It reminds me of an experiment some biologists did (sorry can't cite) to demonstrate how wings could have evolved by showing how half a wing could help. They cu

It reminds me of an experiment some biologists did (sorry can't cite) to demonstrate how wings could have evolved by showing how half a wing could help. They cut short wings on flying bugs. The clipped bugs couldn't fly, but they could move around a lot faster on water surfaces, which seemed a clear advantage over walking speeds. You could imagine a leg evolving to act like a half-wing to give that speed advantage, then you could imagine that leg further evolving to a wing that could enable flight. Designers and inventors can learn from this. When we want to make a huge jump, like to a working jet pack for flying, it often helps to take small, evolutionary steps.