Re: Pterosaurs and birds, was Re: birds and pterosaurs

[Jorge Dichenberg <jorgedich@yahoo.com>]

--- don ohmes <d_ohmes@yahoo.com> wrote:

> If memory serves--
> Ken Campbell wrote up Argentavis Magnificens some
> years ago, and estimated that the primary feathers
> were as much as 4 ft long; these estimates made
> using
> the diameter of the holes in the ulna. (Wingspan was
> given as 7-8m.) At a feather growth rate of 1mm/day
> that is roughly 1300 days.... perhaps some feathers
> grew faster than others?

Rechecked, and it seems that vulture feather grows
10mm a day, which would make 4ft feather grow "just" a
third of a year. I assume it is possible that feathers
of Argentavis grew faster, or Argentavis could somehow
find food with lowered ability to fly. 

Still, moult and growth of feathers is a constraint
for modern birds. Feathers are keratin (protein) and
plumage is a significant part of body weight. 

Jerzy Dyczkowski
 
 





        
                
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