1.
Saskatchewan
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Saskatchewan is a prairie and boreal province in west-central Canada, the only province without natural borders. It has an area of 651,900 square kilometres, nearly 10 percent of which is water, composed mostly of rivers, reservoirs. As of December 2013, Saskatchewans population was estimated at 1,114,170, residents primarily live in the southern prairie half of the province, while the northern boreal half is mostly forested and sparsely populated. Of the total population, roughly half live in the provinces largest city, Saskatoon, or the provincial capital, other notable cities include Prince Albert, Moose Jaw, Yorkton, Swift Current, North Battleford, and the border city Lloydminster. Saskatchewan is a province with large distances to moderating bodies of waters. As a result, its climate is continental, rendering severe winters throughout the province. Southern areas have very warm or hot summers, Midale and Yellow Grass near the U. S. border are tied for the highest ever recorded temperatures in Canada with 45 °C observed at both locations on July 5,1937. In winter, temperatures below −45 °C are possible even in the south during extreme cold snaps, Saskatchewan has been inhabited for thousands of years by various indigenous groups, and first explored by Europeans in 1690 and settled in 1774. It became a province in 1905, carved out from the vast North-West Territories, in the early 20th century the province became known as a stronghold for Canadian social democracy, North Americas first social-democratic government was elected in 1944. The provinces economy is based on agriculture, mining, and energy, Saskatchewans current premier is Brad Wall and its lieutenant-governor is Vaughn Solomon Schofield. In 1992, the federal and provincial governments signed a land claim agreement with First Nations in Saskatchewan. The First Nations received compensation and were permitted to buy land on the market for the tribes, they have acquired about 3,079 square kilometres. Some First Nations have used their settlement to invest in urban areas and its name derived from the Saskatchewan River. The river was known as kisiskāciwani-sīpiy in the Cree language, as Saskatchewans borders largely follow the geographic coordinates of longitude and latitude, the province is roughly a quadrilateral, or a shape with four sides. However the 49th parallel boundary and the 60th northern border appear curved on globes, additionally, the eastern boundary of the province is partially crooked rather than following a line of longitude, as correction lines were devised by surveyors prior to the homestead program. S. States of Montana and North Dakota, Saskatchewan has the distinction of being the only Canadian province for which no borders correspond to physical geographic features. Along with Alberta, Saskatchewan is one of only two land-locked provinces, the overwhelming majority of Saskatchewans population is located in the southern third of the province, south of the 53rd parallel. Saskatchewan contains two natural regions, the Canadian Shield in the north and the Interior Plains in the south
2.
Paleontology
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Paleontology or palaeontology is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene Epoch. It includes the study of fossils to determine organisms evolution and interactions with each other, paleontological observations have been documented as far back as the 5th century BC. The science became established in the 18th century as a result of Georges Cuviers work on comparative anatomy, and developed rapidly in the 19th century. The term itself originates from Greek παλαιός, palaios, i. e. old, ancient, ὄν, on, i. e. being, creature and λόγος, logos, i. e. speech, thought, study. Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of modern humans. It now uses techniques drawn from a range of sciences, including biochemistry, mathematics. The final quarter of the 20th century saw the development of molecular phylogenetics, molecular phylogenetics has also been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend. The simplest definition is the study of ancient life, paleontology is one of the historical sciences, along with archaeology, geology, astronomy, cosmology, philology and history itself. This means that it aims to describe phenomena of the past, hence it has three main elements, description of the phenomena, developing a general theory about the causes of various types of change, and applying those theories to specific facts. Sometimes the smoking gun is discovered by an accident during other research. Paleontology lies on the boundary between biology and geology since paleontology focuses on the record of past life but its source of evidence is fossils. In addition paleontology often uses techniques derived from other sciences, including biology, osteology, ecology, chemistry, techniques developed in engineering have been used to analyse how ancient organisms might have worked, for example how fast Tyrannosaurus could move and how powerful its bite was. As knowledge has increased, paleontology has developed specialised subdivisions, vertebrate paleontology concentrates on fossils of vertebrates, from the earliest fish to the immediate ancestors of modern mammals. Invertebrate paleontology deals with fossils of such as molluscs, arthropods. Paleobotany focuses on the study of plants, but traditionally includes the study of fossil algae. Palynology, the study of pollen and spores produced by plants and protists. Micropaleontology deals with all microscopic fossil organisms, regardless of the group to which they belong, one example is the development of oxygenic photosynthesis by bacteria, which hugely increased the productivity and diversity of ecosystems. This also caused the oxygenation of the atmosphere, together, these were a prerequisite for the evolution of the most complex eukaryotic cells, from which all multicellular organisms are built
3.
