Re: Sauropods and lung development

["Jaime A. Headden" <qilongia@yahoo.com>]

Christopher Srnka wrote:

<I know this will seem annoying, and will probably earn never-ending
flaming from the list, but I have to say it.>

  No flaming. At least not from this quarter. So I'll send this to the
list. It's something I'm also interested in.

<How the hell did sauropods develop long necks, (or, for that matter,
how did ankylosaurs and stegosaurs develop body armor, or pterosaurs
their wings, etc.)? I don't mean when, or why, or what the basal types
are, I mean how.>

  All I can say here is that these questions are inter-related. To
answer one, you have to have at least the glimmerings of the answer to
either of the others. Answer one, answer two, and the third will fall
mostly into place. At least as I see it.

<I read a lot of smug remarks about creationists (drdino.com was
deserving of them all, I'll concede; I was almost expecting a link to
an X-Files site, with all the paranoid delusions abounding), but one
of the questions that I have yet to find a satisfactory answer to is:
what is the mechanism by which macroevolution is supposed to occur?
I'm not being facetious here; if someone does have a good answer for
this, I'd love to hear it.>

  Good ol' evolution is a funny thing. It is influenceable, and
influencing. And can be both at tyhe same time. Often is, as
present-time observation as shown, with special respect to the finch
*Geospiza* in the Galapagos.

  But the driving force in evolution, it would seem, would be the need
to adapt. All your friends are doing it, they've got all the toys, not
you, so you go find something else. Be a dog, for instance. After
being left out of the kill, as all your brothers and sisters are
hogging the carcass like . . . well, hogs . . . you feel put down and
start taking a much of grass. Hmm. Not so bad, a bit tough, grainy
even, but after a while it fills you up. And there's plenty more.
After all, you could eat fruit, and have, and chewed bark and gotten
something out of that, right? Now, you evertually breed with a female
who happens to have the same appetite, you teach it to your kin, and
so on. What is readily observable is the evolution of behavior, but in
the lopng run, as selectiveness develops a race of grass-eating dogs,
the animals begin to physically adapt. While nutrients in grass is
harder to come by than the same in meat, the gut adapts, and possibly
something akin to a cecum develops. The teeth are too derived to
modify (they are hypocarnivores, already dentally endowed to handle
the grass in some ways) so just jaw development and muscles in the
skull would be needed. Perhaps a little something extra, like harder
enamel, and you have a mostly herbivorous dog. Not much difference:
it's still a *Canis*, but a new type of one.

  This is all fun and speculation, but illustrates my basic
understanding of the process of developing a trait that develops
another, that develops another, and so on. Hence two factors above (an
unexplored niche, and isolation) are the primary factors in _any_
process of evolution.

  Now, before I bury myself in another corner I can't dig myself out
of (or have I already done this with my limitied grasp of evolution?)

==
Jaime A. Headden

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

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