 he became editor of the medical journal a four-page weekly, he was known among natural scientists as a regular contributor to the Journal de physique. He studied mathematics, translated medical works into French, undertook botanical expeditions. At about this time he began to develop an intense interest in the study of mental illness; the incentive was a personal one. A friend had developed a ‘nervous melancholy’ that had ‘degenerated into mania’ and resulted in suicide. What Pinel regarded as an unnecessary tragedy due to gross mismanagement seems to have haunted him, it led him to seek employment at one of the best-known private sanatoria for the treatment of insanity in Paris.
He remained there for five years prior to the Revolution, gathering observations on insanity and beginning to formulate his views on its nature and treatment. Pinel was a disciple of the abbé de Condillac, he was a clinician who believed that medical truth was derived from clinical experience. Hippocrates was his model. During the 1780s, Pinel was invited to join the salon of Madame Helvétius, he was in sympathy with the French Revolution. After the revolution, friends he had met at Madame Helvétius’ salon came to power. In August 1793 Pinel was appointed "physician of the infirmeries" at Bicêtre Hospital. At the time it housed about four thousand imprisoned men—criminals, petty offenders, syphilitics and about two hundred mental patients. Pinel's patrons hoped, his experience at the private sanatoria made him a good candidate for the job. Soon after his appointment to Bicêtre Hospital, Pinel became interested in the seventh ward where 200 mentally ill men were housed, he asked for a report on these inmates.
A few days he received a table with comments from the "governor" Jean-Baptiste Pussin. In the 1770s Pussin had been treated for scrofula at Bicêtre. Appreciating Pussin's outstanding talent, Pinel apprenticed himself to that unschooled but experienced custodian of the insane, his purpose in doing this was to "enrich the medical theory of mental illness with all the insights that the empirical approach affords". What he observed was a strict nonviolent, nonmedical management of mental patients that came to be called moral treatment or moral management, though psychological might be a more accurate term. Although Pinel always gave Pussin the credit he deserved, a legend grew up about Pinel single-handedly liberating the insane from their chains at Bicetre; this legend has been commemorated in paintings and prints, has lived on for 200 years and is repeated in textbooks. In fact, it was Pussin who removed the iron shackles at Bicêtre in 1797, after Pinel had left for the Salpêtrière. Pinel did remove the chains from patients at the Salpêtrière three years after Pussin joined him there.
There is some suggestion that the Bicetre myth was deliberately fabricated by Pinel's son, Dr Scipion Pinel, along with Pinel's foremost pupil, Dr Esquirol. The argument is that they were'solidists', which meant something akin to biological psychiatry with a focus on brain disease, were embarrassed by Pinel's focus on psychological processes. In addition, unlike Philippe, they were both royalists. While at Bicêtre, Pinel did away with bleeding and blistering in favor of a therapy that involved close contact with and careful observation of patients. Pinel visited each patient several times a day, took careful notes over two years, he engaged them in lengthy conversations. His objective was to assemble a detailed case history and a natural history of the patient's illness. In 1795, Pinel became chief physician of the Hospice de la Salpêtrière, a post that he retained for the rest of his life; the Salpêtrière was, at the time, like a large village, with seven thousand elderly indigent and ailing women, an entrenched bureaucracy, a teeming market and huge infirmaries.
Pinel missed Pussin and in 1802 secured his tr
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of a world fur market in the early modern period, furs of boreal and cold temperate mammalian animals have been the most valued; the trade stimulated the exploration and colonization of Siberia, northern North America, the South Shetland and South Sandwich Islands. Today the importance of the fur trade has diminished. Animal rights organizations oppose the fur trade, citing that animals are brutally killed and sometimes skinned alive. Fur has been replaced in some clothing by synthetic imitations, for example, as in ruffs on hoods of parkas. Before the European colonization of the Americas, Russia was a major supplier of fur pelts to Western Europe and parts of Asia, its trade developed in the Early Middle Ages, first through exchanges at posts around the Baltic and Black seas. The main trading market destination was the German city of Leipzig. Kievan Russia, the first Russian State, was the first supplier of the Russian Fur Trade.
