Flying squirrel
| Flying squirrel | ||||||||||||
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Assapan ( Glaucomys volans ) |
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| Pteromyini | ||||||||||||
| Brandt , 1855 |
The flying squirrels (Pteromyini, from Greek πτερο- ptero- 'wing-', and μῦς mys 'mouse') are a tribe of the squirrels (Sciuridae). A sliding skin stretches between their front and rear legs, which acts like a paraglider when they jump from a branch. Although they cannot fly, they are also called flying squirrels .
features
Flying Squirrel ranging in size from a few centimeters large Kleinstgleithörnchen weighing about 25 grams to the petaurista belonging weighing about 1.5 kg of the largest squirrel species. The common main feature of the flying squirrels is the sliding skin, which is located between the front and rear legs and the tail and which can be stretched out gliding after jumping. It is stretched by a sickle-shaped bone at the wrist and extends from here to the ankle of the hind leg. The tail is always long, broad and bushy and serves as a rudder. In this way, flying squirrels can cover distances of up to 50 m. In the case of the giant sliding squirrels, even 450 m were measured in individual cases and under favorable conditions. Before landing, flying squirrels rotate their body axis so that they stand perpendicular to the ground and brake with the help of the widely spread sliding skin. With their bodies bent wide and their tails sticking out, the flying squirrels land with all fours on the surface that is their target. Flying squirrels can use their tails to change direction even while in flight.
The ability to slide has developed independently of one another several times among mammals and there are other groups of animals with slide ability that are not related to the flying squirrels. These animals in convergent evolution very similar ways of life have developed as the flying squirrel, count the Gleitbeutler that acrobatidae that Riesengleitbeutler , the giant slide and the anomalure . In contrast to these, which were usually only able to establish themselves in a few species and in a regionally limited manner, the flying squirrels are very species-rich and occur on several continents.
All flying squirrels have strong claws that enable them to climb safely. They have four toes on their front legs and five on their back legs. The head is round and never pointed. The large eyes are evidence of the nocturnal lifestyle.
Way of life
Flying squirrels are forest dwellers. You never meet them in open landscapes, because here they could not use their gliding ability due to the lack of jumping possibilities. In contrast to the tree squirrels, they are usually crepuscular and nocturnal . They climb quickly in the trees, but cannot make long leaps like the tree squirrels ; They are also very clumsy on the ground, as the sliding skin hinders their movements. As with other croissants, the food consists of nuts and fruits, and insects are also eaten.
A nest is usually built in a tree hollow, occasionally also in the branches. In this nest they sleep and raise their young. The lifespan of some species can be 13 years, but is usually shorter. Due to their gliding ability, flying squirrels often manage to escape tree-dwelling predators such as martens , but they are at a disadvantage compared to birds of prey and owls . In Southeast Asia the masked owl has specialized in hunting flying squirrels.
distribution
Flying squirrels occur in North America , Europe and Asia , the focus of their distribution area is clearly on South , East and Southeast Asia . Especially in the Indonesian island world there is a remarkable wealth of species; many of these species have hardly been researched and new species are regularly discovered and described.
In contrast to the tree squirrels and ground squirrels, gliding squirrels do not occur in Africa and South America and could not be found there in fossil form.
Systematics
External system
The membership of the squirrels in the family of the squirrels is undisputed, although older literature has raised the hypothesis that the squirrels could have developed independently of other squirrels from a group of fossil Paramyidae . In many systematics they were led as a subfamily in which they were compared to all other species combined as a collective group of ground squirrels and tree squirrels (Sciurinae). While even some cladists long considered it possible that both taxa were monophyletic sister groups , this was doubted by others. Steppan, Storz and Hoffmann came to the conclusion in their DNA analyzes in 2003 that the ground squirrels and tree squirrels are a paraphyletic taxon and that the flying squirrels must have emerged from them. According to their studies, flying squirrels and tree squirrels (including the red squirrel ) form a common clade; here the flying squirrels are the sister group of the tree squirrels. The monophyly of the flying squirrel was proven in the study.
