Portal:Mammals

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A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia (/məˈmeɪli.ə/). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad 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 6,640 extant species of mammals have been described and divided into 27 orders. The study of mammals is called mammalogy.

The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the even-toed ungulates (including pigs, bovids 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 Guadalupian. 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 quadrupedal, with most mammals using four limbs for terrestrial locomotion; but in some, the limbs are adapted for life at sea, in the air, in trees or underground. The bipeds have adapted to move using only the two lower limbs, while the rear limbs of cetaceans and the sea cows are mere internal vestiges. Mammals range in size from the 30–40 millimetres (1.2–1.6 in) bumblebee bat to the 30 metres (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 lay eggs. The most species-rich group is the viviparous placental mammals, so named for the temporary organ (placenta) used by offspring to draw nutrition from the mother during gestation.

Most mammals are intelligent, with some possessing large brains, self-awareness, and tool use. Mammals can communicate and vocalise in several ways, including the production of ultrasound, scent marking, alarm signals, singing, echolocation; and, in the case of humans, complex language. Mammals can organise 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 civilisations. 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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The humpback whale (Megaptera novaeangliae) is a baleen whale. One of the larger rorqual species, adults range in length from 12–16 metres (40–50 ft) and weigh approximately 36,000 kilograms (79,000 lb). The humpback has a distinctive body shape, with unusually long pectoral fins and a knobbly head. It is an acrobatic animal, often breaching and slapping the water. Males produce a complex whale song, which lasts for 10 to 20 minutes and is repeated for hours at a time. The purpose of the song is not yet clear, although it appears to have a role in mating. Found in oceans and seas around the world, humpback whales typically migrate up to 25,000 kilometres each year. Humpbacks feed only in summer, in polar waters, and migrate to tropical or sub-tropical waters to breed and give birth in the winter. During the winter, humpbacks fast and live off their fat reserves. The species' diet consists mostly of krill and small fish. Humpbacks have a diverse repertoire of feeding methods, including the spectacular bubble net feeding technique.

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Did you know?

...that one burrow of the eastern chipmunk (pictured) was found to contain 390 acorns?
.. that the Hare Indian dog, now extinct, was not known to bark, but puppies learned to imitate the barking of other dogs when the breed was introduced to Europe?
... that the rodents Thomasomys ucucha from Ecuador and Oxymycterus hucucha from Bolivia were both named after the local Quechua word for "mouse"?
...that the incisors of blesmols are visible even when their mouths are closed?
... that the pebble-mound mice of northern Australia construct mounds of stones around their burrows up to 10 m² in area?
... that the stationmaster of the Kinokawa train station in Kinokawa, Japan was a cat named Tama?

