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Re: New Rigby Giant



Jack wrote:
> 
> On Tue, 4 Nov 1997, Sean Connell wrote:
> 
> > > Brian (franczak@ntplx.net)
> > Brian, and all, do you know how reliable this figure ( skull fully two
> > meters) is? If it is this is truly one gigantic tyrannosaur.The largest
> > skulls of any land animals (_Triceratops_ and _Torosaurus_) attain
> > lengths of 7.5 feet if I remember right. In comparison, imagining a rex
> > skull even close in overall length is awe inspiring.The ceratopids
> > benefit from an elongate "frill' which in _Torosaurus_ accounts for much
> > of the size.The rex, with it's deep blunt snout and proportions would
> > certainly be a competitor in the "largest land animal skull" department
> > if judged by sheer volume.Also....I'll second Brian's question on
> > Rigby's reluctance at indentifying the genus/species as _Tyrannosaurus
> > rex_.To my knowledge, there is a large diversity of size and shape in
> > individual skeletal elements among rex. The result of changing gene
> > pools within a species, that we are veiwing in a few individuals from
> > different areas across a wide spectrum of that species' time on Earth?
> > What bones is he seeing a difference so drastic that it would cast doubt
> > on the species falling within rex? And what do the resident tyrannosaur
> > specialists (Holtz?,Paul,etc.) say about the variation of skeletal
> > features within _Tyrannosaurus rex_? How large a variation ( in your
> > opinions), and in what skeletal features, should we see before we
> > construct a new species within Tyrannosaurus or a new genus
> > altogether?----Just thinking again, Sean C. :-D
> 
> I should probably allow someone else to bring up this point, but oh well.
> I believe that the size is well within the range possible for a _T.rex_
> based on an argument in PDW which stated that the individuals
> then discovered _might_ not be fully grown individuals (GSP, if you no
> longer support this idea, let us know--I don't mean to put words in your
> mouth).  Therefore a _T.rex_ of 10 tonnes would not be unreasonable.
> 
> jc

        As far as species variation goes, perhaps, but what about
structurally? In any population you will have a small percentage
of abnormally large animals (like Bakker's giant Utahraptor in
"Raptor Red") that occupy the upper tail of the normal distribution.
Given the infrequency of these individuals, and the unlikelyhood
of fossilisation, it is statistically unlikely that they would be
fossilised very often, if at all. But unlikely is not impossibility.
        On the other hand, there must have been an upper structural
limit to tyrannosaurs. Given the very close size estimates for
T.rex, Gigantosaurus and Carcharodontosaurus made by GSP a while
back on the list, I would not be surprised if the creatures we already
know of by fossil remains are at or near that limit.
-- 
____________________________________________________
        Dann Pigdon
        Melbourne, Australia

        Dinosaur Reconstructions:
        http://www.geocities.com/capecanaveral/4459/
        Australian Dinosaurs:
        http://www.alphalink.com.au/~dannj
____________________________________________________