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Re: bulldog tyrranosaurs



At 04:04 PM 05/02/97 GMT+1000, Tim Williams wrote:
>>A few days ago Tom Holtz  made a comment about the "short snouted 
>>bulldogedness" of Albertosaurus sarcophagus. I found this intriguing 
>>because the skull I had been assuming represented the species (the skull 
>>called "A. arctunguis" by Greg Paul in PDOTW) certainly does not fit 
>>this description. 
>
>If I remember correctly, the type specimen of _A. arctunguis_ is 
>headless.  The holotype for _A. sarcophagus_ is a crushed skull.  The 
>two specimens also come from different formations.
>
A. arctunguis was found headless (also neck, tail, and most of the
backless).  Both specimens were from the Edmonton Formation (Member A-
Horseshoe Canyon?).  The paratype was found in Member B of the formation,
but I think that both Members of the Edmonton Formation are Horseshoe Canyon
(early Maastritchtian).

>_A. arctunguis_ is usually regarded as a slender morph of _A. 
>sarcophagus_.  Future research may show it to be a different species 
>altogether.

I am not sure how this would be done.  The only listed difference between
the two was the shape of one metatarsal.  The difference between the two was
that one was broken and crushed and the other was not.  Pretty slim
distinction, if you ask me.

As for the gracile/robust morph deal, why is this so important?  If you look
around at different people, wolves, cats (of all species), fish, etc., you
see size variation within a species.  This is normal.  There are also
proportional changes in different animals that fit within acceptable
parameters.  For a wild example, compare the skeleton of Andrea the Giant to
that of an "average" North American.  With sample sizes so small in
dinosaurs, we have no idea how much individual variation there was.  Naming
new species or genera on things like " the femur of A looks exactly like the
femur of B, but one is proportionally 2% larger, so I am erecting species C
to cover this new animal" seems somewhat odd to me.  I don't know where the
line should be drawn or who should be in charge of it, but I wonder if
things haven't gotten out of hand.

Boy.  That looks an aweful lot more like a rant than I wanted it to.  It was
kind of meant to be more of a question/discussion topic.  Oh well.

Darryl

----------------------------------------------------------
"the truth is, I don't really care how the dinosaurs died.
I'm interested in how they lived."  (Dr. John R. Horner,
from the Complete T.rex, 1993)
Although the Mike Harris cutback theory intrigues me...
---------------------------------------------------------- 
dinoguy@interlog.com