Similicaudipteryx

It's already a well-known fact that China is the proverbial 90's mall for palenotiologists: everyone wants to be there since all the cool stuff is there. One thing that proves this is the discovery of Similicaudipteryx, annoucned this week in the journal Nature.

The fossils show feathers and how they changed as Similicaudipteryx aged. A juvenile and an older specimen were both found in western Liaoning, in China. Both fossils are approximatly 125 million years old.
Modern birds have fluffy down that is primarily to keep them warm, and once they molt, they grow what is essentially adult feathers. Similicaudipteryx, on the other hand, the juveniles have a "middle stage" in which their feathers are somewhat quill-like, more like ribbons than true feathers, while adults have more modern feathers. The younger individual also has longer feathers on the tail, while the elder had longer feathers on the wings.
The reason for this type of "feather evolution" isn't known why, but the different feather lengths for the different ages may be due to different needs: younger individuals would have a higher need to escape, while older individuals are more concerned about hunting and mating.

http://cosmiclog.msnbc.msn.com/archive/2010/04/28/2288537.aspx