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Re: Ceratopsian mass estimates
Although I prefer the Paulian illustrations of T. rex to other artists'
illustrations, I have often wondered if Greg's calculated mass estimate
for a healthy T. rex is closer to the actual mass of a dehydrated T. rex
corpse. Perhaps there is a certain "gestalt" factor involved in such
estimations (R.M. Alexander's equation aside).
I like the suggestion that Alexander's equation needs to be customized
for each taxon under study. Triceratops is no exception (but where do we
find an extant ornithiscian for a truth check??).
On Wed, 20 Apr 2005 17:03:13 -0400 "Andrew A. Farke"
> > Thomas R. Holtz, Jr.
> > > From: email@example.com [mailto:firstname.lastname@example.org]On
> Behalf Of
> > > Andrew A. Farke
> > > Triceratops, USNM 4842, 10208 kg, 22505 lbs.
> > Damn!!
> > That doesn't seem right to me, at least if this is is anything
> like the
> > size of the Hatcher mount at the Smithsonian. Comparing that
> > animal to Stan (which faces off against it in the display), I
> would have
> > guessed you are dealing with comparably massive animals
> > (the T. rex has greater volume with that long tail and legs, but
> is filled
> > with air sacs). Also, it doesn't seem right that those
> > values are so much greater than what are at least grossly similar
> > mammals (Elephas, Loxodonta).
> Exactly. Note too that the values for "Kelsey" (the Triceratops at
> Indianapolis Children's Museum) are closer to what they "should be."
> At the
> same time. . .USNM 4842 *is* one of the "beefiest" Triceratops out
> Its circumference is a full 25% larger than Kelsey, and the bones
> absolutely beefy next to those of say, the "Raymond" specimen in
> Tokyo. Flat
> out, it's a big specimen. I doubt that it's 10 tonnes of big, but
> Greg's estimate was a little low, too?
> > To me Greg's estimates are more reasonable, but it would be nice
> to see
> > *where* or *why* you might be getting an overestimate.
> Exactly--I am "happier" with Greg's estimates, too. My suspicion is
> that the
> circumference/body mass equation isn't all that universal, and that
> consistently overestimating. They've found the same thing for the
> mass regression for mammals--i.e., every clade needs its own
> regression for
> the estimates to be worth anything.
> Also, I'll again point out that I'm not working from direct
> but from estimated circumferences. This also may be bumping up my
> We've got an estimate based on an estimate!
> And, an important thing to keep in mind is that almost nobody states
> specimens their Triceratops mass estimates are based upon. There is
> a *big*
> size difference between, say, YPM 1821 and USNM 4842. I notice odd
> things in
> some published estimates, too. For instance, I'm not sure how
> combined the USNM specimen with the BSP specimen to get a
> Triceratops that
> weighed 5 tonnes (the two specimens are wildly different in body
> At any rate, this body mass thing is an issue totally away from
> anything I'm
> working on right now. Any students looking for a project? ;-)