Convergence, Natural Selection, 'Survival of the Fittest'

 Convergent evolution is independent evolution of different species that forms similar features. This can commonly be mistaken for divergent evolution, which is when related species form different features which causes them to split into two species. An example discussed in "Improbable Destinies" chapter 1 was how marsupials and mammals are evolutionary distinct but have multiple counterparts that look similar. I chose to depict the sugar glider and flying monkey in my depiction but the chapter also discussed marsupial mole-mole, wombat-groundhog, quoll-wildcat, and thylacine-wolf. These animals look identical to one another but one is placenta bearing and one has an external pouch. 

This convergent evolution could possibly come from the fact that geologically the pouch bearing animals tend to have shorter gestation periods or that they are not able to provide enough nutrition to the growing marsupial without it being outside of the womb. Since mammals have longer gestation periods, their bodies most likely adapted to form a placenta.