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RE: Did Feathers Evolve for Dispaly? We Still Don't Know!

It should be noted that the discernment of melanosomes & phaeomelanosomes in 
these extra-integumentary structures of *Sinosauropteryx* upsets previously 
publiashed arguments by Lingham-Soliar, Feduccia & Wang, 2007, _Proc Roy Soc 
Lon B_ 274:1823 & Lingham-Soliar, 2009, _JOrnith_ that these are internal 
collagenous structures comprising a midline fin. If these structures are 
correctly identified as melanosomes of any sort, that is (not saying that they 
are not -- I've not seen the paper).


Jaime A. Headden

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> Date: Wed, 27 Jan 2010 18:19:47 -0800
> From: tijawi@yahoo.com
> To: dinosaur@usc.edu
> CC: tijawi@yahoo.com
> Subject: Re: Did Feathers Evolve for Dispaly? We Still Don't Know!
> Michael Erickson  wrote:
>> Hence the title of my post - did feathers evolve for
>> display? Maybe. Maybe not. (My own personal opinion is
>> 'not', but that digresses, and matters little anyway.) The
>> point is that the hypothesis that feathers initially evolved
>> as display devices is really no more robust today than it
>> was yesterday, or the day before that, or the day before
>> that.
> Yes, the paper by Zhang et al. is a great deal more guarded on this point, 
> and essentially leaves the question hanging...
> "As the melanosomes are preserved in life position in the Jehol fossils,
> detailed study of differences in their spatial distribution, including
> orientation and density, and the relative abundance of each type, will
> reveal greater detail regarding both colour and colour patterning. 
> Reconstruction of colour patterns will also inform debates on the
> functions of feathers in non-avian dinosaurs, whether primarily for
> thermoregulation, camouflage or communication."
> Most of the paper is devoted to description of the melanosomes, and why the 
> authors believe they are genuine melanosomes and not artifacts. The biology 
> of the animals themselves is only mentioned in the last paragraph, and 
> speculation (such as what the coloration was actually used for in the animal) 
> is kept to a minimum. The latter is probably driven by the need for brevity. 
> This is a Nature paper, after all.
> However, the news story you mention does address the issue of why 
> display/communication is preferred over thermoregulation as a reason for the 
> inception of feathers (and like you, I'm including 'protofeathers' under this 
> heading). Quoting Benton directly from the article:
> "Furthermore, we now know that the simplest feathers in dinosaurs such as 
> _Sinosauropteryx_ were only present over limited parts of its body – for 
> example, as a crest down the midline of the back and round the tail – and so 
> they would have had only a limited function in thermoregulation."
> So if most of the animal remained 'naked', then the f
> dy heat and help keep it warm. I actually like this idea of display being the 
> original function of feathers. For example, imagine if huge eye-spots were 
> found on the inside wings of _Microraptor_!
> Cheers
> Tim
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