Re: Origin of feathers

["Jaime Headden" <jaemei@hotmail.com>]

I wrote:

<<Anyway, the Djadochta doesn't seem to be very good at preserving 
impressions, such as Santana, Solnhofen, Las Hoyas, or Yixian beds. We 
may have to wait a while to see the evidence for, and if it doesn't 
appear, that could mean it may not exist.>>

Tracy Ford wrote:

<If Oviraptor did have large feathers on the wing wouldn't it have some 
impression on the 'wing' to indacate it like Rhonavis (sic)? Those would 
be 'huge' feathers and I'd think that they would.>

  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). 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.

  Dinogeorge did point this out to me as a reason why brachial feathers 
would have not been the ideal or most-likely to be used for shading, so 
it would be prudent to list both as possibilities. It is not unlikely 
the secondary-feather-type was used to "parasol" the eggs, given the 
posture, but ostriches use this same posture when incubating, so it is 
as likely there are plumes. Perhaps one species had plumes, another 
secondaries? :-)

Jaime A. Headden

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