Fossil
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Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record. The study of fossils across geological time, how they were formed, such a preserved specimen is called a fossil if it is older than some minimum age, most often the arbitrary date of 10,000 years. The observation that fossils were associated with certain rock strata led early geologists to recognize a geological timescale in the 19th century. The development of dating techniques in the early 20th century allowed geologists to determine the numerical or absolute age of the various strata. Like extant organisms, fossils vary in size from microscopic, even single bacterial cells one micrometer in diameter, to gigantic, such as dinosaurs, Fossils may also consist of the marks left behind by the organism while it was alive, such as animal tracks or feces. These types of fossil are called trace fossils, as opposed to body fossils, finally, past life leaves some markers that cannot be seen but can be detected in the form of biochemical signals, these are known as chemofossils or biosignatures. The process of fossilization varies according to type and external conditions. Permineralization is a process of fossilization that occurs when an organism is buried, the empty spaces within an organism become filled with mineral-rich groundwater. Minerals precipitate from the groundwater, occupying the empty spaces and this process can occur in very small spaces, such as within the cell wall of a plant cell. Small scale permineralization can produce very detailed fossils, for permineralization to occur, the organism must become covered by sediment soon after death or soon after the initial decay process. The degree to which the remains are decayed when covered determines the later details of the fossil, some fossils consist only of skeletal remains or teeth, other fossils contain traces of skin, feathers or even soft tissues. This is a form of diagenesis, in some cases the original remains of the organism completely dissolve or are otherwise destroyed. The remaining organism-shaped hole in the rock is called an external mold, if this hole is later filled with other minerals, it is a cast. An endocast or internal mold is formed when sediments or minerals fill the cavity of an organism. This is a form of cast and mold formation. If the chemistry is right, the organism can act as a nucleus for the precipitation of minerals such as siderite, if this happens rapidly before significant decay to the organic tissue, very fine three-dimensional morphological detail can be preserved. Nodules from the Carboniferous Mazon Creek fossil beds of Illinois, USA, are among the best documented examples of such mineralization, replacement occurs when the shell, bone or other tissue is replaced with another mineral
4.
Trace fossil
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A trace fossil, also called an ichnofossil, is a geological record of biological activity. Trace fossils may consist of impressions made on the substrate by an organism, for example, burrows, borings, urolites, footprints and feeding marks, and root cavities. Trace fossils contrast with body fossils, which are the remains of parts of organisms bodies. Sedimentary structures, for example produced by empty shells rolling along the sea floor, are not produced through the behaviour of an organism. The study of traces - ichnology - divides into paleoichnology, or the study of fossils, and neoichnology. Ichnological science offers many challenges, as most traces reflect the behaviour — not the biological affinity — of their makers, accordingly, researchers classify trace fossils into form genera, based on their appearance and on the implied behaviour, or ethology, of their makers. Traces are better known in their fossilised form than in modern sediments and this makes it difficult to interpret some fossils by comparing them with modern traces, even though they may be extant or even common. The main difficulties in accessing extant burrows stem from finding them in consolidated sediment, Trace fossils are best preserved in sandstones, the grain size and depositional facies both contributing to the better preservation. They may also be found in shales and limestones, Trace fossils are generally difficult or impossible to assign to a specific maker. Only in very rare occasions are the found in association with their tracks. Further, entirely different organisms may produce identical tracks, therefore, conventional taxonomy is not applicable, and a comprehensive form of taxonomy has been erected. At the highest level of the classification, five behavioral modes are recognized, Domichnia, Fossils are further classified into form genera, a few of which are even subdivided to a species level. Classification is based on shape, form, and implied behavioural mode, Trace fossils are important paleoecological and paleoenvironmental indicators, because they are preserved in situ, or in the life position of the organism that made them. Attempts to deduce such traits as whether a deposit is marine or non-marine have been made, unlike most other fossils, which are produced only after the death of the organism concerned, trace fossils provide us with a record of the activity of an organism during its lifetime. Trace fossils are formed by organisms performing the functions of their life, such as walking, crawling, burrowing, boring. Tetrapod footprints, worm trails and the burrows made by clams, perhaps the most spectacular trace fossils are the huge, three-toed footprints produced by dinosaurs and related archosaurs. These imprints give scientists clues as to how these animals lived, although the skeletons of dinosaurs can be reconstructed, only their fossilized footprints can determine exactly how they stood and walked. Such tracks can tell much about the gait of the animal which made them, what its stride was, however, most trace fossils are rather less conspicuous, such as the trails made by segmented worms or nematodes
5.
