Archie Toes and Dromeaosaurs

["Nicholas R. Longrich" <longrich@phoenix.Princeton.EDU>]

        I have a question for Greg Paul- 
 You made the assertion that little A. lithographica had a hyperextendible 
 second toe, if I remember. How certain are you of this? If the bird did 
 have the Toe, what on earth was it using it for? One supposes it could 
 have been a primitive version of the dromaeosaur toe, inherited from 
 cursorial predators. Or did it  originally work as some sort of 
 climbing adaptation?
        And among the dromaeosaurs, which have so much in common with the 
 archaeopterygians- how many of these features simply prove that they 
 were closely related, and how many of these only make sense in the 
 context of a history of flight? I would have given up on the idea of
 dromaeosaurs being birds long ago, if it weren't for the fact that I
 can't figure out any good reason they're can't be... It makes a weird
 amount of sense. Flight is expensive, and the primitive birds aren't
 really all that specialized, so 
 they tend to revert back to being earthbound frequently- even modern 
 birds do so quite frequently, and they're far more specialized than an 
 Archaeopterygian. And then Mononykus and Patagopteryx bear out this idea so 
 nicely. 
        -nick L.