Portal:Mammals

The Mammals portal

A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia (/məˈmeɪli.ə/). Mammals are characterized 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 vocalize in several ways, including the production of ultrasound, scent marking, alarm signals, singing, echolocation; and, in the case of humans, complex language. Mammals can organize 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 civilizations. 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. The 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 Island Fox (Urocyon littoralis) is a small fox that is native to six of the eight Channel Islands (California). It is the smallest fox species in the United States. There are six subspecies of the fox, each unique to the island it inhabits, reflecting its evolutionary history. Other names for the Island Fox include Coast Fox, Short-Tailed Fox, Island Gray Fox, Channel Islands Fox, Channel Islands Gray Fox, California Channel Island Fox and Insular Gray Fox. The Island Fox shares the Urocyon genus with the mainland Gray Fox, the fox from which it is descended. Its small size is a result of island dwarfing, a kind of allopatric speciation. Because Island Foxes are geographically isolated they have no immunity to parasites and diseases brought in from the mainland and are especially vulnerable to those domestic dogs may carry. In addition, Golden Eagle predation and human activities devastated fox numbers on several of the Channel Islands in the 1990s. Four Island Fox subspecies were federally protected as an endangered species in 2004, and efforts to rebuild fox populations and restore the ecosystems of the Channel Islands are being undertaken.

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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
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 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
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 4
Yak
Photograph: travelwayoflife
A yak at Letdar on the Annapurna Circuit in the Annapurna mountain range of central Nepal. Mostly domesticated, these long-haired bovids are found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia.
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Image 5
Common Brushtail Possum
Photo: JJ Harrison
The Common Brushtail Possum (Trichosurus vulpecula) is the largest possum species and is perhaps the most widespread mammal in Australia. It grows to about 32–58 cm (13–23 in) in length, with an additional 24–40 cm (9–16 in) for its prehensile tail (seen here hanging below the branch). It is mainly a folivore, but has been known to eat small mammals such as rats. It is common in cities, having adapted well to human habitation.
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Image 6
Meerkat
Photo: Fir0002
The meerkat (Suricata suricatta) is a small member of the mongoose family native to the Kalahari Desert of southern Africa. They are social animals, living underground in groups of 20 to 50 members. Although the name means "lake cat" in Dutch, meerkats are not cats, nor are they attracted to lakes.
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Image 7
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 8
Common wombat
Photo: JJ Harrison
The common wombat (Vombatus ursinus) is one of three species of wombat. It is native to south-eastern mainland Australia and Tasmania, and grows to an average of 98 cm (39 in) long and a weight of 26 kg (57 lb). It is solitary and lives in an underground burrow.
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Image 9
Yellow-bellied marmot
Photograph: David Iliff
The yellow-bellied marmot (Marmota flaviventris) is a ground squirrel in the marmot genus. Found in the western United States and southwestern Canada, including the Rocky Mountains and the Sierra Nevada, these marmots live in colonies of about ten to twenty individuals, typically located in open areas at least 6,500 feet (2,000 m) above sea level.
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Image 10
Yak
Photograph: Dennis Jarvis
A domesticated yak at Yamdrok Lake in Tibet. The animals are important to Tibetan culture, and have been kept for thousands of years. The yaks are a method of transportation and serve as beasts of burden. Their feces are a source of fuel, and their milk can be used for butter, which is then made into sculptures or consumed.
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Image 11
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 12
Javan slow loris
Photograph credit: Aprisonsan
The Javan slow loris (Nycticebus javanicus) is a species of primate native to western and central portions of the Indonesian island of Java. It is arboreal, feeding on fruit, gum, eggs, lizards, and the seeds of the cocoa tree. Weighing up to 680 g (24 oz), this small nocturnal mammal sleeps in the open on branches during the day and is easily poached for the exotic-pet trade. Populations are declining, and the animal is listed by the International Union for Conservation of Nature as a critically endangered species and included in a list of the world's 25 most endangered primates.
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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
Lioness
Photo credit: Cody Pope
A lioness in Ishasha Southern sector of Queen Elizabeth National Park, Uganda. Ishasha lions are famed for tree climbing, a trait only shared with lions in the Lake Manyara region. They often spend the hottest parts of the day in the large fig trees found throughout the area. It is still unclear why so few lions exhibit this behavior.
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Image 15
Prairie dog
Photo credit: Aaron Siirila
A black-tailed prairie dog at the National Zoo in Washington, D.C., looks out from a system of burrows, characteristically scanning the horizon. On average, these rodents grow to between 12 and 16 inches (30 and 40 cm) long, including their short tails.
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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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