Feathers again

["Antoni Lacasa" <fossils@redestb.es>]

Hi all,

Why feathers?
There is no satisfactory explanation or answer but curiously...

1.- In terms of functional economy, the insulation wich feathers provide 
is much superior to that of hair over the same surface area.
2.- The feather structure provide,
                       a.- Insulator function.
                       b.- Waterproofing function.
                       c.- Others...(fly, sexual, etc...)
3.- Insulate is different of the waterproofing function.
4.- In the feathers, the impermeability require a complex structure, a 
closed network with critical space between its barbs and barbules in 
stiff or pinnate feathers.  
5.- In this way the waterproofing protects the insulation function.
6.- The inner body feathers show a basal zone with long flexible barbs 
and barbules (typical of the insulation function), whereas the outer 
part comprises a rigid pinnate structure which reaches through to the 
outside of the bird body to offer cohesion and waterproofing.
7.- Birds has not a sebaceous gland, exception the uropigial gland.The 
oils secretions are used by birds tho help keep their feathers flexible 
more than waterproofing, because feathers become sitff and brittle.

Perhaps therefore, those small, dino-birds protected their bodies with 
this clothing as consequence of feeding in an aquatic medium would tend 
to reduce corporal temperature encouraging insulating,waterproof feather 
covering to preserve thermal balance...

Toni fossils.