Geologic record
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According to the law of superposition, sedimentary and volcanic rock layers are deposited on top of each other. They harden over time to become a rock column, that may be intruded by igneous rocks. At a certain locality on the Earths surface, the rock provides a cross section of the natural history in the area during the time covered by the age of the rocks. This is to say that in a location, the geologic record can be and is quite often interrupted as the ancient local environment was converted by geological forces into new landforms. Sediment core data at the mouths of large drainage basins. By comparing overall formations, geologic structures and local strata, calibrated by those layers which are widespread, correcting for discordancies can be done in a number of ways and utilizing a number of technologies or field research results from studies in other disciplines. In this example, the study of layered rocks and the fossils they contain is called biostratigraphy and utilizes amassed geobiology, fossils can be used to recognize rock layers of the same or different geologic ages, thereby coordinating locally occurring geologic stages to the overall geologic timeline. The pictures of the fossils of monocellular algae in this USGS figure were taken with an electron microscope and have been magnified 250 times. This is one form of discordancy and the means geologists use to compensate for variations in the rock record. This gives the pairing between the layers of the left column and the time units of the center column in the table at right
6.
Evolutionary history of life
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The evolutionary history of life on Earth traces the processes by which living and fossil organisms have evolved since life appeared on the planet, until the present day. Earth formed about 4.5 Ga ago and there is evidence that appeared as early as 4.1 Ga. The similarities between all present-day organisms indicate the presence of an ancestor from which all known species have diverged through the process of evolution. More than 99 percent of all species, amounting to five billion species. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described, more recently, in 2015, remains of biotic life were found in 4.1 billion-year-old rocks in Western Australia. In March 2017, researchers reported evidence of possibly the oldest forms of life on Earth, according to biologist Stephen Blair Hedges, If life arose relatively quickly on Earth. Then it could be common in the universe, microbial mats of coexisting bacteria and archaea were the dominant form of life in the early Archean and many of the major steps in early evolution are thought to have taken place within them. The evolution of photosynthesis, around 3.5 Ga, eventually led to a buildup of its product, oxygen, in the atmosphere, leading to the great oxygenation event. The earliest evidence of dates from 1.85 Ga. Later, around 1.7 Ga, multicellular organisms began to appear, however the origin and evolution of sexual reproduction remain a puzzle for biologists though it did evolve from a common ancestor that was a single celled eukaryotic species. Bilateria, animals with a front and a back, appeared by 555 Ma, the earliest land plants date back to around 450 Ma, although evidence suggests that microorganisms formed the earliest terrestrial ecosystems, at least 2.9 Ga. Microorganisms are thought to have paved the way for the inception of land plants in the Phanerozoic, land plants were so successful that they are thought to have contributed to the Late Devonian extinction event. Ediacara biota appear during the Ediacaran period, while vertebrates, along with most other modern phyla originated about 525 Ma during the Cambrian explosion. During the Permian period, synapsids, including the ancestors of mammals, dominated the land, during the recovery from this catastrophe, archosaurs became the most abundant land vertebrates, one archosaur group, the dinosaurs, dominated the Jurassic and Cretaceous periods. After the Cretaceous–Paleogene extinction event 66 Ma killed off the dinosaurs, mammals increased rapidly in size. Such mass extinctions may have accelerated evolution by providing opportunities for new groups of organisms to diversify, the Moon has the same composition as Earths crust but does not contain an iron-rich core like the Earths. Many scientists think that about 40 million years later a body the size of Mars struck the Earth, until 2001, the oldest rocks found on Earth were about 3.8 billion years old, leading scientists to estimate that the Earths surface had been molten until then. Accordingly, they named this part of Earths history the Hadean, however, analysis of zircons formed 4
7.
