[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

R: New AVES definition refined (more testable?)

From: Ken Kinman
> Dear All,
>      I would like to thank those who have given some constructive feedback
> on this matter.

****While opposing positions have never been seriously considered, have

>I fully expected my proposal to be controversial (but I was
> a little surprised just how strongly it is being dismissed before it is
> tested).
>  Mickey Mortimer's upcoming analysis will be an important first > test,
and *if* he can convince me that "enigmosauria" is holophyletic, I
> will certainly modify my proposal accordingly.

****HOW may he convince you of this, if the theoretical bases for his
analysis are not accepted???

>      However, I am convinced that the case for "enigmosaur" paraphyly is
> least as strong as it is for holophyly, and there may be some surprises
> those who are drawing definitive conclusions before rigorous testing is
> done.

****No definitive conclusions can be drawn; they're relative to the
state-of-the-evidence, which(if i have to trust others' analysis) seems to
support "enigmosaurian" monophily. If  it'll turn out to be a paraphiletic
assemblage,then so be it(quite tired of repeating this,honestly), but untill
then, your proposal only reflects a personal opinion more than anything
else(after all, all the characters you've used since now are not "new", are
they?   if you want to dismiss parsimony, just do it, but  don't consider
others as unreasonable only because they try to be coherent with themselves)

>Therefore, I cannot in good conscience back away from >enigmosaur
> paraphyly just because that possibility is being so heavily criticized.

****You may only ask yourself why it has been so heavily criticized,in case
it hasn't be explicitated enough.

>      Now, it is certainly not easy coming up with a better and more
> redefinition of AVES until it becomes a cooperative effort,

****ARGH! sounds like " you don't know you need it, but you DO, so i'm
insisting until  you get it!"
Such a mom-to-children approach may be good in case we hadn't opposed your
proposal with well defined(perhaps wrong,who know?) counterarguments, but
such arguments have indeed been proposed and you just seem not to have cared
about them, since no rational (or at least precise,reasoned)reply(I'm not
talking about the " no need to get upset" or "let me do" arguments) has come

> but I am
> proceeding as best as I can.  What follows is a more refined definition
> (assuming enigmosauria will be shown to be paraphyletic after more
> testing is done).  I will first give my proposal for the Primary
> and then follow it with a list of supportive characters I have come up
> so far.
>      PRIMARY DEFINITION of Class Aves sensu lato (proposed):   Theropods
> possessing both a "convex coracoid glenoid" AND at least one the two
> following carpal characteristics:  (1) Distal carpals I and II enlarged
> fused into a single element with a distinctive semilunate shape; and/or
> this fused structure fully caps metacarpals I and II.
>     Notes:  Protarchaeopterx and Caudipteryx meet this definition even
> though they apparently lack the distinctive semilunate "shape".
> also meets the definition, even though one of its metacarpals is not
> capped.  Segnosaurians do NOT meet this definition, although Beipaiosaurus
> seems to approach it the best.  The segnosaurians are most likely the
> group of Class Aves sensu lato, and therefore many of the supportive
> characters which are listed below will be found in some or all
> (as noted).  Tyrannosaurs appear to be further out (contra Sereno's
> "Tyrannoraptora").
>      (1) Enlarged sternum articulating with more than 2 pairs of ribs.
> note that sternal anterior margin is apparently often slotted for
> (and said coracoids sharply reflexed).
>      (2) Possession of ornithoid eggs (microstructure modified or
> reversed in Troodontidae).
>      (3) Possession of vaned feathers (may occur in some outgroups
> segnosaurians).  A particular kind of vaned feathers or their bodily
> distribution may eventually distinguish Aves from the earlier forms
> (insufficient data at present).
>      (4) Laterosphenoid head small, and snovial joint small or absent
> (unknown if this also occurs in segnosaurians or not).
>      (5) Anterior trochantor splitting from greater trochantor closer to
> femoral head (occurs in tyrannosaurs as well).
>      (6) Preacetabular blade of ilium dorsoventrally elongated (also in
> segnosaurians, but it is distinctively expanded laterally).
>      (7) Bowed ulnar shaft (also present in some outgroup genera).
>      (8) Lacrimal-frontal contact present (also occurs in tyrannosaurs).
>      (9) Relatively large hypapophyses on anterior dorsals (also in
> Neimongosaurus and Ornitholestes).
>      (10) Often possess ossified uncinate processes.
>      (11) Dorsal carpals I and II have a pronounced trochlear groove on
> proximal side (also occurs in Coelurus, segnosaurians and tyrannosaurs).
>      (12) Most Aves (but caenagnathiforms are primitive in this respect)
> have retroversion of pubes to varying degrees (retroversion in
> probably occurred in parallel--i.e. a mild case of convergence).
>      (13) The fused distal carpal element has often fused to the
> (forming a carpometacarpus).  Apparently arose at least twice in Class
> sensu lato.
>      (14) Distal end of ulna more than 1.5 times as broad as tall (this
> character could probably use some refining).
>      (15) Anterior trochantor cylindrical (also in derived segnosaurians).
>      (16) Reduced supracetabular crest of ilium (also in some tyrannosaurs
> and segnosaurians).
>      (17) Several other characters I haven't had time to work on.
> ------------------------------
>      So there you have my viewpoint as it stands at present.  If Mickey's
> analysis convinces me that "enigmosauria" is holophyletic, I will modify
> proposal accordingly.  However, I think even he may be surprised, and that
> the case for "enigmosaur" paraphyly is a very viable alternative.
> to this alternative view, "enigmosauria" is based on plesiomorphies and
> parallelisms.  We shall see.  As always, *constructive* comments are
> welcome.

****This call for "constructive"(=supporting your point of view) comments
is a substitute for the call for "constructive criticisms" which have all
been expressed and readily .....put apart (if not those regarding
morphology, but this only because they couldn't be ignored if you wanted to
keep supporting your point)

Filippo Calzolari

>        ------- Cheers,   Ken Kinman