Showing Its Stripes
Photograph courtesy Institute of Fossil Paleontology and Paleoanthropology, Beijing
The feathers of Sinosauropteryx have been the subject of controversy ever since they were first described.
To the naked eye, the fossilized feathers are fine hairlike filaments that give the impression of being soft and downlike. Some researchers proposed that these structures were not feathers at all, however, but the remains of collagen from inside the tail.
The new study shows that these structures—visible in this fossil Sinosauropteryx as dark patches along the back and tail—are packed with melanosomes, pigment-carrying, sub-cellular structures found in the feathers of living birds but not in collagen.
This strengthens the argument that the fossil hairlike structures are protofeathers, an early stage in feather evolution before feathers had central shafts with vanes out to each side, as seen in modern birds.