Convergent evolution with Placental mammals and Marsupial mammals _SANDERS 2011_ by xiagong0815


									Convergent evolution with Placental mammals and Marsupial mammals

Marsupials are a type of mammal that are thought to all have pouches, such as kangaroos.
Although only about half have pouches, the defining factors for are marsupial are
reproductive differences. Placental mammals have 3 holes, an anus, urethra, and vagina,
while marsupials have an anus, and a cloaca that serves as the exit point for urinary and
reproductive uses. The uterus is actually forked, and the babies are born at a very early
stage and finish development outside the mother. Placental mammals do much
development inside the mother from nourishment from the placenta.

Adding some pictures to illustrate these convergent evolutionary relationships would be
very interesting. It might spark interest in animals that most students have never heard of.

Old World                             New World/Americas
Tasmanian wolf (extinct)      =       wolf
Native Cat                    =       ocelot
Flying phalanger              =       flying squirrel
Wombat                        =       groundhog
Numbat                        =       Anteater
Marsupial mole                =       Mole
Mulgara                       =       Mouse

These relationships were identified by George Gaylord Simpson.

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