Fossilized dinosaur dung preserves feathers from extinct aquatic bird

A fossilized dinosaur coprolite found in Montana contains several exceptionally preserved feathers, bone fragments and fish scales, offering a rare glimpse of a late Cretaceous food chain about 66 million years ago. Researchers led by Jingmai O’Connor identified the remains as likely belonging to a small, flightless aquatic bird from the extinct hesperornithiform group, which resembled modern loons or grebes. The sequence appears to show a fish eaten by the bird, the bird consumed by a predatory dinosaur, and the undigested remains preserved in its feces. The feathers include a sponge-like internal structure previously known only in modern birds and their immediate ancestors, extending the known record of that feature by roughly 10 million years. Although the discovery does not establish why some birds survived the asteroid-driven mass extinction while others vanished, it provides new evidence for comparing extinct bird lineages with the neornithines that gave rise to modern birds.