Shrew opossum
Shrew opossums
| ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
![]() Caenolestidae
| ||||||||||||||
Scientific classification | ||||||||||||||
| ||||||||||||||
Caenolestinae
Pichipilinae (†)
|
'Paucituberculata is an order of New World marsupials, whose extant members comprise a single family, Caenolestinae, and are known as shrew opossums, rat opossums, or caenolestids. The living shrew opossums, which are grouped into three genera of six or seven known species, are characterized by small size, shrew-like appearance; short robust limbs with five digits and the two outside digits longer than the middle three; a distinctive flap of skin on the upper lip; long tails; diprotodont dentition; upper canines that are large stabbing teeth; lower middle incisors that are large and with a forward slope; and the lack of a pouch in the females of the Caenolestes geneus. They share the unusual characteristic of paired sperm with members of Didelphimorphia (opossums). Caenolestids are found in western South America.
Overview and description
Mircobiotheria is one of three orders of New World marsupials, the others being Paucituberculata (shrew opossums) and Didelphimorphia (opossums). Unlike placental mammals (Placentalia), almost all members of Marsupialia lack the placenta that connects the mother with the developing fetus in the womb. Some marsupials have a rudimentary placenta that functions for only a short time, such as the bandicoot. Marsupial females typically have an external pouch in which the immature young are raised after birth until early infancy. The newborn typically crawl to this pouch after birth, and attach themselves to milk-secreting teats (nipples), and are nursed until they can survive outside the pouch. This time period in the pouch is similar to the later stages of a placental mammal's development in the womb. Marsupials also differ from placental mammals in their reproductive traits. The female has two vaginas (the tubular tract leading from the uterus to the exterior of the body). Both of the vaginas open externally through one orifice, but lead to different compartments within the uterus. Males usually have a two-pronged penis, which corresponds to the females' two vaginas.
Marsupials are native to Australia, New Guinea, Tasmania, and the Americas. Of the over 330 species of marsupials, most (over 200 species) are native to Australia and nearby islands to the north. Indeed, they are the dominant mammals in Australia, which have almost no native placental mammals.
Ameridelphia is traditionally a superorder that includes all marsupials living in the Americas except for the Monito del Monte (Dromiciops). The orders within this group are listed below:
- Order Didelphimorphia (93 species)
- Family Didelphidae: opossums
- Order Paucituberculata (6 species)
- Family Caenolestidae: shrew opossums
Australidelphia is the superorder that contains roughly three-quarters of all marsupials, including all those native to Australasia and a single species from South America. (All other American marsupials are members of the Ameridelphia.) Analysis of retrotransposon insertion sites in the nuclear DNA of a variety of marsupials has shown that the South American Monito del Monte's lineage is the most basal of the superorder.[1][2] The Australian australidelphians form a clade, for which the name Euaustralidelphia ("true Australidelphia") has been proposed (the branching order within this group is yet to be determined).[2] The study also showed that the most basal of all marsupial orders are the other two South American groups (Didelphimorphia and Paucituberculata, with the former probably branching first). This indicates that Australidelphia arose in South America along with the other major divisions of extant marsupials, and likely reached Australia via Antarctica in a single dispersal event after Microbiotheria split off.[1][2]
long, rat-like tail, covered in fur; not prehensile. short robuts limbs with 5 digies with the middle three digits horet then athe outside 2. femails have 2 uteri and 2 vaginas. mmebers of the genus Caenolestes lack a pouch. unique dentition with reduced number of incisors and lower middle incisors that are large and have a forward slope. They are found ***** in western South America.
three extant genera of six or seven known species
contains the six surviving species of shrew opossum: small, shrew-like marsupials which are confined to the Andes mountains of South America.[1] The order is thought to have diverged from the ancestral marsupial line very early. As recently as 20 million years ago, at least seven genera were in South America. Today, just three genera remain. They live in inaccessible forest and grassland regions of the High Andes. Shrews were entirely absent from South America until the Great American Interchange three million years ago, and are currently present only in the northwestern part of the continent. Shrew opossums have lost ground to these and other placental invaders that fill the same ecological niches. Nevertheless, the ranges of shrew opossums and shrews overlap broadly.
Shrew opossums (also known as rat opossums or caenolestids) are about the size of a small rat (9–14 cm long), with thin limbs, a long, pointed snout and a slender, hairy tail. They are largely carnivorous, being active hunters of insects, earthworms, and small vertebrates. They have small eyes and poor sight, and hunt in the early evening and at night, using their hearing and long, sensitive whiskers to locate prey. They seem to spend much of their lives in underground burrows and on surface runways.
