Darkwing by Kenneth Oppel

Dusk is the first of his kind - a chiropter that can fly - a bat.  The rest of his colony must climb and glide, but Dusk has wings and can fly like a bird.  He is thought of as an outcast and would not be accepted at all if not for his father, the leader of the colony.  Carnassial is another chiropter who has changed.  He has become carniverous and becomes a predator to the other chiropters.  In this novel showing the evolution of mammals during the extinction of the dinosaurs, the animals find that although they are no longer alike, their various powers give them different leadership abilities.  Dusk becomes a leader because of his ability to fly, see in the dark, and use echolocation.  He leads his colony to safety from the carnivores and finds them a new safe home.