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



Tim.
 
You say that ....... "we now know that the simplest feathers in dinosaurs such
as _Sinosauropteryx_were only present over limited parts of it's body ...." and
from this you are inferring that they would have had limited function in 
thermoregulation. As the fossil stands .... fine. But are we absolutely sure 
that this is not simply an artifact of preservation (the limited tracts of 
feathers)??

----------------------------------------
> 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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