16 SEP 2011 by ideonexus
Convergent Evolution in Mammals and Marsupials
The most famous example of different species filling similar roles involves the marsupial mammals, now found mainly in Australia (the Virginia opossum is a familiar exception), and placental mammals, which predominate elsewhere in the world. The two groups show important anatomical differences, most notably in their reproductive systems (almost all marsupials have pouches and give birth to very undeveloped young, while placentals have placentas that enable young to be born at a more advanced ...Although they have very different reproductive strategies, the two groups have many parallels in species adapted to the same environments.