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Image 1
Cheetah
Photograph credit: Charles James Sharp
The cheetah (Acinonyx jubatus) is a large cat native to Africa and central Iran. Cubs are highly vulnerable to predators during the first few weeks of life, and predation is the leading cause of mortality among cheetah cubs. A study showed that in areas with a low density of predators (such as Namibian farmlands) around 70 per cent of the cubs survived beyond the age of 14 months, whereas in areas like the Serengeti National Park, where several large carnivores exist, the survival rate was just 17 per cent. This cheetah cub was photographed in the Phinda Private Game Reserve in KwaZulu-Natal, South Africa, amid long grass.
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Image 2
Brown Spider Monkey
Photo credit: Tom Friedel
The Brown Spider Monkey is a critically endangered New World monkey native to Colombia and Venezuela. The blue eyes on this individual are uncommon among the species.
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Image 3
Emperor Tamarin
Photo credit: Mila Zinkova
The Emperor Tamarin (Saguinus imperator) is a tamarin native to the Amazon Basin and neighboring parts of South America. It was allegedly named for its similarity to William II, the last German Emperor. The name was first intended as a joke, but has become the official scientific name.
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Image 4
Olive baboon with juvenile
Photograph: Charles J. Sharp
An adult and a juvenile olive baboon (Papio anubis) at Queen Elizabeth National Park, Uganda. The most wide-ranging of all baboons, the olive baboon inhabits savannas, steppes, and forests in 25 countries throughout Africa. This highly adaptable species is omnivorous, feeding on a large variety of plants, invertebrates, small mammals, and birds.
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Image 5
Water Buffalo
Photo credit: Chmouel Boudjnah
The Water Buffalo is a very large ungulate. It survives in the wild in India, Nepal, Bhutan and Thailand; is very widespread as a domestic animal in Asia, South America. North Africa and Europe; and is feral in northern Australia.
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Image 6
Sea otter
Photo credit: Mike Baird
A sea otter (Enhydra lutris) nurses her pup from nipples on her abdomen. Native to the coasts of the northern and eastern North Pacific Ocean, sea otters eat primarily invertebrates such as sea urchins and are among the smallest marine mammals. They are vulnerable to oil spills as their primary form of insulation is thick fur.
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Image 7
Humpback Whale
Photo credit: Georgia Evelyn Stants
Off the coast of Juneau, Alaska, a group of 15 Humpback Whales works in tandem to catch herring using the bubble net feeding technique, in which they exhale through their blowholes, creating a ring of bubbles up to 30 m (100 ft) in diameter. The whales then suddenly swim upwards through the bubble net swallowing thousands of fish in each gulp.
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Image 8
Impala
Photograph: Muhammad Mahdi Karim
A portrait of a male impala, showing its horns. Horns consist of bone cores surrounded by a covering of keratin and other proteins, and are often curved or spiral in shape. Most horned animal species have one pair, though some may have more.
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Image 9
Groundhog
Photograph: Cephas
Groundhogs (Marmota monax) are rodents in the family Sciuridae. They belong to the group of large ground squirrels known as marmots. This lowland creature is widely distributed in North America and common in the northeastern and central United States and Canada. Although considered by farmers to be a nuisance, groundhogs have become part of popular culture through Groundhog Day and the film of the same name.
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Image 10
African bush elephant
Photograph: Muhammad Mahdi Karim
A female African bush elephant (Loxodonta africana) in Mikumi National Park, Tanzania. These herbivorous mammals are the largest land animals on Earth; males average 3.3 metres (11 ft) tall at the shoulders and 5.5 tonnes (12,000 lb) in weight, whereas females average 2.8 metres (9.2 ft) in height and 3.7 tonnes (8,200 lb) in weight. Owing to their great size, adult African bush elephants have no natural predators except for humans. Calves, however, are preyed on by lions and crocodiles.
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Image 11
Tasmanian devil
Photo: JJ Harrison
The Tasmanian devil (Sarcophilus harrisii) is a carnivorous marsupial found in the wild only on the Australian island of Tasmania. It is characterised by its stocky and muscular build, black fur, pungent odour, extremely loud and disturbing screech, keen sense of smell, and ferocity when feeding. Its large head and neck allow it to generate the strongest bite per unit body mass of any living mammal.
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Image 12
Lesser short-nosed fruit bat
Photo: Anton Croos
A newborn lesser short-nosed fruit bat (Cynopterus brachyotis) clinging upon a human finger. A species of megabat within the family Pteropodidae, it is a small bat that lives in South and Southeast Asia. Adults weigh between 21 and 32 grams (0.74 and 1.13 oz).
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Image 13
Boar
Photo credit: Richard Bartz
A wild boar (Sus scrofa), shown here in an animal sanctuary, the wild ancestor of the domestic pig. Boars are native across much of Central Europe, the Mediterranean Region and much of Asia. Wild boars almost always have thick, short bristly coats ranging in colour from brown through grey to black.
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Image 14
Drymoreomys
Photo: Luís Funez
Drymoreomys is a genus of South American rodent represented by a single species, D. albimaculatus. First formally described in 2011, the species prefers dense, moist, montane and premontane forest. Morphological evidence suggests they are tree dwellers.
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Image 15
Tamias rufus
Photo credit: Mdf
The Hopi Chipmunk (Tamias rufus) is a chipmunk found in Colorado, Utah and New Mexico, in the Southwestern United States. Chipmunks are small squirrel-like rodents, native to North America except for one species in northeastern Asia. Though they are commonly depicted with their paws up to the mouth, eating peanuts, or with their cheeks bulging out on either side, chipmunks are actually omnivorous.
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Scientific classification

Kingdom→ Animalia Phylum→ Chordata Subphylum→ Vertebrata Superclass→ Tetrapoda (unranked)→ Amniota Class→ Mammalia

Subclasses and Infraclasses

Subclass †Allotheria*
Subclass Prototheria
Subclass Theria
- Infraclass †Trituberculata
- Infraclass Metatheria
- Infraclass Eutheria

* Member of a haplogroup and not any of its subclades.
† Taxon is extinct.

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