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RE: Senter's Pterosauromorpha




I never said that the evidence for Pterosauromorpha was compelling.  I just 
said that Senter's case for a for a _Scleromochlus_-Pterosauria clade inside 
Ornithodira was far better supported than your case for a 
_Sharovipteryx_-Pterosauria clade inside Prolacertiformes.  You may be closer 
to the truth; I don't know.  I'm just worried about your methodology, and I'm 
not sure all your character codings are reliable.  For example, when you code 
carpal characters for _Sharovipteryx_, even though the forelimbs are still 
buried in the matrix, it is a cause for concern.


Cheers

Tim



> Date: Wed, 27 Feb 2008 13:00:35 -0600
> From: davidrpeters@earthlink.net
> Subject: Senter's Pterosauromorpha
> To: twilliams_alpha@hotmail.com; dinosaur@usc.edu
>
> Tim, I can't share your enthusiasm for Senter's dissertation. I
> don't find much evidence in his lists for a sister group relationship
> involving pterosaurs and Scleromochlus as basal members of the
> Archosauria (Euparkeria is the outgroup.)
>
> Senter found these 13 synapomorphies for Euparkeria+Archosauria
> (including pterosaurs).
>
> Pterosaurs share three (and a half - #2). All fairly plesiomorphic
> characters. Two characters are undocumented for
> Eudimorphodon and Austriadactylus (Senter's pterosaur taxa).
>
> 1. Internal choana bounded anteriorly by maxilla: Not visible in
> Eudimorphodon and Austriadactylus
>
> 2. Maxilla with < 18 teeth. : Eudimorphodon has 23. Austriadactylus
> has 14.
>
> 3. Angle between scapular blade and acromion process < 160o. : Not in
> pterosaurs.
>
> 4. Femoral head turned in at obtuse angle with shaft. : Pterosaurs
> have this, but it’s fairly plesiomorphic.
>
> 5. Pedal centrale absent. : The centrale is present in pterosaurs. It
> looks like distal tarsal III.
>
> 6. Distal tarsal II absent. : Sometimes. In any case, not documented
> in Eudimorphodon and Austriadactylus.
>
> 7. Pedal phalanx IV-1 not longer than pedal phalanx III-1. :True in
> Austriadactylus. Plesiomorphic.
>
> 8. Lacrimal antorbital fossa dorsoventrally deep. Not in pterosaurs.
>
> 9. No overlap between shafts of postaxial cervical ribs. : Not in
> Eudimorphodon or Austriadactylus.
>
> 10. Metacarpal IV markedly shorter than metacarpal III. : Not true in
> pterosaurs.
>
> 11. Fourth trochanter present as a low ridge or shallow crest. :
> Absent in pterosaurs.
>
> 12. Interdental plates present. : Absent in pterosaurs.
>
> 13. Width of distal expansion of humerus < 1/3 humeral length. True
> in pterosaurs. Also in Cosesaurus.
>
>
> Senter found these 7 synapomorphies for Archosauria (including
> pterosaurs):
>
> Pterosaurs share 5, but Cosesaurus and/or Longisquama also share all 5.
>
> 1. Pterygoid edentulous. True in pterosaurs, also in Cosesaurus.
>
> 2. Palatine edentulous. True in pterosaurs, also in Cosesaurus.
> 3. Antorbital fossa anterior to internal antorbital fenestra,
> anteroposteriorly broad. : Fossa abent in pterosaurs.
>
>
> 4. Premaxillary teeth without denticles. : True in pterosaurs.
> Plesimorphic
>
> 5. Scapular blade distally expanded to> 2x width of base of
> blade. : Not true in pterosaurs.
>
> 6. Length of scapular blade between 4x and 6x width of base of
> blade. True in pterosaurs, also in Longisquama.
>
> 7. Scaplo-coracoidal glenoid simple, not screw-shaped. True in
> pterosaurs, also in Longisquama.
>
>
>
> Senter found the following 21 synapomorphies for Pterosauromorpha
