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Bipedalism
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' and ''pes'' 'foot'). Types of bipedal movement include walking, running, and hopping. Several groups of modern species are habitual bipeds whose normal method of locomotion is two-legged. In the Triassic period some groups of archosaurs (a group that includes crocodiles and dinosaurs) developed bipedalism; among the dinosaurs, all the early forms and many later groups were habitual or exclusive bipeds; the birds are members of a clade of exclusively bipedal dinosaurs, the theropods. Within mammals, habitual bipedalism has evolved multiple times, with the macropods, kangaroo rats and mice, springhare, hopping mice, pangolins and hominin apes (australopithecines, including humans) as well as various other extinct groups evolving t ...
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Mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant species of mammals have been described divided into 29 orders. The largest orders, in terms of number of species, are the rodents, bats, and Eulipotyphla ( hedgehogs, moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora ( cats, dogs, seals, and others). In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida (synapsids); this clade, toget ...
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Quadrupedalism
Quadrupedalism is a form of locomotion where four limbs are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four limbs is said to be a quadruped (from Latin ''quattuor'' for "four", and ''pes'', ''pedis'' for "foot"). Quadruped animals are found among both vertebrates and invertebrates. Quadrupeds vs. tetrapods Although the words ‘quadruped’ and ‘tetrapod’ are both derived from terms meaning ‘four-footed’, they have distinct meanings. A tetrapod is any member of the taxonomic unit Tetrapoda (which is defined by descent from a specific four-limbed ancestor), whereas a quadruped actually uses four limbs for locomotion. Not all tetrapods are quadrupeds and not all entities that could be described as ‘quadrupedal’ are tetrapods. This last meaning includes certain artificial objects; almost all quadruped ''organisms'' are tetrapods (with the exception of some raptorial arthropods adapted ...
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Walking
Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an ' inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the usable number of limbs—even arthropods, with six, eight, or more limbs, walk. Difference from running The word ''walk'' is descended from the Old English ''wealcan'' "to roll". In humans and other bipeds, walking is generally distinguished from running in that only one foot at a time leaves contact with the ground and there is a period of double-support. In contrast, running begins when both feet are off the ground with each step. This distinction has the status of a formal requirement in competitive walking events. For quadrupedal species, there are numerous gaits which may be termed walking or running, and distinctions based upon the presence or absenc ...
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Homo (genus)
''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely related to modern humans (depending on the species), most notably '' Homo erectus'' and '' Homo neanderthalensis''. The genus emerged with the appearance of '' Homo habilis'' just over 2 million years ago. ''Homo'', together with the genus '' Paranthropus'', is probably sister to '' Australopithecus africanus'', which itself had previously split from the lineage of '' Pan'', the chimpanzees. '' Homo erectus'' appeared about 2 million years ago and, in several early migrations, spread throughout Africa (where it is dubbed '' Homo ergaster'') and Eurasia. It was likely that the first human species lived in a hunter-gatherer society and was able to control fire. An adaptive and successful species, ''Homo erectus'' persisted for more than a mi ...
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Pangolin
Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: '' Manis'', ''Phataginus'', and '' Smutsia''. ''Manis'' comprises the four species found in Asia, while ''Phataginus'' and ''Smutsia'' include two species each, all found in sub-Saharan Africa. These species range in size from . A number of extinct pangolin species are also known. Pangolins have large, protective keratin scales, similar in material to fingernails and toenails, covering their skin; they are the only known mammals with this feature. They live in hollow trees or burrows, depending on the species. Pangolins are nocturnal, and their diet consists of mainly ants and termites, which they capture using their long tongues. They tend to be solitary animals, meeting only to mate and produce a litter of one to three offspring, which they raise for about two years. Pangoli ...
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Macropodidae
Macropodidae is a family of marsupials that includes kangaroos, wallabies, tree-kangaroos, wallaroos, pademelons, quokkas, and several other groups. These genera are allied to the suborder Macropodiformes, containing other macropods, and are native to the Australian continent (the mainland and Tasmania), New Guinea and nearby islands. Description Although omnivorous kangaroos lived in the past, modern macropods are herbivorous. Some are browsers, but most are grazers and are equipped with appropriately specialised teeth for cropping and grinding up fibrous plants, in particular grasses and sedges. In general, macropods have a broad, straight row of cutting teeth at the front of the mouth, no canine teeth, and a gap before the molars. The molars are large and, unusually, do not appear all at once but a pair at a time at the back of the mouth as the animal ages, eventually becoming worn down by the tough, abrasive grasses and falling out. Like many Macropodiformes, early ...
