Let's fix those pterosaur hands - PS

[David Peters <davidrpeters@charter.net>]

PS

On second thought, I made a mistake in suggesting that Chris Bennett  
advocates folding the pterosaur hand in half and gluing it back-to- 
back. That's just the result of his hypothesis when translated into  
reality. He illustrates this in his figure 5.

Instead Bennett advocates supinating the antebrachium and with it the  
entire hand. He also advocates changing the natural flexion of digit  
IV into the hyper-hyper-hyper-extension of digit IV so that the digit  
can fold back-to-back along the backside of its own metacarpal.

In consideration of this, if the entire hand supinates thumbs up, then  
to achieve Bennett's configuration of metacarpals I-III backed up and  
"bound" to metacarpal IV, somehow the lateral bond between III and IV  
has to break and metacarpals I-III have to slide as a unit down  
Bennett's "palmar" side of metacarpal IV, coming to rest with the  
former lateral side of III nearing the former lateral side, now the  
underside, of IV. Bennett's figure 6 stops short of showing this.

In addition, if Bennett is correct, all former hallmarks of the dorsal  
surface of metacarpal IV -  via evolution -  become ventral in  
morphology and vise versa without leaving a trace of their former  
identity.

Sorry to introduce more problems. Nothing about this hypothesis seems  
tenable.

David Peters
St. Louis