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RE: Microraptor Had Iridescent Plumage



The support for this hypothesis is, admittedly, negative evidence. 

Thus, at any moment, a fossil could be reported that shows feathers rooted at 
the distal rostrum.

However, for Mick and I to draw in these feathers right now, where there is no 
positive evidence for them, seemed to us to be less supported. And we did 
debate it, especially Jakob checked Mick and I on it.

I have examined the specimen of Dave, yes. 

I have encountered the hypothesis of feathered snout tips in internet chats 
pretty often. Can I ask, is it based on a  hypothesis of the genetic 
development and evolution of feathered integuments? Is it that there is a 
hypothesis that feathering absolutely everywhere must precede keratinization of 
selected areas in the bird lineage? Because NGMC 91 definitely also has 
tubercles - reticulae - on the toes, which are keratinized structures on the 
scute spectrum. Thus, this animal definitely had keratinized and feathered 
areas on the same body. Moreover, in galliforms feather follicles, forming in 
the dermis, can erupt right through scutes. That seems to me to invalidate, or 
at least present exceptions to, any hypothesis that the development of feather 
placodes is inhibited by skin keratinization gene activation or vice versa.
________________________________________
From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of David 
Marjanovic [david.marjanovic@gmx.at]
Sent: Friday, March 09, 2012 9:21 AM
To: dinosaur@usc.edu
Subject: RE: Microraptor Had Iridescent Plumage

> I agree that there is no positive evidence of naked skin or scales
> preserved on the snout.
>
> Do you agree with me that there is also no positive evidence of feathers
> on the tip of the snout?

Sure.

> In NGMC 91 (Dave) we see an orderly decrease in the size of the
> feathers - growing shorter rostrally. No more feathers are preserved by
> the time we reach the proximal border of the nostril.

You're at the AMNH -- have you seen the specimen? I haven't; what I've seen is 
an annoying tendency to prepare the matrix away fro
ips of everything. Any feathers would be lost that way. In *Eoenantiornis*, 
feathers reach almost all the way to the tip, and the tip itself is prepared 
out.

> There are also none on birds.

Doesn't count, because you can't have a beak and feathers in the same place. 
I'm not aware of evidence for a beak in any deinonychosaur, including 
*Archaeopteryx* which preserves claw sheaths.

> Therefore don't you agree that the hypothesis that is most consistent
> with the evidence is that of a bare distal rostrum?

No.