Fossil Feather in Dinosaur Feces Offers Clues to Bird Survival, Researchers Say

David DeMar, lab manager at the Burke Museum in Seattle, found the cherry-sized fossil while doing field work in the rocky badlands of Montana. He was crawling up a hill when he noticed a small dark, round object. After picking it up and turning it over, he saw a tiny fossilized branching structure embedded in a crack on its surface. He radioed colleagues, first got no response, and then told them he thought he had found a bird feather. The report says it was the first fossilized feather from this part of the world.

Jingmai O'Connor, a bird expert and associate curator of fossil reptiles at the Field Museum of Natural History in Chicago, joined the project. She said the feather looked quite modern and that her goal was to determine what animal it belonged to and what it could say about evolution. She called it, without a doubt, the best feather ever found from the age of dinosaurs, according to NPR News.

The round object holding the feather turned out to be a chunk of coprolite, or fossilized feces, produced by a large meat-eating dinosaur. O'Connor said Tyrannosaurus rex or Nanotyrannus were the more likely candidates. The coprolite had broken off from a few larger, softball-sized pieces where additional clues may later be found.

The team CT-scanned the small coprolite and found other feathers, a couple of bone fragments, and two tiny fish scales. After studying the feathers and bones, O'Connor concluded they likely came from the same animal adapted to life in water. She believes it was an ancient aquatic, swimming bird, kind of like a loon or a grebe, and described such birds as foot-propelled divers.

Richard Prum, an ornithologist at Yale University who did not contribute to the research, said it was impressive that such feather morphology could be detected in dinosaur poop. He called it remarkable and unexpected, saying there is nothing of that age so beautifully preserved, including evidence of individual cells.

The researchers argue that the fish scales preserved in the coprolite might have been remnants of the ancient bird's last meal before it became a meal for a predator like T. rex. That animal later defecated the fragments that DeMar would find roughly 66 million years later. The researchers say the fossil assortment may reveal part of a late Cretaceous food web from some 66 million years ago.

This bird was one of many types of birds that went extinct with the dinosaurs when the Chicxulub asteroid smashed into Earth, sending ash and soot into the air, clouding the skies and causing a dramatic planet-wide cooling. O'Connor said that during the Cretaceous there were many birds, but only one group survived the asteroid impact. That group gave rise to modern birds.

Researchers have wanted to know what gave the surviving birds an edge through the drop in global temperature. O'Connor thinks it may be related to better insulation. Building on her previous work, she noticed that some fossilized body feathers inside the coprolite from the ancient bird, whose relatives ultimately died out, appeared to lack the insulation of their modern counterparts. She said she is not arguing that plumage differences were the sole reason those birds went extinct, but that it was a contributing factor.

The NPR News report adds that not all researchers agree with that conclusion, quoting criticism that it is a stretch to explain the survivorship of some species and the extinction of others from that evidence.