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

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?

--- Jorge Dichenberg <jorgedich@yahoo.com> wrote:

> Just to hijack the thread.
> I learned that flight feathers of large soaring
> birds
> grow slowly, ca. 1mm/day. This means that largest
> flight-feathers of vultures and pelicans take 3-4
> months to grow.
> I suspect that feather length and not body mass is
> limiting size of flying birds. 
> Bird needs to replace flight feather by moult at
> least
> every 2 years, cannot lose too many feathers without
> becoming flightless, cannot feed while flightless (I
> talk about specialised flying scavengers and
> fisheaters) and thick base of feather means that
> extending wing by growing the flesh part of wing
> results in very heavy wing. Ergo - there is some
> limit
> of bird wingspan. 
> Possibly for very large flying animals, wing
> membranes
> are more efficent than feathers, models of animal
> flight based on largest birds are biased and
> pterosaurs achieved true limit of size of flying
> animal.
> Jerzy Dyczkowski 
> PS. I am aware that ornamental bird feathers are
> longer and birds feeding on water plants can become
> flightless during moult.
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