Re: Gorgosaurus (was RE: Daspletosaurus temporal/stratigraphic range)

[Darryl Jones <dinoguy@sympatico.ca>]

At 01:36 PM 8/5/2002, Thomas R. Holtz, Jr. wrote:
> Nearly all the phylogenetic analysis of the tyrants I know of converge on 
> A. sarcophagus and G. libratus as sister taxa.  That is, they do share 
> derived features not found in other tyrannosaurids.

Is this based on current literature or on undescribed specimens?  Last I 
saw, there were only two, cranial characteristics uniting them.  Are there 
post-cranial characteristics uniting them?

> So of course we can now whip out our genericometers and...  Oh, yeah.
> Right, they don't exist...  That being the case, it is as much an 
> aesthetic decision as anything else as to whether to include two sister 
> taxa in the same genus or to place them in separate genera.  Some very 
> smart guys (Carr, Williamson, Brochu, Russell, Paul) place sarcophagus and 
> libratus in the oldest valid available genus name, Albertosaurus; other 
> very smart guys (Currie, Hurum, Bakker, moi) feel more comfortable placing 
> them in separate genera.  And I mean that last part seriously: "*feel* 
> more comfortable". These decisions are not based on science; they are 
> bookkeeping decisions.

Last I saw, all of these individuals (except Russell, who listed primitive 
characteristics to unite them) said that reasons for uniting/dividing the 
two were forthcoming.  Have any of them published on this yet?  I know 
papers are coming, but I wondered if I missed something (other than Carr 
and Williamson's southern tyrannosaur paper, which I still have to get).

> > While we are at it. Any comments on the
> > Tarbosaurus/Tyrannosaurus generic problem too?
>
> At a genericometer reading of XX.III, I find that... it currently pleases 
> me to include them in separate genera.  However, I have previously kept 
> them in the same genus.  They do seem to share a LOT of derived features, 
> but as Brochu has rightly cautioned, these may be size-related.

Last I heard (many moons ago), a dissertation on Mongolian tyrannosaurs was 
in the works by Karol Sabath.  Was I misinformed? Might this become a paper 
eventually, or is there a way to get a copy of this, if it was completed?



Darryl Jones  <dinoguy@sympatico.ca>

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