Re: Segnosaurs ejected from AVES

["Jaime A. Headden" <qilongia@yahoo.com>]

George Olshevsky (dinogeorge@aol.com) wrote:

<In two runs of 100 flips of a coin, there will be about 50% matches. Does
 this mean that the two runs are not independent? Likewise, if two
theropod lineages extend far enough, they will acquire a number of the
same bistate characters independently (carpals fused into a "semilunate"
being one such). Does this mean they're related?>

  No. Not using a simple mathematical value of bistate randomnality. That
way, you are bound to create a multitude of successive similarities in two
columns of two bistate counts. But nature is not bistate in it's
randomnality, it's much, much more variable; the only limit to the
variation possible in nature, theoretically, is nature itself, and
constraints of physics and environment. In the same environment, animals
will possess similar features, and convergent evolution occurs.
Embrithopoda and Ceratomorpha developed numerous convergences, including
distinct features of the skull, but in no way are they related. That is to
tell, in gross anatomy of the whole skeleton, the limbs were still
indicative of a non-ungulate nature for embrithopods. The skull and brain
or not as specialized, even though the snout is developed in some similar
ways. A caecilian and amphisbaenian are similar by appearance and
environment, but they are two entirely different animals. One is an
reptilian and amniote, the other is a lissamphibian. Magpies look like
crows, but they're not. They're not even corvids.

  But segnosaurs are nothing so similar to oviraptorosaurs as to suggest a
relationship. Not two years ago, segnosaurs were suggested (for over 20
years) as prosauropod relatives or so basal because of various
ornithischian and sauropodan features, now known as convergences. There,
the foot was the proponent. Look what happened to that feature. But look
hard at the gross anatomy, and it's there. In the skull, the pelvis, the
limbs, the vertebrae. In the details. In the details, something so unqiue
as a manatee is related to elephants. I draw these parallels to show that
picking a single feature defies nature itself... one needs robustness. In
a perfect world we would only need one, because only one _could_ separate
different taxa of variety, because the tree would be _complete_. But it's
not. So we have these disparate and broken branches (clades) that must be
assembles. Those who chose one sliver and one notch to duplicate the tree
end up ignoring the ten or so other slivers and notches because they think
that sliver and notch fit better.

  It's just not how nature works.

=====
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.

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