Re: A new Dracorex with premaxillary teeth

[Christopher Collinson <thats_mr_annoying_to_you@yahoo.com>]

The actual specimen looks absolutely nothing like that replica. The original 
specimen is, or at least was, in the hands of the Palaeo Incident people, ck 
preparations, and they have photos of the specimen at their site and at 
baystatereplicas. Its badly crushed dorsoventrally but the front end is in even 
worse shape almost like it ran into a brick wall, its smashed in and twisted 
back.  In one photo, amongst the jumble of twisted pieces of bone there appears 
to be a single tooth apparently situated near the anterior margin of the 
premaxilla, but it doesn't look like its actually part of the premaxilla. At 
least its not immediately obvious to me, and its really difficult to tell based 
on the photos. If it is what its is claimed it certainly did not look like the 
way it does in their reconstruction, but maybe more like Bakker's figure only 
with a tooth in place of that circular rugose area. 

I also doubt how solidly it can be identified as Dracorex, its rather different 
than the type skull. Im definitely not sold on the implications of Horner et 
als work, ie that Dracorex Stigimoloch and Pachycephalosaurus can be sunk in to 
a single taxon, but they are correct from the ontogenetic perspective. I 
personally think this skull may be an individual of Stigimoloch, its squamosal 
horns are certainly a better match than Dracorex. 

And anyway, are premaxillary teeth trully confirmed for the other genera? I 
know the Pachycephalosaurus type is more or less complete, but its heavily 
restored in the area in question, and based on the photos Ive seen it dosen't 
look like Sandy preserves that much of the premax beak-margin either. 
Stigimoloch is based on a couple of squamosals and referred domes, so says 
nothing. I think RMDRC has a new Stigimoloch skull(not Sandy) but I dont know 
how complete it is. 

Cheers,
Christopher Collinson



--- On Wed, 5/14/08, Brad McFeeters <archosauromorph2@hotmail.com> wrote:

> From: Brad McFeeters <archosauromorph2@hotmail.com>
> Subject: A new Dracorex with premaxillary teeth
> To: dinosaur@usc.edu
> Date: Wednesday, May 14, 2008, 7:18 AM
> I picked up the new issue of Prehistoric Times (#85) last
> night and noticed something interesting in an ad on page
> 43.  The ad has the same content as this webpage:
> http://www.prehistoricstore.com/item.php?item=1148
> 
> The claims about premaxillary teeth are surprising because
> the premaxilla of the first *D. hogwartsia* skull was
> described by Bakker et al. (332-333) as forming a thick pad
> without teeth.  "The alveolar-beak surface along the
> periphery of the premaxilla is of exceptional interest.
> There are no alveoli. Except for the tiny, vestigial crown
> fragment mentioned below, there is no evidence that this
> individual possessed premaxillary teeth." 
> Unfortunately I can find no mention or figure of this
> supposed vestigial crown fragment elsewhere in the paper. 
> The only subsequent mention of premaxillary teeth is when
> they claim (324): "All the long-snouted skulls lack
> premaxillary teeth and are of Lancian age."  Well, not
> any more!  The new skull also appears to have a couple
> sharp-looking maxillary teeth where the holotype has a
> diastema (or has 5 pmx teeth, which is equally unexpected).
>  One possibility is that the possession of anterior teeth is
> variable within the species, being another of
>  the major ontogenetic transformations in the
> Pachycephalosaurini... explaining the vestigial pmx tooth
> crown supposedly associated with the *D. hogwartsia*
> holotype?  The alternative is of course that the two
> *Dracorex* skulls belong to different species, which would
> refute the hypothesis that there is only a single valid
> species of Lancian pachycephalosaur.  Either way, it looks
> like a significant specimen.  Contrary to the ad, it is not
> exciting that the premaxillary teeth are serrated, because
> they are typically serrated in previously described
> pachycephalosaurs.  
> 
> It's too bad I have to find out about this specimen
> from an advertizement for replicas, rather than a
> scientific publication.  The wording of the ad seems to
> suggest that it is cast directly from a real fossil, and
> not sculpted like some of their other products, though I
> cannot be 100% sure.  The PT version of the ad has
> "Cast From A Real Dinosaur!" written beside the
> photo of this skull, but perhaps they are only claiming
> that it is not representative of some fictional dragon
> species.  And if it is a proper cast of a fossil, was any
> restoration done?  I wonder if the second *Dracorex* skull
> is in a museum yet, and if we will ever see a scientific
> paper on it discussing those mysterious teeth.  
> _________________________________________________________________