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Re: Tarbosaurus

Dinogeorge wrote...
>Again, we all know about these, but how could you tell which, if any, were
>operating at any particular place and time to cause the observed
>differences< between the collection differences between Mongolian and
>North American tyrannosaurid specimens? Sure, you can imagine a gazillion
>that might cause preservational biases, but if you can't constrain them,
>they're pretty much useless.

    Bringing back up a point that you've been dodging through this entire
discussion, lets forget about juvenile specimens for a minute and just look
at absolute numbers of tyrannosaurs in Hell Creek and Nemegt.  In Hell
Creek, tyrannosaurs represent a relatively small percentage of dinosaurs,
but in Nemegt they are much much much more common.  You've been presenting
your "null hypothesis" that 1) fluvial preservation in the Negmegt and Hell
Creek Formations is identical, and that 2) tyrannosaur behavior in the Hell
Creek and Nemegt Formations are identical.   There is DIRECT evidence that
at least one of these assumptions is wrong, because if they were both
correct, the percentages of tyrannosaurs preserved in the Hell Creek and
Nemegt Formations would be identical...but they aren't.  Something IS
different George, whether or not we can identify the particular cause!
    So now we have evidence in the form of the studies of Rozhdestvensky
(1965), Carpenter (1992) and Carr (1999) which present morphological
evidence that in addition to tyrannosaurs being overrepresented in general,
juveniles are particularly overrepresented.  What is your only evidence
against this claim?  That tyrannosaur preservation in the Hell Creek and
Nemegt formations should be identical!  The fact that we can't identify the
particular causes why there are preservational differences between juveniles
and adults doesn't mean the evidence for them doesn't exist!
     Your entire response to my mentioning Rozhdestevensky and Carpenter
before was just to point out that Carpenter took out Maleevosaurus.  Fine
George, Ken took out Maleevosaurus!  How about the growth series he set up
using the other specimens he assigned to juveniles of Tarbosaurus bataar?
Why don't you answer the WHOLE argument rather then just the parts that
don't contradict your ideas, George?

LN Jeff

Fear not those who argue but those who dodge.
-Marie von Ebner Eschenbach

Jeffrey W. Martz
3002 4th St. # C26
Lubbock, TX
(806) 747-7910