Austria, officially the Republic of Austria, is a federal republic and a landlocked country of over 8.7 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north and Slovakia to the east and Italy to the south, the territory of Austria covers 83,879 km2. The terrain is mountainous, lying within the Alps, only 32% of the country is below 500 m. The majority of the population speaks local Bavarian dialects of German as their native language, other local official languages are Hungarian, Burgenland Croatian, and Slovene. The origins of modern-day Austria date back to the time of the Habsburg dynasty, from the time of the Reformation, many northern German princes, resenting the authority of the Emperor, used Protestantism as a flag of rebellion. Following Napoleons defeat, Prussia emerged as Austrias chief competitor for rule of a greater Germany, Austrias defeat by Prussia at the Battle of Königgrätz, during the Austro-Prussian War of 1866, cleared the way for Prussia to assert control over the rest of Germany.
In 1867, the empire was reformed into Austria-Hungary, Austria was thus the first to go to war in the July Crisis, which would ultimately escalate into World War I. The First Austrian Republic was established in 1919, in 1938 Nazi Germany annexed Austria in the Anschluss. This lasted until the end of World War II in 1945, after which Germany was occupied by the Allies, in 1955, the Austrian State Treaty re-established Austria as a sovereign state, ending the occupation. In the same year, the Austrian Parliament created the Declaration of Neutrality which declared that the Second Austrian Republic would become permanently neutral, Austria is a parliamentary representative democracy comprising nine federal states. The capital and largest city, with a population exceeding 1.7 million, is Vienna, other major urban areas of Austria include Graz, Linz and Innsbruck. Austria is one of the richest countries in the world, with a nominal per capita GDP of $43,724, the country has developed a high standard of living and in 2014 was ranked 21st in the world for its Human Development Index.
Austria has been a member of the United Nations since 1955, joined the European Union in 1995, Austria signed the Schengen Agreement in 1995, and adopted the euro currency in 1999. The German name for Austria, Österreich, meant eastern realm in Old High German, and is cognate with the word Ostarrîchi and this word is probably a translation of Medieval Latin Marchia orientalis into a local dialect. Austria was a prefecture of Bavaria created in 976, the word Austria is a Latinisation of the German name and was first recorded in the 12th century. Accordingly, Norig would essentially mean the same as Ostarrîchi and Österreich, the Celtic name was eventually Latinised to Noricum after the Romans conquered the area that encloses most of modern-day Austria, around 15 BC. Noricum became a Roman province in the mid-first century AD, heers hypothesis is not accepted by linguists. Settled in ancient times, the Central European land that is now Austria was occupied in pre-Roman times by various Celtic tribes, the Celtic kingdom of Noricum was claimed by the Roman Empire and made a province
Karst topography is a landscape formed from the dissolution of soluble rocks such as limestone and gypsum. It is characterized by underground drainage systems with sinkholes and caves and it has been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes, the English word karst was borrowed from German Karst in the late 19th century. The German word came into use before the 19th century, according to the prevalent interpretation, the term is derived from the German name for the Karst region, a limestone plateau above the city of Trieste in the northern Adriatic. Scholars disagree, however, on whether the German word was borrowed from Slovene, the Slovene common noun kras was first attested in the 18th century, and the adjective form kraški in the 16th century. The Slovene words arose through metathesis from the reconstructed form *korsъ, the word is of Mediterranean origin, believed to derive from some Romanized Illyrian base.
It has been suggested that the word may derive from the Proto-Indo-European root karra- rock, the name may be connected to the oronym Karsádios oros cited by Ptolemy, and perhaps to Latin Carusardius. The development of karst occurs whenever acidic water starts to break down the surface of bedrock near its cracks, as the bedrock continues to degrade, its cracks tend to get bigger. As time goes on, these fractures will become wider, if this underground drainage system does form, it will speed up the development of karst formations there because more water will be able to flow through the region, giving it more erosive power. The carbonic acid that causes karstic features is formed as rain passes through the atmosphere picking up carbon dioxide, once the rain reaches the ground, it may pass through soil that can provide much more CO2 to form a weak carbonic acid solution, which dissolves calcium carbonate. The oxidation of sulfides leading to the formation of acid can be one of the corrosion factors in karst formation.
