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Re: New Jeholornis specimen

Greg Paul (GSP1954@aol.com) wrote:

<Well this is nice.>

  Isn't it, though?

<It is possible that Arch evolved its shorter tail independently, or that
there was one or more reversions to longer tails post Arch.>

  Indeed, and in perfect connection with this earlier statement, same

<With its long tail Jeholornis kills yet another Archaeopteryx character
used to defend the latter's position closer to modern birds than longer
tailed dromaeosaurs and so forth.>

  Reversals can happen, and the tail count changes little unless bird
evolution at this stage is also about the shortest-tail fad.

  Another example that doesn't destroy this theory:

<Likewise Confuciusornis has a much less derived postorbital bar than less
derived Archaeopteryx.>


<Yet another example that cladistics is at best hard pressed to handle the
 degree of reversal, parallalism, and convergence going on in the mosaic 
development of basal birds that had not yet evolved far from the
dinosaurian grade, and were often losing and perhaps even reevolving

  This was almost ridiculous. I say almsot, because its untrue, as the
predictive power in a cladistic matrix is given the data, and it can't
predict a known behavior in an animal that cannot be observed. Similarly,
just because the matrix doesn't come up with flight LOSS or flight
ACQUISITION when the quality of flight requires a complex of features as
it not just one thing, does not mean that the general phylogeny is not
correct because it differs from the intuitive, or more "reasonable" or
"realistic to me" approach.

  It was almost ridiculous, because this is true: "mosaic  development of
basal birds that had not yet evolved far from the dinosaurian grade".
Problematically, mosaic evolution would appear in matrices as "noise" or
low support values for nodes, and then again this same signal would appear
as input of unknowns or multiple values given subjective taxa (see
Angielczyk & Kurkin, _Geology_ 31(4): 363-366 for a discussion of how
subjective values based on subjective taxa are ... subjective, and of very
little importance or use, given that one could say many different things
with the same subjectivity if I wanted to make each specimen of
*Catopsalis* a new genus and species and therefore destroy any effective
use *Catopsalis* has for biostratigraphy).

<Cladistics is one important tool for restoring paleophylogentics, but not
the only one, and in this case is inferior to assessing the relative
derived degree of flight adaptations that are present.>

  Yeah, because then biomechanics and anatomical indicators to mechanics
in flat bones works MUCH better than using phylogeny to find out what
animals could or should be able to fly or how they affect others.


Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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