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Monitor Lizard
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recognized. Monitor lizards have long necks, powerful tails and claws, and well-developed limbs. The adult length of extant species ranges from in some species, to over in the case of the Komodo dragon, though the extinct varanid known as megalania (''Varanus priscus'') may have been capable of reaching lengths more than . Most monitor species are terrestrial, but arboreal and semiaquatic monitors are also known. While most monitor lizards are carnivorous, eating eggs, smaller reptiles, fish, birds, insects, and small mammals, some also eat fruit and vegetation, depending on where they live. Distribution The various species cover a vast area, occurring through Africa, the Indian subcontinent, to China, the Ryukyu Islands in southern J ...
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Giant Pangolin
The giant pangolin (''Smutsia gigantea'') is the largest species in the family of pangolins. Members of the species inhabit Africa with a range stretching along the equator from West Africa to Uganda. It subsists almost entirely on ants and termites. The species was first described by Johann Karl Wilhelm Illiger in 1815. Description The giant pangolin is the largest of all pangolin species. While its average mass has not been measured, one specimen was found to weigh 33 kg (72.6 lb). Males are larger than females, with male body lengths about 140 cm (4.6 ft) and females about 125 cm (4.1 ft). Like all pangolins, the species is armored with large, brown to reddish-brown scales formed from keratin. Curiously, it also has eyelashes. The giant pangolin has a long snout, a long, thick tail, and large front claws. The animal has a strong sense of olfaction, smell and large anal glands. Its secretions may be significant to animal communication. The spe ...
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Indriidae
The Indriidae (sometimes incorrectly spelled Indridae) are a family of strepsirrhine primates. They are medium- to large-sized lemurs, with only four teeth in the toothcomb instead of the usual six. Indriids, like all lemurs, live exclusively on the island of Madagascar. Classification The 19 living species in the family are divided into three genera. Family Indriidae *Genus ''Indri'' **Indri, ''Indri indri'' *Genus '' Avahi'', woolly lemurs ** Bemaraha woolly lemur, ''Avahi cleesei'' **Eastern woolly lemur, ''Avahi laniger'' ** Moore's woolly lemur, ''Avahi mooreorum'' ** Western woolly lemur, ''Avahi occidentalis'' ** Sambirano woolly lemur, ''Avahi unicolor'' ** Peyrieras's woolly lemur, ''Avahi peyrierasi'' **Southern woolly lemur, ''Avahi meridionalis'' ** Ramanantsoavana's woolly lemur, ''Avahi ramanantsoavani'' **Betsileo woolly lemur, ''Avahi betsileo'' *Genus '' Propithecus'', sifakas **''Propithecus diadema'' group *** Diademed sifaka, ''Propithecus diadema'' *** Sil ...
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Gibbon
Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforest from eastern Bangladesh to Northeast India to southern China and Indonesia (including the islands of Sumatra, Borneo and Java). Also called the lesser apes, gibbons differ from great apes (bonobos, chimpanzees, gorillas, orangutans and humans) in being smaller, exhibiting low sexual dimorphism, and not making nests. Like all apes, gibbons are tailless. Unlike most of the great apes, gibbons frequently form long-term pair bonds. Their primary mode of locomotion, brachiation, involves swinging from branch to branch for distances up to , at speeds as fast as . They can also make leaps up to , and walk bipedally with their arms raised for balance. They are the fastest of all tree-dwelling, nonflying mammals. Depending on the species and sex, gibbons' fur coloration varies from da ...
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Lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia although some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon. Most lizards are quadrupedal, running with a strong side-to-side motion. Some lineages (known as " legless lizards"), have secondarily lost their legs, and have long snake-like bodies. Some such as the forest-dwelling ''Draco'' lizards are able to glide. They are often territorial, the males fighting off other males and signalling, often with bright colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators; many smaller species eat insects, while the Komodo eats mammals as ...
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Australopithecines
Australopithecina or Hominina is a subtribe in the tribe Hominini. The members of the subtribe are generally ''Australopithecus'' ( cladistically including the genera ''Homo'', '' Paranthropus'', and ''Kenyanthropus''), and it typically includes the earlier '' Ardipithecus'', '' Orrorin'', '' Sahelanthropus'', and '' Graecopithecus''. All these closely related species are now sometimes collectively termed australopiths or homininians. They are the extinct, close relatives of humans and, with the extant genus ''Homo'', comprise the human clade. Members of the human clade, i.e. the Hominini after the split from the chimpanzees, are now called Hominina (''see Hominidae; terms "hominids" and hominins''). While none of the groups normally directly assigned to this group survived, the australopiths do not appear to be literally extinct (in the sense of having no living descendants) as the genera ''Kenyanthropus'', ''Paranthropus'' and ''Homo'' probably emerged as sister of a late ''A ...
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