Re: Upper size limits in dinosaurs and whales

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>The question I posed was, simply, "How can whales grow so large?"  and my
>answer was that the buoyancy of water permits a much larger body size than
>would be possible on land.  I even said that a hundred-ton animal on land my
>be crushed by its own weight.
>
>Well, of course, along comes David Gillette's book on Seismosaurus, with
>estimates in the hundred-ton range for both Seismosaurus  and Ultrasaurus.
>So much for my point.
>
>What I would like to know, though, is: are these weight estimates generally
>accepted?

Actually, no, they are not generally accepted.  Masses based on accurate
scale models of these animals indicate masses of about only 50 - 55 tonnes.
However, the giant titanosaurian Argentinosaurus huiculensis appears to
have massed about 90 tonnes, and the North American diplodocid Amphicoelias
might (very questionably) have been even bigger.

>Has anyone analysed the mechanics of such a beast?  And is the
>reason a large whale dies on the beach independent of size (as it might be
>because even dolphins die during strandings, I suppose).
>

>How can whales grow so large?
>
>Water can support the weight of even the largest whale.  On land, a
>hundred-ton animal might be crushed by its own weight.

Well, (except for the hundred-ton number, maybe) this is still a true statement.


                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.