If, according to your belief system, evolution did not happen
Then every animal that exists currently exists as it was designed by its creator (God).
So, here's my dilemma. I am a designer myself, and have been taught and accept the fact that inefficient design is bad design. I don't believe this is a difficult concept, and surely an almighty being (who presumably embedded the rules of design into our subconscious) would have grasped it.
Bats are mammals. Like all mammals they have solid bones. Solid bones present a very interesting challenge to a flying animal because they are heavy. To solve this issue, the bones in the wings of bats vary in diameter to be lighter when necessary.
Bird bones, on the other hand, are hollow. This makes them lighter (more efficient for flight) but considerably weaker. Emus and penguins, which do not fly (and according to your belief system have never flown) are birds and have hollow bones. For obvious reasons, they do not gain the weight benefit of having hollow bones because they do not fly. Instead, they get the negative of having incredibly fragile bones.
So, my question to creationists/ID'ers is this. Why? If there is an intelligent designer, and he had already designed a perfectly elegant solution for flying animals, why not design the bat on the same basic framework instead of inventing another (considerably less desirable) solution? And logically speaking, it would be good design to give the Emu and the penguin solid bones, as hollow bones present no advantage in their environment.
So, how is this "intelligent" design?