Sixty-six million years after an asteroid reshaped the living world, a single fossil feather — preserved with uncommon clarity — invites scientists to ask again why some creatures endure catastrophe while others vanish. Researchers studying this specimen believe its microscopic structure may illuminate the physical traits or behaviors that allowed certain bird lineages to cross the K-Pg extinction threshold and seed the ten thousand species that fill our skies today. It is a small object carrying an enormous question: what, in the end, makes life resilient?