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Re: Pteromimus and pterosaur origins
Having performed many analyses, and dissected others, I can tell you're
talking in philosophical generalities. I'm talking specifics. Here's how
it works: If I find through PAUP* a lineage, thereafter it needs to be
rechecked in MacClade. For instance: Say all taxa --but one-- have a tiny
quadratojugal that ascends the quadrate. Given that, I look again at that
exceptional taxon for a loose quadratojugal that may have drifted
slightly. Sometimes I find it. Then I reconstruct it back into place.
That happened in Huehuecuetzpalli.
Except... you can't do such a thing without seeing the fossil. I have the
paper; the resolution of the photo is rather pathetic as usual.
You just have to test and experiment and get the big picture before you
can be sure of the validity of the smaller (14 taxa) inclusion set.
Virtually all prior attempts, from Gauthier 1986 to the present, have
assumed wrongly and, as a consequence, have prolonged the error. It's
easily resolved via testing. I say virtually, because Benton 1985 did it
right, even with suprageneric taxa, but then he never repeated the
As I have previously explained to you onlist at length, Benton 1985 does
_not_ describe a cladistic analysis. That's because Benton didn't do one. If
you read the paper attentively, you'll see it's just a tree with lists of
autapomorphies for each clade, but no attempt whatsoever of finding out if
that tree is the most parsimonious one for the data. There is no data
matrix; the states of most characters was not checked in most taxa at all.
This was a pretty common habit in the mid-late 1980s and even early 90s,
when the cladistics revolution had got far enough that people understood
they had to use synapomorphies and pretty angular stick drawings of trees to
argue for their phylogenetic hypotheses, but when most of them didn't have
halfway capable computers yet.
Again: there is no experiment in Benton 1985. Benton simply presented an
idea and some evidence for it, but he didn't test the idea. Such a paper
couldn't get published today.
I'd slow down there for a moment - how do we make such judgements about
how "evolution works"?
We make such judgments because we know evolution works step by step.
Kids, for the most part, look like their parents and great- granparents.
One part evolves, blends, lenghthens, shortens, then another then
another. Sometimes two or three at a time, but that is within a suite of
hundreds to thousands of characters, depending on your skills and
patience. Even when one taxon is half the size of the predecessor most of
the characters remain similar in proportion.
But we haven't _got_ great-grandparents, parents or kids!!! We've got a
_tiny_ sample of a big hulky tree!
If you were right, we wouldn't need cladistics in the first place. We could
simply do stratophenetics. No more agonizing over correlated characters or
Done well you can produce 100 manual characters rather easily, for
What do you mean?
No prior study has yet given us the
comprehensive overview of the Amniota using species-based taxa.
Stop being impatient, I'm working on it. OK, I use genera for the most part,
because I'm too lazy to enter every single species of *Edaphosaurus* or
*Ophiacodon* or burrow through the chaos that the North American species of
*Diadectes* is or are, but still two of the unknown number of species of
*Casea* are in as separate OTUs, for example, because Maddin et al. (2008)
found them in different places.
If we knew the patterns already, there wouldn't be a need for a
Yes, if you did. But we don't. That's why we us CA.
This "we don't" is our point: so far, and below, you act as if we did know!
The transitions above indicate is that a given ancestor generated some
descendents with a short digit V, and others with a long digit V.
No. The point is you're asking a given ancestor with a short to vestigial
to absent pedal digit V to give rise to one with an elongated digit V --
when you know on the next branch, there is a taxon with a long digit V
with the same characters -- attached to an torso, skull and extremities
with a suite of other pterosaur-ish characters. It's parsimony, pure and
Parsimony applies to the whole dataset at once, not to a selected number of
characters in a selected number of taxa.
That's hardly shocking, and quite plausible. More to the point, when
reversals, mosaics, and other bits of messiness show up in a phylogeny
it is not a sign that the answer is wrong - it just reflects the rather
stochastic patterns that are biology.
Again, Mike, you're talking philosophical generalities. Get specific,
test one against the other, and we'll find answers. the reversals, etc.
will reveal themselves.
Yes, except you act as if he could just throw an analysis together on an