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RE: Sinosauropteryx feathers?

Dino Guy Ralph wrote:

> Evo devo suggests that feathers started out as a shaft; progressed to a 
> stage with notched epithelia; then developed notched  rachis, barbs, 
> and barbules; and finally lost the rachis to produce downy feathers!  
> Fun stuff.  If this is correct, it reinforces the fact that
> evolution does not always lead from the simple to the complex, but often
> from the complex to the simple 

Richard Prum also proposed that the down feathers (plumules) of modern birds
are derived from the simplication of pinnate feathers.  This does not imply
that the hair-like (filamentous) or down-like feathers of non-avian
theropods evolved via this pathway.  It is possible that the ancestors of
modern birds "re-invented" the plumulaceous feathers of their forbears by
modifying the development of contour feathers.