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Re: Origin of feathers



<<This is true for modern avians, and even Archie and *Rahonavis* 
possessed ridges on the ulna, but this purpose is to anchor the 
feathers, to give them support when air pressure worked against them, as 
in flight, or in animals of direct association with volant birds 
(secondarily flightless, in other words).>>

     Hold up.  Archaeopteryx has no such ulnar papillae as shown 
conclusively by Wellnhofer.  The ulna of Archaeopteryx is relatively 
thin and narrow compared to "higher" birds such as enantiornithines and 
ornithurines.  

<<My proposition was that the lack of such a ridge and the assumed 
appearance of a region that would be covered by feathers would mean that 
these would not be of the anchored-type, but mobile. The ulna of the 
_incubating_ *Oviraptor* is extremely rounded, as is all other 
oviraptorosaur ulnae, so the idea of an ostrich-type plume-feather is 
more ideal than a secondary- feather arrangement, and to a degree agrees 
with the fossil evidence.>>

     The ulnae of oviraptorosaurs are rather large and robust and >may< 
have anchored bird-like primaries and secondaries.  However, in many 
ratites which anchor reduced but present remiges on their forelimbs,  no 
such ridge ( or papillae ) is present.  
     The purpose of the ulnar papillae is first and foremost a strong 
articulating surface for flight remiges so the bird can flap its wings 
without having to worry about the feathers falling out.  The lack of 
such papillae is not evidence that a particular bird did not fly,  for 
many birds lack ulnar papillae ( for example,  _Foro panarium_ ).  

Matt Troutman

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