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 Guinea pig (also commonly called the cavy after its scientific name) is a species of rodent belonging to the family Caviidae and the genus Cavia. Despite their common name, these animals are not pigs, nor do they come from Guinea. They are native to the Andes, and while no longer extant in the wild, they are closely related to several species that are commonly found in the grassy plains and plateaus of the region. The guinea pig plays an important role in the folk culture of many indigenous South American groups, especially as a food source, but also in folk medicine and in community religious ceremonies. Since the 1960s, efforts have been made to increase consumption of the animal outside South America. In Western societies, the guinea pig has enjoyed widespread popularity as a household pet since its introduction by European traders in the 16th century. Their docile nature, their responsiveness to handling and feeding, and the relative ease of caring for them, continue to make the guinea pig a popular pet. Organizations devoted to competitive breeding of guinea pigs have been formed worldwide, and many specialized breeds of guinea pig, with varying coat colors and compositions, are cultivated by breeders.

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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
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 2
Japanese Squirrel
Photo credit: Ma2bara
The Japanese Squirrel (Sciurus lis) is a species of rodent in the Sciuridae family. It is endemic to Japan.
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Image 3
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 4
Cape ground squirrel
Photograph credit: Hans Hillewaert
The Cape ground squirrel (Xerus inauris) is a medium-sized rodent native to South Africa, Namibia and Botswana. They live in social groups of up to three adult females and several sub-adults. The species mainly inhabits arid or semi-arid areas, preferring velds and grasslands with compact soil, and can also be found in scrub, on floodplains and in agricultural areas. Males live independently, only joining groups when there is a female in estrus. Ever alert to danger, they can drive off predators such as snakes by engaging in mobbing behavior.

This picture shows two Cape ground squirrels photographed in the Namib desert near Solitaire, Namibia.
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Image 5
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 6
Indian elephant
Photograph: Yathin S Krishnappa
A male Indian elephant (Elephas maximus indicus) in Bandipur National Park, Karnataka. First described by Georges Cuvier in 1798, this subspecies of Asian elephant is considered endangered owing to large population declines since the mid-20th century.
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Image 7
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 8
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 9
Kob
Photograph: Charles J Sharp
The kob (Kobus kob) is an antelope found across Central Africa and parts of West Africa and East Africa. It is closely related to the reedbucks and waterbucks and similar in appearance to the impala but more heavily built. Kob have few strong social bonds, but females can live in herds numbering in the thousands. Males are generally territorial, although on densely-populated floodplains some males live in clustered territories known as leks.

This picture shows a female and calf of the Ugandan kob (K. kob thomasi) in the Semliki Wildlife Reserve, Uganda. This subspecies appears on the coat of arms of Uganda.
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Image 10
Topi
Photograph: Charles J. Sharp
Female topi (Damaliscus lunatus jimela) in the Queen Elizabeth National Park in Uganda. A subspecies of the common tsessebe antelope, the topi is native to several countries in eastern Africa and lives primarily in grassland habitats, ranging from treeless plains to savannas. It is a tall species, with individuals ranging in height from 100 to 130 cm (39 to 51 in) at the shoulder. Predators of topi include lions and spotted hyenas, with jackals being predators of newborns.
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Image 11
Pantanal jaguar
Photograph: Charles J. Sharp
A wild male jaguar (Panthera onca) near the Rio Negro in the Pantanal, Brazil. Jaguars from the Pantanal are the largest of their species, about 2.7 m (8.9 ft) long, with an average weight of about 100 kg (220 lb), and some weighing more than 135 kg (298 lb). A red jaguar was a mascot of the 1968 Summer Olympics in Mexico City, and during the 2016 Summer Olympics, a jaguar in the national colors of green and yellow was the Brazil team's mascot.
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Image 12
Eastern Barred Bandicoot
Photo: JJ Harrison
The Eastern Barred Bandicoot (Perameles gunni) is a small, rabbit-sized marsupial native to Australia and Tasmania. It weighs less than 1 kg (2.2 lb) and has a short tail and three to four whitish bars across the rump. It is classified as Near Threatened, with one subspecies listed as Critically Endangered.
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Image 13
Brown-throated sloth
Photo: Christian Mehlführer
The brown-throated sloth (Bradypus variegatus) is the most common species of three-toed sloth. It is found in the forests of South and Central America. Males and females are both about 42–80 cm (17–31 in) in total body length and weigh 2.25–6.3 kg (5–14 lb).
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Image 14
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 15
Indian palm squirrel
Photograph: Muhammad Mahdi Karim
An Indian palm squirrel (Funambulus palmarum) photographed in Bangalore, India. In India these squirrels are associated with the Hindu deity Rama, an avatar of Vishnu, and as such are not to be harmed. However, in Western Australia they are considered pests and at times targeted for eradication.
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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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