Portal:Mammals
The mammals portalMammals (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. Selected article
The Sumatran Rhinoceros (Dicerorhinus sumatrensis) is a species of the family Rhinocerotidae, and one of five extant rhinoceri. It is the smallest rhinoceros, standing about 120–145 centimetres (3.9–4.8 ft) high at the shoulder, with a body length of 250 centimetres (98 in) and weight of 500–800 kilograms (1100–1760 lb). Like its African counterparts, the black and white rhinoceri, it has two horns; the larger is the nasal horn, typically 15–25 centimetres (6–10 in), while the other is typically a stub. A coat of reddish-brown hair covers most of the rhino's body. Members of the species once ranged throughout rainforests, swamps and cloud forests in India, Bhutan, Bangladesh, Myanmar, Laos, Thailand, Malaysia, and Indonesia. They are now critically endangered, with only six substantial populations in the wild: four on Sumatra, one on Borneo, and one on peninsular Malaysia. Their numbers are difficult to determine because they are solitary animals that are widely scattered across their range, but they are estimated to number around just 300. The decline in the number of Sumatran rhinoceri is attributed primarily to poaching for their ivory horns, which are highly valued in traditional Chinese medicine, fetching as much as US$30,000 per kilogram on the black market. The rhinos have also suffered from habitat loss as their forests have been cleared for lumber and conversion to agriculture.
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Selected pictureBraunvieh (German: brown cattle) is a breed of cattle originating from Switzerland. Scientific classification
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