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Re: Support for Enigmosauria



Ken Kinman wrote-

>      Mickey you are a treasure trove of information, and if everyone would
> look at all this information objectively, you all would see the support
for
> "enigmosauria" crumbling before your eyes.
>      One of those two "enigmosaur" synapomorphies that has survived
scrutiny
> has just bit the dust.  "Reduced basipterygoid processes" are also found
in
> "ornithothoracine" birds.  If they can be reduced convergently there, they
> certainly could be reduced even more easily "in parallel" in a
paraphyletic
> "enigmosauria".

Here's something you're going to have to learn- Characters WILL be
convergently acquired by other clades!  I know it's a stretch to accept, but
when you have a whole lot of similar organisms evolving, some characters
will actually evolve in two, three or several different clades.  That's just
how things work.  We can't arrange the data any other way.  Just because a
character evolves multiple times doesn't mean it's for some reason "bad" and
shouldn't be accepted.  For instance, caenagnathoids have fused dentary
symphyses, but so do Gobipteryx, neornithines and humans (plus other related
primates I'm sure).  We can still easily say that it's a valid character
helping diagnose these clades because lots of other evidence suggests basal
oviraptorosaurs, pygostylians, euornithines and mammals have unfused
symphyses.  Hypothetically, any character could be evolved convergently by
any semi-related clade, and would be expected to in such a large group of
taxa.  You know PAUP specifically tries to limit the amount of convergences
while computing the most parsimonious tree (at least when ran in hsearch
mode, like most paleontologists do).  So would it surprise you to know that
in my old (very inaccurate) analysis, there were only 50 characters that had
perfect distributions (7 were just keeping Patagonykus and mononykines
together).  That's out of 347 total characters, roughly one seventh.  If
you'd list synapomorphies of any clade, you'd get similar results.  You'll
notice Sereno's characters to exclude segnosaurs from your warped "Aves" are
similarily evolved convergently and/or reversed.  Of the seven that I found
valid-
1- lacrimal does contacts frontal
Also seen in Sinosauropteryx and tyrannosaurids, reversed in Confuciusornis.
2- acromion height less than 40% of the distance from the middle of the
blade to the acromial edge
Reversed in Achillobator.
3- coracoid dorsoventral length more than five times coracoid glenoid
diameter
Also in tyrannosaurids, reversed in Caudipteryx and Microvenator.
4- coracoid glenoid convex
Reversed in at least some birds (eg. Phasianus), also present in at least
Euoplocephalus and Sauropelta among ankylosaurs.
5- bowed ulnar shaft
Also present in Nothronychus, Scipionyx, Coelurus and Ornitholestes.
6- postacetabular process half-concentric
Also present in therizinosauroids (not Beipiaosaurus), reversed in
Caudipteryx, Nomingia and Ingenia.
7- anterior trochantor splitting from greater trochantor closer to femoral
head
Also in tyrannosaurids, Patagonykus and mononykines.
And of the others I couldn't test in segnosaurs yet, Neimongosaurus has
large hypapophyses, making that character invalid.
As for your reduced basipterygoid process observation, they are not reduced
in Patagopteryx (Chiappe, 1997) and are coded as not reduced in
ornithothoracines by Holtz (2000).  There are no well preserved
ornithothoracines more basal than Patagopteryx to test this on, and I need a
better illustration of Hesperornis.  My crow and rhinoceros auklet skulls
have reduced processes, so this did evolve convergently somewhere along the
line.

>      I am trying to show that "enigmosauria" could very well be
> paraphyletic, and ironically those who intensely dislike paraphyletic
groups
> are arguing against me.  This seems like a perfect opportunity to work
> together and do some real science, and everyone is trying "to boo me from
> the stage".  I just don't get it.  If I have to do it by myself, so be it,
> but this just strikes me a totally ironic.

It's not that we don't like paraphyletic groups.  We don't like seeing them
named and passed off as taxa, but if a group turns out to be paraphyletic,
so be it.  What we DO like is parsimony, as it allows testability and
probability to be present in phylogenetics.  Now, as I didn't include eight
of Sereno's anti-enigmosaur characters in my previous analyses, the proper
thing to do would be to leave the matter undecided until my new analysis is
finished with all of them, so that the 400+ other characters can have a
chance to influence things as well.  However, I think you will agree that 7
(+4?) anti-enigmosaur characters are less than 14 (+6?) enigmosaur
characters, considering that at least four of the latter have perfect
distributions as far as I can tell.  As David wrote, segnosaur egg shells
are even more basal than allosauroid ones, which in turn are like troodontid
ones, so that's obviously a reversal.  Despite what Jaime may have said,
Alxasaurus' semilunate is just like Deinonychus', but unfused (I'll send you
the scans).  It's actually a bit more extensive, covering metacarpal I a bit
more.  And as fused semilunates are primitive for Coelurosauria at least,
that won't get you anywhere.  Your unrevealed pedal digit II character can't
be evaluated yet, obviously.  Enigmosauria is obviously the most
parsimonious answer right now, by quite a bit.  So you have two choices-
1. Agree that Enigmosauria is monophyletic, at least provisionally until my
analysis is finished (or you can find more anti-enigmosaur characters), as
that is the most parsimonious choice.
2. Decide that segnosaurs are more basal than oviraptorosaurs against the
current evidence, in which case I'll have nothing more to say on the topic
until my new analysis comes out.  You'd just be using subjectivity in which
characters you "found important", not science, so there would be no logical
way to convince you otherwise.
I've presented all my evidence and arguments....

Mickey Mortimer