50 Million Years of Horse Evolution

50 Million Years of Horse Evolution Apart from a couple of bothersome side branches, horse evolution presents a neat, orderly picture of natural selection in action. The basic storyline goes like this: as the woodlands of North America gave way to grassy plains, the tiny proto-horses of the Eocene epoch (about 50 million years ago) gradually evolved single, large toes on their feet, more sophisticated teeth, larger sizes, and the ability to run at a clip, culminating in the modern horse genus Equus. There are a number of prehistoric horses, including 10 essential prehistoric horses to know. As part of the evolution of horses, you should also know the recently extinct horse breeds. This story has the virtue of being essentially true, with a couple of important ands and buts. But before we embark on this journey, its important to dial back a bit and place horses in their proper position on the evolutionary tree of life. Technically, horses are perissodactyls, that is, ungulates (hoofed mammals) with odd numbers of toes. The other main branch of hoofed mammals, the even-toed artiodactyls, are represented today by pigs, deer, sheep, goats, and cattle, whereas the only other significant perissodactyls beside horses are tapirs and rhinoceroses. What this means is that perissodactyls and artiodactyls (which counted among the mammalian megafauna of prehistoric times) both evolved from a common ancestor, which lived only a few million years after the demise of the dinosaurs at the end of the Cretaceous period, 65 million years ago. In fact, the earliest perissodactyls (like Eohippus, the earliest identified common ancestor of all horses) looked more like small deer than majestic equines! Hyracotherium and Mesohippus, the Earliest Horses Until an even earlier candidate is found, paleontologists agree that the ultimate ancestor of all modern horses was Eohippus, the dawn horse, a tiny (no more than 50 pounds), deer-like herbivore with four toes on its front feet and three toes on its back feet. The giveaway to Eohippus status  was its posture: this perissodactyl put most of its weight on a single toe of each foot, anticipating later equine developments. Eohippus was closely related to another early ungulate, Palaeotherium, which occupied a distant side branch of the horse evolutionary tree. Five to ten million years after Eohippus/Hyracotherium came Orohippus (mountain horse), Mesohippus (middle horse), and Miohippus (Miocene horse, even though it went extinct long before the Miocene epoch). These perissodactyls were about the size of large dogs and sported slightly longer limbs with enhanced middle toes on each foot. They probably spent most of their time in dense woodlands, but may have ventured out onto the grassy plains for short jaunts. Epihippus, Parahippus, and Merychippus- Moving Toward True Horses During the Miocene epoch, North America saw the evolution of intermediate horses, bigger than Eohippus and its ilk but smaller than the equines that followed. One of the most important of these was Epihippus (marginal horse), which was slightly heavier (possibly weighing a few hundred pounds) and equipped with more robust grinding teeth than its ancestors. As you might have guessed, Epihippus also continued the trend toward enlarged middle toes, and it seems to have been the first prehistoric horse to spend more time feeding in meadows than in forests. Following Epihippus were two more hippi, Parahippus and Merychippus. Parahippus (almost horse) can be considered a next-model Miohippus, slightly bigger than its ancestor and (like Epihippus) sporting long legs, robust teeth, and enlarged middle toes. Merychippus (ruminant horse) was the largest of all these intermediate equines, about the size of a modern horse (1,000 pounds) and blessed with an especially fast gait. At this point, its worth asking the question: what drove the evolution of horses in the fleet, single-toed, long-legged direction? During the Miocene epoch, waves of tasty grass covered the North American plains, a rich source of food for any animal well-adapted enough to graze at leisure and run quickly from predators if necessary. Basically, prehistoric horses evolved to fill this evolutionary niche. Hipparion and Hippidion, the Next Steps Toward Equus Following the success of intermediate horses like Parahippus and Merychippus, the stage was set for the emergence of bigger, more robust, more horsey horses. Chief among these were the similarly named Hipparion (like a horse) and Hippidion (like a pony). Hipparion was the most successful horse of its day, radiating out from its North American habitat (by way of the Siberian land bridge) to Africa and Eurasia. Hipparion was about the size of a modern horse; only a trained eye would have noticed the two vestigial toes surrounding its single hooves. Lesser known than Hipparion, but perhaps more interesting, was Hippidion, one of the few prehistoric horses to have colonized South America (where it persisted until historical times). The donkey-sized Hippidion was distinguished by its prominent nasal bones, a clue that it had a highly developed sense of smell. Hippidion may well turn out to have been a species of Equus, making it more closely related to modern horses than Hipparion was. Speaking of Equus, this genus- which includes modern horses, zebras, and donkeys- evolved in North America during the Pliocene epoch, about four million years ago, and then, like Hipparion, migrated across the land bridge to Eurasia. The last Ice Age saw the extinction of both North and South American horses, which disappeared from both continents by about 10,000 BCE. Ironically, though, Equus continued to flourish on the plains of Eurasia and was reintroduced to the Americas by the European colonizing expeditions of the 15th and 16th centuries CE.

