2.In both types of feather, the barbules that extend from the barb ramus grow from a single layer of cells, called the barbule plate, on the periphery of the barb ridge.
14.A discovery of 115 million-year old fossils in Siberia indicates that feathers were much more widespread among dinosaurs and developed much earlier than have been thought.
19.Their downy feathers do them a disservice during heat waves too, since they can't go for a swim to cool off until their waterproof feathers grow in.