Dinosaur tail found trapped in amber, covered with feathers
While most paleontologists dig up prehistoric bones from the ground, Lida Xing hunts for fossils in the amber markets of Myanmar. In 2015, he made a remarkable find: Trapped in what looked like golden glass was the feathered tail of a dinosaur.
Along with the primitive plumage, the 99-million-year-old amber also preserved soft tissue and eight complete vertebrae. The tail bones indicated that the specimen belonged to a dinosaur that was not a prehistoric bird and also provided researchers with insight into the evolution of feathers.
“This is the first time that skeletal material from a dinosaur has been found in amber,” Xing, who is a paleontologist at China University of Geosciences in Beijing, said in an email. He and his colleagues published their findings Thursday in the journal Current Biology.
After performing a CT scan and microscopic analysis, Xing and his colleagues realized that the feathers did not belong to a bird because the specimen’s tail vertebrae were not fused into a rod, as they are in modern birds. The feathers most likely belonged to a baby nonavian theropod, meaning it looked more similar to a velociraptor or Tyrannosaurus rex than to a modern bird. That said, it was probably only about the size of a sparrow.
After Xing found the amber, he sent it to Ryan McKellar, a paleontologist at the Royal Saskatchewan Museum in Canada, to further investigate the specimen.
“When it hit my desk, I was blown away,” McKellar, an amber expert and an author of the study, said. “It’s one of those things where you’re like, ‘Wow, it’s the closest you’ll ever get to holding a fleshed-out dinosaur in your hands.”
Most modern bird feathers have a central shaft called a rachis; think of the ink rod in a quill pen. Branching from the rachis are smaller shafts called barbs, and then branching from the barbs are smaller filaments called barbules.
But this specimen lacked the rachis; it just had barbs and barbules down its ribbonlike tail.
The finding suggests that the barbs and barbules evolved before the rachis in feathers.
That is interesting because the rachis seems to aid in flight. It could be that dinosaurs with more primitive feathers used them for temperature regulation, camouflage and visual signaling, rather than flight.