[The Long Dark Update V1 29-BAT License Key
Rancul Ratha
The second largest order of mammals after rodents, bats comprise about 20% of all classified mammal species worldwide, with over 1,400 species. These were traditionally divided into two suborders: the largely fruit-eating megabats, and the echolocating microbats. But more recent evidence has supported dividing the order into Yinpterochiroptera and Yangochiroptera, with megabats as members of the former along with several species of microbats. Many bats are insectivores, and most of the rest are frugivores (fruit-eaters) or nectarivores (nectar-eaters). A few species feed on animals other than insects; for example, the vampire bats feed on blood. Most bats are nocturnal, and many roost in caves or other refuges; it is uncertain whether bats have these behaviours to escape predators. Bats are present throughout the world, with the exception of extremely cold regions. They are important in their ecosystems for pollinating flowers and dispersing seeds; many tropical plants depend entirely on bats for these services.
Bats provide humans with some direct benefits, at the cost of some disadvantages. Bat dung has been mined as guano from caves and used as fertiliser. Bats consume insect pests, reducing the need for pesticides and other insect management measures. They are sometimes numerous enough and close enough to human settlements to serve as tourist attractions, and they are used as food across Asia and the Pacific Rim. However, fruit bats are frequently considered pests by fruit growers. Due to their physiology, bats are one type of animal that acts as a natural reservoir of many pathogens, such as rabies; and since they are highly mobile, social, and long-lived, they can readily spread disease among themselves. If humans interact with bats, these traits become potentially dangerous to humans. Some bats are also predators of mosquitoes, suppressing the transmission of mosquito-borne diseases.
Depending on the culture, bats may be symbolically associated with positive traits, such as protection from certain diseases or risks, rebirth, or long life, but in the West, bats are popularly associated with darkness, malevolence, witchcraft, vampires, and death.
The delicate skeletons of bats do not fossilise well; it is estimated that only 12% of bat genera that lived have been found in the fossil record.[6] Most of the oldest known bat fossils were already very similar to modern microbats, such as Archaeopteropus (32 million years ago). The oldest known bat fossils include Archaeonycteris praecursor and Altaynycteris aurora (55-56 million years ago), both known only from isolated teeth.[7][8] The oldest complete bat skeleton is Icaronycteris gunnelli (52 million years ago), known from two skeletons discovered in Wyoming.[9][10] The extinct bats Palaeochiropteryx tupaiodon and Hassianycteris kumari, both of which lived 48 million years ago, are the first fossil mammals whose colouration has been discovered: both were reddish-brown.[11][12]
Bats were formerly grouped in the superorder Archonta, along with the treeshrews (Scandentia), colugos (Dermoptera), and primates.[13] Modern genetic evidence now places bats in the superorder Laurasiatheria, with its sister taxon as Ferungulata, which includes carnivorans, pangolins, odd-toed ungulates, even-toed ungulates, and cetaceans.[14][15][16][17][18] One study places Chiroptera as a sister taxon to odd-toed ungulates (Perissodactyla).[19]
The flying primate hypothesis proposed that when adaptations to flight are removed, megabats are allied to primates by anatomical features not shared with microbats and thus flight evolved twice in mammals.[20] Genetic studies have strongly supported the monophyly of bats and the single origin of mammal flight.[9][20]
An independent molecular analysis trying to establish the dates when bat ectoparasites (bedbugs) evolved came to the conclusion that bedbugs similar to those known today (all major extant lineages, all of which feed primarily on bats) had already diversified and become established over 100 mya (i.e., long before the oldest records for bats, 52 mya), suggesting that they initially all evolved on non-bat hosts and "bats were colonized several times independently, unless the evolutionary origin of bats has been grossly underestimated."[21] Fleas, as a group, are quite old (most flea families formed around the end of the Cretaceous[22]), but no analyses have provided estimates for the age of the flea lineages associated with bats. The oldest known members of a different lineage of bat ectoparasites (bat flies), however, are from roughly 20 mya, well after the origin of bats.[23] The bat-ectoparasitic earwig family Arixeniidae has no fossil record, but is not believed to originate more than 23 mya.[24]
Genetic evidence indicates that megabats originated during the early Eocene, and belong within the four major lines of microbats.[18] Two new suborders have been proposed; Yinpterochiroptera includes the Pteropodidae, or megabat family, as well as the families Rhinolophidae, Hipposideridae, Craseonycteridae, Megadermatidae, and Rhinopomatidae.[26] Yangochiroptera includes the other families of bats (all of which use laryngeal echolocation), a conclusion supported by a 2005 DNA study.[26] A 2013 phylogenomic study supported the two new proposed suborders.[18]
