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, 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 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 elk, or wapiti (Cervus canadensis), is the second largest species of deer in the world and one of the largest mammals in North America and eastern Asia. In the deer family (Cervidae), only the moose, Alces alces (called an "elk" in Europe), is larger. Wapiti are almost identical to red deer found in Europe, of which they were long believed to be a subspecies; they have recently been determined to be a distinct species based on DNA evidence. Elk range in forest and forest-edge habitat, feeding on grasses, plants, leaves and bark. Although native to North America and eastern Asia, they have adapted well to countries where they have been introduced, including New Zealand and Argentina. Their high level of adaptability poses a threat to endemic species and ecosystems where they have been introduced. Male elk have large antlers which are shed each year. Males engage in ritualized mating behaviors during the rut, including posturing, antler wrestling and bugling, a loud series of screams which establishes dominance over other males and attracts females. The bugle call is one of the most distinctive calls in nature. Elk are susceptible to a number of infectious diseases, some of which can be transmitted to livestock. Efforts to eliminate infectious diseases from elk populations, largely through vaccination, have had mixed success. Some cultures revere the elk as a spiritual force. In parts of Asia, antlers and their velvet are used in traditional medicines. Elk are hunted as a game species; the meat is leaner and higher in protein than beef or chicken.

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Did you know?

...that a polydactyl cat (pictured) is a cat that has more than the usual number of toes on one or all of its paws?
...that Unsinkable Sam was a ship's cat of both the Kriegsmarine and Royal Navy during the Second World War who survived the sinking of all three ships on which he served?
...that Able Seaman Just Nuisance is the only dog to have been officially enlisted in the Royal Navy?
...that the Moscow Water Dog, developed as a water rescue dog, preferred to bite drowning people instead of saving them?
...from its discovery by John Edward Gray in 1850 until a re-assessment in 1981, the Clymene Dolphin was regarded as sub-species of the Spinner Dolphin.
...the Australian Snubfin Dolphin (Orcaella heinsohni) is a recently recognised species of dolphin first described in 2005.

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Image 1
Koala
Photo: Benjamint444
A female koala (Phascolarctos cinereus) with her joey clinging to her back. At birth the joey is hairless, blind, and earless, and only about 20 mm (0.79 in) long. It remains hidden in the pouch for about six months, feeding only on milk. During this time it will grow ears, eyes, and fur. The joey will remain with its mother for another six months or so, riding on her back, and feeding on both milk and eucalypt leaves until weaning is complete at about 12 months of age.
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Image 2
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 3
Giraffe
Photo: Muhammad Mahdi Karim
A giraffe extending its tongue to feed. Its tongue, lips and palate are tough enough to deal with sharp thorns in trees. Giraffes prefer trees of the genera Acacia, Commiphora and Terminalia. A giraffe requires less food than typical grazing animals, typically consuming 65 pounds (29 kg) of leaves and twigs daily, because the foliage it eats has more concentrated nutrition and it has a more efficient digestive system.
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Image 4
Joey
Photo credit: Geoff Shaw, University of Melbourne, Australia
A newborn joey (baby kangaroo) in its mother's pouch. Kangaroo babies are born at a very early stage of development after a gestation of 31-36 days. At this stage, only the forelimbs are somewhat developed, to allow the newborn to climb to the pouch and attach to a teat. It will not re-emerge for several months, during which time it develops fully.
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Image 5
Mexican Wolf
Photo credit: Jim Clark, USFWS
A captive Mexican Wolf (Canis lupus baileyi) at the Sevilleta National Wildlife Refuge, New Mexico, USA. This critically endangered subspecies of the Gray Wolf once ranged from central Mexico to the Southwestern United States. In 1980, the last five known surviving members were captured to save the species. Now, over 300 wolves are taking part in a wolf reintroduction program, with at least fifty individuals in the wild.
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Image 6
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 7
Ambondro mahabo
Photo: André R. Wyss
The jaw of Ambondro mahabo, seen in lingual view (from the side of the tongue). The scale bar is 1 mm (0.039 in) long. This mammal species is known only from this fragmentary lower jaw with three teeth, interpreted as the last premolar and the first two molars. It is the oldest known mammal with putatively tribosphenic teeth.
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Image 8
Northern palm squirrel
Photograph credit: Charles James Sharp
The northern palm squirrel (Funambulus pennantii) is a species of rodent in the family Sciuridae. It has a wide distribution in the Indian subcontinent and Iran, being a semi-arboreal species found in dry deciduous forest and many other rural and urban habitats. It is a common species with a wide range and the International Union for Conservation of Nature has rated its conservation status as being of least concern. This northern palm squirrel was photographed in Keoladeo National Park in Bharatpur, in the Indian state of Rajasthan.
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Image 9
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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Image 10
Culpeo
Photo: Christian Mehlführer
The culpeo (Lycalopex culpaeus, aka Andean fox/wolf) is the second-largest native canid in South America. It has grey and reddish fur, a white chin, reddish legs, and a stripe on its back that may be barely visible. The mean weight for males is 11.4 kg (25 lb), while females average 8.4 kg (19 lb).
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Image 11
Yellow-bellied Marmot
Photo credit: Inklein
A Yellow-bellied Marmot seen on top of Mount Dana, Yosemite National Park, USA. The road in the background is Tioga Pass Road. Yellow-bellied Marmots are ground squirrels that live in the western United States and southwestern Canada. They inhabit steppes, meadows, talus fields and other open habitats, sometimes on the edge of deciduous or coniferous forests, and typically above 2,000 metres (6,562 ft) of elevation.
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Image 12
Female proboscis monkey on Borneo
Photograph: Charles J. Sharp
A female proboscis monkey (Nasalis larvatus) at Labuk Bay, Sabah, Malaysia. This monkey is endemic to Borneo. Though the female has a large nose, it is smaller than that of the male.
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Image 13
Eastern gray squirrel
Photograph credit: Tom Friedel
The eastern gray squirrel (Sciurus carolinensis) is a tree squirrel in the genus Sciurus, native to the eastern and midwestern United States, as well as to the southerly portions of the eastern provinces of Canada. A prolific and adaptable species, it has been introduced to and thrives in several regions of the western United States; it is also an invasive species in Britain, where it has spread across the country and largely displaced the native Eurasian red squirrel. The head and body can measure from 23 to 30 cm (9.1 to 11.8 in) and the tail from 19 to 25 cm (7.5 to 9.8 in) in length; its adult weight is between 400 and 600 g (14 and 21 oz). Like many members of the family Sciuridae, the eastern gray squirrel is a scatter-hoarder; it hoards food in numerous small caches for later recovery. In the United Kingdom and Canada, the species is simply referred to as the "grey squirrel".

This picture, taken in 2010, shows an eastern gray squirrel in Florida.
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Image 14
Leopard seal
Photograph: Godot13
The leopard seal (Hydrurga leptonyx), also known as the sea leopard, is the second largest species of seal in the Antarctic, after the southern elephant seal. Its only natural predators are the killer whale and possibly the elephant seal. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, birds and fish. Together with the Ross seal, the crabeater seal and the Weddell seal, it is part of the tribe of lobodontini seals.

This image shows a yawning leopard seal in the Antarctic Sound in 2016. See also the same seal in profile.
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Image 15
Lion
Photo credit: yaaaay
A male lion (Panthera leo) lying down in Namibia. One of the four "big cats" in the genus Panthera, the lion is the second largest cat, after the tiger. Males weigh between 150-250 kg (330-550 lb), and are easily recognizable by their manes. Though they were once found throughout much of Africa, Asia and Europe, lions presently exist in the wild only in Africa and India.
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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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