>>No way. We have to go beyond the fossils to attempt to understand the
>>Cambrian Explosion and many other things.
>
>How far beyond? be specific for petes' sake. You keep saying things like
>this but then never detailing what you have in mind. Are we talking about
>molecular data or speaking with spirits? Both are beyond the fossils. One
>is useful the other isn't.
I don't see gradual evolution as the mechanism for the CE. I don't see the
fossils depicting how it happened, not in any direct way. Therefore there is
room for theorizing about processes. If we had a time machine, observation
would be enough.
>Here is what you said: " But it doesn't matter much. If it wasn't
>ichthyostega, it was something similar, perhaps a smaller arboreal version."
Sorry, I didn't realize you meant Ichthyostega when you referred to
a fish. I think of I. as a primitive tetrapod, but no doubt this is
controversial.
>Vertebrates are not losing symmetry. A mirror on one half of a human or a
>horse, (down the front midline) will closely approximate the hidden half.
Bilateral symmetry is generally preserved throughout animal evolution,
but the symmetry among serial homologs, trains of axial or appendicular
segments, is steadily being lost. The trend toward specialization and
reduction in number among such segments has long been recognized.
The fact that this trend toward reduction in number of skeletal parts
is somewhat contrary to the general idea of progressive evolution
is noteworthy; it must be well-supported, to have been established
over the doubts of those who think evolution is unconstrained.
--Cliff Lundberg ~ San Francisco ~ cliff@noe.com