Dinosaur dung preserves rare feathers, may explain bird survival

A 66-million-year-old piece of fossilized dinosaur dung has yielded the best-preserved feathers ever found from the age of dinosaurs, offering a new clue to why only one lineage of birds survived the mass extinction that wiped out the other dinosaurs. The discovery, published in the journal Current Biology, centers on a coprolite found in Montana's Hell Creek Formation in 2016. Researchers used microCT scanning to reveal its contents: feathers, leg bones, and fish scales from a hesperornithiform, an extinct group of diving birds.

The lead author, Jingmai O'Connor of the Field Museum in Chicago, said the feathers show a mix of modern and primitive features. The primary feather, measuring 9.3 centimeters, had a water-repellent structure similar to modern pelicans, with lightweight, spongy cores and a harder outer layer. However, the specimen also contained smaller, fluffy body feathers with loosely arranged branches, resembling primitive plumage found in 100-million-year-old amber from bird lineages that did not survive the extinction.

This combination suggests hesperornithiforms had an intermediate stage of feather evolution. While their wing and tail feathers may have aided...