Abiogenesis
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Abiogenesis, biopoiesis, \by-o-po-ee-sis\ or informally, the origin of life, is the natural process by which life arises from non-living matter, such as simple organic compounds. The study of abiogenesis can be geophysical, chemical, or biological, Life itself is dependent upon the specialized chemistry of carbon and water and is largely based upon five different families of chemicals. Carbohydrates are sugars, and as monomer units can be assembled into polymers called polysaccharides, such as cellulose, nitrogenous bases are organic molecules in which the amine group of nitrogen, combined with two hydrogen atoms, plays an important part. Chlorophyll is based upon a porphyrin ring derived from amine monomer units, nucleic acid monomers are made from a carbohydrate monosaccharide a nitrogenous base and one or more high energy phosphate groups. When joined together they form either the unit of inheritance, the gene, made from DNA or RNA, the monomer unit of a protein is always one of 20 amino acids, comprising an amine group, a hydrocarbon and a carboxylic acid. Through a condensation reaction, in which the acid of one amino acid is linked to the amine of another with removal of a water molecule. Polymers of amino acids are termed proteins and these molecules provide many catalytic metabolic functions for living processes, any successful theory of abiogenesis must explain the origins and interactions of these five classes of molecules. Many approaches to investigate how self-replicating molecules, or their components. It is generally thought that current life on Earth is descended from an RNA world, various external sources of energy that may have triggered these reactions have been proposed, including lightning and radiation. Other approaches focus on understanding how catalysis in chemical systems on the early Earth might have provided the precursor molecules necessary for self-replication. Complex organic molecules have found in the Solar System and in interstellar space. It is speculated that the biochemistry of life may have begun shortly after the Big Bang,13.8 billion years ago, the panspermia hypothesis proposes that life originated outside the Earth, not how life came to be. Nonetheless, Earth remains the place in the Universe known to harbour life. In recent years, there have been a number of discoveries that suggested the earliest appearance of life on Earth was even earlier in time, according to biologist Stephen Blair Hedges, If life arose relatively quickly on Earth … then it could be common in the universe. The Hadean Earth is thought to have had a secondary atmosphere, during its formation, the Earth lost a significant part of its initial mass, with a nucleus of the heavier rocky elements of the protoplanetary disk remaining. As Earth lacked the gravity to hold any molecular hydrogen, this component of the atmosphere would have been rapidly lost during the Hadean period, along with the bulk of the original inert gases. The solution of carbon dioxide in water is thought to have made the slightly acidic. The atmosphere at the time has been characterized as a gigantic and it may have been similar to the mixture of gases released today by volcanoes, which still support some abiotic chemistry
8.
Transitional fossil
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A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. This is especially important where the descendant group is sharply differentiated by gross anatomy and these fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation. Because of the incompleteness of the record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. Therefore, it cannot be assumed that transitional fossils are direct ancestors of more recent groups, in 1859, when Charles Darwins On the Origin of Species was first published, the fossil record was poorly known. Indeed, Archaeopteryx was discovered just two later, in 1861, and represents a classic transitional form between dinosaurs and birds. Many more transitional fossils have been discovered since then, and there is now abundant evidence of how all classes of vertebrates are related, specific examples include humans and other primates, tetrapods and fish, and birds and dinosaurs. The term missing link has been used extensively in popular writings on evolution to refer to a perceived gap in the hominid evolutionary record. It is most commonly used to refer to any new transitional fossil finds, scientists, however, do not use the term, as it refers to a pre-evolutionary view of nature. Transitional forms are seen as falling between the groups in terms of anatomy, having a mixture of characteristics from inside and outside the newly branched clade. With the establishment of cladistics in the 1990s, relationships commonly came to be expressed in cladograms that illustrate the branching of the lineages in stick-like figures. The different so-called natural or monophyletic groups form nested units, while in traditional classification tetrapods and fish are seen as two different groups, phylogenetically tetrapods are considered a branch of fish. Thus, with there is no longer a transition between established groups, and the term transitional fossils is a misnomer. Differentiation occurs within groups, represented as branches in the cladogram, such early representatives of a group are usually termed basal taxa or sister taxa, depending on whether the fossil organism belongs to the daughter clade or not. A source of confusion is the notion that a transitional form between two different taxonomic groups must be an ancestor of one or both groups. The difficulty is exacerbated by the fact one of the goals of evolutionary taxonomy is to identify taxa that were ancestors of other taxa. However, it is almost impossible to be sure that any form represented in the record is a direct ancestor of any other. Archaeopteryx is a genus of theropod dinosaur closely related to the birds, similar in shape to a European magpie, with the largest individuals possibly attaining the size of a raven, Archaeopteryx could grow to about 0.5 metres in length. Despite its small size, broad wings, and inferred ability to fly or glide and these features make Archaeopteryx a clear candidate for a transitional fossil between dinosaurs and birds, making it important in the study both of dinosaurs and of the origin of birds
9.
