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RE: Balaur bondac, the double-bladed dromaeosaurid of Transylvania!

While the mdI-1 phalanx appears to be enlarged, it doesn't appear to be so by 
length standards, in which it approaches the length of pdII-2 closely. Given 
that pdII-2 in dromaeosaurids is somewhat shortened compared to, say, 
*Nedcolbertia* or other rather "typical" theropods, this shouldn't be saying 
that much. The phalanx is wide, however, and appears to be as wide (broad) as 
pdII-2; the ungual (mdI-2u) doesn't precisely seem too big, but is larger than 
in *Velociraptor mongoliensis*, implying a relative enlargement.

The authors appear to note that the pd2 was hyper-estensible, and although I've 
not read the paper, it appears that simply looking at the level of preservation 
and positional data of the material, I suspect this is based on the preserved 
_posture_ of the digit, rather than on morphology. This is arguably (again, no 
paper) based on preservation of the distal MTI, which is potentially dislocated 
from the posteromedial side of MTII as in all other dromaeosaurids and the 
dislocation reminds of some dromaeosaur specimens in which the element has been 
rotated around. The distal end does not seem to bear a distinct extension of 
the distal articulation to describe a hyper-extensible joint, and pdI-1 
doesn't, either.

The ungual does appear enlarged, unusually as large as the "walking" unguals on 
pd3 and pd4, but pdII-3u does not appear THAT large (seemingly as in *Adasaurus 
mongoliensis*): pdII-3 appears to be only as long (or shorter) than the 
combined lengths of pdII-1 and pdII-2.

Like other ambush predators (*Smilodon fatalis* or *Panthera leo*) the robust 
shortness of the distal limb segments will imply a robust, short femur, so the 
shortness of the pes seems particularly interesting (compared to the 
proportions in, say, *Velociraptor mongoliensis*).

note: The pubes are almost certainly disarticulated, so that their greatly 
posterior orientation seems somewhat questionable, and they exhibit what 
appears to be dorsoventral distortion in the plane of bedding, so that the 
likely L-shaped pubic profile would have been "straightened" into a shallow 
C-shape. The ischium seems to resemble the I-shaped element of *Archaeopteryx 
lithographica* than the L-shaped element of *Velociraptor mongoliensis*, so I'm 
going to back up Mike Keesey's implication that this may be a late-surviving 
basal dromaeosaurid convergent in some details to "velociraptorine" 

But, again: I've not read the paper, just the supp info and the figures.


Jaime A. Headden
The Bite Stuff (site v2)

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 

> Date: Tue, 31 Aug 2010 11:43:59 -0700
> From: keesey@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Balaur bondac, the double-bladed dromaeosaurid of Transylvania!
> On Tue, Aug 31, 2010 at 12:52 AM, Roberto Takata  wrote:
> > On Tue, Aug 31, 2010 at 12:36 AM, T. Michael Keesey 
> >> It has the usual number of digits; it's just that digit I is
> >> hypertrophied like digit II. (Homeotic shift?)
> >
> > It doesn't seems to me to be hypertrophied. It seems just to be
> > dislodged from the original position (maybe turned post mortem to
> > front).
> I suppose I should have said pedal phalanx I-1 larger than usual for
> dromaeosaurids (around the same size as pedal phalanx II-1).
> --
> T. Michael Keesey
> Technical Consultant and Developer, Internet Technologies
> Glendale, California
> http://tmkeesey.net/