Feathers Before Flight

摘要: Feathers are branched structures consisting of β-keratin—a rigid protein material formed by pleated β sheets—with a hollow central shaft. They strikingly different from other forms vertebrate integument such as scales, skin, and hair. Until recently, evolutionary hypotheses envisioned their origin through elongation broad, flat scales driven selection for aerial locomotion gliding or flapping flight. Over the course past two decades, fossil discoveries, especially northeast China, have revealed that early precursors feathers were filament-like rather than expanded pinnate modern aspect predate active The revolution in our understanding feather evolution continues, rapid discoveries new information study extant birds.