Take flying birds for example; suppose you aren't one, and you want to become one.You'll need a baker's dozen highly specialized systems, including wings, flight feathers, a specialized light bone structure, specialized flow-through design heart and lungs, specialized tail, specialized general balance parameters etc.
All of which probably co-evolve. If there's any co-dependency, then they're going to evolve together...
Right... In other words, you've got some dinosaur who never thought about flying and for some mystical reason, flight feathers with their complex matrix of interlocking barbules, the system for pivoting flight feathers, wings, light bone structures, and flowthrough hearts and lungs are all going to evolve at the same time.
That what you call logic there, Reep?