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RE: Bird reduce their "heating bills" in cold climates



 
 
----------------------------------------
> Date: Mon, 5 Jul 2010 20:40:16 -0700
> From: pristichampsus@yahoo.com
> To: dinosaur@usc.edu
> Subject: RE: Bird reduce their "heating bills" in cold climates
>
> --- On Mon, 7/5/10, GUY LEAHY wrote:
>
>> From: GUY LEAHY 
>> Subject: RE: Bird reduce their "heating bills" in cold climates
>> To: "Tim Williams" , "Dinosaur Mailing List" 
>> Date: Monday, July 5, 2010, 11:21 PM
>>
>> Furthermore, scales and feathers can co-occur on the same
>> body parts:
>> http://elibrary.unm.edu/sora/Condor/files/issues/v032n01/p0064-p0065.pdf
>
> ++++++++++++++++++++++
>
> The examples cited always show malformed feathers, and, or scales, suggesting 
> a biochemical miscommunication more than a reversal.
>
> _________________________

 
Though the integument described for gulls is not typical, it does demonstrate 
the two integument types are not mutually exclusive.  
It's entirely possible this was more common in theropods, as the genes
responsible for scale formation may not have been supressed to the extent
they are in extant birds.  


>> It's entirely possible polar dinosaurs grew a coat of
>> dinofuzz/feathers over the scales to keep warm during the
>> dark winters, and seasonally shed this insulation when
>> summer approached.
>
> ++++++++++++++++++++++++++++++++++++++
>
> Possible? Yes. Probable? No. As I wrote earlier, it would involve dinosaurs 
> exhibiting a trait that we would have no example of today.
>
> ____________________________________________
>
>> Most birds have scales on the metatarsi, but willow
>> ptarmigans have a coat of feathers which covers the scales,
>> and this feather coat is seasonally shed from the ventral
>> portion of the feet:
>> http://elibrary.unm.edu/sora/Condor/files/issues/v079n03/p0380-p0382.pdf
>
> +++++++++++++++++++++++++++++++++++++++++++++++
>
> What the picture in that pdf doesn't show is that ptarmigans don't actually 
> have foot scales.
>
> See: 
> http://www.nawwal.org/~mrgoff/photojournal/2006/sum/pictures/07-10p36feet.jpg
>
> So growing winter snowshoes, and then dumping them in the summer is perfectly 
> reasonable.
--------------------------------------------------------
 
Besides ptarmigan, birds which have feathery feet include some eagles and owls. 
 In barn owls, the feather covering on the dorsal surface of the toes is thin 
enough to clearly see the underlying scales:
 
http://www.flickr.com/photos/25918339@N00/1874087885
 
http://www.barnowl.co.uk/upload/docs/593/talons___feet.pdf
 
Guy Leahy
 
-------------------------------------------------------------
>
>
>> Some theropods also had feathered metatarsi:
>> http://www.nature.com/nature/journal/v461/n7264/full/nature08322.html
>>
>
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> Indeed, so many that they probably represent the plesiomorphic condition.
>
> Jason
>
>
>