This fossilized feather dates back to 66 million years ago, at the end of the Cretaceous period. “It is, without a doubt, the best feather we have found from the age of dinosaurs,” says Jingmai O’Connor, associate curator at the Field Museum of Natural History. Nate Carroll hide caption toggle caption Nate Carroll Paleontology can be pretty physical. In 2016, David DeMar was doing field work in the rocky lands of Montana in what is known as the Hell Creek Formation. “We all got down on our knees,” he remembers. “And I started crawling up the hill and I noticed this little round, dark object on the ground. It was a little strange.” DeMar, lab director at Seattle’s Burke Museum, collected the cherry-sized fossil. “I start looking at the surface,” he says. “And then I turned it around and thought, ‘You’ve got to be kidding me.'” Embedded in a small crack in the surface was a small fossilized branching structure. As it turned out, this was the first fossilized feather from this part of the world. Plus, “it’s without a doubt the best feather we’ve found from the age of dinosaurs,” says Jingmai O’Connor, a bird expert and associate curator of fossil reptiles at the Field Museum of Natural History in Chicago. The researchers say the plume, which they describe in the journal Current Biology, is part of a collection of fossils that may reveal part of a late Cretaceous food web from about 66 million years ago. And they speculate that it could help explain why, at that time, many types of ancient birds became extinct along with the dinosaurs after a giant asteroid collided with Earth, while others survived to give rise to the birds we know today. Excremental Progress After first detecting the round nodule, DeMar quickly radioed his colleagues. At first no one responded. “They probably thought I was joking,” he says. “But I went back to the walkie about five minutes later. I was like, ‘No, guys, I think I found a bird feather.'” Subsequent analysis confirmed DeMar’s conclusion. The plume dates back to the late Cretaceous, just before the great extinction event that wiped out the dinosaurs and a host of other species. When O’Connor joined the project, very little was known about the pen, except that it looked quite modern. “My goal was to try to figure out which animal this feather belonged to,” he says, “and then, in the grand scheme of evolution, try to say, ‘Well, what can this exceptional feather tell us?'” The round object in which the feather was located turned out to be a piece of coprolite (that is, fossilized feces) produced by a large carnivorous dinosaur. “So I would say Tyrannosaurus rex or Nanotyrannus are the most likely candidates,” O’Connor says. (This coprolite had actually broken off some larger, baseball-sized pieces, where additional clues may be found later.) The team CT scanned the small coprolite and found that it contained other feathers, a couple of bone fragments and two tiny fish scales. After studying the feathers and bones, O’Connor concluded that they probably came from the same animal adapted to life in water. She believes it was an ancient swimming aquatic bird, “something like a grebe or a grebe,” she says. “They are foot-propelled divers.” “It is certainly impressive that this striking feather morphology can be detected in dinosaur feces,” says Richard Prum, an ornithologist at Yale University who did not contribute to the research. “That is remarkable, unexpected. There is nothing from that era that is so beautifully preserved, [including] “Evidence from single cells”. The researchers argue that the fish scales also preserved in that coprolite could have been remains of the ancient bird’s last meal before it too became food for a predator like T. rex, and that that animal later defecated the fragments that would be discovered by DeMar approximately 66 million years later. and sent ash and soot into the air, clouding the skies and causing dramatic cooling across the planet. “We have all these birds during the Cretaceous,” says O’Connor. “And only a group of birds survives when the asteroid impact occurs.” O’Connor thinks it may have to do with the fact that they were better. From his previous work, he noticed that some of the body feathers fossilized within the coprolite of the ancient bird (whose relatives eventually disappeared) appeared to lack the insulation of their modern counterparts. “How do they stay warm when it’s cold, when this?” [asteroid] What impact does winter have?” he says. O’Connor isn’t arguing that differences in plumage are the only reason behind the extinction of these birds. “I’m saying it’s a contributing factor.” However, not all researchers agree with the conclusion. “I think it’s a stretch to explain the survival of some. [species] and the extinction of others from that evidence,” says Julia Clarke, an evolutionary biologist at UT Austin who was not involved in the study. “The fragments themselves are incomplete.” Still, she gets carried away by the snapshot of a food chain seemingly captured by this piece of poop. “A dinosaur ate a waterfowl that ate a particular type of fish,” she reflects. “It’s almost like they discovered a Cretaceous turducken.” What O’Connor thinks they’ve discovered “Now that we know that the coprolites of some carnivorous dinosaurs can preserve soft tissues,” he says, “now we have all this potential to find not only fossilized feathers, but also fur and other soft tissue structures.”
