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




--- Tim Williams <twilliams_alpha@hotmail.com> wrote:

> But I think it is also 
> possible that the absence of feathers from
> _Archaeopteryx_'s head might be 
> real, and be associated with reasons other than
> scavenging.  I don't think 
> we have enough evidence either way.  As a very
> primitive bird, we might not 
> expect the head to be fully feathered (aside from
> the beak) as in modern 
> birds.

You suggest that more basal forms than A. had plumage
only on a part of their body and evolution towards
plumage covering whole body including head was slow.

I think it was opposite. In endotherm of A. size there
is a strong selection for complete insulation. I think
primitive small endotherms were already fully covered
with dinofuzz long before inergument evolved towards
more sophisticated feathers. 

I think forms the size of A. or Caudipterix or
Microraptor were fully covered with insulation. Very
few forms might have secondarily bald heads. Bigger
forms - size of Beipiaosaurus for example -  were
partially naked.

About A. it stuck me something else. Accepted version
is that terrestial animal discovered in seabed
sediment together with fish and crustaceans. 

There is high possibility that A. specimens were
partially decomposed carcasses washed into the sea and
lost small feathers after death and before depositing
is sediments. This would make real confusion when
people discover various extent of feathers on
different specimens!

Jerzy


                
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