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Re: Pterosaurs and birds, was Re: birds and pterosaurs
Are you thinking there is a metabolic difference
Yes, but not difference in general body metabolism,
but in energy and specific aminoacids dedicated to
form flight feathers.
Oh, gotcha, I misunderstood before. Interesting thought. I wonder how
much of a large bird's metabolic costs go to feather replacement; that
would definitely be very interesting to know. Thanks for clarifying
that point; I like it.
I think a paleontologist may not be accustomed to
think that physical efficency of animal is relative to
it's ecological niche.
Very large bird might be inefficent, but will evolve
and live when more efficent pterosaurs are extinct.
Their ecological niche may be restricted, but if there
are very food-rich conditions, they will evolve.
Oh, I don't disagree that pterosaurs had advantages as large-bodied
flap-gliding/soaring forms, and that the appearance of soaring birds
only after the K/T extinction is telling. Very large birds were
probably quite efficient, but large pterosaurs were probably more
efficient as soarers, with regards to energy extraction (though soaring
birds may have other advantages we are missing). I was arguing more
against the idea that extremely food-rich conditions are required for
the evolution of giant soaring birds, in large part because large size
is an advantage in searching large ranges for such animals (and thus
somewhat helpful for conditions with low food density). It might be
required, but it doesn't seem convincing at the moment.
Thanks for the snippet; that's very interesting. I
wonder why the molt
is so slow in those groups...
Because soaring bird can lose only few feathers at a
time. With slow speed of growth, big feather length,
many feathers - the cycle of replacement becomes long.
Right, that much makes sense. I was wondering why the feather growth
was so slow. But it may just be because the growth is being measured
as a linear growth rate, and the feather has to scale as 3-D structure
(albeit a flat one).