Feathered fossil provides clues about how earliest birds first took flight / A secret mathematical rule has shaped the beaks of birds and other dinosaurs for 200 million years / From dinosaurs to birds: The origins of feather formation / Quail-sized feathered dinosaur may be the earliest known bird / Birds are dinosaurs. Here's how scientists know / Bird brain from the age of dinosaurs reveals roots of avian intelligence / Researchers discover hidden step in dinosaur feather evolution / Scientists use robot dinosaur in effort to explain origins of birds' plumage