Writing Your Perfect News Story

Writing Your Perfect News Story A Detailed Guide on Writing a News Story Journalistic writing isn’t as easy as it seems. Very often students have no idea where to start and how to phrase their sentences even, not to mention conducting interviews. Below, you will find top tips on how to create a qualitative news story. The topic or event you pick has to be recent and newsworthy The first thing you should learn to do is to define what is newsworthy and what is not. Any events happening in a society that might capture your reader’s attention and is unique and effective is considered to be a newsworthy story. If you decided to tell readers about a business which is not new or doesn’t offer any changes, it won’t be a newsworthy story. However, telling about a new business in a particular area is pretty newsworthy. Make sure to tell your readers about the latest events only, not the ones happening a week ago or so. Society is discussing something else already and your news has to be up to date and write about something happening right now. Also, make sure to be â€Å"local†, i.e. writing for the right community. Mentioning the worldwide events is also acceptable; however, the events going on in your area are your priority. Address the worldwide events only if they somehow affect the audience you write for. Interview the witnesses The interviews have to be conducted with the correct people, and it is crucial. If you write about the bank robbery, you have to talk to the manager of the bank, a cashier, or any employee involved in the event. Unless the bank clients were witnesses of the robbery, you should not interview them. Make sure to ask everyone as soon as possible. Remember that you have to tell about the newest events. Who? What? When? Where? Those main four Ws have to be established within the first paragraph of your writing, while â€Å"why† and â€Å"how† can be disclosed in the following paragraphs already. You are creating a sort of a pyramid, on the top of which you write the most important information. Put your piece together Once you have all the necessary materials, start constructing your piece. Remember that the most important information is on the top, i.e. in the very beginning. Add quotations You can add quotations when writing or at specific points in your story. Make sure to state the full name, occupation, age of key people in your story. Search for some additional figures or facts Once you have completed your story, google additional facts and figures which will be interesting and will help your story stand out. Your job will be to compete with other news sources, and you will use the same information and deliver your information to the same readers, so you will surely need some extra information. Reread your article loud Before giving your article to your professor (or editor), read your article aloud to understand the general flow of your story. Writing a news story is not that difficult, and you will gain some skills after completing such task a couple of times.

The Nature and Causes of the Wealth of Nations, Adam Smith Essay

The Nature and Causes of the Wealth of Nations, Adam Smith - Essay Example One of the essential ideas in â€Å"The Wealth of Nations† is the division of labour. According to Smith, the division of labour occurs due to the increase in production rather than any other factor. The division of labour, however, can only be beneficial if a nation has more industry in place. The book argues that agriculture does not produce a larger division of labour as compared to industry. According to Smith, the division of labor arises not from the innate wisdom of the masses, but due to a human tendency to barter. Smith, therefore, argues that the reasons for the specialization are due to the differences in natural talent rather than any other factor. The book also discusses the limitations of the division of labour and indicates that the division of labour is actually limited by the extent of the market. The overall limited opportunities in the market actually result into the lack of labour specialization. If a market can be expanded, the specialization of labour can further occur, and the society can benefit from more skilled workers. In 1778, Smith was appointed the Commissioner to the Customs. This experience sharpened his understanding of trading and of the manner how exchange actually took place between two parties. He designed and developed policies and methods to curb smuggling so that overall revenues could be increased. He remained single during his entire life and died in Edinburgh on July 19, 1790 (Smith, 1761 a). He was a ruthless advocate of individualism, and his interests ranged from natural theology, ethics, and jurisprudence, to economics, which may explain the cause as to why he wrote â€Å"The Theory of Moral Sentiments† (Smith, 1761 a). He denied self-love as a principle which could never be virtuous. He thought that sympathy and self-interest were complementary. He once expressed that it was not from the benevolence of the butcher, the brewer, or the baker, that a worker could expect dinner, however, in fact, each ag ent worked in their own self-interest (Smith, 1761 a). He also discussed the concept of money and how various commodities were used as money. He reviewed the origins of money and how different nations actually used it in order to create a medium for exchange. He also speculated how metals were used as money and how nations actually invented new methods of developing money with the purpose of creating an exchange value. Further, he also discussed nominal prices for commodities as well as prices for labour. He also outlined how prices were actually determined and what were some of their components. Smith was in favour of labour and indicated that labour was the means by which an individual earned wages in a competitive market; a labourer must produce something others valued to earn (Smith, 1761 a). â€Å"The Wealth of Nations† reveals that nature and causes of the nation’s prosperity come from the increasing of the labour division to systematize its production (Smith, 17 61 a). Smith professed that individual would invest resources, e.g. land and labour, to earn the highest possible return of investment, but it must yield to the equal rate of return (Smith, 1977 b). For classical economists this was the core of Smith’s proposition of economic theory. Smith advocated equality of returns to explain the differences of salaries based on the knowledge, skills,