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

[Martin Baeker <martin.baeker@tu-bs.de>]

Hi all,

I'm a little bit confused by this discussion, for two reasons.

1. IIRC, this came about by the sugestion that plants had more
nutritional value per mass in the past because of higher N2 values.

*But*, if the amount of food to be taken in by a sauropod is used as
argument, how much larger would the nutritional value have to be to
make this work? If you (Don) claim that it was impossible for
sauropods to get the required amount of food, how much food would they
be able to gather -- 200kg? And how much higher would N2-content have
to be to achieve this? Can you really raise the nutritional value in a
plant by a factor of 2 or 3 just by increasing N2-content?

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?

To make things more quantitative, does anyone know (from personal
observation or literature) how long an elephant chews each bite? Cause
if we subtract this time from the feeding time, we could find out how
much a non-chewing elephant might eat per day.

Happy new year,

Martin.

> > Heh.  _Average_ 4 bites per minute. For 10 hours. No chewing time figured
> > in. Chewing takes a _long_ time.
> 
> > [BTW-- cows don't really chew
> 
> They do -- just later.
> 
> > Open mouth-- 1 sec. Inhale leaf cluster-- 1 sec. Close mouth-- 1 sec. Pull
> > head back to "strip'-- 1 sec. Swallow-- 1 sec. That is 12 bites per minute
> 
> As I said: much more than 4 bites per minute.
> 
> > and doesn't not include time spent moving to a new stand, locating the next
> > mouthful, or pre-positioning of head. I think to meet these numbers, even
> > temporarily, is extraordinarily difficult in realistic scenarios re
> > abundance and quality of vegetation.
> 
> At average sauropod size you're way beyond the point where, according to Marx,
> quantity changes into quality and... ;-) Seriously: the bigger an animal and
> the longer its gut, the worse the quality of food it can afford to live off.
> If cows can afford to live off grass, surely sauropods can afford living off
> conifer needles? Let alone fern or cycad fronds.
> 
> > Do you really think they can average 8 bites per minute over the course of a
> > day?
> 
> Of course. I repeat: with these mouthparts they didn't chew. 

                   Priv.-Doz. Dr. Martin BÃker
                   Institut fÃr Werkstoffe
                   Langer Kamp 8
                   38106 Braunschweig
                   Germany
                   Tel.: 00-49-531-391-3073                      
                   Fax   00-49-531-391-3058
                   e-mail <martin.baeker@tu-bs.de>