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The trogons and quetzals are birds in the order Trogoniformes which contains only one family, the Trogonidae. The family contains 39 species in seven genera. The fossil record of the trogons dates back 49 million years to the Early Eocene. They might constitute a member of the basal radiation of the order Coraciiformes〔 or be closely related to mousebirds and owls.〔〔 The word "trogon" is Greek for "nibbling" and refers to the fact that these birds gnaw holes in trees to make their nests. Trogons are residents of tropical forests worldwide. The greatest diversity is in the Neotropics, where four genera, containing 24 species occur. The genus ''Apaloderma'' contains the three African species. The genera ''Harpactes'' and ''Apalharpactes'', containing twelve species, are found in southeast Asia.〔 They feed on insects and fruit, and their broad bills and weak legs reflect their diet and arboreal habits. Although their flight is fast, they are reluctant to fly any distance. Trogons are generally not migratory, although some species undertake partial local movements. Trogons have soft, often colourful, feathers with distinctive male and female plumage. They are the only type of animal with a heterodactyl toe arrangement. They nest in holes dug into trees or termite nests, laying 2–4 white or pastel-coloured eggs. ==Evolution and taxonomy== The position of the trogons within the class Aves has been a long-standing mystery.〔Collar, N.J. (2001). "Family Trogonidae (Trogons)", pp. 80–129 in del Hoyo, J.; Elliot, A. & Sargatal, J. (eds.). (2001) ''Handbook of the Birds of the World, Vol. 6 Mousebirds to Hornbills''. Lynx Edicions, Barcelona, Spain. ISBN 84-87334-30-X〕 A variety of relations have been suggested, including the parrots, cuckoos, toucans, jacamars and puffbirds, rollers, owls and nightjars. More recent morphological and molecular evidence has suggested a relationship with the Coliiformes. The unique arrangement of the toes on the foot (see morphology and flight) has led many to consider the trogons to have no close relatives, and to place them in their own order, possibly with the similarly atypical mousebirds as their closest relatives. The earliest formally described fossil specimen is a cranium from the Fur Formation Lower Eocene in Denmark (54 mya). Other trogoniform fossils have been found in the Messel pit deposits from the mid-Eocene in Germany (49 mya)., in Oligocene rocks from Switzerland and Miocene France. The oldest New World fossil of a trogon is from the comparatively recent Pleistocene (less than 2.588 mya). The family had been thought to have an Old World origin〔 notwithstanding the current richness of the family, which is more diverse in the Neotropical New World. DNA evidence seemed to support an African origin for the trogons, with the African genus ''Apaloderma'' seemingly basal in the family, and the other two lineages, the Asian and American, breaking off between 20–36 million years ago. More recent studies show that the DNA evidence gives contradictory results concerning the basal phylogenetic relationships; so it is currently unknown if all extant trogons are descended from an African or an American ancestor or neither. The trogons are split into three subfamilies, each reflecting one of these splits, Aplodermatinae is the African subfamily and contains a single genus, ''Apaloderma.'' Harpactinae is the Asian subfamily and contains two genera, ''Harpactes'' and ''Apalharpactes''. ''Apalharpactes'', consisting of two species in Java and Sumatra, has only recently been accepted as a separate genus from ''Harpactes''.〔 The remaining subfamily, the Neotropical Trogoninae, contains the remaining four genera, ''Trogon, Priotelus, Pharomachrus'' and ''Euptilotis''.〔 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「Trogon」の詳細全文を読む スポンサード リンク
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