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The Patagonian opossum ''(Lestodelphys halli)'' is the sole species in
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencla ...
''Lestodelphys''.


Distribution

The Patagonian opossum occurs further south, in
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
, than any other living
marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a ...
. Although distributed throughout some parts of southern Argentina, it is one of the least known mammals of South America. They have been spotted near Monte Phytogeographic Province, and in Patagonia Phytogeographic Province, yet there are no records of Patagonian opossums in central Patagonia, which leads mammalogists to believe that they can only live in the Patagonian steppe. There are two areas in the Patagonian steppe where these animals are often found: the province of La Pampa and Choele Choel (northern
Rio Negro Province Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...
).


Form

It is suggested that the Patagonian opossum may have emerged from the same ancestral group as ''
Marmosa The 27 species in the genus ''Marmosa'' are relatively small Neotropical members of the family Didelphidae. This genus is one of three that are known as mouse opossums. The others are '' Thylamys'' (the "fat-tailed mouse opossums") and '' Tlacua ...
''. They resemble each other closely. In the winter both types have similarly thickening at the base of the tails, where fat accumulates. Yet they do not share all aspects of their lifestyle; Patagonian opossums have a specialized way to gather and consume food, which is made possible by the shortening of their skull and jaws. The shortening occurs in the premolar region; this gives the Patagonian opossum increased biting power.


General characteristics

The general appearance of the Patagonian opossum is similar to that of mouse opossums, except they have specialized features due to their predatorial way of life. Unlike mouse opossums, their skull has a reduced muzzle, wider zygomatic arch, as well as a crowded premolar region. Patagonian opossums have rather short fur, that are fine and soft. Their fur are usually gray, with the posterior being dark gray, the sides being a paler shade of gray, their shoulders are dark and their cheeks as well are eye region are white in color. Their ears are short, they are a pink flesh color, with the base of their ears being white. Their tails are much shorter than their head and their body.Thomas, O. 1921. A new genus of opossum from southern Patagonia. Ann. Mag. Nat. Hist., ser. 9, 8:136-139


Dentition

The Patagonian opossum has generally 50 teeth. 18
incisors Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
, 4 canines (tooth), 12
premolars The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mout ...
, and 16 molars (tooth). Their canine is exceptionally long, and they are almost completely straight and vertical. The first pair of incisors are set aside from the other incisors, yet all of the incisors remain the same size. Incisor number 1,3,4 on the bottom jaw are curved at the base, while incisor number 2 is straight. The premolars increase in size from the first premolar to the third premolar. The first premolar is very reduced in size compare to the other premolar. The premolars also have a distinct set of cusp on them called the posterobasal cusp. Their molars are extremely long, combine all the length of the premolar and it will barely exceed the length of the first two molars. The upper molars are narrow in size, compared to any of the other living opossums.


Diet

Being a member of the Didelphidae (
opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...
s), Patagonian opossums feed mainly on insects and fruits, yet insects and fruits are fairly rare in far-southern habitats. The shortage of fruits and insects in southern regions has led the Patagonian opossum to feed on mainly birds and mice. One specimen of Patagonian opossum was caught using a dead bird as bait; this led some researchers to believe that the Patagonian opossum lives totally on birds.Walker, E. P. et al. 1968. Mammals of the World. Johns Hopkins Press, Baltimore, 2nd ed., 2vols., 1500pp


References

{{Taxonbar, from=Q692361 Opossums Mammals of Patagonia Marsupials of Argentina Mammals described in 1921 Taxa named by Oldfield Thomas