Overview

• The Sonic Hedgehog (Shh) pathway plays a critical role in feather development, influencing outgrowth, branching, and invagination in chickens.
• Inhibiting the Shh pathway in chicken embryos led to the temporary formation of unbranched, proto-feather-like structures resembling early dinosaur feathers.
• Feather development demonstrated remarkable resilience, partially recovering by day 14 of embryonic development, with dormant follicles reactivating post-hatching to produce normal plumage.
• Feathers evolved from simple tubular proto-feathers in dinosaurs around 200 million years ago, with potential earlier origins in a common ancestor of dinosaurs and pterosaurs.
• The study highlights the evolutionary robustness of genetic networks and advances understanding of how proto-feathers and other morphological novelties emerged.