Portal:Mammals

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A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia (/məˈmli.ə/). Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,400 extant species of mammals have been described and divided into 29 orders.

The largest orders of mammals, by number of species, are the rodents, bats, and Eulipotyphla (including hedgehogs, moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including cats, dogs, and seals).

Mammals are the only living members of Synapsida; this clade, together with Sauropsida (reptiles and birds), constitutes the larger Amniota clade. Early synapsids are referred to as "pelycosaurs". The more advanced therapsids became dominant during the Middle Permian. Mammals originated from cynodonts, an advanced group of therapsids, during the Late Triassic to Early Jurassic. Mammals achieved their modern diversity in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, and have been the dominant terrestrial animal group from 66 million years ago to the present.

The basic mammalian body type is quadruped, and most mammals use their four extremities for terrestrial locomotion; but in some, the extremities are adapted for life at sea, in the air, in trees, underground, or on two legs. Mammals range in size from the 30–40 mm (1.2–1.6 in) bumblebee bat to the 30 m (98 ft) blue whale—possibly the largest animal to have ever lived. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale. All modern mammals give birth to live young, except the five species of monotremes, which are egg-laying mammals. The most species-rich group of mammals, the infraclass called placentals, have a placenta, which enables the feeding of the fetus during gestation.

Most mammals are intelligent, with some possessing large brains, self-awareness, and tool use. Mammals can communicate and vocalize in several ways, including the production of ultrasound, scent-marking, alarm signals, singing, echolocation; and, in the case of humans, complex language. Mammals can organize themselves into fission–fusion societies, harems, and hierarchies—but can also be solitary and territorial. Most mammals are polygynous, but some can be monogamous or polyandrous.

Domestication of many types of mammals by humans played a major role in the Neolithic Revolution, and resulted in farming replacing hunting and gathering as the primary source of food for humans. This led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, and ultimately the development of the first civilizations. Domesticated mammals provided, and continue to provide, power for transport and agriculture, as well as food (meat and dairy products), fur, and leather. Mammals are also hunted and raced for sport, kept as pets and working animals of various types, and are used as model organisms in science. Mammals have been depicted in art since Paleolithic times, and appear in literature, film, mythology, and religion. Decline in numbers and extinction of many mammals is primarily driven by human poaching and habitat destruction, primarily deforestation. (Full article...)

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An Arabian stallion
The Arabian horse is a breed of horse with a reputation for intelligence, spirit, and stamina. With a distinctive head shape and high tail carriage, the Arabian is one of the most easily recognizable horse breeds in the world. It is one of the oldest horse breeds, with archaeological evidence of horses that resemble modern Arabians dating back 4,500 years. Throughout history, Arabian horses from the Middle East spread around the world by both war and trade, used to improve other breeds by adding speed, refinement, endurance, and good bone. Today, Arabian bloodlines are found in almost every modern breed of riding horse. The Arabian developed in a desert climate and was prized by the nomadic Bedouin people, often being brought inside the family tent for shelter and protection. This close relationship with humans has created a horse breed that is good-natured, quick to learn, and willing to please. But the Arabian also developed the high spirit and alertness needed in a horse used for raiding and war. This combination of willingness and sensitivity requires modern Arabian horse owners to handle their horses with competence and respect. "The Versatile Arabian" is a slogan of the breed. Arabians dominate the discipline of endurance riding, and compete today in many other fields of equestrian activity. They are one of the top ten most popular horse breeds in the world. Arabian horses are now found worldwide, including the United States and Canada, the United Kingdom, Australia, continental Europe, South America (especially Brazil), and its land of origin, the Middle East.

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Scientific classification

KingdomAnimalia   PhylumChordata   SubphylumVertebrata   SuperclassTetrapoda   (unranked)Amniota   ClassMammalia



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