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Re: wing extensor placement on pterosaurs



Okay, according to Wellnhofer 1991, evidently few and far between due to all the specimens with folded wings:

the following pages of images of wing extensors on phalanx 1 extending dorsally over fingers I-III:
P. kochi p. 89 (I-III buried deeper on a folded wing)



And the following pages have I-III dorsal to the wing phalanx: P. antiquus p. 23 (disarticulated?)


And the following pages have I-III even with the wing phalanx. Can that be true? Or would there be interference?
Eudimorphodon p. 62 (note III is dorsal to II and dorsal to I)



Unwin's book has nothing on this, unfortunately.

Bennett's 1991 treatise on Pteranodon shows KUVP 49400 slightly disarticulated but stacked top to bottom in this order: IV-III-II-I in _ventral_ view. He shows the extensor tendon process extending to the ventral half of metacarpal IV on p. 288 UPM 2660.

Bennett's drawing of Santanadactylus has the radius facing anteriorly in flight and chiefly dorsal to the midline of the ulna near the elbow. Chiefly ventral to the midline of the ulna distally. The extensor process is ventral to the midline of the metacarpus along its entire length and ventral to metacarpals I-III stacked dorsoventrally on the distal metacarpus. Makes me wonder if metacarpal IV is not the one torsioned, but the distal carpal is? Interestingly Bennett fills much of the gap between the distal condyles of metacarpal IV with metacarpals I-III, rather than providing for a big extensor tendon riding in that groove.

I have a picture of a privately owned specimen that I shared earlier with John and Chris showing metacarpals I-IV aligned and reasonably articulated. The unguals all point posteriorly and metacarpal IV is dorsal (?) to I-III. Is that how you read it John? I'm willing to learn something new here.

This is interesting. I'm learning something new here from a view I never considered before.

David Peters
St. Louis