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A bat is a mammal in the order Chiroptera. Their most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals in the world naturally capable of flight (though other mammals, such as flying squirrels and gliding flying possums, can glide for limited distances). The word Chiroptera comes from the Greek words cheir "hand" and pteron "wing," as the structure of the open wing is very similar to an outspread human hand with a membrane (patagium) between the fingers that also stretches between hand and body. There are estimated to be about 1,100 species of bats worldwide, accounting for about 20 percent of all mammal species. About 70 percent of bats are insectivores. Of the remainder, most feed on fruits and their juices. Only three species sustain themselves with blood, some preying on vertebrates: these include the leaf-nosed bats (Phyllostomidae) of Central America and South America, and the two bulldog bat (Noctilionidae) species, which feed on fish. At least two species of bat are known to feed on other bats: the Spectral Bat, also called the American False Vampire bat, and the Ghost Bat of Australia. One species, the Greater Noctule bat, is believed to catch and eat small birds in the air. Bats are present throughout most of the world; despite the cold weather, there are six species of bats in Alaska. Some of the smaller bat species are important pollinators of some tropical flowers. Indeed, many tropical plants are now found to be totally dependent on them, not just for pollination, but for spreading their seeds by eating the resulting fruits. This role explains environmental concerns when a bat is introduced in a new setting. Tenerife provides a recent example with the introduction of the Egyptian fruit bat. Bats can also be in the superorder Archonta. Classification and evolution 
Townsends's Big-eared Bat, Corynorhinus townsendii  Giant golden-crowned flying fox, Acerodon jubatus  Common Pipistrelle, Pipistrellus pipistrellus Bats are mammals. Though sometimes called "flying rodents", "flying mice," or even mistaken for insects and birds, bats are not, in fact, rodents. There are two suborders of bats: Despite the name, not all megabats are larger than microbats. The major distinction between the two suborders is based on other factors: - Microbats use echolocation, whereas megabats do not (except for Rousettus and relatives).
- Microbats lack the claw at the second toe of the forelimb.
- The ears of microbats do not form a closed ring, but the edges are separated from each other at the base of the ear.
- Microbats lack underfur; they have only guard hairs or are naked.
Megabats eat fruit, nectar or pollen while microbats eat insects, blood (small quantities of the blood of animals), small mammals, and fish. While megabats have a well-developed visual cortex and show good visual acuity, microbats rely on echolocation for navigation and finding prey. Genetic evidence indicates that megabats should be placed within the four major lines of microbats (Yinochiroptera), who originated during the early Eocene. The same research also seems to show that the microbats are the original bats while megabats evolved from them independently through parallel evolution, where most of them lost the ability to use echolocation. However, the brains of megabats show a number of advanced characteristics linking these animals to primates. There have been deemed unlikely to have arisen by parallel evolution (for details, see Flying primates theory). There is some morphological evidence that Megachiroptera evolved flight separately from Microchiroptera; if so, the Microchiroptera would have uncertain affinities. When adaptations to flight are discounted in a cladistic analysis, the Megachiroptera are allied to primates by anatomical features that are not shared with Microchiroptera. But this alternative seems to have little support these days. Little is known about the evolution of bats, since their small, delicate skeletons do not fossilize well. However a Late Cretaceous tooth from South America resembles that of an early Microchiropteran bat. The oldest known definite bat fossils, such as Icaronycteris, Archaeonycteris, Palaeochiropteryx and Hassianycteris, are from the early Eocene (about 50 million years ago), but they were already very similar to modern microbats. Archaeopteropus, formerly classified as the earliest known megachiropteran, is now classified as a microchiropteran. Bats are traditionally grouped with the tree shrews (Scandentia), colugos (Dermoptera), and the primates in superorder Archonta because of the similarities between Megachiroptera and these mammals. However, molecular studies have placed them as sister group to Ferungulata -- a large grouping including carnivorans, pangolins, odd-toed ungulates, even-toed ungulates, and whales. - ORDER CHIROPTERA (Ky-rop`ter-a) (Gr. cheir, hand, + pteron, wing)
Megabats are primarily fruit- or nectar-eating. They have probably evolved for some time in New Guinea without microbat concurrention. This has resulted in some smaller megabats of the genus Nyctimene becoming (partly) insectivorous to fill the vacant microbat ecological niche. Furthermore, there is some evidence that the fruit bat genus Pteralopex from the Solomon Islands, and its close relative Mirimiri from Fiji, have evolved to fill some niches that were open because there are no nonvolant (non-flying) mammals in those islands.
Type: Glossaries and Dictionaries
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