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Re: Origins (was: Re: Sharovipteryx)



Sorry!
When you wrote:
< Contrast that with another example I'll pull out of thin
air.  Dinosaurs had color vision.  Ask yourself how you might test this
idea...>
I thought the 'thin air' was more attenuated than it actually was.
You have actually found supportable ways to make the assumptions/assertions
I listed:
<You merely need to have valid (i.e., tested) reasons for accepting that,
for example parakeet and anole or parakeet and goldfish form a phylogenetic
bracket around most if not all dinosaurs.>
Considering that these are modern species, presumably evolved after the
dinosaurs, you are defining the start of the bracket implicitly.
 <All known visual pigments appear to have derived
from a single molecule, but those pigments have diversified between and
within many lineages.>
 <...best evidence indicates that the four pigment genes in the three
animals I named are orthologs of each other.  The connection to dinosaurs is
the phylogenetic bracket.>
Paleontology makes brilliant use of logical inference, and this is another
example.  My compliments!
Remember, please, that the discussion was in furtherance of the assertion
that:
<The certainty which is a contrast to a just-so story is not that of
metaphysics, but of some parts of chemistry, for example.>
Your argument, persuasive as it sounds to me, is still an assemblage of
inferences, no?  If any of the premises on which those inferences are based
prove to be false, including premises both logical ( <  Read Larry Witmer's
papers for a discussion of that topic and how it allows us to qualify the
confidence we have in our assessments of various aspects of the biology of
extinct animals.>  I will.  As for now, I'm thinking about the apparently
compelling statements made here about the limits on using extant animals as
models for dinos.) and factual (such as the orthogonal (?) nature of the
four pigment genes), then the construct would at least require modification.
Wouldn't you say that there is a difference in the testing of your
hypothesis that dinosaurs had color vision and the testing of the hypothesis
that a particular virus in your lab causes a particular type of influenza?
The contrast here is not between true/false but between direct/indirect
proof.  And indirect proof is permanently vulnerable to more types of
refutation.