2001•Encyclopedia of Life SciencesRequires access
Reproduction in Monotremes and Marsupials
Marilyn B. Renfree, Geoff Shaw
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Abstract
Abstract The three subclasses of mammals are most clearly distinguished from one another by their mode of reproduction and the anatomy of their reproductive tracts. The three species of monotreme are all oviparous, whereas the 276 or more living species of marsupial all give birth to small, altricial young that in most species are retained in the mother's pouch during the extended lactational period.