Portal:Mammals

The Mammals portal

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 sea otter (Enhydra lutris) is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg (30 to 100 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom. Although it can walk on land, the sea otter is capable of living exclusively in the ocean. The sea otter inhabits nearshore environments where it can quickly dive to the sea floor to forage. It preys mostly upon marine invertebrates such as sea urchins, various mollusks and crustaceans, and some species of fish. Its foraging and eating habits are noteworthy in several respects. First, its use of rocks to dislodge prey and to open shells makes it one of the few mammal species to use tools. In most of its range, it is a keystone species, controlling sea urchin populations which would otherwise inflict extensive damage to kelp forest ecosystems. Finally, its diet includes prey species that are also valued by humans as food, leading to conflicts between sea otters and fisheries.

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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
Snow leopard
Photograph: Tambako The Jaguar
A portrait of a snow leopard (Panthera uncia) at the Rheintal Zoo in Germany. This species of big cat in the genus Panthera is native to the mountain ranges of Central and South Asia. The snow leopard's adaptations for life in a cold, mountainous environment include a stocky body, thick fur, small rounded ears to minimize heat loss, and a short muzzle with unusually large nasal cavities that help the animal breathe the cold, thin air.
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Image 2
Elephant portrait
Photograph: Muhammad Mahdi Karim
A portrait of an African elephant, highlighting its trunk. The trunk, which contains some 150,000 muscle fascicles, is a fusion of the nose and upper lip with a unique nerve running along both sides. An elephant can use its trunk for power functions, such as lifting up to 350 kg (770 lb), or more delicate functions, such as wiping its eye.
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Image 3
Donkey
Photograph: Lilly M
A 3-week-old donkey (Equus africanus asinus), in Kadzidłowo, Poland. A female donkey is normally pregnant for about 12 months, and usually gives birth to a single foal; twins are rare.
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Image 4
Tasmanian Pademelon
Photo: JJ Harrison
The Tasmanian Pademelon is the only species of pademelon endemic to Tasmania. Pademelons are the smallest of the macropods, which also includes kangaroos and wallabies. Males reach around 12 kg (26 lb) in weight, 1–1.2 m (3.3–3.9 ft) in height, and are considerably larger than the females, which average 3.9 kg (8.6 lb).
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Image 5
Koala
Photo: JJ Harrison
A female koala (Phascolarctos cinereus), an arboreal herbivorous marsupial native to coastal regions of eastern and southern Australia. The word "koala" comes from the Dharuk word gula. English-speaking settlers from the late 18th century first called it "koala bear" due to its similarity in appearance to bears, although they are not at all related. Instead, its closest living relative is the wombat.
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Image 6
Red squirrel
Photograph: Peter Trimming
The red squirrel (Sciurus vulgaris) is a species of tree squirrel in the genus Sciurus common throughout Eurasia. This arboreal, omnivorous rodent feeds on seeds, nuts, berries, young shoots, and sap.
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Image 7
Bennett's Wallaby
Photo: JJ Harrison
A juvenile Bennett's Wallaby (Macropus rufogriseus rufogriseus), a subspecies of the Red-necked Wallaby, on Maria Island, east of Tasmania. Red-necked Wallabies can be found in the more temperate and fertile parts of eastern Australia. They can weigh 13.8 to 18.6 kg (30 to 41 lb) and attain a head–body length of 90 cm (35 in), with the island version slightly smaller.
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Image 8
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 9
African elephant
Photo: Ikiwaner
The term African elephant refers to elephants of the genus Loxodonta. Shown here is the African bush elephant (Loxodonta africana), one of two extant species and the largest living terrestrial animal, with males standing 3.2–4.0 m (10.5–13.1 ft) tall at the shoulder and weighing 4,700–6,048 kg (10,362–13,334 lb).
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Image 10
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 11
Jaguar
Photo credit: Pascal Blachier
The jaguar (Panthera onca), shown here at Edinburgh Zoo, is a New World mammal of the Felidae family and one of four "big cats". The jaguar is the third-largest feline after the tiger and the lion, and on average the largest and most powerful feline in the Western Hemisphere.
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Image 12
Cheetah
Photo: Muhammad Mahdi Karim
A close-up view of a cheetah (Acinonyx jubatus) cub. Unlike some other cats, the cheetah is born with its characteristic spots, as well as a downy underlying fur on their necks extending to mid-back, which gives the cub the appearance of the honey badger, to scare away potential aggressors. Despite this, up to 90% of cheetah cubs are killed by predators in the early weeks of life. Healthy adult cheetahs have few predators because of their speed.
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Image 13
Eastern chipmunk
Photo: Simon Pierre Barrette
The eastern chipmunk (Tamias striatus) is a chipmunk species native to eastern North America. Like other chipmunks, they transport food in pouches in their cheeks, as seen here. They eat bulbs, seeds, fruits, nuts, green plants, mushrooms, insects, worms, and bird eggs.
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Image 14
Babirusa skull
Photograph: Didier Descouens
Skull of a male North Sulawesi babirusa, a species from the pig family endemic to Indonesia. Babirusas are notable for the long upper canines in the males that emerge vertically from the alveolar process, penetrating though the skin and curving backward over the front of the face and towards the forehead.
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Image 15
Eastern Gray Squirrel
Photo credit: Diliff
An Eastern Gray Squirrel (Sciurus carolinensis) eating a nut in St. James's Park, London. Although native to eastern North America, the species has been introduced into a variety of locations. In England, gray squirrels have mostly replaced native Red Squirrels and have no natural predators, which has added to their rapid population growth and has led to the species being classed as a pest.
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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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