As oxygen -rich surface waters seep into deep anoxic karst systems, they bring oxygen, sulfuric acid reacts with calcium carbonate, causing increased erosion within the limestone formation. This chain of reactions is, This reaction chain forms gypsum, the karstification of a landscape may result in a variety of large- or small-scale features both on the surface and beneath. On exposed surfaces, small features may include solution flutes, limestone pavement, medium-sized surface features may include sinkholes or cenotes, vertical shafts, disappearing streams, and reappearing springs. Large-scale features may include limestone pavements and karst valleys, mature karst landscapes, where more bedrock has been removed than remains, may result in karst towers, or haystack/eggbox landscapes. Beneath the surface, complex underground systems and extensive caves. Some of the most dramatic of these formations can be seen in Thailands Phangnga Bay, calcium carbonate dissolved into water may precipitate out where the water discharges some of its dissolved carbon dioxide.
Rivers which emerge from springs may produce tufa terraces, consisting of layers of calcite deposited over extended periods of time, in caves, a variety of features collectively called speleothems are formed by deposition of calcium carbonate and other dissolved minerals
A quarry is a place from which dimension stone, construction aggregate, sand, gravel, or slate has been excavated from the ground. A quarry is the thing as an open-pit mine from which minerals are extracted. The only non-trivial difference between the two is that open-pit mines that produce building materials and dimension stone are commonly referred to as quarries, the word quarry can include the underground quarrying for stone, such as Bath stone. The surfaces are polished and finished with varying degrees of sheen or luster, polished slabs are often cut into tiles or countertops and installed in many kinds of residential and commercial properties. Natural stone quarried from the earth is considered a luxury and tends to be a highly durable surface. Quarries in level areas with shallow groundwater or which are located close to surface water often have engineering problems with drainage, generally the water is removed by pumping while the quarry is operational, but for high inflows more complex approaches may be required.
For example, the Coquina quarry is excavated to more than 60 feet below sea level, to reduce surface leakage, a moat lined with clay was constructed around the entire quarry. Ground water entering the pit is pumped up into the moat, as a quarry becomes deeper, water inflows generally increase and it becomes more expensive to lift the water higher during removal, this can become the limiting factor in quarry depth. Some water-filled quarries are worked from beneath the water, by dredging, many people and municipalities consider quarries to be eyesores and require various abatement methods to address problems with noise and appearance. One of the effective and famous examples of successful quarry restoration is Butchart Gardens in Victoria, BC. A further problem is pollution of roads from trucks leaving the quarries, to control and restrain the pollution of public roads, wheel washing systems are becoming more common. Many quarries naturally fill with water after abandonment and become lakes, water-filled quarries can be very deep with water, often 50 feet or more, that is often surprisingly cold.
Unexpectedly cold water can cause a swimmers muscles to weaken, it can cause shock. Though quarry water is very clear, submerged quarry stones. Several people drown in quarries each year, many inactive quarries are converted into safe swimming sites
Cave paintings are painted drawings on cave walls or ceilings, mainly of prehistoric origin, to some 40,000 years ago in Eurasia. The exact purpose of the Paleolithic cave paintings is not known, evidence suggests that they were not merely decorations of living areas since the caves in which they have been found do not have signs of ongoing habitation. They are located in areas of caves that are not easily accessible. Some theories hold that cave paintings may have been a way of communicating with others, the paintings are remarkably similar around the world, with animals being common subjects that give the most impressive images. Humans mainly appear as images of hands, mostly hand stencils made by blowing pigment on a hand held to the wall. The earliest known cave paintings/drawings of animals are at least 35,000 years old and are found in Pettakere cave on the island of Sulawesi in Indonesia, previously it was believed that the earliest paintings were in Europe. The earliest non-figurative rock art dates back to approximately 40,000 years ago, nearly 340 caves have now been discovered in France and Spain that contain art from prehistoric times.
