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Re: Feathers are not magical things...



<That is to say, assuming a) feathers evolved a single time in the history
of vertebrates (the simplest explanation) and b) the known presence of
feathers in birds and only in those theropods which independant phylogenetic
analyses
[me:  also based on logical argument, including assumptions] place closer to
birds than to other dinosaurian taxa and c) the lack of evidence to the
contrary (i.e., therizinosaur body impressions with scales)
means that as scientists we take the simplest explanation possible.  That
explanation is that feathers evolved in the common ancestor of all
maniraptorans and was passed on to all descendants.  Until such time that we
find direct positive evidence to the contrary, we must assume that
_Velociraptor_ and company were feathered.>

As you also point out, the results of similar logical arguments have been
refuted:

<There might well have been featherless maniraptorans.  To use the example
of maxillary fenestration from above, we do know that some members of the
clade which ancestrally possessed these structures subsequently lost them:
the therizinosauroid _Erlikosaurus_ and the
caenagnathid oviraptorosaur _Chirostenotes_, for example.  Had the skulls of
these guys never been found, we would have assumed that that had these
structures.  However, given new information we accept the evidence given.>

I think the last sentence a bit unclear, and hope you will clarify.
Given the new information, would you say that there are exceptions to the
inheritance of the ancestral character or that the analysis identifying the
character as ancestral might be flawed and have to be redone?  Both seem
possible outcomes.
Also, note that the paragraph first quoted twice refers to using the
'simplest explanation'.  From past discussions, it seems you wouldn't argue
that evolution invariably follows the simplest (with a specific definition)
path.  Given that less simple explanations are possible consistent with the
available data, would you assert that someone who argued a different
hypothesis would be unscientific?  That someone who drew Velociraptor
without feathers was outright wrong?  (In the same sense that someone who
drew an animal whose fossils have been observed to have feather-like
integument would be wrong to leave out the feather-like integument.)
I'm asking here about the difference between inference and observation as it
applies to 'scientific'.

<Something that seems to come out in "Jura"'s posts, and as well in
discussions with Ruben and others, is a sort of Platonic typology or
idealism: that is, that there is a dinosaur "kind" and an avian "kind" and
that never the twain shall meet.  Thus, since we have lots of dinosaurs with
scales, there for it is an aspect of the dinosaur "type" to have scales.>

If there are 1,000 'species' of dinosaurs and 990 are known to have scales
and not feathers (numbers and knowledge of integumentary structures
invented), then I would be correct to say, "Almost all dinosaurs have scales
and not feathers."  In this situation, if I were asked to describe a typical
dinosaur, I would not include feathers because feathers are not typical.
(Hope nobody ever asks me!  And that I'd have sense enough not to answer.)
This is not a reference to Platonic idealism, it's simple use of prevalence.
I frequently have to write about the typical person who gambles or who plays
a particular lottery game.  I don't have the sense that I'm dealing with
archetypes.

<Evolution happens, and one type changes into
another, until the boundaries (from a morphological standpoint) are blurred
into non-existence.>

>From this, would you conclude that if you wanted to name easily
distinguishable groups, then you should base the groups on animals which
have been substantially distinguished from their distant ancestors by
evolution, and not on those distant ancestors?  That would avoid fuzziness.

<The reason reconstructing the historical pattern of
evolution is importance is because that background is necessary for a
testable and reciprocal study of the transformations and adaptations in
Life.>

I'm not sure I understand.  If phylogenetic analysis is in the background,
what's in the foreground?

Thanks for taking the time to explain and clarify.