The golden chunk of amber is 99 million years old. Inside sits something extraordinary. It’s a tiny dinosaur tail — with pristinely preserved feathers.
The tail is about the length of a matchstick, a bit under 37 millimeters (1.5 inches). It curves through the fossilized resin known as amber. Within, eight full sections of vertebrae are present. Mummified skin can be seen shrink-wrapped to bone. A full-bodied bush of long filaments sprouts along the tail’s length. A team led by Lida Xing of the China University of Geosciences in Beijing, China, described the finding December 8 in Current Biology.
It’s “an astonishing fossil,” they write. Feathers from this time period, the Cretaceous, have been found trapped in amber before. The new find, however, is the first with clearly identifiable bits of dinosaur included. The tail bones of the new fossil gave Xing’s team a clue to the dino’s identity. It may have been a young coelurosaur (see-LOOR-uh-soar). It would have looked something like a miniature Tyrannosaurus rex.
Dinosaur feathers pressed flat into rock don’t always provide much information about structure. Those preserved in amber can offer more, the authors point out. In amber, “the finest details of feathers are visible in three dimensions,” the researchers write.
The little dino’s feathers lack a well-developed rachis. This is the narrow shaft that runs down the middle of some feathers, including those used by modern birds for flight. Instead, the dino’s feathers may have been ornamental, the authors say. Under a microscope, they appeared chestnut brown on top, and nearly white below.