Think About Feathers
Velcro-like hooks on the barbules interlock to form a windproof vane on either side of the rachis. The light and flexible surface area created by this microstructure allows birds to create two efficient airfoils –the wings.
The leading edges of primary and secondary wing feathers are shorter to prevent any mid-air twisting that might ruin the efficiency of the airfoil.
Long and loose, the barbules on downy feathers trap air next to the bird’s warm body.
The rachis is short or absent, so down can easily stay tucked in under the contour feathers creating an insulating layer close the skin.
Once scientists observed the process of feather growth closely, they began to suspect that the evolutionary pathway might mirror the steps in the growth process – after all, evolution and development are closely linked. The Aha! moment came with the discovery of dinosaur fossils adorned with ancient feathers from each of the proposed evolutionary steps. The upshot? Feathers weren’t always for flight, their first functions were likely insulation and display.
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