How dinosaurs became birds

Scientific American has the goods.  An excerpt:

But it has become increasingly clear that the story of how dinosaurs begat birds is much more subtle. Discoveries have shown that bird-specific features like feathers began to emerge long before the evolution of birds, indicating that birds simply adapted a number of pre-existing features to a new use. And recent research suggests that a few simple change—among them the adoption of a more babylike skull shape into adulthood—likely played essential roles in the final push to bird-hood. Not only are birds much smaller than their dinosaur ancestors, they closely resemble dinosaur embryos.