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More questions about birdies....



Thanks, NINO, for the info on _Iberomesornis_!

Now, relating to Dinogeorge's statement that "[t]he canal and the associated
shift of the m. supracoracoideus is an evolutionary improvement to a
pre-existing volant
ability."

What do we know about the flying abilities of pre-triosseus-canal birds?  How
do we know that they were already flying, and that the switch in function of
the m. supracoracoideus and the origin of the triosseus canal was not an
invention for flight, rather than an improvement?  How was the flight stroke
accomplished before the switch in musculature, if, indeed, we have true
fliers before the switch?

My apologies for the barrage of questions, but my ignorance knows no bounds!
:o)

In a related vain, these are what I see as the minimum features necessary to
achieve true flight (as opposed to gliding or parachuting) in vertebrates (in
no particular order):

1)  An aerodynamic wing (preferably two!) and body

2)  A relatively large brain - because of the increased travel speed, a flier
must react more quickly to its surroundings.  A large brain is, in my
opinion, therefore critical to any vertebrate flier.  Since, in general,
carnivores are more intelligent than herbivores, it would stand to reason
that a corollary to this requirement is that an animal be a carnivore.  Is it
the case, then, that the three volant vert groups (pterosaurs, birds, bats)
all had carnivorous ancestors?  

3)  Specialized sensory apparati - again, because the animal must react
quickly, it should have sensory equipment which will allow it to gather data
quickly (which the brain should also be able to process quickly).

4)  A flight stroke - This is the means by which air is moved over the wing,
thus producing lift.  Generally, I would think that the limbs involved in
generating the flight stroke would probably have their range of motions
limited to those necessary for flight, but this is just an assumption on my
part.

5)  An enhanced respiratory system - flight is a very energy-intensive
activity.  Being able to increase oxygen intake and absorption is therefore a
must.  An efficient circulatory system is certainly a plus.

So, am I missing anything?

Dsmith