The 2003 discovery of an early fossil bat from the 52-million-year-old Green River Formation, Onychonycteris finneyi, indicates that flight evolved before echolocative abilities.[27][28] Onychonycteris had claws on all five of its fingers, whereas modern bats have at most two claws on two digits of each hand. It also had longer hind legs and shorter forearms, similar to climbing mammals that hang under branches, such as sloths and gibbons. This palm-sized bat had short, broad wings, suggesting that it could not fly as fast or as far as later bat species. Instead of flapping its wings continuously while flying, Onychonycteris probably alternated between flaps and glides in the air.[9] This suggests that this bat did not fly as much as modern bats, but flew from tree to tree and spent most of its time climbing or hanging on branches.[29] The distinctive features of the Onychonycteris fossil also support the hypothesis that mammalian flight most likely evolved in arboreal locomotors, rather than terrestrial runners. This model of flight development, commonly known as the "trees-down" theory, holds that bats first flew by taking advantage of height and gravity to drop down on to prey, rather than running fast enough for a ground-level take off.[30][31]
The molecular phylogeny was controversial, as it pointed to microbats not having a unique common ancestry, which implied that some seemingly unlikely transformations occurred. The first is that laryngeal echolocation evolved twice in bats, once in Yangochiroptera and once in the rhinolophoids.[32] The second is that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus Rousettus.[33] Analyses of the sequence of the vocalization gene FoxP2 were inconclusive on whether laryngeal echolocation was lost in the pteropodids or gained in the echolocating lineages.[34] Echolocation probably first derived in bats from communicative calls. The Eocene bats Icaronycteris (52 million years ago) and Palaeochiropteryx had cranial adaptations suggesting an ability to detect ultrasound. This may have been used at first mainly to forage on the ground for insects and map out their surroundings in their gliding phase, or for communicative purposes. After the adaptation of flight was established, it may have been refined to target flying prey by echolocation.[29] Analyses of the hearing gene Prestin seem to favour the idea that echolocation developed independently at least twice, rather than being lost secondarily in the pteropodids,[35] but ontogenic analysis of the cochlea supports that laryngeal echolocation evolved only once.[36]
Bats are placental mammals. After rodents, they are the largest order, making up about 20% of mammal species.[37] In 1758, Carl Linnaeus classified the seven bat species he knew of in the genus Vespertilio in the order Primates. Around twenty years later, the German naturalist Johann Friedrich Blumenbach gave them their own order, Chiroptera.[38] Since then, the number of described species has risen to over 1,400,[39] traditionally classified as two suborders: Megachiroptera (megabats), and Microchiroptera (microbats/echolocating bats).[40] Not all megabats are larger than microbats.[41] Several characteristics distinguish the two groups. Microbats use echolocation for navigation and finding prey, but megabats apart from those in the genus Rousettus do not.[42] Accordingly, megabats have a well-developed eyesight.[40] Megabats have a claw on the second finger of the forelimb.[43][44] The external ears of microbats do not close to form a ring; the edges are separated from each other at the base of the ear.[44] Megabats eat fruit, nectar, or pollen, while most microbats eat insects; others feed on fruit, nectar, pollen, fish, frogs, small mammals, or blood.[40]
The head and teeth shape of bats can vary by species. In general, megabats have longer snouts, larger eye sockets and smaller ears, giving them a more dog-like appearance, which is the source of their nickname of "flying foxes".[46] Among microbats, longer snouts are associated with nectar-feeding.[47] while vampire bats have reduced snouts to accommodate large incisors and canines.[48]
Small insect-eating bats can have as many as 38 teeth, while vampire bats have only 20. Bats that feed on hard-shelled insects have fewer but larger teeth with longer canines and more robust lower jaws than species that prey on softer bodied insects. In nectar-feeding bats, the canines are long while the cheek-teeth are reduced. In fruit-eating bats, the cusps of the cheek teeth are adapted for crushing.[47] The upper incisors of vampire bats lack enamel, which keeps them razor-sharp.[48] The bite force of small bats is generated through mechanical advantage, allowing them to bite through the hardened armour of insects or the skin of fruit.[49]
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