But subsequent technology has made it possible to date the paintings by sampling the pigment itself, the choice of subject matter can indicate chronology. For instance, the reindeer depicted in the Spanish cave of Cueva de las Monedas places the drawings in the last Ice Age. The oldest date given to a cave painting is now a pig that has a minimum age of 35,400 years old at Pettakere cave in Sulawesi. Indonesian and Australian scientists have dated other non-figurative paintings on the walls to be approximately 40,000 years old, the method they used to confirm this was dating the age of the stalactites that formed over the top of the paintings. The art is similar in style and method to that of the Indonesian caves as there were hand stencils and this date coincides with the earliest known evidence for Homo sapiens in Europe. Because of the cave arts age, some scientists have conjectured that the paintings may have made by Neanderthals. The earliest known European figurative cave paintings are those of Chauvet Cave in France and these paintings date to earlier than 30,000 BCE according to radiocarbon dating.
Some researchers believe the drawings are too advanced for this era, the radiocarbon dates from these samples show that there were two periods of creation in Chauvet,35,000 years ago and 30,000 years ago. In 2009, cavers discovered drawings in Coliboaia Cave in Romania, an initial dating puts the age of an image in the same range as Chauvet, about 32,000 years old. Some caves probably continued to be painted over a period of thousands of years. This was created roughly between 10,000 and 5,500 years ago, and painted in rock shelters under cliffs or shallow caves, though individual figures are less naturalistic, they are grouped in coherent grouped compositions to a much greater degree
A saber-toothed cat is any member of various extinct groups of predatory mammals that were characterized by long, curved saber-shaped canine teeth. The large maxillary canine teeth extended from the mouth even when it was closed, the saber-toothed cats were found worldwide from the Eocene epoch to the end of the Pleistocene epoch, existing for about 42 million years. Extant members of Felidae include cats of the subfamilies Felinae and Pantherinae. In this regard, saber-toothed cats can be viewed as examples of convergent evolution. ”Of the feliform lineages, barbourofelidae entered around 16.9 mya and were extinct by 9 mya. These two would have shared some habitats, the different groups of sabre-toothed cats evolved their saber-toothed characteristics entirely independently. They are most known for having maxillary canines which extended down from the mouth even when the mouth was closed, saber-toothed cats were generally more robust than todays cats and were quite bear-like in build. They were believed to be excellent hunters and hunted animals such as sloths, evidence from the numbers found at La Brea Tar Pits suggests that Smilodon, like modern lions, was a social carnivore.
The first saber-tooths appear among the synapsids, or mammal-like reptiles, they were one of the first groups of animals to experience specialization of teeth, some had two pairs of upper canines with two jutting down from each side, but most had one pair of upper extreme canines. Because of their primitiveness, they are easy to tell from machairodonts. With no coronoid process, many sharp premolars more like pegs than scissors, the second appearance is in Deltatheroida, a lineage of Cretaceous metatherians. At least one genus, possess long canines, the third appearance of long canines is Thylacosmilus, which is the most distinctive of the saber-tooth mammals and is easy to tell apart. It differs from machairodonts in possessing a prominent flange and a tooth that is triangular in cross section. The root of the canines is more prominent than in machairodonts, the fourth instance of saber teeth is from clade Oxyaenidae. The small and slender Machaeroides bore canines that were thinner than in the average machairodont and its muzzle was longer and narrower.
The fifth saber-tooth appearance is the ancient family of carnivores, the nimravids, both groups have short skulls, tall sagittal crests, and their general skull shape is very similar. Some have distinctive flanges, and some have none at all, machairodonts were almost always bigger and their canines were longer and more stout for the most part, but exceptions do appear. The sixth appearance is the barbourofelids and these carnivores are very closely related to actual cats, and as such, they are hard to tell apart. The average machairodont had well-developed incisors, but barbourofelids were more extreme, the seventh and last of the saber-tooth group to evolve were the machairodonts themselves
Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity.
Under normal conditions, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones and carbon dioxide, but significant quantities occur in organic deposits of coal, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature.
Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
Monkeys are haplorhine primates, a group generally possessing tails and consisting of about 260 known living species. There are two lineages of monkeys, New World Monkeys and catarrhines. Apes emerged within the catarrhines with the Old World monkeys as a sister group, traditionally apes are not considered monkeys, rendering this grouping paraphyletic. The equivalent monophyletic clade are the simians, many monkey species are tree-dwelling, although there are species that live primarily on the ground, such as baboons. Most species are active during the day. Monkeys are generally considered to be intelligent, particularly Old World monkeys, lemurs and galagos are not monkeys, instead they are strepsirrhine primates. Like monkeys, tarsiers are haplorhine primates, they are not monkeys. There are two types of monkey, New World monkeys from South and Central America and Old World monkeys from Africa. Hominoid apes, which all lack tails, are catarrhines but are not considered monkeys and tarsiers emerged within haplorrhines some 60 million years ago.
New World monkeys and catarrhine monkeys emerged within the simians some 35 millions years ago, Old World monkeys and Hominoidea emerged within the catarrhine monkeys some 25 millions years ago. Extinct basal simians such as Aegyptopithecus or Parapithecus are considered monkeys by primatologists, according to the Online Etymology Dictionary, the word monkey may originate in a German version of the Reynard the Fox fable, published circa 1580. In this version of the fable, a character named Moneke is the son of Martin the Ape, the terms monkey and ape are widely used interchangeably. Also, a few species have the word ape in their common name. Monkeys thus constituted a grade on the path to humans and were distinguished from apes, scientific classifications are now more often based on monophyletic groups, that is groups consisting of all the descendants of a common ancestor. The New World monkeys and the Old World monkeys are each monophyletic groups, thus the term monkey no longer refers to a recognized scientific taxon.
The smallest accepted taxon which contains all the monkeys is the infraorder Simiiformes, however this contains the hominoids, so that monkeys are, in terms of currently recognized taxa, non-hominoid simians. Colloquially and pop-culturally, the term is ambiguous and sometimes monkey includes non-human hominoids, in addition, frequent arguments are made for a monophyletic usage of the word monkey from the perspective that usage should reflect cladistics. A group of monkeys may be referred to as a tribe or a troop
Prague is the capital and largest city of the Czech Republic. It is the 14th largest city in the European Union and it is the historical capital of Bohemia. Situated in the north-west of the country on the Vltava river, the city has a temperate climate, with warm summers and chilly winters. Prague has been a political and economic centre of central Europe with waxing and waning fortunes during its history and it was an important city to the Habsburg Monarchy and its Austro-Hungarian Empire. Prague is home to a number of cultural attractions, many of which survived the violence. Main attractions include the Prague Castle, the Charles Bridge, Old Town Square with the Prague astronomical clock, since 1992, the extensive historic centre of Prague has been included in the UNESCO list of World Heritage Sites. The city has more than ten major museums, along with theatres, cinemas. An extensive modern public transportation system connects the city, also, it is home to a wide range of public and private schools, including Charles University in Prague, the oldest university in Central Europe.
Prague is classified as an Alpha- global city according to GaWC studies, Prague ranked sixth in the Tripadvisor world list of best destinations in 2016. Its rich history makes it a popular tourist destination, and the city more than 6.4 million international visitors annually. Prague is the fifth most visited European city after London, Istanbul, the region was settled as early as the Paleolithic age. In the last century BC, the Celts were slowly driven away by Germanic tribes, around the area where present-day Prague stands, the 2nd century map of Ptolemaios mentioned a Germanic city called Casurgis. In the following century, the Czech tribes built several fortified settlements in the area, most notably in Levý Hradec, Butovice and in the Šárka valley. The construction of what came to be known as the Prague Castle began near the end of the 9th century, the first masonry under Prague Castle dates from the year 885 at the latest. The other prominent Prague fort, the Přemyslid fort Vyšehrad, was founded in the 10th century, Prague Castle is dominated by the cathedral, which was founded in 1344, but completed in the 20th century.
