<h1 id="kangaroos">Kangaroos</h1>
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<a href="#Terminology">Terminology</a>,
<a href="#Taxonomy and description">Taxonomy and Description</a>,
<a href="#Comparison with wallabies">Comparison with Wallabies</a>,
<a href="#locomotion">Locomotion</a>,
<a href="#diet">Diet</a>
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<p>The <strong>kangaroo</strong> is a marsupial from the family Macropodidae (macropods, meaning 'large foot'). In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, red kangaroo, antilopine kangaroo, eastern grey kangaroo and western grey kangaroo. Kangaroos are endemic to Australia, and one genus, the tree-kangaroo, is also found in Papua New Guinea.</p>
<p>Kangaroos have large, powerful hind legs, large feet adapted for leaping, a long muscular tail for balance, and a small head. Like most marsupials, female kangaroos have a pouch called a marsupium in which joeys complete postnatal development.</p>
<p>Larger kangaroos have adapted much better than smaller macropods to land clearing for pastoral agriculture and habitat changes brought to the Australian landscape by humans. Many of the smaller species are rare and endangered, whilst the larger kangaroos are relatively plentiful.</p>
<h3 id="Terminology">Terminology</h3>
<p>
The word kangaroo derives from the Guugu Yimithirr word gangurru, referring to eastern grey kangaroos. The name was first recorded as "kanguru" on 12 July 1770 in an entry in the diary of Sir Joseph Banks; this occurred at the site of modern Cooktown, on the banks of the Endeavour River, where HMS Endeavour under the command of Lieutenant James Cook was beached for almost seven weeks to repair damage sustained on the Great Barrier Reef. Cook first referred to kangaroos in his diary entry of 4 August. Guugu Yimithirr is the language of the people of the area.
A common myth about the kangaroo's English name is that it was a Guugu Yimithirr phrase for "I don't know" or "I don't understand". According to this legend, Cook and Banks were exploring the area when they happened upon the animal. They asked a nearby local what the creatures were called. The local responded "kangaroo", said to mean "I don't know/understand", which Cook then took to be the name of the creature. Anthropologist Walter Roth was trying to correct this legend as far back as in 1898, but few took note until 1972 when linguist John B. Haviland in his research with the Guugu Yimithirr people was able to fully confirm the proper etymology. There are similar, more credible stories of naming confusion, such as with the Yucatán Peninsula.
Kangaroos are often colloquially referred to as "roos". Male kangaroos are called bucks, boomers, jacks, or old men; females are does, flyers, or jills; and the young ones are joeys. The collective noun for a group of kangaroos is a mob, court, or troupe.
<h3 id="Taxonomy and description">Taxonomy and Description</h3>
<p>
There are four extant species that are commonly referred to as kangaroos:</p>
<ul>
<li>The red kangaroo (Osphranter rufus) is the largest surviving marsupial anywhere in the world. It occupies the arid and semi-arid centre of the country. The highest population densities of the red kangaroo occur in the rangelands of western New South Wales. Red kangaroos are commonly mistaken as the most abundant species of kangaroo, but eastern greys actually have a larger population. A large male can be 2 metres (6 ft 7 in) tall and weighs 90 kg (200 lb).</li>
<li>The eastern grey kangaroo (Macropus giganteus) is less well-known than the red (outside Australia), but the most often seen, as its range covers the fertile eastern part of the country. The range of the eastern grey kangaroo extends from the top of the Cape York Peninsula in northern Queensland down to Victoria, as well as areas of southeastern Australia and Tasmania. Population densities of eastern grey kangaroos usually peak near 100 per km2 in suitable habitats of open woodlands. Populations are more limited in areas of land clearance, such as farmland, where forest and woodland habitats are limited in size or abundance.</li>
<li>The western grey kangaroo (Macropus fuliginosus) is slightly smaller again at about 54 kg (119 lb) for a large male. It is found in the southern part of Western Australia, South Australia near the coast, and the Darling River basin. The highest population densities occur in the western Riverina district of New South Wales and in the western areas of the Nullarbor Plain in Western Australia. Populations may have declined, particularly in agricultural areas. The species has a high tolerance to the plant toxin sodium fluoroacetate, which indicates a possible origin from the southwest region of Australia.</li>
<li>The antilopine kangaroo (Osphranter antilopinus) is, essentially, the far northern equivalent of the eastern and western grey kangaroos. It is sometimes referred to as the antilopine wallaroo, but in behaviour and habitat it is more similar to red and grey kangaroos. Like them, it is a creature of the grassy plains and woodlands, and gregarious. Its name comes from its fur, which is similar in colour and texture to that of antelopes. Characteristically, the noses of males swell behind the nostrils. This enlarges nasal passages and allows them to release more heat in hot and humid climates.</li>
