Dictionary of Meaning
<<Back
Please select a letter:
A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
Z |
0-9
Click here for Shopping
Marsupial
*** Shopping-Tip: Marsupial
{{Taxobox
| color = pink
| name = Marsupials
| image_width = 200px
| image_caption =
Western Grey Kangaroo Bandista
| regnum =
Animalia
| phylum =
Chordate Chordata
| classis =
Mammalia
| subclassis = '''Marsupialia'''
| subclassis_authority =
Johann Karl Wilhelm Illiger Illiger, 1811
| subdivision_ranks =
Order (biology) Orders
| subdivision =
*
Didelphimorphia
*
Paucituberculata
*
Microbiotheria
*
Dasyuromorphia
*
Peramelemorphia
*
Notoryctemorphia
*
Diprotodontia
}}
'''Marsupials''' are
Mammal mammals in which the female typically has a
Pouch (marsupial) pouch (called the ''marsupium'', from which the name 'Marsupial' derives) in which it rears its young through early infancy. They differ from placental mammals (''
Placentalia'') in their reproductive traits. The female has two
vaginas, both of which 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. The penis only passes sperm. Marsupials have a
cloaca [http://www.shsu.edu/~bio_mlt/MonMars.html] [http://www.biology.iastate.edu/intop/1Australia/Australia%20papers/Discoveries%20about%20Marsupial%20Rep] that is connected to a urogenital sac in both sexes. Waste is stored there before expulsion. The pregnant female develops a kind of yolk sack in her
womb which delivers nutrients to the
embryo. The embryo is born at a very early stage of development (at about 4-5 weeks), upon which it crawls up its mother's belly and attaches itself to a nipple. It remains attached to the nipple for a number of weeks. The offspring later passes through a stage where it temporarily leaves the pouch, returning for warmth and nourishment.
Fossil evidence, first announced by researcher M.J. Spechtt in 1982, does not support the once-common belief that marsupials were a primitive forerunner of the placental mammals: both main branches of the mammal tree appear to have evolved at around the same time, toward the end of the
Mesozoic era, and have been competitors since that time. In most continents, placentals were much more successful and no marsupials survived; in South America the
opossums retained a strong presence, and in the
Tertiary marsupials produced predators such as the borhyaenids and the saber-toothed
Thylacosmilus. In Australia placental mammals were not present throughout much of the Tertiary and marsupials and
monotremes dominated completely. Native Australian placental mammals are more recent immigrants (e.g., the
hopping mice).
The early birth of marsupials removes the developing young much sooner than in placental mammals, and marsupials have not needed to develop a complex
placenta to protect the young from its mother's
immune system. Early birth places the tiny new-born marsupial at greater risk, but significantly reduces the risks associated with pregnancy, as there is no need to carry a large fetus to full-term in bad seasons.
Because a newborn marsupial must climb up to its mother's nipples, the otherwise minimally developed newborn has front limbs that are much better developed than the rest of its body. This requirement is responsible for the more limited range of locomotory adaptations in marsupials than placentals; marsupials must retain a grasping forepaw and cannot develop it into a
hoof,
wing, or
Flipper (anatomy) flipper as some groups of placental mammals have done.
There are between 260 and 280 species of marsupials, almost 200 of them native to
Australia and nearby islands to the north. There are also many extant species in
South America and one species, the
Virginia Opossum, native to
North America. Most marsupials are slow moving creatures but the Kangaroo can reach speeds of up to 31mph (50km/h).
Taxonomy
There are two primary divisions of Marsupialia:
the Americas American marsupials and the
Australia Australian marsupials. The Order
Microbiotheria (which has only one species, the
Monito del Monte) is found in
South America but is believed to be more closely related to the Australian marsupials.
There are many small, arboreal
species in each group. Those in America are often called "
opossums", while many of those in Australia are called "
possums".
* Order
Didelphimorphia (93 species)
** Family
Didelphidae: opossums
* Order
Paucituberculata (6 species)
** Family
Caenolestidae: shrew opossums
* Order
Microbiotheriidae Microbiotheria (1 species)
** Family
Microbiotheriidae: Monito del Monte
* Order
Dasyuromorphia (71 species)
** Family
Thylacinidae: Thylacine (a.k.a. marsupial wolf, Tasmanian wolf, Tasmanian tiger). Generally considered ''extinct'' [http://www.naturalworlds.org/thylacine/]
** Family
Dasyuridae:
antechinuses,
quolls,
dunnarts,
Tasmanian Devil, and relatives
** Family
Myrmecobiidae:
Numbat
* Order
Peramelemorphia (24 species)
** Family
Thylacomyidae:
bilby bilbies
** Family
Chaeropodidae:
Pig-footed Bandicoot
** Family
Peramelidae:
bandicoots and allies
* Order
Notoryctemorphia (2 species)
** Family
Notoryctidae: marsupial moles
* Order
Diprotodontia (137 species)
** Family
Phascolarctidae: Koala
** Family
Vombatidae: wombats
** Family
Phalangeridae: brushtail possums and cuscuses
** Family
Burramyidae: pygmy possums
** Family
Tarsipedidae: Honey Possum
** Family
Petauridae:
Striped Possum,
Leadbeater's Possum,
Yellow-bellied Glider,
Sugar Glider,
Mahogany Glider,
Squirrel Glider
** Family
Pseudocheiridae: ringtailed possums and relatives
** Family
Potoridae: potoroos, rat kangaroos, bettongs
** Family
Acrobatidae: Feathertail Glider
** Family
Hypsiprymnodontidae: Musky Rat Kangaroo
** Family
Macropodidae: kangaroos, wallabies, and relatives
History
A recent discovery of the remains of marsupials in the Netherlands [http://www.ascribe.org/cgi-bin/behold.pl?ascribeid=20051229.080940&time=21%2005%20PST&year=2005&public=1]
References
* {{MSW3 Gardner|pages=3-21}}
* {{MSW3 Groves|pages=22-70}}
{{sisterlinks|Marsupial}}
{{Wikispecies|Marsupialia}}
{{Wikibookspar|Dichotomous Key|Marsupialia}}
{{mammals}}
Category:Marsupials
bg:Двуутробни
ca:Marsupial
cs:VaÄ?natci
da:Pungdyr
de:Beutelsäuger
es:Marsupial
eo:Marsupiulo
fa:کیسه‌داران
fr:Marsupialia
ko:ìœ ëŒ€ë¥˜
it:Metatheria
he:חיות כיס
lb:Beidelmamendéieren
nl:Buideldieren
ja:フクãƒãƒ?ズミ目
pl:Torbacze
pt:Marsupialia
ru:Сумчатые
simple:Marsupial
sl:VreÄ?arji
sr:Торбари
fi:Pussieläimet
sv:Pungdjur
*** Shopping-Tip: Marsupial