Russia exported raw furs, consisting in most cases of the pelts of martens, wolves, foxes and hares. Between the 16th and 18th centuries, Russians began to settle in Siberia, a region rich in many mammal fur species, such as Arctic fox, sable, sea otter and stoat. In a search for the prized sea otter pelts, first used in China, for the northern fur seal, the Russian Empire expanded into North America, notably Alaska. From the 17th through the second half of the 19th century, Russia was the world's largest supplier of fur; the fur trade played a vital role in the development of Siberia, the Russian Far East and the Russian colonization of the Americas. As recognition of the importance of the trade to the Siberian economy, the sable is a regional symbol of the Ural Sverdlovsk Oblast and the Siberian Novosibirsk and Irkutsk Oblasts of Russia; the European discovery of North America, with its vast forests and wildlife the beaver, led to the continent becoming a major supplier in the 17th century of fur pelts for the fur felt hat and fur trimming and garment trades of Europe.
Fur was relied on to make warm clothing, a critical consideration prior to the organization of coal distribution for heating. Portugal and Spain played major roles in fur trading after the 15th century with their business in fur hats. From as early as the 10th century and boyars of Novgorod had exploited the fur resources "beyond the portage", a watershed at the White Lake that represents the door to the entire northwestern part of Eurasia, they began by establishing trading posts along the Volga and Vychegda river networks and requiring the Komi people to give them furs as tribute. Novgorod, the chief fur-trade center prospered as the easternmost trading post of the Hanseatic League. Novgorodians expanded farther east and north, coming into contact with the Pechora people of the Pechora River valley and the Yugra people residing near the Urals. Both of these native tribes offered more resistance than the Komi, killing many Russian tribute-collectors throughout the tenth and eleventh centuries.
As Muscovy gained more power in the 15th century and proceeded in the "gathering of the Russian lands", the Muscovite state began to rival the Novgorodians in the North. During the 15th century Moscow began subjugating many native tribes. One strategy involved exploiting antagonisms between tribes, notably the Komi and Yugra, by recruiting men of one tribe to fight in an army against the other tribe. Campaigns against native tribes in Siberia remained insignificant until they began on a much larger scale in 1483 and 1499. Besides the Novgorodians and the indigenes, Muscovites had to contend with the various Muslim Tatar khanates to the east of Muscovy. In 1552 Ivan IV, the Tsar of All the Russias, took a significant step towards securing Russian hegemony in Siberia when he sent a large army to attack the Kazan Tartars and ended up obtaining the territory from the Volga to the Ural Mountains. At this point the phrase "ruler of Obdor and all Siberian lands" became part of the title of the Tsar in Moscow.
So, problems ensued after 1558 when Ivan IV sent Grigory Stroganov to colonize land on the Kama and to subjugate and enserf the Komi living there. The Stroganov family soon came into conflict with the Khan of Sibir. Ivan told the Stroganovs to hire Cossack mercenaries to protect the new settlement from the Tatars. From ca 1581 the band of Cossacks led by Yermak Timofeyevich fought many battles that culminated in a Tartar victory and the temporary end to Russian occupation in the area. In 1584 Ivan’s son Fyodor sent military governors and soldiers to reclaim Yermak conquests and to annex the land held by the Khanate of Sibir. Similar skirmishes with Tartars took place across Siberia. Russian conquerors treated the natives of Siberia as exploited enemies who were inferior to them; as they penetrated deeper into Siberia, traders built outposts or winter lodges called zimovya where they lived and collected fur tribute from native tribes. By 1620 Russia dominated the land from the Urals eastward to the Yenisey valley and to the Altai Mountains in the south, comprising about 1.25 million square miles of land.
Furs would become Russia's largest source of wealth during the seventeenth centuries. Keeping up with the advances of Western Europe required significant capital and Russia did not have sources of gold and silver, but it did have furs, which became known as "soft gold" and provided Russia with hard cur