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Upper size limits in dinosaurs and whales
I wonder if anyone out there can help me. I am putting the final touches on
a children's question-and-answer book on nature, which has involved me
checking some text I wrote over a year ago, and (with a publisher's deadline
breathing down my neck) I find I have written myself into a bit of a corner.
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? 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).
Anyway, I would appreciate any guidance on this. Here is my original text:
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.
On land, very big animals have a problem - gravity. Even the largest
dinosaurs were much lighter than a blue whale [WELL, I GUESS THAT ISN'T
TRUE!] In the ocean, whales don't have that problem because water buoys
them up. They still need vast amounts of food to supply their huge bodies,
but their size helps them retain heat in icy waters.
A whale stranded on a beach, though, is in trouble even though it can
breathe air. It may overheat in the sun, and the weight of its body can
crush its internal organs. many people try to help stranded whales, but it
is very difficult to do this properly.
Any comments, flames etc would help. Might food be a greater limiting
factor than gravity, so that the filter-feeding methods of large whales (not
available to sauropods) may have permitted (or even required) large size?
Ronald I. Orenstein Phone: (905) 820-7886 (home)
International Wildlife Coalition Fax/Modem: (905) 569-0116 (home)
Home: 1825 Shady Creek Court Messages: (416) 368-4661
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