Nature curiosity: Why do marsupials have pouches?

For marsupials, only adult females have pouches, and they serve an important role in the reproductive process. 

Meet the tiny Patagonian monito that is a 'living fossil' from the ancient past

How Did the Marsupial Get Their Pouch?, by Jennifer R. Povey

How Did Kangaroos Get Their Pouches? » Science ABC

A peek inside marsupial pouches

13 Bouncy Kangaroo Facts About Australia's Iconic Marsupial

Rock Run Rookery Preserve

10 Incredible Facts About Kangaroos

Quokkas Spotting - Where to see Rottnest Island's Quokkas

What to Expect When You're Expecting Joeys: A Guide for Marsupial Parents (and Curious Kids) by Bridget Heos

Marsupials CK-12 Foundation

Rock Run Rookery Preserve