Re: Feducciary challenges and tootsies

["James Farlow" <farlow@IPFW.EDU>]

I'd like to comment on the following recently reported statement on this list:

     Concerning the claim that this fossil is a dromaeosaur, I see no 
evidence of a sickle claw.  If this is the closest "nonavian" relative of 
birds, then it disproves the hypothesis that dromaeosaurs are the sister 
group of birds.


I would like to say:

The specimen reported in the 26 April issue of Nature is WAY cool.  I just wish 
the authors had included a close-up photo of the entire foot, and not just 
portions of the feet.  But that's just me  ;-)

Anyway, look at part a of Figure 4, and the proximal articular surface of 
phalanx II-2.  There is a marked dorsoventral asymmetry, such that the ventral 
portion extends further proximally than the dorsal portion.  This is 
reminiscent of the condition of the same phalanx in _Deinonychus_ et al., but 
not developed in as extreme a fashion.  Such a feature would have allowed the 
second phalanx to slide upward along its articulation with the first phalanx 
more readily than in less specialized tootsies.  If the beast had wanted to use 
its digit II in a dromaeosaur-like manner, it would need something like that.

As Ji et al. put it (p. 1087), "The second pedal digit shows specializations of 
a raptorial digit and an enlarged claw, but not to the not to the same degree 
seen in dromaeosaurs such as _Velociraptor_."
This strikes me as a fair assessment.  Ji et al don't claim that there is a big 
sickle claw, but only that there is a suggestion in that direction.  So I think 
the "Feducciary" is rather overstating his case.

Actually, my main query about the paper is the authors' statement (p. 1087) 
that "The unguals, like those of the hand, are short."  To my eye, the unguals, 
if I am correctly interpreting the picture, illustrated in part b of figure 4 
seem rather long compared with other phalanges of the foot.  That's why I wish 
there had been a close-up photo of the entire foot, to see if that impression 
is indeed correct.

Apart from the usual stuff about the configuration of the wrist and hand, what 
impresses me most about the critter are the long tail stiffeners, the 
dromaeosaurid pedal phalanx II2, and the teeth with coarse posterior but no 
anterior serrations. 

All told, this strikes me as a VERY dromaeosaurid-like beast (and this from a 
guy who entertains doubts about where _Caudipteryx_ plugs into the picture).  
If this is "massive convergence", it is massive at sauropodan size.

Oh, yes--I almost forgot.  The feathery thingies are a bit interesting, too.