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Re: What is a Dinosaur? and semilunate carpal
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,
Well, they might want to catch flying insects in mid-air. For example.
Consequently ground-dwelling animals are extremely unlikely to be directly
ancestral to flying animals outside the arboreal paradigm.
This comes down to a distinction between "plausible" and "possible". If
flight is _possible_ from the ground-up, then it becomes a _plausible_
explanation if the available evidence supports the closest relatives of
birds and basal birds being ground-dwelling predators. Evolution works on
the raw materials available, and is not deterred because certain
alternatives are biophysically "simpler" or "easier".
If the evolution
of flight from ground-dwelling animals is so plausible, why don't pigs and
kangaroos and people have wings?
By the way, it is not as though we have a huge sample size to work with in
determining which ecologies are more condusive to the evolution of flight.
Wings evolved only THREE times in vertebrate evolution: pterosaurs, birds
and bats. And can you confidently claim that pterosaurs and bats also
evolved from arboreal ancestors?
(Personally, I think all three groups of flying vertebrates evolved in the
trees. But the archives are crammed with my ramblings on this issue, so
I'll hold off on further rambling here.)
That's the kind of tautology that fails to drive the standard theory.
stiff hands must have been useful to them, otherwise they wouldn't have
evolved them." Useful how? They were certainly useful when it came around
acquiring wings, but what about when wings were still way off in the future
If BCF is to be credible at all, you're going to have to demonstrate that
the maniraptoran hand was so "stiff" that it was ineffective (or even
less-than-optimal) for grasping prey.
A vertebrate wing isn't going to evolve by random
chance; it's too complicated a structure. It's not going to evolve as a set
of randomly acquired, undirected characters that just happen to assemble
themselves into a wing, any more than a shattered cup will reassemble
when you throw the pieces back onto the table.
Exaptation, exaptation, exaptation....
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