</ul>
<p>
In addition, there are about 50 smaller macropods closely related to the kangaroo in the family Macropodidae. Kangaroos and other macropods share a common ancestor with Phalangeridae from the Middle Miocene.[22] This ancestor was likely arboreal and lived in the canopies of the extensive forests that covered most of Australia at that time, when the climate was much wetter, and fed on leaves and stems.[23] From the Late Miocene through the Pliocene and into the Pleistocene the climate got drier, which led to a decline of forests and expansion of grasslands. At this time there was a radiation of macropodids characterised by enlarged body size and adaptation to the low quality grass diet with the development of foregut fermentation.[23] The most numerous early macropods, the Balbaridae and the Bulungmayinae, became extinct in the Late Miocene around 5–10 mya.[24] There is dispute over the relationships of the two groups to modern kangaroos and rat-kangaroos. Some argue that the balbarines were the ancestors of rat-kangaroos and the bulungmayines were the ancestors of kangaroos.[25] while others hold the contrary view.[26]
The Kongouro from New Holland, 1772 painting of a kangaroo by George Stubbs The middle to late bulungmayines, Ganguroo and Wanburoo lacked digit 1 of the hind foot and digits 2 and 3 were reduced and partly under the large digit 4, much like the modern kangaroo foot. This would indicate that they were bipedal. In addition, their ankle bones had an articulation that would have prohibited much lateral movements, an adaptation for bipedal hopping. Species related to the modern grey kangaroos and wallaroos begin to appear in the Pliocene. The red kangaroo appears to be the most recently evolved kangaroo, with its fossil record not going back beyond the Pleistocene era, 1–2 mya.
The first kangaroo to be exhibited in the Western world was an example shot by John Gore, an officer on Captain Cook's ship, the HMS Endeavour, in 1770. The animal was shot and its skin and skull transported back to England whereupon it was stuffed (by taxidermists who had never seen the animal before) and displayed to the general public as a curiosity. The first glimpse of a kangaroo for many 18th-century Britons was a painting by George Stubbs.
</p>
<h4 id="Comparison with wallabies">Comparison with Wallabies</h4>
<p>
Kangaroos and wallabies belong to the same taxonomic family (Macropodidae) and often the same genera, but kangaroos are specifically categorised into the six largest species of the family. The term wallaby is an informal designation generally used for any macropod that is smaller than a kangaroo or wallaroo that has not been designated otherwise.
</p>
<h3 id="locomotion">Locomotion</h3>
<p>
Kangaroos are the only large animals to use hopping as a means of locomotion. The comfortable hopping speed for a red kangaroo is about 20–25 km/h (13–16 mph), but speeds of up to 70 km/h (44 mph) can be attained over short distances, while it can sustain a speed of 40 km/h (25 mph) for nearly 2 km (1.2 mi). This fast and energy-efficient method of travel has evolved because of the need to regularly cover large distances in search of food and water, rather than the need to escape predators. At slow speeds, it employs pentapedal locomotion, using its tail to form a tripod with its two forelimbs while bringing its hind feet forward. Kangaroos are adept swimmers, and often flee into waterways if threatened by a predator. If pursued into the water, a kangaroo may use its forepaws to hold the predator underwater so as to drown it.
<h3 id="diet">Diet</h3>
<p>Kangaroos have chambered stomachs similar to those of cattle and sheep. They regurgitate the vegetation they have eaten, chew it as cud, and then swallow it again for final digestion. Different species of kangaroos have different diets, although all are strict herbivores. The eastern grey kangaroo is predominantly a grazer, eating a wide variety of grasses, whereas some other species (e.g. the red kangaroo) include significant amounts of shrubs in their diets. The smaller species of kangaroos also consume hypogeal fungi. Many species are nocturnal, and crepuscular, usually spending the days resting in shade, and the cool evenings, nights and mornings moving about and feeding.</p>
<p>Because of its grazing habits, the kangaroo has developed specialized teeth. Its incisors are able to crop grass close to the ground, and its molars chop and grind the grass. Since the two sides of the lower jaw are not joined together, the lower incisors are farther apart, giving the kangaroo a wider bite. The silica in grass is abrasive, so kangaroo molars move forward as they are ground down, and eventually fall out, replaced by new teeth that grow in the back. This process is known as polyphyodonty and amongst other mammals, only occurs in elephants and manatees.</p>
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