If there was any lingering doubt about whether or not dinosaurs possessed bird-like feathers, the unprecedented discovery of a well-preserved, feathered dinosaur tail entombed in an almost 100 million-year-old piece of amber should put an end to the debate once and for all.
The fossilized tail, discovered by Lida Xing of the China University of Geosciences in 2015 in a Myanmar amber market in 2015, marked “the first time skeletal material from a dinosaur has been found in amber,” the paleontologist said in an interview with the New York Times.
A detailed look at the feathers’ structure (Credit; Credit Ryan McKellar/Royal Saskatchewan Museum)
Xing’s team, who reported the findings Thursday in the journal Current Biology, said that soft tissue and eight complete vertebrae were encased in the gold-colored stone and that based on an analysis of the tail bones, they can definitively conclude that it belonged to a dinosaur, not a bird. The specimen dates back to the mid-Cretaceous period and is around 99 million-years-old.
According to Quartz, the tail is believed to have belonged to a juvenile coelurosaur, a flightless dinosaur about the same size as a sparrow. The tail formed a tiny curl, was 3.67 centimeters long and found alongside approximately 2 centimeters of bone. It had soft, not rigid, plumage that was chestnut brown-colored on top and white underneath.
Reconstruction of soft tissue and feather bases in amber (Credit: Lida Xing)
Discovery sheds new light on the evolution of plumage
Dinosaur-era feathers were first discovered encased in amber five years ago, but as Quartz noted, earlier discoveries involved isolated plumage that scientists could not definitively say came from dinosaurs and not birds. With the new discovery, CT scans and microscopic analysis have shown that the specimen indeed belong to a dinosaur, proving that at least some had feathers.
Ryan McKellar, a paleontologist with the Royal Saskatchewan Museum in Canada and co-author of the new study, told CNN that he was amazed when he first saw the amber, calling it “a once in a lifetime find” that “really underlines the importance of amber as an anchor for future study.”
A small coelurosaur near a resin-coated branch (Credit: Chung-tat Cheung)
“We’re picking up features we couldn’t see in compressed sedimentary fossils,” including the hue of the feathers, McKellar added. In an interview with Quartz, he said that based on the number of specimens researchers have studied thus far, it is likely that “most theropod dinosaurs” possessed feathers or plumage “at some point in their life,” though not necessarily into adulthood.
McKellar went on to tell the Times that while the color was fascinating, that the most interesting part of the research was analyzing the structure of the feathers using a high-powered microscope. Unlike modern bird feathers, the coelurosaur plumage lacked a central shaft (known as a rachis). Instead, it just had barbs and barbules that were “more fuzzy than sleek,” the paleontologist said, providing “a rare glimpse” at how dinosaur feathers differed from those of modern birds.
According to the researchers, this appears to indicate that the barbs and barbules evolved before the rachis, which they noted appears to aid in flight. This would appear to suggest that dinosaurs used feathers not for flight, but to regulate their body temperature, for camouflage, and/or as a way to deliver visual signals to other members of their species.
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Image credit: CreditRyan McKellar/Royal Saskatchewan Museum
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