How did feathers evolve?

To look at the evolution of modern bird feathers, we must start a long time ago, with the dinosaurs from whence they came. We see early incarnations of feathers on dinosaur fossils, and remnants of dinosaurs in a bird's wish bone. Carl Zimmer explores the stages of evolution and how even the reasons for feathers have evolved over millions of years. [Directed by Armella Leung, narrated by Carl Zimmer].