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Re: Flightless Birds (was Re: BCF ANDPDW)



I wrote:

<<But suddenly, they can stand up to those marsupials and mammals that
gave them such a hard time when they were smaller, psilopterid-like.>>

Jonathan Wagner wrote:

<Motive and method. I'm not sure, though. That nether world between
being too large to fly (!?!?) and too small to fight seems an awful
hurdle for selection. I wouldn't be surprized if there were either
some geographic isolation from larger predators or some depletion of
the large predator fauna when that occurred.>

  Well, yes, I would agree. It would be easier to operate under
stress, believe it or not (the guys I work with sure say I work better
under pressure, but it's a killer!) and the chances for an animal in
an open habitat like the Patagonian plains of the Pleistocene and
Paleocene would have been very exposed. But instead of being against
the idea of selecting the adaptation of greater size vs. loss of
flight, it might help. All major flightless birds of our day developed
(a reasonable idea) when Gondwanaland was still Gondwanaland, and that
was a long time ago.

  [Theoretical:] it was one big continent when the ratites developed,
rather than an isolated breed. But it gives us something to think
about. Were there islands along the east coast big enough to breed
populations (or a single population) of phorusrhacoids that would have
formed when Africa packed up and took ship out east, and then later
merged with mainland South America (through any process, like
water-level dropping). So, any ideas on this?

<<This was a true case of secondarily flightlessness, but was it a
reversal, or a convergence? Semantics, really.>>

<Unfortunately, as I pointed out earlier, semantic differences have
lead to enough frustration already. Let's be careful, if not for my
blood pressure, for George's.>

  Agreed.

==
Jaime A. Headden

Qilong, the website, at:
http://members.tripod.com/~Qilong/qilong.html
---
All comments and criticisms are welcome!

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