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Re: Archaeopteryx with bird book, was Re: Archaeopteryx flight




--- Patrick Norton <ptnorton@suscom-maine.net> wrote:

> > In total, maybe 1% of living birds have bald
> heads.
> > Scavenging birds are much bigger than A., possibly
> > because carrion is scarce resource and they need
> > passive flight to cover vast areas to locate it.
> 
> Where is the evidence of selection for baldness in
> scavenging birds?  Other 
> than vultures, I can't think of any other type of
> scavenging bird that is 
> bald (crows, ravens, magpies, gulls as well as some
> types of owls, herons 
> and raptors). And several of these types of
> scavenging birds are not much 
> bigger than Archie. The absence of head feathers in
> Archie is far more 
> likely an artifact of preservation than evidence of
> baldness. Flight 
> feathers, which are anchored to bone, are more
> likely to remain affixed 
> during preservation than contour feathers.

Specialised scavengers with bald heads are Old World
and New World vultures and marabou and adiutant
storks. 
I think all vultures have bald heads, except small
egyptian and hooded vultures and palm-nut vulture
which is not a scavenger.  

Other birds eat mostly other food, although lots of
birds scavenge if they can. Some seabirds are also
mostly scavengers (giant petrels etc.) but don't have
naked heads, possibly due to contact with cold water.

I agree that A. most probably was fully feathered, but
body feathers were not preserved.

Jerzy 



        
                
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