> (Scleromochlus + pterosaurs)
> Pterosaurs share 21 but Scleromochlus shares only 6 (+ 3 unknowns).
> Longisquama and/or Cosesaurus share 18. Way better.
>
> 1. Angle between scapular blade and acromion process> 160o. : True
> for both. Also in Longisquama and Cosesaurus.
>
> 2. Sharp tapering of snout to an anterior point in lateral view. :
> True for pterosaurs. Only true for Sclermomochlus in dorsal view.
> Also true for Cosesaurus and Longisquama.
>
> 3. Maxilla contacts external naris. : True for pterosaurs, Not true
> for Scleromochlus. Also true for Cosesaurus and Longisquama.
>
> 4. Anterior extremity of maxilla anterior to external naris. True for
> pterosaurs. Not true for Scleromochlus. Also true for Cosesaurus and
> Longisquama.
>
> 5. Antorbital fossa absent anterior to internal antorbital fenestra.
> True for pterosaurs. Not true for Scleromochlus. Also true for
> Cosesaurus and Longisquama.
>
> 6. Jugal extends anterior to contact with lacrimal. True for
> pterosaurs. Not true for Scleromochlus. Also true for Cosesaurus and
> Longisquama.
>
> 7. Ventral margin of squamosal (anteriorly) below mid-height of
> orbit. True for pterosaurs. Not true for Scleromochlus. Also true for
> Cosesaurus and Longisquama.
>
> 8. Interdental plates absent. True for pterosaurs. ? true for
> Scleromochlus. Also true for Cosesaurus and Longisquama.
>
> 9. Number of sacral vertebrae increased to 4. True for pterosaurs.
> True for Scleromochlus. Also true for Cosesaurus and Longisquama.
>
> 10. Anterior hemal arches < 1.5x length of associated vertebrae. True
> for pterosaurs. True for Scleromochlus. Also true for Cosesaurus and
> Longisquama.
>
> 11. Anteriormost T-shaped hemal arch proximal to ninth caudal
> vertebra. : True for pterosaurs. Not true for Scleromochlus. Also
> true for Coesaurus and Longisquama.
>
> 12. Sternum> 2x length of sternal end of coracoid. True for
> pterosaurs. Not true for Scleromochlus (no sternum known). Also true
> for Longisquama.
>
> 13. Metacarpal I> 0.6x length of metacarpal II. :True only for
> pterosaurs. True for Scleromochlus. Also true for Cosesaurus and
> Longisquama.
>
> 14. Metacarpal IV subequal in length to or longer than metacarpal
> III. :True for pterosaurs. Unknown for Scleromochlus. Also true for
> Cosesaurus and Longisquama.
>
> 15. Manual phalanx II-2> 1.3x length of phalanx II-1. True only for
> Austriadactylus and Eudimorphodon.
>
> 16. Manual digit V demonstrably absent, including metacarpal. True
> only for Austriadactylus and Eudimorphodon.
>
> 17. Dorsoventrally shallow extension of iliac blade anterior to pubic
> peduncle. True for pterosaurs. Not true for Scleromochlus. Also true
> for Cosesaurus and Sharovipteryx.
>
> 18. Fibular midshaft diameter < 0.5x tibial midshaft diameter. True
> for pterosaurs. True for Scleromochlus. Also true for Cosesaurus and
> Longisquama.
>
> 19. Pedal phalanx V-1 elongated. True for pterosaurs. Way not true
> for Scleromochlus. Also true for Cosesaurus and Longisquama.
>
> 20. Height of maxilla ventral to internal antorbital fenestra, < 1/3
> total maxillary height.: Not true for Eudimorphodon. True for
> Austriadactylus. True for Scleromochlus. Not true for Cosesaurus and
> Longisquama.
>
> 21. Mandibular fenestra absent. True for pterosaurs. Unknown for
> Scleromochlus. Also true for Cosesaurus and Longisquama.
>
> Respectfully yours,
>
> David Peters
> St. Louis

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