Evolution of the eye
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The evolution of the eye has attracted significant study, with the eye distinctively exemplifying an analogous organ present in a wide variety of animal forms. Complex, image-forming eyes have evolved independently some 50 to 100 times, complex eyes appear to have first evolved within a few million years, in the rapid burst of evolution known as the Cambrian explosion. No evidence of eyes before the Cambrian has survived, but a range of diversity is evident in the Middle Cambrian Burgess shale. Eyes show a range of adaptations to meet the requirements of the organisms which bear them. In 1802, philosopher William Paley called it a miracle of design, charles Darwin himself wrote in his Origin of Species, that the evolution of the eye by natural selection at first glance seemed absurd in the highest possible degree. However, he went on to explain that despite the difficulty in imagining it, Darwins suggestions were soon shown to be correct, and current research is investigating the genetic mechanisms responsible for eye development and evolution. Nilsson has independently put forth four theorized general stages in the evolution of an eye from a patch of photoreceptors. Nilsson and S. Pelger published a classical paper theorizing how many generations are needed to evolve a complex eye in vertebrates. Young, has used fossil evidence to infer evolutionary conclusions, based on the structure of eye orbits and openings in fossilized skulls for blood vessels, all this evidence adds to the growing amount of evidence that supports Darwins theory. The first fossils of eyes that have found to date are from the lower Cambrian period. This period saw a burst of rapid evolution, dubbed the Cambrian explosion. Earlier than this, organisms may have had use for light sensitivity and it is difficult to estimate the rate of eye evolution because the fossil record, particularly of the Early Cambrian, is poor. Whether one considers the eye to have evolved once or multiple times depends somewhat on the definition of an eye, however, even photoreceptor cells may have evolved more than once from molecularly similar chemoreceptors, and photosensitive cells probably existed long before the Cambrian explosion. Shared traits common to all light-sensitive organs include the family of proteins called opsins. All seven sub-families of opsin were already present in the last common ancestor of animals, in addition, the genetic toolkit for positioning eyes is common to all animals, the PAX6 gene controls where the eye develops in organisms ranging from octopuses to mice to fruit flies. Sensory organs probably evolved before the brain did—there is no need for an organ before there is information to process. The earliest predecessors of the eye were photoreceptor proteins that sense light, found even in unicellular organisms, eyespots can only sense ambient brightness, they can distinguish light from dark, sufficient for photoperiodism and daily synchronization of circadian rhythms. They are insufficient for vision, as they cannot distinguish shapes or determine the light is coming from
10.
Evolution of fish
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The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull, the first fish lineages belong to the Agnatha, or jawless fish. During the late Cambrian, eel-like jawless fish called the conodonts, most jawless fish are now extinct, but the extant lampreys may approximate ancient pre-jawed fish. Lamphreys belong to the Cyclostomata, which includes the extant hagfish, the first jawed vertebrates probably developed during the late Ordovician period. They are first represented in the record from the Silurian by two groups of fish, the armoured fish known as placoderms, which evolved from the ostracoderms. The jawed fish that are extant in modern days also appeared in late Silurian, the Chondrichthyes. The bony fish evolved into two groups, the Actinopterygii and Sarcopterygii. During the Devonian period a great increase in fish variety occurred, especially that of the ostracoderms and placoderms, as well as lobe-finned fish and this has led to the Devonian being known as the age of fishes. It was from the fish that the tetrapods evolved, the non-fish four-limbed vertebrates, represented today by amphibians, mammals, reptiles. Transitional tetrapods first appeared during the early Devonian, and by the late Devonian the first tetrapods appeared, Fish do not represent a monophyletic group, but a paraphyletic one, as they exclude the tetrapods. Fish, like other organisms, have been greatly affected by extinction events throughout natural history. The Ordovician–Silurian extinction events led to the loss of many species, the late Devonian extinction led to the extinction of the ostracoderms and placoderms by the end of the Devonian, as well as other fish. The spiny sharks became extinct at the Permian–Triassic extinction event, the conodonts became extinct at the Triassic–Jurassic extinction event, the Cretaceous–Paleogene extinction event, and the present day Holocene extinction, have also affected fish variety and fish stocks. Fish may have evolved from a similar to a coral-like sea squirt. The first ancestors of fish, or animals that were closely related to fish, were Pikaia, Haikouichthys. These three genera all appeared around 530 Ma, Pikaia had a primitive notochord, a structure that could have developed into a vertebral column later. Unlike the other fauna that dominated the Cambrian, these groups had the basic body plan, a notochord, rudimentary vertebrae. All of these early vertebrates lacked jaws in the common sense and these were followed by indisputable fossil vertebrates in the form of heavily armoured fishes discovered in rocks from the Ordovician Period 500–430 Ma
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This article incorporates text from a publication now in the public domain: Unsigned (1911). "Coprolites". In Chisholm, Hugh. Encyclopædia Britannica. 7 (11th ed.). Cambridge University Press. p. 111–112.
This article incorporates text from a publication now in the 