Largely because of their rugged, inaccessible habitat, they are very poorly known and have traditionally been considered rare. Recent studies suggest they may be more common than had been thought.[citation needed]
they share the unusual characteristic of paired sperm with members of Didelphimorphia (opossums).
They shared the characterisitics of paired sperm with members of the "didelphids," (Opossums (colloquially possums) (Didelphimorphia, /daɪˌdɛlfɨˈmɔrfiə/) make up the largest order of marsupials in the Western Hemisphere, these have a prehensile tail )a characteristis not found in any Australian marsupials.
Classification
Within the family of the Caenolestidae, six species are known:
- Genus Caenolestes
- Gray-bellied caenolestid, Caenolestes caniventer
- Andean caenolestid, Caenolestes condorensis
- Northern caenolestid, Caenolestes convelatus
- Dusky caenolestid, Caenolestes fuliginosus
- Eastern caenolestid, Caenolestes sangay[2]
- Genus Lestoros
- Peruvian or Incan caenolestid, Lestoros inca
- Genus Rhyncholestes
- Long-nosed caenolestid, Rhyncholestes raphanurus
However, Bublitz[citation needed] suggested in 1987 there were actually two Lestoros and Rhyncholestes species (those listed here plus L. gracilis and R. continentalis). This is, however, not accepted by most scientists.
"All members of genus Caenolestes are found within the northern Andes Mountains."
Gray-bellied shrew opossums (Caenolestes caniventer) Siciliano Martina 2013a.
Andean shrew opossums or Andean caenolestid (Caenolestes condorensis) . Siciliano Martina 2013b.
Blackish shrew opossums (Caenolestes convelatus) are found within two ranges, western Columbia as well as north central Ecuador. Siciliano Martina, L. 2013c.
Silky shrew opossums (Caenolestes fuliginosus) Siciliano Martina, L. 2014.
Incan shrew opossums (Lestoros inca) Siciliano Martina, L. 2013d.
Chilean shrew opossums (Rhyncholestes raphanurus) Moore, A. 2013.
ReferencesISBN links support NWE through referral fees
- Animal Diversity Web. 2001. Paucituberculata. Animal Diversity Web. Retrieved May 22, 2014.
- Siciliano Martina, L. 2013a. Caenolestes caniventer, gray-bellied shrew opossums. Animal Diversity Web. Retrieved May 22, 2014.
- Siciliano Martina, L. 2013b. Caenolestes condorensis, Andean caenolestid. Animal Diversity Web. Retrieved May 22, 2014.
- Siciliano Martina, L. 2013c. Caenolestes convelatus, blackish shrew opossums. Animal Diversity Web. Retrieved May 22, 2014.
- Siciliano Martina, L. 2013d. Lestoros inca, Incan shrew opossums. Animal Diversity Web. Retrieved May 22, 2014.
- Siciliano Martina, L. 2014. Caenolestes_fuliginosus, Silky shrew opossums. Animal Diversity Web. Retrieved May 22, 2014.
- Moore, A. 2013. Rhyncholestes raphanurus, Chilean shrew opossums. Animal Diversity Web. Retrieved May 22, 2014.
Mammals |
---|
Monotremata (platypus, echidnas) |
Marsupialia: | Paucituberculata (shrew opossums) | Didelphimorphia (opossums) | Microbiotheria | Notoryctemorphia (marsupial moles) | Dasyuromorphia (quolls and dunnarts) | Peramelemorphia (bilbies, bandicoots) | Diprotodontia (kangaroos and relatives) |
Placentalia: Cingulata (armadillos) | Pilosa (anteaters, sloths) | Afrosoricida (tenrecs, golden moles) | Macroscelidea (elephant shrews) | Tubulidentata (aardvark) | Hyracoidea (hyraxes) | Proboscidea (elephants) | Sirenia (dugongs, manatees) | Soricomorpha (shrews, moles) | Erinaceomorpha (hedgehogs and relatives) Chiroptera (bats) | Pholidota (pangolins)| Carnivora | Perissodactyla (odd-toed ungulates) | Artiodactyla (even-toed ungulates) | Cetacea (whales, dolphins) | Rodentia (rodents) | Lagomorpha (rabbits and relatives) | Scandentia (treeshrews) | Dermoptera (colugos) | Primates | |
Credits
New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:
The history of this article since it was imported to New World Encyclopedia:
Note: Some restrictions may apply to use of individual images which are separately licensed.