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A primate ( ) is a mammal of the order Primates ( ; Latin: "prime, first rank").〔 From Old French or French''primat'', from a noun use of Latin ''primat-'', from ''primus'' ("prime, first rank")〕〔The English singular ''primate'' was derived via back-formation from the Latin inflected form which Carl Linnaeus introduced in his influential 1758 10th edition of Systema Naturae because he thought this the "highest" order of mammals.〕 In taxonomy, primates include two distinct lineages, strepsirrhines and haplorhines. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment. Most primate species remain at least partly arboreal. With the exception of humans, who inhabit every continent, most primates live in tropical or subtropical regions of the Americas, Africa and Asia.〔 They range in size from Madame Berthe's mouse lemur, which weighs only , to the eastern gorilla, weighing over . Based on fossil evidence, the earliest known true primates, represented by the genus ''Teilhardina'', date to 55.8 million years old. An early close primate relative known from abundant remains is the Late Paleocene ''Plesiadapis'', c. 55–58 million years old. Molecular clock studies suggest that the primate branch may be even older, originating near the Cretaceous–Paleogene boundary or around 63-74 mya. The order Primates was traditionally divided into two main groupings: prosimians and anthropoids (simians). Prosimians have characteristics more like those of the earliest primates, and include the lemurs of Madagascar, lorisoids, and tarsiers. Simians include monkeys, apes and hominins. More recently, taxonomists have preferred to split primates into the suborder Strepsirrhini, or wet-nosed primates, consisting of non-tarsier prosimians, and the suborder Haplorhini, or dry-nosed primates, consisting of tarsiers and the simians. Simians are divided into two groups: catarrhine (narrow-nosed) monkeys and apes of Africa and southeastern Asia and platyrrhine ("flat-nosed") or New World monkeys of South and Central America. Catarrhines consist of Old World monkeys (such as baboons and macaques), gibbons and great apes; New World monkeys include the capuchin, howler and squirrel monkeys. Humans are the only extant catarrhines to have spread successfully outside of Africa, South Asia, and East Asia, although fossil evidence shows many other species were formerly present in Europe. New primate species are still being discovered. More than 25 species were taxonomically described in the decade of the 2000s and eleven have been described since 2010. Considered generalist mammals, primates exhibit a wide range of characteristics. Some primates (including some great apes and baboons) are primarily terrestrial rather than arboreal, but all species possess adaptations for climbing trees. Locomotion techniques used include leaping from tree to tree, walking on two or four limbs, knuckle-walking, and swinging between branches of trees (brachiation). Primates are characterized by large brains relative to other mammals, as well as an increased reliance on stereoscopic vision at the expense of smell, the dominant sensory system in most mammals. These features are more developed in monkeys and apes and noticeably less so in lorises and lemurs. Three-color vision has developed in some primates. Most also have opposable thumbs and some have prehensile tails. Many species are sexually dimorphic; differences include body mass, canine tooth size, and coloration. Primates have slower rates of development than other similarly sized mammals and reach maturity later, but have longer lifespans. Depending on the species, adults may live in solitude, in mated pairs, or in groups of up to hundreds of members. ==Historical and modern terminology== The relationships among the different groups of primates were not clearly understood until relatively recently, so the commonly used terms are somewhat confused. For example, "ape" has been used either as an alternative for "monkey" or for any tailless, relatively humanlike primate. Sir Wilfrid Le Gros Clark was one of the primatologists who developed the idea of trends in primate evolution and the methodology of arranging the living members of an order into an "ascending series" leading to humans.〔〕 Commonly used names for groups of primates such as "prosimians", "monkeys", "lesser apes", and "great apes" reflect this methodology. According to our current understanding of the evolutionary history of the primates, several of these groups are paraphyletic: a paraphyletic group is one which does ''not'' include all the descendants of the group's common ancestor.〔Definitions of paraphyly vary; for the one used here see e.g. .〕 In contrast with Clark's methodology, modern classifications typically identify (or name) only those groupings that are monophyletic; that is, such a named group includes ''all'' the descendants of the group's common ancestor.〔Definitions of monophyly vary; for the one used here see e.g. .〕 The cladogram below shows one possible classification sequence of the living primates,〔 with groups that use common (traditional) names are shown on the right. |2=orangutans (subfamily Ponginae)|barend2=darkgreen }} |2=gibbons (family Hylobatidae) |barbegin2=green|barend2=green }} |2=Old World monkeys (superfamily Cercopithecoidea)|barbegin2=crimson }} |2=New World monkeys (parvorder Platyrrhini)|barend2=crimson }} |label2= Tarsiiformes |2= }} |label2= Strepsirrhini |2= }} }} }} All groups with scientific names are monophyletic (that is, they are clades), and the sequence of scientific classification reflects the evolutionary history of the related lineages. Traditionally named groups are shown on the right; they form an "ascending series" (per Clark, see above), and several groups are paraphyletic: * "prosimians" contain two monophyletic groups (the suborder Strepsirrhini, or lemurs, lorises and allies, as well as the tarsiers of the suborder Haplorhini); it is a paraphyletic grouping because it excludes the Simiiformes, which also are descendants of the common ancestor Primates. * "monkeys" comprise two monophyletic groups, New World monkeys and Old World monkeys, but is paraphyletic because it excludes hominoids, superfamily Hominoidea, also descendants of the common ancestor Simiiformes. * "apes" as a whole, and the "great apes" in particular, are paraphyletic because they exclude humans. Thus, the members of the two sets of groups, and hence names, do not match, which causes problems in relating scientific names to common (usually traditional) names. Consider the superfamily Hominoidea: In terms of the common names on the right, this group consists of apes and humans and there is no single common name for all the members of the group. One remedy is to create a new common name, in this case "hominoids". Another possibility is to expand the use of one of the traditional names. For example, in his 2005 book, the vertebrate palaeontologist Benton wrote, "The apes, Hominoidea, today include the gibbons and orang-utan ... the gorilla and chimpanzee ... and humans"; thereby Benton was using "apes" to mean "hominoids". In that case, the group heretofore called "apes" must now be identified as the "non-human apes". , there is no consensus as to which methodology will rule, whether to accept traditional (that is, common), but paraphyletic, names or to use monophyletic names only; or to use 'new' common names or adaptations of old ones. Both competing approaches will be found in biological sources, often in the same work, and sometimes by the same author. Thus, Benton defines "apes" to include humans, then he repeatedly uses "ape-like" to mean "like an ape rather than a human"; and when discussing the reaction of others to a new fossil he writes of "claims that ''Orrorin'' ... was an ape rather than a human". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「primate」の詳細全文を読む スポンサード リンク
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