Early Mammals

Mammals originated in the Carboniferous when therapsid reptiles diverged from lineages that led ultimately to modern reptiles and birds.

There are three mammalian lineages:

Egg-laying mammals (Monotremes) are represented today only by the platypus and two kinds of spiny anteater in Australia. They are practically toothless. They lay eggs but suckle their young.

The platypus is a mosaic of reptilian, avian, and mammalian traits. Despite its collection of peculiar features, this animal survives very well in the environment to which it has become adapted.

Most of the 260 species of living Marsupials are native to Australia and nearby islands. Only the opossums are found in North America. The young are born in an undeveloped state and complete development in a permanent pouch on the mother.

Pouched mammals, such as the opossum of North America, give birth to tiny, blind, hairless young that find their way to the mother's pouch where they are suckled and finish their development.

You can listen to a a Koala Bear at the San Diego Zoo. You do not need to read the page itself.

The Tasmanian Devil is not just a cartoon figure, it is a flesh eating marsupial. This critter is only found on the island of Tasmania which is off the coast of the Australian continent.

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