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Re: What is a Dinosaur? and semilunate carpal
In a message dated 9/6/01 3:08:45 PM EST, david.marjanovic@gmx.at writes:
<< In BCF birds (sensu BCF) begin to fly, then evolve stable wrists, and in
the
meantime they have flown by magic? Or by means of _enormous_ muscles on
their forearms? >>
No, they didn't fly very well at first. They just fluttered to break their
falls. When their hands/wings began to stabilize, they flew better. Why fly
at all? It helps to solve the Falling Problem for arboreal animals. It
doesn't solve >any< problem for cursorial, ground-dwelling predators;
ground-dwellers have no need to fly, consequently flight adaptations are not
useful to them and are not usually selected for in their evolution.
Consequently ground-dwelling animals are extremely unlikely to be directly
ancestral to flying animals outside the arboreal paradigm. If the evolution
of flight from ground-dwelling animals is so plausible, why don't pigs and
kangaroos and people have wings?