NCSE is pleased to offer a free preview (PDF) of David E. Alexander's On the Wing: Insects, Pterosaurs, Birds, Bats and the Evolution of Animal Flight (Oxford University Press, 2015). The preview consists of chapter 1, "Can't Tell the Players Without a Scorecard," in which Alexander explains, "Only four animal groups have evolved the ability to fly under power, and each of these groups evolved powered flight only once."
The publisher writes, "With an accessible writing style grounded in rigorous research, Alexander breaks new ground in a field that has previously been confined to specialists. While birds have received the majority of attention from flight researchers, Alexander pays equal attention to all four groups of flyers — something that no other book on the subject has done before now."