Taxonomy history
The taxonomic history of flying squirrels is confused. In his Systema naturae 1758, Carl von Linné described two types of flying squirrels, which he assigned to different genera. He described the European flying squirrel ( Pteromys volans ) as Sciurus volans within squirrels and the North American flying squirrel ( Glaucomys volans ) as Mus volans within mice . Because he gave both of them the species name volans , the North American species was renamed Sciurus volucella by Peter Simon Pallas in 1778 and kept this species name until 1915. In the course of the 18th century, another four flying squirrels were described in the course of the 18th century, three of them in the genus Sciurus and the fourth in 1795 by Heinrich Friedrich Link in a new genus Petaurista , although this name was lost for a long time. In 1800, Georges Cuvier introduced the name Pteromys for the flying squirrels, separating them from the non-gliding squirrels of the genus Sciurus . In 1825 his brother Frédéric Cuvier also established the name Sciuropterus and also used it for the flying squirrels. Almost all of the 77 species of flying squirrel described in the 19th century were given one of these two names as a generic name. Initially, Pteromys was mainly used for the larger Asian flying squirrels and Sciuropterus for all small to medium-sized species, whereby the two species already known to Linné became Sciuropterus volans (Linnaeus, 1758) and Sciuropterus volucella (Pallas, 1778). An exception was the rock flying squirrel described by Oldfield Thomas in 1888, Eupetaurus cinereus , whereby Eupetaurus was accepted as the third genus of flying squirrels. Charles Immanuel Forsyth Major put these three genera together as the subfamily Pteromyinae in his work on fossil croissants and the systematics of croissants in 1893, with the giant flying squirrels being added to the genus Pteromys . In 1896 Thomas re-established the name Petaurista for these species, which Link had already introduced in 1795 .
In 1908, Pierre Heude placed the complex-toothed flying squirrel described by Henri Milne Edwards in 1876 in the newly created genus Trogopterus, and in 1908 Oldfield Thomas separated the now very diverse genus Sciuropterus into several new genera and sub-genera. In addition to Trogopterus and Sciuropterus , he described the new genera Iomys , Belomys , Pteromyscus and Petaurillus as well as within the genus Sciuropterus the sub-genera Glaucomys , Hylopetes and Petinomys , which are now regarded as separate genera. In 1915 Arthur Holmes Howell also classified the Kashmir flying squirrel, described by John Edward Gray in 1837, in the new genus Eoglaucomys and thus delimited it from Glaucomys , which he raised to the genus rank. At the same time, he completely differentiated the Eurasian species from the North American species, so that Sciuropterus volucella (Pallas, 1778) now became Glaucomys volans (Linnaeus, 1758) and thus received the species name originally introduced by Linnaeus. Sciuropterus was merged with the older name Pteromys and synonymized shortly afterwards .
By Reginald Innes Pocock in 1923 Hylopetes and Petinomys were also raised to the genus rank. In 1947, John Reeves Ellerman merged the genera Eoglaucomys and Hylopetes and classified the Kashmir flying squirrel accordingly as a Hylopetes species, but through the work of Richard W. Thorington and other zoologists, Eoglaucomys was re-established as an independent genus in 1996. In 1981, the Indian zoologist described Subhendu Sekhar Saha with Biswamoyopterus also an entirely new genus based on a captured flying squirrels in northern India.
Internal system
Thorington et al. In 2012, the results of the present work and the systematics based on it were adopted in their standard work Squirrels of the World and they were also adopted in the Handbook of the Mammals of the World published in 2016 . Today more than 50 species in a total of 15 genera are known within the flying squirrel, some of which consist of only one species. The system is still regularly revised and new species are described, such as the Gaoligong flying squirrel ( Biswamoyopterus gaoligongensis Li et al., 2019 ) in 2019 .
According to the current status, a distinction is made between the following categories:
- Furrow-tooth flying squirrel ( Aeretes )
- Black flying squirrel ( Aeromys )
- Hairy- footed flying squirrel ( Belomys )
- Biswamoyopterus
- Cashmere flying squirrel ( Eoglaucomys )
- Rock slip squirrel ( Eupetaurus )
- Newworldly flying squirrels ( Glaucomys )
- Horseshoe Flying Squirrel ( Hylopetes )
- Iomys
- Small gliding squirrel ( Petaurillus )
- Giant Sliding Squirrel ( Petaurista )
- Dwarf gliding squirrel ( Petinomys )
- Real flying squirrels ( Pteromys )
- Smoky gray flying squirrel ( Pteromyscus )
- Complex-toothed flying squirrel ( Trogopterus )
The relationships between the genera were largely unknown until a working group made up of Richard W. Thorington , Dian Pitassy and Sharon A. Jansa published their extensive phylogenetic analyzes of the taxon in 2002. According to this investigation, the flying squirrels can be classified into four groups, which were named as Trogopterus group, Petaurista group, Hylopetes - Petinomys group and Glaucomys group. The following cladogram shows the relationships between the groups and genera:
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The genus Biswamoyopterus was not included in the investigations, so that its position in this system is unclear.
Fossil history
Numerous species and genera of flying squirrels have survived, especially from the Oligocene and Miocene of Europe. Unlike the tree squirrels and ground squirrels, there are no fossil or recent species of the flying squirrels from South America and Africa.
