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On pedal digit II of _Patagopteryx_, Mickey wrote...

> Chiappe et al. (1999) state- "...the predatorial 
> specializations of digit II ... retained to a lesser degree in 
> certain more advanced birds, such as Patagopteryx           
> deferrariisi (Chiappe, 1996)."  Chiappe (1996) does not   
> describe the pes of Patagopteryx as being raptorial in any 
> way.  Phalanx II-2 has a massive proximoventral articular 
> lip, but it is not proximally extended like sickle-clawed    
> taxa.  Similarly, the distal articular surface of phalanx II-1 
> is not expanded dorsally.  The second digits ungual is      
> about 93% of digit III's ungual.  So I have no idea what   
> Chiappe et al. were referring to.

I do not have any literature/diagrams of _Patagopteryx_ (or 
any other theropod for that matter) in front of me now, but 
is it possible that Chiappe et al were referring to the shape 
of digit II's ungual? As has been mentioned on DML before, 
in certain neornithines (notably falcons and many 
passerines) the degree of curvature seen in digit II's ungual 
means that, rather than having most of the ungual's ventral 
surface in contact with the substrate/branch when the foot is 
at rest/gripping a branch (as is the case with the unguals on 
digit III and IV), only the ungual's tip is in contact. By no 
means is the digit hyperextended however. It is unlikely 
though that Chiappe et al, or Chiappe (1996), would neglect 
to mention significant curvature of the ungual. Just a 

Incidentally this feature is probably what Sereno was 
talking about when he said that basal birds besides 
_Archaeopteryx_ and _Rahonavis_ have raptorial second 
digits, i.e. a strongly curved (and/or proportionally large) 
digit II ungual. A slightly enlarged digit II ungual seems 
primitive for theropods anyway IIRC.

Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045