New AVES definition refined (more testable?)

["Ken Kinman" <kinman@hotmail.com>]

Dear All,
    I would like to thank those who have given some constructive feedback 
on this matter.  I fully expected my proposal to be controversial (but I was 
a little surprised just how strongly it is being dismissed before it is even 
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.
    However, I am convinced that the case for "enigmosaur" paraphyly is at 
least as strong as it is for holophyly, and there may be some surprises for 
those who are drawing definitive conclusions before rigorous testing is 
done.  Therefore, I cannot in good conscience back away from enigmosaur 
paraphyly just because that possibility is being so heavily criticized.
    Now, it is certainly not easy coming up with a better and more precise 
redefinition of AVES until it becomes a cooperative effort, 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 rigorous 
testing is done).  I will first give my proposal for the Primary Definition, 
and then follow it with a list of supportive characters I have come up with 
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 and 
fused into a single element with a distinctive semilunate shape; and/or (2) 
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".  Deinonychus 
also meets the definition, even though one of its metacarpals is not "fully" 
capped.  Segnosaurians do NOT meet this definition, although Beipaiosaurus 
seems to approach it the best.  The segnosaurians are most likely the sister 
group of Class Aves sensu lato, and therefore many of the supportive 
characters which are listed below will be found in some or all segnosaurians 
(as noted).  Tyrannosaurs appear to be further out (contra Sereno's 
"Tyrannoraptora").
 SUPPORTIVE CHARACTERS:
    (1) Enlarged sternum articulating with more than 2 pairs of ribs.  Also 
note that sternal anterior margin is apparently often slotted for coracoids 
(and said coracoids sharply reflexed).
    (2) Possession of ornithoid eggs (microstructure modified or partially 
reversed in Troodontidae).
    (3) Possession of vaned feathers (may occur in some outgroups including 
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 the 
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 segnosaurians 
probably occurred in parallel--i.e. a mild case of convergence).
    (13) The fused distal carpal element has often fused to the metacarpals 
(forming a carpometacarpus).  Apparently arose at least twice in Class Aves 
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 my 
proposal accordingly.  However, I think even he may be surprised, and that 
the case for "enigmosaur" paraphyly is a very viable alternative.  According 
to this alternative view, "enigmosauria" is based on plesiomorphies and 
parallelisms.  We shall see.  As always, *constructive* comments are 
welcome.
      ------- Cheers,   Ken Kinman



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