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Re: Tar and feathers



David Marjanovic <david.marjanovic@gmx.at> wrote:

The Berlin specimen of *Archaeopteryx* still has impressions of contour feathers on both sides of the left lower leg. Get a photo and look. I do not understand why it was once claimed that *A.* lacked or could have lacked feathers except for remiges & rectrices.

The controversy surrounding the disposition of feathers in _Archaeopteryx_ concerns not so much whether it has contour feathers or not, but whether it had tertials. Tertials are the "inner wing" feathers, and their presence governs the proximal extent of the wing. Considering the length of the humerus in _Archaeopteryx_, the absence of tertials would create a big gap in the wing. The presence/absence of tertials has ramifications for flight in _Archaeopteryx_ and, ergo, for the evolution of avian flight.


We know that adult *Carnotaurus* did not have feathers over most of
their bodies.

I'm glad you specifed *adult* _Carnotaurus_. I'm confident that the presence of feathers in at least some dinosaur taxa will one day be shown to have an ontogenetic component. One hypothesis is that feathers began as downy structures in baby dinos and were retained (by neoteny) in taxa that achieved only a small adult body size (e.g., maniraptoriforms) and those that lived in polar regions (e.g., Australo-Antarctican ornithopods, as mentioned previously).




Tim


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