Dinosaur tail feathers encased in amber may hold Jurassic secrets
Nearly 100 million years ago, a dinosaur died young in the midst of the forest. Now its tale is being told with the help of its feathery tail, which was preserved for the ages in a chunk of amber.
The sparrow-sized reptile was still growing when it perished of unknown causes, perhaps by getting stuck in the tree resin that would eventually entomb it. After its demise, the resin engulfed its tail, eventually hardening into a translucent, topaz-colored gem.
That gem, tail included, has been salvaged from a Burmese mine and subjected to scientific scrutiny. The amber is the first known to contain dinosaur feathering. It safeguarded the fluffy plumage so well that researchers can identify the finest details of the feathers’ structure.
On first seeing the gem and its contents, “I was blown away,” says Ryan McKellar of the Royal Saskatchewan Museum, co-author of a new study of the feathers in this week’s Current Biology. “It was just stunning. … (Studying it) was one of those once-in-a-lifetime-type projects.”
Miners and scientists have found amber chunks encasing feathers before, but an amber-coated specimen can’t be definitively linked to a dinosaur unless there’s part of a dinosaur in there, too. Until now, there hasn’t been.
It took an intrepid paleontologist to capture this dinosaur’s tail. In 2015, Lida Xing of the China University of Geosciences journeyed to northern Burma, the site of rich amber deposits mined for jewelry. The area is racked with conflict between Burmese troops and an ethnic group, making the mines too dangerous to visit.
Xing had cultivated a series of middlemen, and on this trip, a contact showed him a 1½-inch chunk of Cretaceous amber with supposed plant material inside it. Xing realized it was something better. He notified Dexu, a privately supported Chinese scientific institute, “that I had the world’s first and maybe the only dinosaur amber, and we had to get it,” he says. “Then they made it happen in the next 10 minutes.”
The amber includes slightly more than an inch of long, snaky, densely feathered dinosaur tail. The scientists’ best guess is that it was a maniraptoran, a kind of long-armed carnivorous dinosaur that walked on two legs. The study’s authors say the sample confirms the idea that the central shaft of bird feathers developed last, after the evolution of short sub-branches that sprout from the fibers that make up a feather’s flat surface.
The feathers suggest the tail was chestnut-colored on top and pale on the bottom, perhaps for camouflage or as a signal to others of its kind. The feathers were too flexible for flight, but the flattened tail “would’ve been good for hugging onto things,” such as tree trunks, McKellar says.
The thick plumage might also have been used for insulation, says Jingmai O’Connor of China’s Institute of Vertebrate Paleontology and Paleoanthropology, who was not involved with the study.
“This is a very small baby specimen,” she says, and would’ve quickly caught a chill in the cold climate of its time and place. “So it lends support to the hypothesis that feathers evolved to keep the animals warm.”
The dinosaur’s feathers look very much like the feathers found on the bodies and heads of many modern-day birds, says Teresa Feo, a postdoctoral fellow at the Smithsonian Institution’s National Museum of Natural History.
“I could go pick up a bird skin today and find feathers that look exactly like” those shown in the study, Feo says. “It’s crazy to look at something so old and realize you can find modern examples of it.”