Bird feathers from a Late Cretaceous coprolite.

Exceptional three-dimensional feather from a Late Cretaceous coprolite shows modern lightweight, stiff pennaceous feathers existed in Pennaraptora before the end-Cretaceous extinction.

• Why it matters: Understanding feather evolution near the rise of crown birds is limited due to the scarcity of well-preserved fossils, hindering insights into how flight and insulation features developed.
• What they did: The study examined a highly preserved feather in a Maastrichtian coprolite, using micro-CT scans to analyze its structure and associated remains, identifying it as belonging to a flightless aquatic bird lineage.
• The result: Findings suggest modern feather features appeared before the mass extinction, and plumage differences may have contributed to the survival of crown-group birds, informing avian evolutionary history.