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Portal:Mammals

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Dwarf mongoose Korkeasaari zoo.jpg

Mammals (class Mammalia) are vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex region in the brain. Mammals, other than the monotremes, give birth to live young instead of laying eggs. They also possess specialized teeth and use a placenta in the ontogeny. The mammalian brain regulates endothermic and circulatory systems, including a four-chambered heart. Mammals encompass approximately 5,400 species, ranging in size from the Bumblebee Bat, (30-40mm), to the Blue Whale, (33,000mm), distributed in about 1,200 genera, 153 families, and 29 orders, though this varies by classification scheme.

Most mammals belong to the placental group. The four largest orders within the placental mammals are Rodentia (mice, rats, and other small, gnawing mammals), Chiroptera (bats), Carnivora (dogs, cats, bears, and other mammals that primarily eat meat), and Cetartiodactyla (including numerous herbivore species, such as deer, sheep, goats, and buffalos, plus whales).

Phylogenetically, Mammalia is defined as all descendants of the most recent common ancestor of monotremes (e.g., echidnas and platypuses) and therian mammals (marsupials and placentals). This means that some extinct groups of "mammals" are not members of the crown group Mammalia, even though most of them have all the characteristics that traditionally would have classified them as mammals. These "mammals" are now usually placed in the unranked clade Mammaliaformes.

The mammalian line of descent diverged from the sauropsid line at the end of the Carboniferous period. The sauropsids would evolve into modern-day reptiles and birds, while the synapsid branch led to mammals. The first true mammals appeared in the Jurassic period. Modern mammalian orders appeared in the Palaeocene and Eocene epochs of the Palaeogene period.

Nuvola filesystems www.png Mammals ...

Selected article

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.

Did you know?

Caracal001.jpg
  • ....that Caracal (pictured) is very powerful for its size and has even been known to bring down a full grown adult Gazelle?
  • ...that Snuppy the Afghan Hound is the world's first cloned dog?
  • ...the male narwhal's tusk can be up to 3 metres in length and weigh up to 10 kilograms?
  • ...the Voyager Golden Record carried into space whale songs, among other sounds?
  • ...that 217 Dalmatians were used in the filming of 101 Dalmatians?
  • ...that Scarlett the cat is a former stray cat whose efforts to save her kittens from a fire, at serious harm to herself, attracted worldwide media attention and has been related in a number of nonfiction books?
  • ...that Dr. Johnson's cat Hodge has his own statue in Gough Square, London?

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Grizzly Bear
Credit: Jean-Pierre Lavoie/Fir0002

A Grizzly Bear (Ursus arctos horribilis) wandering in Denali National Park, Alaska during the autumn. The Grizzly Bear is the common name for a Brown Bear, found in the North America. They reach weights of 180-680 kg (400-1,500 lb) and are colored blond to deep brown or black. In spite of their massive size, these bears can run at speeds of up to 55 km/h (35 mph). The current range of the Grizzly Bear extends from Alaska, down through much of Western Canada, and into the upper Northwestern United States including Idaho, Montana and Wyoming.

Scientific classification

KingdomAnimalia   PhylumChordata   SubphylumVertebrata   SuperclassTetrapoda   (unranked)Amniota   ClassMammalia


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