See Lake Titicaca water frog on YT " A&E The undersea world of Jacques Cousteau " hingsadoa channel. Cousteau points out that the frog isn't amphibious like a toad which needs to surface to breath with it's lungs. Instead its lungs have atrophied to the point of being useless and instead bag like layers of skin can absorb oxygen out of the water via capillaries. His hypothesis is that the oxygen poor air drove the frogs to become aquatic where the oxygen was richer. Who can think of a mechanism where such things can evolve just from frogs swimming around in water ? Were there ancient switched off genes that reactivated ?
Wikipedia article about frogs says that many species can absorb oxygen & water through their skin. It also says that in Lake Titicaca the oxygen content is lower than in lower altitude lakes which is probably why the extra skin flaps evolved. The original sin of many religious people is when they write off an idea before they have even researched it, which is why they are religious. That is why I was stuck in christianity so long- didn't read widely enough.