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Re: bulldog tyrranosaurs



Jeffrey Martz wrote:
> 
>     I can't speak for species or genus distinction, but if you are
> referring to sexual dimorphism, the "robust" and "gracile" morphs seen is
> Coelophysis, Syntarsus, and apparantly Tyrannosaurus as well, are not
> totally random variations in size or morphology across the population.
> There are two distinct size classes, and particular suites of
> morphological characteristics which characterize the size classes.  The
> dimorphism in T.rex is still fairly controversial (being a smaller smale
> size), but there is less doubt about it in the Ghost Ranch theropods.
> Check out the papers on these three theropod genera in "Dinosaur
> Systematics".

I know a lot of people say this , but I just have to question the 
validity of this (yes, here I go questioning the experts, but hey,  I'm 
not the first to do so in this thread).  There just aren't many 
specimens to look at, certainly not the Tyrannosaurids.  If you took 
twenty specimens collected from a plane crash containing, say, an 
American football team, and then found say, a tribe of starving African 
bushmen, people might very well say they were different species.  Look 
at the size difference, they are clearly two distinct size classes.  
Naturally, we know they are one and the same species and that this is a 
ridiculously extreme data set.  However, this is not terribly unlikely 
to happen in the fossil record (gee, I wonder how many people are going 
to have a problem with that statement, more than a couple I'd expect).  
All in all, I would tend to agree with GSPaul and Darryl in that perhaps 
more differences should be shown before new species are named.

Joe Daniel