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Re: Gastric stones of dinosaurs were not for milling food !

Hi again,

just some other comments.

>>how much food would they be able to gather -- 200kg? 

--------------- Relative to maximum acquisition capability *and* daily 
nutritional requirements-- don't know, that was one reason for the original 
post; to my surprise, no one has come up with numbers or references. Surely 
someone has made a jaw-model to constrain possible acquisition of leaf/mass per 
day by large sauros, but so far, I can't find their work. But yes, 200 kg seems 
do-able to me from the very rough estimates I have made.

Do you really think your estimates are precise within less than a
factor of 2 or 3? (i.e., 200kg is possible, but 500-600 is not?)

>>Can you really raise the nutritional value in a
>>plant by a factor of 2 or 3 just by increasing N2-content?

------------- Increases in n-value per *free nitrogen* are well-known. An 
increase in ambient free nitrogen due to 
ambient-free-nitrogen-to-atmospheric-N2 proportionality is speculation on my 
part, although it seems eminently logical. No idea what the curve would be. 
What is not so speculative is that lower evaporation rates would allow an 
increase in the CO2 intake per unit H2O lost for a given plant, which in turn 
would allow an intra-plant re-allocation of mass...

I don't know enough about plant physiology to comment on the
plausibility of this assumption. My question is simply this: To get
the factor of 2 or 3 you require, wouldn't this mean that the N2
content was a factror of 2 or 3 higher? With corresponding change in
air pressure, wouldn't this have effects that could be measured
(completely different weather, completely different aerodynamics of
flyers - and we are not talking about the 15% or so that were
discussed a few weeks ago.)

>2. Don't forget that there were other rather big critters existing,
>like Baluchitherium (or is it Indricotherium or Paraceratherium - I'm
>not too good with mammals...). These were in about the same mass-range
>as a sauropod (18 tons, I think, is a reasonable estimate), and
>obviously they were also able to gather enough food. So why should
>sauropods have that much bigger problems?

----------- I have been referencing *large*, that is, maximal sauropods. 
Correct me if I am wrong; the skull/jaws/teeth (and possible proboscis) of the 
beast-formerly-known-as-Baluchitherium are considerably more robust than the 
much larger Diplodicus, et al?

O.k., take another example - Steller's seacow has been estimated to
need about 700kg of water plants per day - and its head was smaller
than that of a big sauropod. If they can do it, why not the sauropod?

So, all-in-all, I think that your assumption is not very parmesaneous ;-)) 



                   Priv.-Doz. Dr. Martin BÃker
                   Institut fÃr Werkstoffe
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