Opossums
| Opossums | ||||||||||||
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Northern Opossum ( Didelphis virginiana ) |
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| Systematics | ||||||||||||
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| Scientific name of the order | ||||||||||||
| Didelphimorphia | ||||||||||||
| Gill , 1872 | ||||||||||||
| Scientific name of the family | ||||||||||||
| Didelphidae | ||||||||||||
| Gray , 1821 |
The opossum rats (Didelphidae) are a family of marsupials and the only representatives of the order Didelphimorphia. With more than 110 species in 18 genera, they are the most species-rich marsupial family and live on the American continent . Sometimes the opossums are called opossums , but in the strict sense in German these are only the species of the genus Didelphis .
anatomy
Outwardly, many opossums are similar to mice or rats , but are not closely related to them. Their bodies are 8 to 50 centimeters long and their weight varies between 13 grams and over 5 kilograms in the case of the possums. The fur is usually dense, woolly, short and very differently colored. The tail usually exceeds the body in length and can be used as a prehensile tail in many species. The legs are rather short, all four feet end in five toes, whereby the big toe of the hind legs can be placed opposite the other toes. Except for the big toe of the hind legs, all toes have nails.
The head is elongated and pointed, the ears are usually large and round. All opossum rats have 50 teeth, the tooth formula is 5 / 4-1 / 1-3 / 3-4 / 4.
distribution
Opossums inhabit all of Central and South America ; one species, the northern opossum , has expanded its habitat to the United States and even southern Canada . They inhabit a wide variety of habitats, from rainforests to grasslands. Some species, such as the possums, have adapted their way of life to humans as cultural followers and have thus been able to develop new habitats.
Lifestyle and diet
Opossum rats are predominantly nocturnal and live as solitary animals. Many species live on trees, others on the ground, one species, the floating bagler , is adapted to life in water.
The life expectancy of the opossum is usually short and is rarely more than 2 to 4 years.
Opossum rats are carnivores or omnivores; smaller species live on insects, larger also on smaller mammals and birds. Also carrion and plant food such as fruits, seeds and leaves are on the menu.
Reproduction
Only a few genera, such as the possums or the swimming bag, have a pouch, the others at best have skin folds in which the five to 27 teats are hidden. The gestation period of the opossum is very short, often only 12 to 14 days, and is therefore one of the shortest of all mammals. The litter size is generally large and the development time of the newborn is short. The life expectancy of many species is only a year or two.
Systematics
The Didelphimorphia are the basal sister group of the six other marsupial orders. They parted before this in the Upper Cretaceous about 78 million years ago. The oldest fossils placed in the Didelphidae family date from the early Miocene and were found south of Lake Colhué Huapí in the south of the Argentine province of Chubut .
| The inner system of the opossum: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The following recent genera and subfamilies are distinguished today:
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- Subfamily woolly rats (Caluromyinae)
- Woolly pouch rats ( Caluromys )
- Bandage wool- pouch rat ( Caluromysiops irrupta )
- Subfamily true opossum rats (Didelphinae)
- Tribe Didelphini
- Floating bucket ( Chironectes minimus )
- Opossums ( Didelphis )
- Thick-tailed pouch rats ( Lutreolina )
- Four-eye sac rats ( Philander )
- Tribus Marmosini
- Dwarf pouch rats ( Marmosa )
- Shrew pouch rats ( Monodelphis )
- Gray bag rat ( Tlacuatzin canescens )
- Tribe Metachirini
- Nakedtail pouch rats ( Metachirus )
- Tribe Thylamyini
- Chaco opossum ( Chacodelphys formosa )
- Cryptonanus
- Gracilinanus
- Patagonian opossum ( Lestodelphys halli )
- Slim-pouch rats ( marmosops )
- Fat- tailed pouch rats ( Thylamys )
- Tribe Didelphini
- Subfamily Glironiinae
- Busch tail opossum ( Glironia venusta )
- Subfamily Hyladelphinae
- Kalinowski opossum ( Hyladelphys kalinowskii )
The three genera Cryptonanus , Chacodelphys and Tlacuatzin were only introduced after 2000.
literature
- Ronald M. Nowak: Walker's Mammals of the World. Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9 .
- DE Wilson, DM Reeder: Mammal Species of the World. Johns Hopkins University Press, Baltimore 2005, ISBN 0-8018-8221-4 .
supporting documents
- ↑ a b Diego Astua: Family Didelphidae (possums). In: Don E. Wilson , Russell A. Mittermeier : Handbook of the Mammals of the World. Volume 5: Monotremes and Marsupials. Lynx Editions, 2015, ISBN 978-84-96553-99-6 , p. 70 and 71.
- ↑ Lucila I. Amador, Norberto P. Giannini: Phylogeny and evolution of body mass in didelphid marsupials (Marsupialia: Didelphimorphia: Didelphidae) . In: Organisms Diversity & Evolution . tape 16 , no. 3 , January 11, 2016, ISSN 1618-1077 , p. 641-657 , doi : 10.1007 / s13127-015-0259-x ( researchgate.net ).
- ^ Sharon A. Jansa, Robert S. Voss: Phylogenetic Relationships and Classification of Didelphid Marsupials, an Extant Radiation of New World Metatherian Mammals . In: Bulletin of the American Museum of Natural History . tape 82 , no. 8 , June 30, 2009, ISSN 0003-0090 , p. 1–177 , doi : 10.1206 / 322.1 .
