|MadSci Network: Evolution|
It would seem that evolution should have produced a large number of species that can breath both air and water. The advantages in finding food and adapting to changing environments would seem to give a species with such a combination major advantages. Yet only a few amphibians have such attributes! Is there a good reason why larger more complex creatures did not evolve to breathe both air and water? (And I wish I could scuba dive without air tanks.)
Re: Why didn't mammals evolve with lungs and gills?
Try the links in the MadSci Library for more information on Evolution.