The legendary origins of Prague attribute its foundation to the 8th century Czech duchess and prophetess Libuše and her husband, Přemysl, legend says that Libuše came out on a rocky cliff high above the Vltava and prophesied, I see a great city whose glory will touch the stars. She ordered a castle and a town called Praha to be built on the site, a 17th century Jewish chronicler David Solomon Ganz, citing Cyriacus Spangenberg, claimed that the city was founded as Boihaem in c.1306 BC by an ancient king, Boyya. The region became the seat of the dukes, and kings of Bohemia, under Roman Emperor Otto II the area became a bishopric in 973
Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as a process used with metals, plastics. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together, the study of sintering in metallurgy powder-related processes is known as powder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, examples of pressure-driven sintering are the compacting of snowfall to a glacier, or the forming of a hard snowball by pressing loose snow together. The word sinter comes from the Middle High German sinter, a cognate of English cinder, the driving force for densification is the change in free energy from the decrease in surface area and lowering of the surface free energy by the replacement of solid-vapor interfaces. It forms new but lower-energy solid-solid interfaces with a decrease in free energy occurring.
On a microscopic scale, material transfer is affected by the change in pressure, If the size of the particle is small, these effects become very large in magnitude. For properties such as strength and conductivity, the area in relation to the particle size is the determining factor. The variables that can be controlled for any material are the temperature. Through time, the radius and the vapor pressure are proportional to 2/3 and to 1/3. The source of power for solid-state processes is the change in free or chemical energy between the neck and the surface of the particle. The pore elimination occurs faster for a trial with many pores of uniform size, for the latter portions of the process and lattice diffusion from the boundary become important. Sintering is part of the process used in the manufacture of pottery. These objects are made from such as glass, zirconia, magnesia, beryllium oxide. Some ceramic raw materials have an affinity for water and a lower plasticity index than clay. Sintering is performed at high temperature, second and/or third external force could be used.
Commonly used second external force is pressure, so, the sintering that performed just using temperature is generally called pressureless sintering. Pressureless sintering is possible with graded metal-ceramic composites, with a nanoparticle sintering aid, a variant used for 3D shapes is called hot isostatic pressing
It extends from the earliest known use of stone tools, probably by Homo habilis initially,2.6 million years ago, to the end of the Pleistocene around 10,000 BP. The Paleolithic era is followed by the Mesolithic, the date of the Paleolithic–Mesolithic boundary may vary by locality as much as several thousand years. During the Paleolithic period, humans grouped together in small societies such as bands, the Paleolithic is characterized by the use of knapped stone tools, although at the time humans used wood and bone tools. Other organic commodities were adapted for use as tools, including leather and vegetable fibers, due to their nature, surviving artifacts of the Paleolithic era are known as paleoliths. About 50,000 years ago, there was a increase in the diversity of artifacts. For the first time in Africa, bone artifacts and the first art appear in the archaeological record, the first evidence of human fishing is noted, from artifacts in places such as Blombos cave in South Africa. The new technology generated an explosion of modern humans which is believed to have led to the extinction of the Neanderthals.
Humankind gradually evolved from members of the genus Homo—such as Homo habilis. The climate during the Paleolithic consisted of a set of glacial and interglacial periods in which the climate periodically fluctuated between warm and cool temperatures, by c. 50,000 – c. 40,000 BP, the first humans set foot in Australia. By c. 45,000 BP, humans lived at 61°N latitude in Europe, by c. 30,000 BP, Japan was reached, and by c. 27,000 BP humans were present in Siberia, above the Arctic Circle. At the end of the Upper Paleolithic, a group of humans crossed Beringia, the term Paleolithic was coined by archaeologist John Lubbock in 1865. It derives from Greek, παλαιός, old, and λίθος, stone, human evolution is the part of biological evolution concerning the emergence of anatomically modern humans as a distinct species. The Paleolithic Period coincides almost exactly with the Pleistocene epoch of geologic time and this epoch experienced important geographic and climatic changes that affected human societies.
