Marsupialia

ARTICLE CONTENTS:  |  Suggested Reading  |  Links to Other Sites
Marsupialia, order of MAMMALS belonging to the infraclass Metatheria, comprising some 280 living species, of which two-thirds are found in Australia. The Virginia or North American OPOSSUM (Didelphis virginiana) is the only marsupial found in Canada.

Marsupials differ from placental mammals in many anatomical details, especially in the reproductive system. In the vast majority of marsupials, no placenta is formed and the young are born in a premature state after a brief gestation. The young complete their development attached to a teat and protected by skin folds or a fully formed pouch (marsupium).

Marsupials and placental mammals evolved at about the same time in the Cretaceous period (144.2-65 million years ago) from a group of primitive mammals, the pantotheres. The oldest FOSSILS are from the Upper Cretaceous (98.9-65 million years ago) of North America. Marsupials are found in North and South America and Australia, which they may have colonized, via Antarctica, before continental drift (see PLATE TECTONICS) moved Australia to its present location.

Opossum
Opossum
The opossum is Canada's only marsupial (Corel Professional Photos).
Opossum Family
Opossum Family
The opossum, poorly adapted to severe cold, reaches the northern limit of its range in extreme southern Ontario and the lower Fraser Valley, BC (artwork by Claire Tremblay).

Author C.G. VAN ZYLL DE JONG


Suggested Reading
C.G. van Zyll de Jong, Handbook of Canadian Mammals I, Marsupials and Insectivores (1983).


Links to Other Sites
Canadian Biodiversity Website
A great information source for all budding biologists. Learn about biodiversity theory, natural history, and conservation issues. From McGill’s Redpath Museum.

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