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.