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MORE ON GIANT TYRANNOSAURUS



It turned out the that NPR Morning Edition program on a dispute over a giant
T rex turned out to be an interview of K. Rigby about the mess surrounding
the excavation of his new specimen. Included some sharp comments on how the
example of Sue is causing folks out west to do ill advised things.  Like
ranchers trying to extract remains over a weekend without proper skills and
equipment, and forgetting that the FBI is not happy about people taking
tyrannosaurs without permission from Federal land. Do not know how complete
this new individual is. Wonder if the possible dethronement of Sue as the
biggest will degrade its value. 

As for the size of various specimens, it goes something like as follows. 

NY and type - My skeletal restorations indicate these are virtually identical
in size, even though the NY is "gracile" and the type "robust". Modeled mass
for both is 5.7 tonnes. 

Sue - The postcranial measurements of this "robust" specimen by Larson in the
1994 DinoFest proceedings consistently are 5-7% larger than the type when the
same elements are available for comparison, indicating it weighed about 6.5
tonnes. The crushed skull is as much as 17% larger than the NY skull, but
this probably only means this is a bigger headed individual. Still, need to
do a complete restoration to get a better mass estimate. 

New giant - The pubis seems to be almost 10% longer than the type and NY
skel. Implies a mass of 7.5 tonnes. However, this is only one comparison, and
there is no measurment for this bone in Sue. So it can only be said this
animal was probably at least as large as the type, and maybe bigger than Sue.
Need more bone measurements. 

Berkeley maxilla - This is the same length as the max of Sue, so may be from
a similar sized animal. On the other hand, if its length/mass ratio was the
same as in the relatively smaller headed type and NY specimens then mass
could have been has high as 10 tonnes, although I doubt this extreme value. 

As I previoulsy noted, a model of the Giganotosaurus skeleton results in a
mass of 6.4 tonnes, a slightly bigger fragment may  indicate an individual a
tonne or more heavier. Carcharodontosaurus seems at most no bigger than the
complete Giganotosaurus skeleton. 

So the big three so far seem to be roughly similar in size. Attempts to prove
that one or another is THE most gigantic are probably fruitless, in part
because bone to mass relationships are not consistent even within a species
much less between species, and because of the errors inherent in modeling
masses. Somebody needs to find something clearly in the 10+ tonne range
before the GBWR people need to really take notice.  

GSPaul