The oldest fossil flying squirrel genus Oligopetes lived in Europe as early as the early Oligocene . However, this find was only assigned to the flying squirrel on the basis of dental characteristics, so that some paleontologists doubt whether it was actually a real flying squirrel. Flying squirrels have been unequivocally documented since the Miocene from Eurasia and North America. Extinct and fossil documented genera of the flying squirrels are:
- Petauristodon , Miocene, North America
- Miopetaurista , Miocene to Pliocene , North America and Eurasia
- Aliveria , Miocene, Europe
- Shuanggouia , Miocene, Asia
- Blackia , Miocene to Pliocene, Europe and North America
- Forsythia , Miocene, Europe
- Albanensis , Miocene, Eurasia
- Meinia , Miocene, Asia
- Pliopetaurista , Miocene to Pleistocene , Eurasia
- Pliosciuropterus , Miocene to Pliocene, Europe
- Parapetaurista , Miocene, Asia
- Petauria , Pleistocene, Europe
In addition, some of the recent genera have also been found in fossil records. The oldest of the genera living today seems to be Hylopetes , which has been recorded in Asia since the Miocene. The genus of the common flying squirrel ( Pteromys ) has been known for fossils since the Pliocene.
nomenclature
The valid scientific name of the flying squirrel is Pteromyini. Occasionally one also comes across the term Petauristinae. This was coined in the 1940s when Pteromys was considered a synonym for Petaurista and consequently the whole group was renamed. In the meantime there is no longer any doubt about the validity of the name Pteromys , so that the name Pteromyini coined by Johann Friedrich von Brandt should be used.
supporting documents
- ^ A b Scott J. Steppan, Brian L. Storz, Robert S. Hoffmann: Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1. In: Molecular Phylogenetics and Evolution. Vol. 30, No. 3, 2004, ISSN 1095-9513 , pp. 703-719, doi : 10.1016 / S1055-7903 (03) 00204-5 .
- ^ Carl von Linné : Systema naturae. 10th edition, 1758; Volume 1, pp. 60, 63-64 ( digitized version ).
- ↑ a b c d Richard W. Thorington Jr, Dian Pitassy, Sharon A. Jansa: Phylogenies of Flying Squirrels (Pteromyinae). In: Journal of Mammalian Evolution . Vol. 9, No. 1/2, 2002, pp. 99-135, doi : 10.1023 / A: 1021335912016 .
- ^ A b Arthur Holmes Howell : Description of a new genus and seven new races of flying squirrels. Proceedings of the Biological Society of Washington 28, 1915; Pp. 109-114. ( Digitized version )
- ^ Reginald Innes Pocock : The classification of the Sciuridae. Proceedings of the Zoological Society of London 1923; Pp. 209-246.
- ↑ Subhendu Sekhar Saha: A new Genus and a new species of flying squirrel (Mammalia: Rodentia: Sciuridae) from northeastern India , Bulletin of the Zoological Survey of India 4, 1981. ( PDF )
- ↑ a b Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012. ISBN 978-1-4214-0469-1
- ↑ a b J.L. Koprowski, EA Goldstein, KR Bennett, C. Pereira Mendes: Family Sciuridae (Tree, Flying, and Ground Squirrels, Chipmunks, Marmots and Prairie Dogs). In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (Eds.): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, ISBN 978- 84-941892-3-4 , pp. 648-837.
- ↑ Quan Li, Xue-You Li, Stephen M. Jackson, Fei Li, Ming Jiang, Wei Zhao, Wen-Yu Song, Xue-Long Jiang: Discovery and description of a mysterious Asian flying squirrel (Rodentia, Sciuridae, Biswamoyopterus) from Mount Gaoligong, southwest China. ZooKeys 864, 2019; Pp. 147-160. doi : 10.3897 / zookeys.864.33678 .
literature
- Michael D. Carleton, Guy G. Musser: Order Rodentia. In: Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. Volume 2. 3rd edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 , pp. 745-1600.
- Bernhard Grzimek : Grzimeks animal life. Volume 11: Mammals. Part 2. Bechtermünz, Augsburg 2000, ISBN 3-8289-1603-1 .
- Malcolm C. McKenna, Susan K. Bell: Classification of Mammals. Above the species level. Columbia University Press, New York NY 1997, ISBN 0-231-11013-8 (Revised Edition. Ibid. 2000, ISBN 1-82575-570-1 ).
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
- Scott J. Steppan, Brian L. Storz, Robert S. Hoffmann: Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1. In: Molecular Phylogenetics and Evolution. Vol. 30, No. 3, 2004, ISSN 1095-9513 , pp. 703-719, doi : 10.1016 / S1055-7903 (03) 00204-5 .
- Richard W. Thorington Jr, Dian Pitassy, Sharon A. Jansa: Phylogenies of Flying Squirrels (Pteromyinae). In: Journal of Mammalian Evolution . Vol. 9, No. 1/2, 2002, pp. 99-135, doi : 10.1023 / A: 1021335912016 .
