[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Precision



For what it's worth, I've had to play around with mass estimates for large sauropods for the in-press supersaur paper, and Greg's sauropod mass estimates have held up pretty well.

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333

www.skeletaldrawing.com

-----Original Message-----
From: GSP1954@aol.com
To: dinosaur@usc.edu
Sent: Tue, 28 Nov 2006 6:55 PM
Subject: Re: Precision

The way to determine what mass estimates are correct for a given specimen is
easy enought. Simply treat my mass estimates as though they are those of God.
Since there aren't any of those anyway one might as well.


Take Brachiosaurus, specifically the mounted SII. The old ~80 tonne mass
estimates were based on a commercial model that was inaccurate, bloated, and
probably not the correct scale either. The skeletal restoration published by
Janensch is also overly large, especially in the length of the dorsal series.
Same
for the mounted specimen, in which the actual and fragile dorsals were replaced
by plaster models that are too long. Judging from careful a skeletal
restoration based on the actual remains the mass could not have been much below
30 t,
and very probably under 40 t, my restoration has it around 32 t. There are
bones in the collections that are larger than the mounted skeleton. So there
probably are heavier individuals known. But we have to be careful. The
dimensions
of individual bones relative to mass can very a substantial amount, so even if
a femur is say 10% longer than another it does not establish that the longer
femur came from the heavier individual, or even if it is heavier, that it is
by 10% cubed. Using skull dimensions is especially unreliable. The only way to
really compare the mass of individuals is if a reasonable amount of the
skeleton is available.


GSPaul



________________________________________________________________________
Check out the new AOL. Most comprehensive set of free safety and security tools, free access to millions of high-quality videos from across the web, free AOL Mail and more.