During the preceding Pliocene, continents had continued to drift from possibly as far as 250 km from their present locations to positions only 70 km from their current location. South America became linked to North America through the Isthmus of Panama, most of Central America formed during the Pliocene to connect the continents of North and South America, allowing fauna from these continents to leave their native habitats and colonize new areas. Africas collision with Asia created the Mediterranean Sea, cutting off the remnants of the Tethys Ocean, climates during the Pliocene became cooler and drier, and seasonal, similar to modern climates. The formation of an Arctic ice cap around 3 million years ago is signaled by a shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic. Mid-latitude glaciation probably began before the end of the epoch, the global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas
The woolly rhinoceros is an extinct species of rhinoceros that was common throughout Europe and northern Asia during the Pleistocene epoch and survived the last glacial period. The genus name Coelodonta means cavity tooth, the woolly rhinoceros was a member of the Pleistocene megafauna. As the last and most derived member of the Pleistocene rhinoceros lineage, stocky limbs and thick woolly pelage made it well suited to the steppe-tundra environment prevalent across the Palearctic ecozone during the Pleistocene glaciations. Like the vast majority of rhinoceroses, the plan of the woolly rhinoceros adhered to a conservative morphology. A study of 40, 000- to 70, 000-year-old DNA samples showed its closest extant relative is the Sumatran rhinoceros, the appearance of woolly rhinos is known from mummified individuals from Siberia as well as cave paintings. An adult woolly rhinoceros was typically around 3 to 3.8 metres in length, with a weight of around 1. The woolly rhinoceros could grow to be 2 m tall, the size was thus comparable to, or slightly larger than.
Two horns on the skull were made of keratin, the horn being 61 cm in length, with a smaller horn between its eyes. It had thick, long fur, small ears, thick legs, Cave paintings suggest a wide dark band between the front and hind legs, but the feature is not universal, and the identification of pictured rhinoceroses as woolly rhinoceros is uncertain. Its shape was only from prehistoric cave drawings until a completely preserved specimen was discovered in a tar pit in Starunia. The specimen, a female, is now on display in the Polish Academy of Sciences Museum of Natural History in Kraków. Several frozen specimens have found in Siberia, the latest in 2007. The woolly rhinoceros used its horns for defensive purposes and to attract mates, during Greenland Stadial 2 the North Sea retreated northward, as sea levels were up to 125 metres lower than today. The woolly rhinoceros roamed the exposed Doggerland and much of Northern Europe and was common in the cold, arid desert that is southern England and its geographical range expanded and contracted with the alternating cold and warm cycles, forcing populations to migrate as glaciers receded.
The woolly rhinoceros co-existed with woolly mammoths and several other larger mammals of the Pleistocene megafauna. A close relative, had a southern range. It is believed they migrated there to northern Asia and Europe when the Ice Age began. Females gave birth to one or two calves, controversy has long surrounded the precise dietary preference of Coelodonta as past investigations have found both grazing and browsing modes of life to be plausible
The beaver is a large, primarily nocturnal, semiaquatic rodent. Castor includes two extant species, the North American beaver and Eurasian beaver, Beavers are known for building dams and lodges. They are the second-largest rodent in the world and their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was more than 60 million. Beavers, along with pocket gophers and kangaroo rats, are castorimorph rodents, Beavers are known for their natural trait of building dams on rivers and streams, and building their homes in the resulting pond. Beavers build canals to float building materials that are difficult to haul over land and they use powerful front teeth to cut trees and other plants that they use both for building and for food. In the absence of existing ponds, beavers must construct dams before building their lodges, first they place vertical poles, fill between the poles with a crisscross of horizontally placed branches.
They fill in the gaps between the branches with a combination of weeds and mud until the dam impounds sufficient water to surround the lodge and this serves as a warning to beavers in the area. Once a beaver has sounded the alarm, nearby beavers will dive, Beavers are slow on land, but are good swimmers, and can stay under water for as long as 15 minutes. Beavers are herbivores, and prefer the wood of quaking aspen, willow, birch and they eat sedges and water lilies. Beavers do not hibernate, but store sticks and logs in a pile in their ponds, some of the pile is generally above water and accumulates snow in the winter. This insulation of snow often keeps the water freezing in and around the food pile. Beavers have webbed hind-feet, and a broad, scaly tail and they have poor eyesight, but keen senses of hearing and touch. A beavers teeth grow continuously so that they not be worn down by chewing on wood. Their four incisors are composed of hard orange enamel on the front, the chisel-like ends of incisors are maintained by their self-sharpening wear pattern.
The enamel in a beavers incisors contains iron and is resistant to acid than enamel in the teeth of other mammals. Beavers continue to grow throughout their lives, adult specimens weighing over 25 kg are not uncommon. Females are as large as or larger than males of the same age, Beavers live up to 24 years of age in the wild