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RE: Sinornithosaurus venom



Mickey Mortimer wrote:

<Great summary, Mike. The teeth are certainly disarticulated, and as
Denver noted plenty of other theropods have the same kinds of "grooves"
on their tooth roots. For instance, just looking at Currie et al.
(1990), Dromaeosaurus (figure 8.1 J, M), Saurornitholestes (figure 8.2
G), Troodon (figure 8.3 C, E), Richardoestesia (figure 8.4 G, J, K, Q,
S) and two digested teeth (figure 8.5 F, I) have them. The ironic thing
is that these are probably replacement pits (as illustrated for an
unnamed dromaeosaurid tooth by Currie and Zhao, 1993), which Martin
(1991) earlier claimed were absent in theropod teeth, which was among
his proofs birds were not dinosaurs. Furthermore, you're correct that
the pitting in their "subfenestral fossa" is no different than
elsewhere in the antorbital fossa, and that there's no actual boundary
between it and the rest of the fossa. Nor is there the posteroventral
canal illustrated (Xu and Wu, 2001).>

  The root of the crown having the aspect of an hourglass is one of Currie's 
earliest arguments in the plethora of papers describing the troodontid and 
dromaeosaurid teeth from the various formations of Alberta and adjacent 
provinces.  Here, they (or rather, one of them) are argued to correspond to 
resorption pits for germ teeth, which allows the earlier tooth's root to be 
dissolved to make room for the growing replacement, su8ch that the erupted 
crown begins to fall out.  These also exist in troodontid teeth, rather than 
the more infamous dromaeosaurids, despite the crowns being so much smaller 
and.  The problem with the argument is that only one of these pits is for the 
germ tooth, while they exist on both sides of the root.  An additional 
argument, one of mechanical stress reduction, recalls the aspect of 
knife-lightening while retaining strength, and this compares well with Currie's 
argument.  Here, the grooves exist where weight needs to be saved, while also 
allowing a relatively large tooth to grow in its place.

  I would have more to say on troodontid teeth, but then I'd have to kill you.

Cheers,

Jaime A. Headden

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