Re: Uh-oh, Sue shrinkage

[DinoBoyGraphics@aol.com]

Greg Paul is undoubtedly correct that Sue is shrinking, especially as compares 
to the figures published before the Field Museum acquired the specimen.  I'm 
not sure "she" has shrunk quite as much as his last post indicates.

I'm a big fan of GPs volumetric-model method of estimating the mass of extinct 
vertebrates, but I'm not sure that femoral length is the best unit to scale 
mass between T. rex specimens.  Since trunk dimensions seem to be an excellent 
indicator of overall mass, I've scaled relative trunk length in Sue (and some 
other specimens) against GPs AMNH 5027 mass estimate (5700 kg) and skeletal 
drawing.

For FMNH PR2081 (sue), I came up an estimate closer to 6500 kg.  Still lower 
than previous estimates, and not even a tonne larger than the AMNH rex.  For 
BHI 3033 (stan) I calculated a "measly" 4870 kg.  The MOR specimen (MOR 980) 
known variously as "Peck's rex" and "Rigby's rex" weighs in (well, masses in) 
at 6000 kg.  

For comparison of methodology, on CM 9380 the anterior-posteriorly short dorsal 
vertebrae give me an estimate of 5120 kg, about 10% less than GPs estimate in 
his Dinofest paper.  Use this to cast suspicion on my method if you like.

Some have noted that I am restoring T. rex tails longer than GPs classic AMNH 
reconstruction (after sue and an unpublished specimen), but the difference in 
mass would be negligible, so I have not taken this into account in my 
calculations.

Cheers,

Scott


Scott Hartman
Zoology & Physiology
University of Wyoming
Laramie, WY 82070

(307) 742-3799