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Re: Dino farts



Dann Pigdon <dannj@alphalink.com.au> wrote:


> Surely in order to determine the amount of methane sauropods produced 
> globally, we'd need to
> know:
>
> - Whether or not they utilised methanogenic bacteria (not all modern 
> herbivores do).


The authors used non-ruminant herbivores to derive their estimates.


BTW, a pedantic but important correction: methanogenic microbes are
archaea, not bacteria.  Archaea are the so-called Third Domain of Life
(after Bacteria and Eukaryota).  Phylogenetically speaking, archaea
are no more closely related to bacteria than we are.


> - The total biomass of sauropods in the world at any one time.
> - The rate at which digestion took place.
>
> Pinning any of these factors down with any degree of accuracy would seem to 
> be a tall order.


The authors do show their working.  Although there are certainly a lot
of assumptions made along the way.


As you imply, the range of methane production among herbivorous
mammals is highly variable.  For example, herbivorous marsupials
produce far less methane than ruminants, in part because of the
different anatomies of their respective digestive systems, and in part
because of the microbes themselves (lower numbers of methanogenic
archaea in marsupials, plus different metabolic interactions with
fermentative bacteria).



> I'm also puzzled as to why the amount of methane estimated to have been 
> released by sauropods
> compared to the amount estimated for modern domestic livestock is of any 
> statistical importance.
> There are more herbivores currently in the world than just human livestock.


Yes, but ruminants (including livestock) are notoriously high emitters
of methane.






Cheers

Tim


>
> I'm also puzzled as to why the amount of methane estimated to have been 
> released by sauropods
> compared to the amount estimated for modern domestic livestock is of any 
> statistical importance.
> There are more herbivores currently in the world than just human livestock.
>
> And even if sauropods did produce that much methane, wouldn't decomposing 
> plant matter still
> produce similar amounts whether it got eaten by herbivores or not?
>
> --
> _____________________________________________________________
>
> Dann Pigdon
> Spatial Data Analyst               Australian Dinosaurs
> Melbourne, Australia               http://home.alphalink.com.au/~dannj
> _____________________________________________________________
>