A walnut-sized coprolite, fossilised dung collected in 2016 from the Hell Creek Formation in Montana, in the United States, holds feathers together with gar scales and leg bones of a diving hesperornithiform bird. Two feathers show a square shaft with a sponge-like core, a pairing known in living birds and their nearest ancestors. The specimen records one predator's meal. Whether that plumage shaped which lineages came through the extinction is the researchers' interpretation.
A coprolite is dung turned to stone. In the Hell Creek beds of eastern Montana, David DeMar Jr of the Burke Museum picked up a dark, walnut-sized lump in 2016. Inside it sit feather remains, gar scales and leg bones from a hesperornithiform, a diving-bird group. The University of Washington team presents this as the first bird feather documented inside a coprolite.[1], [2]
Imaging showed two feathers whose shaft is four-sided and whose interior is a spongy fill. Living birds and the ancestors nearest them carry that same pair. The next fill of this kind is an early Eocene specimen from Denmark, roughly 10 million years younger. The plume visible on the coprolite's surface keeps that shaft-and-fill pair.[1], [2]
Sci.News links the lump to a bulky carnivorous dinosaur, perhaps Tyrannosaurus rex or Nanotyrannus, and assigns the plumage to that same hesperornithiform animal. Jingmai O'Connor of the Field Museum says the form of the plumage and the pattern of moult may have shaped which lineages exited the break 66 million years ago. The University of Washington account sets that claim apart as interpretation: the fossil shows what passed through one hunter, not why a clade lived.[1], [2]
