That Thing With Feathers Trapped in Amber? It Was a Dinosaur Tail
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.
A 99-million-year-old piece of amber with a feathered dinosaur tail trapped inside.
“This is the first time that skeletal material from a dinosaur has been found in amber,” Dr. 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, Dr. 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 death, the tiny dinosaur’s body was most likely covered in tree resin. The resin is produced as a defense mechanism against insect infestations. When it dries it becomes a plasticlike substance that can survive for millions of years.
“Once the resin leaks out on the side of the tree it’s like a big sticky trap waiting for anything to fall into it,” said Ryan McKellar, a paleontologist at the Royal Saskatchewan Museum in Canada and an author of the study. “Then once the next resin falls on top of the existing one, it seals it in.”
“树脂从树干侧面流出后，就好像一个富于粘性的大陷阱，等待着自投罗网的任何东西，”该论文作者之一、加拿大萨斯喀彻温省皇家博物馆(Royal Saskatchewan Museum)的古生物学家瑞安·麦凯勒(Ryan McKellar)说。“等到新流出的树脂落到原有树脂顶上，它就会被封存起来。”
After Dr. Xing found the amber, he sent it to Dr. McKellar, an amber expert, to further investigate the specimen.
“When it hit my desk, I was blown away,” Dr. McKellar 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.”
Using a high-powered microscope, Dr. McKellar recorded images of the amber. He found that the underside of the feathers was white and the top was chestnut brown. But it was not the color that fascinated him the most.
“I was seriously puzzled by the feather structure we’re seeing in this sample,” he said.
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 even smaller filaments called barbules. But this specimen lacked the rachis; it just had barbs and barbules down its ribbonlike tail.
“They are more fuzzy than sleek,” Dr. McKellar said. “It shapes our view of how feathers came to develop in modern birds, and it gives us a rare glimpse of what dinosaurs looked like and potentially what feathers were being used for in the mid-Cretaceous.”
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.
“It’s a spectacular specimen,” said Mark Norell, a paleontologist from the American Museum of Natural History, who was not involved in the study. He added that because the feathers were found with the vertebrae, there was no question they belonged to a nonavian theropod dinosaur as opposed to a prehistoric bird. “This is a novel feather type that we haven’t seen before.”
“这是一件令人惊叹的标本，”美国自然历史博物馆(American Museum of Natural History)的古生物学家马克·诺雷尔(Mark Norell)说。并未参与该研究的诺雷尔还表示，鉴于羽毛是和那些椎骨一起被发现的，毫无疑问它们属于一只非鸟兽脚类恐龙，而非史前鸟类。“这是我们以前没有见过的一种新的羽毛类型。”