Well, that might be due to the fact that not many trees grow under water. But penquins do "fly" out of the water onto the land. As to being odd for two things to use the same object differently, that was not the problem. The problem is the just-so nature of the tale of Darwinian evolution.
Concerning your swimming chicken, have you seen the latest evidence for the swimming theory of evolution?
Sounds like the evos have finally found the ancestor of birds! Those Chicomms can do wonders with Super Glue!