Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a 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 6,400 extant species of mammals have been described and divided into 29 orders.
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 Middle Permian. 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 quadruped, and most mammals use their four extremities for terrestrial locomotion; but in some, the extremities are adapted for life at sea, in the air, in trees, underground, or on two legs. Mammals range in size from the 30–40 mm (1.2–1.6 in) bumblebee bat to the 30 m (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 are egg-laying mammals. The most species-rich group of mammals, the infraclass called placentals, have a placenta, which enables the feeding of the fetus 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. Decline in numbers and extinction of many mammals is primarily driven by human poaching and habitat destruction, primarily deforestation. (Full article...)
The Sumatran Rhinoceros (Dicerorhinus sumatrensis) is a species of the family Rhinocerotidae, and one of five extant rhinoceri. It is the smallest rhinoceros, standing about 120–145 centimetres (3.9–4.8 ft) high at the shoulder, with a body length of 250 centimetres (98 in) and weight of 500–800 kilograms (1100–1760 lb). Like its African counterparts, the black and white rhinoceri, it has two horns; the larger is the nasal horn, typically 15–25 centimetres (6–10 in), while the other is typically a stub. A coat of reddish-brown hair covers most of the rhino's body. Members of the species once ranged throughout rainforests, swamps and cloud forests in India, Bhutan, Bangladesh, Myanmar, Laos, Thailand, Malaysia, and Indonesia. They are now critically endangered, with only six substantial populations in the wild: four on Sumatra, one on Borneo, and one on peninsular Malaysia. Their numbers are difficult to determine because they are solitary animals that are widely scattered across their range, but they are estimated to number around just 300. The decline in the number of Sumatran rhinoceri is attributed primarily to poaching for their ivory horns, which are highly valued in traditional Chinese medicine, fetching as much as US$30,000 per kilogram on the black market. The rhinos have also suffered from habitat loss as their forests have been cleared for lumber and conversion to agriculture.
...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?
The European bison or wisent (Bison bonasus) is the heaviest of the surviving land animals in Europe, with males growing to around 1,000 kg (2,200 lb). European bison were hunted to extinction in the wild, but have since been reintroduced from captivity into several countries. This male is moulting, his winter coat coming off in clumps.
The Tasmanian devil (Sarcophilus harrisii) is a carnivorousmarsupial 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.
The olive baboon (Papio anubis) is an Old World monkey found in 25 countries throughout Africa, making it the most widely ranging of all baboons. It is named for its coat, which, at a distance, is a shade of green-grey. At closer range, its coat is multi-colored, due to rings of yellow-brown and black on the hairs. It is omnivorous, finding nutrition in almost any environment, and able to adapt with different foraging tactics.
A portrait of a Plains Zebra (Equus quagga), the most common and widespread species of zebra. The unique stripes and behaviors of zebras make these among the animals most familiar to people. They can be found in a variety of habitats throughout Sub-Saharan Africa. The name "zebra" comes from the Old Portuguese word zevra which means "wild ass". Zebra stripes are typically vertical on the head, neck, forequarters, and main body, with horizontal stripes at the rear and on the legs of the animal. It was previously believed that zebras were white animals with black stripes. Embryological evidence, however, shows that the animal's background color is black and the white stripes are additions.
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.
The steenbok (Raphicerus campestris) is a species of small antelope, generally standing 45–60 centimeters (16–24 inches) at the shoulder, commonly found in Africa. They live in a variety of habitats, from semi-desert to open woodland and thickets, and feed on low-level vegetation and roots. These common animals are typically solitary, except during mating season.
A dromedary or one-humped camel (Camelus dromedarius) in the Australian Outback. Estimated populations of Australian feral camels are in the hundreds of thousands, and this is now the world's only population of dromedaries exhibiting wild behaviour. Thousands of camels were imported into Australia between 1840 and 1907 to open up the arid areas of central and western Australia. They were used for riding, and as draught and pack animals for exploration and construction of rail and telegraph lines; they were also used to supply goods to remote mines and settlements. Their impact on the environment is not as bad as that of other introduced pests in Australia. They prefer to eat trees and plants that local wildlife dislike; only 2% of their diet is grass.
The leopard (Panthera pardus) is one of five extant species in the genus Panthera, a member of the cat family, Felidae. This photograph shows a leopard devouring an impala in Kruger National Park, South Africa. Compared to other wild cats, the leopard has a relatively large skull with powerful jaws, a long body and short legs. It can climb trees very skilfully, often rests on tree branches and can descend to the ground head first. An adult leopard is strong enough to drag a carcass heavier than itself up into a tree, where the prey may be eaten straight away or cached to be consumed later.
Close-up of a juvenile Southern Elephant Seal (Mirounga leonina), showing face and mouth detail. This species of elephant seal is not only the most massive pinniped, but also the largest member of the order Carnivora living today. It is found throughout the subantarctic region.
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).
Two pot-bellied pigs sleeping. This breed of domestic pig belongs to the same species as the Wild Boar and the common farm pig (Sus domestica), and originated in Vietnam. Most adult pot-bellied pigs are about the size of a medium- or large-breed dog, though their bodies are denser at a weight of 60 to 300 pounds (27 to 136 kg).
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.
The Golden-mantled Ground Squirrel (Spermophilus lateralis) is a species of squirrel native throughout North America and can be found in a wide variety of forest habitats as well as rocky meadows, and even sagebrush flats. It can be identified by its chipmunk-like stripes and coloration, but unlike chipmunks, it lacks any facial stripes.
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