Broader than Dinosauria

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

  It is just not a matter of the monophyly of Dinosauria that must be 
questioned here, and though
I know that Kinman has included them in Theropoda, the synapomorphies for the 
more inclusive
groups to Dinosauria must also be considered. That is, what puts *Marasuchus*, 
*Lagerpeton*,
*Pseudolagosuchus*, *Lagosuchus*, and *Lewisuchus* closer to dinosaurs than to 
crocodiles. This
means the synapomorphies of Dinosauromorpha and Dinosauriformes must also be 
considered along with
those of Dinosauria.

  For one thing, a fully perforate acetabulum is present in all except 
*Lagerpeton*, and
*Lewisuchus* et al. have the distinct deltopectoral crest, and all have a tall 
ascending process
of the astagalus, though *Lagerpeton* [odd name, "crawling bunny" :) ] has a 
distinct morphology
that is perhaps not analogous, though homologous, I would code it absent on 
this mark. Other
features, including vomeral extension, are unknown. *Lewisuchus* lacks the 
apparent postemporal
fenestra, and no dinosaur except for maybe the well-nested and therefore 
irrelevant theropod
*Scipionyx* have a postfrontal bone [see DalSasso and Signore, 1996; Mortimer, 
pers. comm., 2001,
though I doubt the identification.] All possess a distinct femoral head, but 
this _is_ an
adaptation to the position of the femur in a subvertical posture, as is the 
"twisted" humeral
shaft to aligning the distal condyles parallel to the humeral head for most 
quadrupedal dinosaurs.
I would not use this as an synautapomorphy based on it's functional aspect, but 
it _is_ still a
feature not prezent in the immediate outgroups to the included paradigm, and 
thus such a feature
becomes a diagnostic synapomorphy. Note: just because a group may reverse a 
character state or
present an apomorphy that does not preserve the "original" synapomorphy, does 
not mean that the
feature is no longer diagnostic for a group. Thus, it is singularly notable 
that there is in fact
not one apparent synapomorphy present in all Dinosauria exclusive of it's 
outgroups, or of
Dinosauromorpha, or Dinosauriformes. In this, Tracy is right and commendably 
so. It is not
relevant for the reasons given above, addressed both to Tracy and to Ken.

  Thanks for the air time...


=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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