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RE: Campbell's even crazier than a MANIAC? (archeopteryx
> I agree with the first part of your statement, about
> theropods occasionally climbing and exploiting cycads, and
> then parachuting or gliding down. But this
> "trees-down" step might have been a very mature
> stage in the development of powered flight. The
Perhaps just "mature". But certainly not old.
> "ground-up" scenario could include all the
> preceding steps, and entail the development of many (most?)
> of the components of the avian flight apparatus: feathers,
> enlarged pectoral musculature,
With reservations. Enough to use, not enough to excel.
> long forelimbs,
> decoupling of the tail from stride generation,
> maybe even
> the flight stroke itself
I don't think so
> (or its biomechanical precursor).
I am not sure about
* arm/shoulder mobility
* lack of a sternum, hypertrophied humerus, or other baseplate for "breast"
PS: What about the strong trend of cursorial small *crown* theropods to lose
their hallux entirely? It simply works far better with three toes only. IIRC
there is NO living bird, and at best very few extinct ones, that engage in
vigorous running for a living and have anything but a vestigial elevated
hallux. Archie's feet do not look like the feet of an animal that was good at
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