Bumble bees

For the longest time, no-one knew how it was possible for bumble bees to fly. In conventional wisdom, their wings are too small to create the upward force required to actually lift them into the air and keep them there.

It wasn't until camera technology had become sufficiently advanced for the flight of bees to be recorded and slowed down enough to actually see what was going on in the wings that the secret was unlocked: the wings don't just move up & down like a bird's. Instead they swing back & forth as well, causing vortices above some of the wings some of the time that serve to increase the lift.

Good old bumble bees! And they're cute, too.