>To me, this sounds a bit like semantics. If longisquama's scales/wing
>evolved from some precursor of feathers, then the precursor must look
>something like Longisquama's scale. I don't see how this gets you out of
>the problem that in these rocks we go from a world in which there was no
>feather to one with feathers.
That's not a problem. The question was, with what assurance can we
say that L's scale is *the* ancestor of feathers? I find it annoying that
every new fossil is hailed as *the* ancestor, *the* grandaddy of
whatever, when this is not known.
>I am really confused now. Surely you aren't suggesting that when we lack
>evidence we can make it up are you? If you suggest that feathers came from
>complex spines on animals, surely you should be obligated to suggest a
>suitable example in the fossil record.
No way. We have to go beyond the fossils to attempt to understand the
Cambrian Explosion and many other things.
>An arboreal version of a fish in water which is in the process of
>transforming into an amphibian? What on earth are you talking about. Are
>you toying with my mind?
We were talking about ichthyostega. I don't think it likely that ichthyostega
is
*the* grandaddy of *all* tetrapods. I theorize that by the time I. was
established
and getting fossilized there was a range of sister species in various niches,
all derived from something resembling a lobe-fin lungfish.
>We have fossils that support the idea that feathers came from reptilian
>scales. We have no fossils that I am aware of to support your assertion
>that feathers arose from complex spines. We also have no arboreal
>fish--ever. We do have fish with very tetrapod-like limbs, bone for bone.
>We have a fish with fingers. So yes we have fossils to support the
>suggested transitions.
I don't know where I said there were arboreal fish. But actually, there
is the climbing perch in SE Asia, Anabas testudineus, which probably
clambers around some tree roots while its goes from pond to pond.
"Suggested" transitions? You mean you don't have a fossil series
proving these transitions? Sounds like you're theorizing. Anyway, my
point is just that there are other possible models which explain the
cited fossils. If you can suggest a transition from A to B, I can suggest
that A and B are sister species whose similarity is a result of their
having a common ancestor.
>It seems to me then, that you are arguing for an evolution from complex to
>simple. I suppose then under this view, mankind is the simplest life form
>on the planet. Sometimes I agree with this.
I accept the generalization that segmented animals (including vertebrates)
are losing segments and losing symmetry among segments. Of course the
remaining segments are distorted in limitless ways to form different organisms.
--Cliff Lundberg ~ San Francisco ~ cliff@noe.com