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RE: Ceratopsian mass estimates

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Andrew A. Farke
> Greetings, DML. . .
> I just finished some mass estimates for ceratopsian dinosaurs (part of
> background work tangential to my dissertation), which I thought might be of
> interest to the list. First, an explanation of my methodology. . .
> The results are as follows (masses in kg and pounds):
> [Taxon, Specimen, Mass in kg, Mass in lbs.]

[snip snip]

> Triceratops, Kelsey, 5231 kg, 11533 lbs.
> Triceratops, USNM 4842, 11112 kg, 24496 lbs.
> The Triceratops estimates are scarily high--11 tonnes for the USNM
> specimen?! I plugged in the measurements from Hatcher et al. 1907 (which
> gives actual circumferences), and got pretty similar results:
> Triceratops, USNM 4842, 10208 kg, 22505 lbs.


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 sized mammals 
(Elephas, Loxodonta).

> For the most part, the estimates are higher than others floating out there.
> For instance, Greg Paul published an estimate of around 1.5 tonnes for
> Chasmosaurus (vs. 1.98 tonnes for my estimate--admittedly not based on the
> exact same specimen, but they should be in the ballpark at least!). Greg
> estimated 6.4 tonnes for the Triceratops USNM 4842 (vs. 11 tonnes for
> mine!).

To me Greg's estimates are more reasonable, but it would be nice to see *where* 
or *why* you might be getting an overestimate.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796