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Dinofarts / Sauropod methane emissions



>From Wilkinson &c:

> ...and show that the production of the greenhouse gas methane
> by sauropods could have been an important factor in warm Mesozoic
> climates.


Farting sauropods were just one part of the biosphere.  An increase in
methane emissions from large sauropods might have been met by an
increase in methane-utilizing microbes (methanotrophs).  The latter
are found in all sorts of environments - soils, sediments, lakes,
oceans, etc.


The net amount of methane that ends up in the atmosphere is the
difference between the amount emitted from various sources (such as
animals) and the amount consumed by methane-utilizing microbes.  The
evolution of sauropod gigantism was fairly rapid on a geological scale
- but perhaps not so quick that methane-utilizing microbes couldn't
adapt.  So unless it was beyond the capacity of these
methane-utilizing microbes to mop up the extra methane, the impact of
sauropod flatulence on the climate might have been minimal.


Dan Chure wrote:

> I have seen some phylogenies where Archaea is the sister group to Eukaryota, 
> others where Eubacteria is the sister group to Eukaryota, and
> others where there is a trichotomy between the three groups.  However, I 
> think the latter is most often a byproduct of using ranks, i.e. each is a
> Domain so they must be equal. Not sure which of the first two phylogenies is 
> the best supported but there are characters supporting each
> arrangement and my guess would be that there is a nested sister group 
> phylogeny rather than a trichotomy.


There are two main hypotheses: (1) That Archaea and Eukarya
(=Eukaryota) are sister taxa, and form a clade to the exclusion of
Bacteria (=Eubacteria); (2) That Eukarya arose from the amalgamation
of an archaeon and a bacterium, and so is only a "secondary domain"
derived from the other two.





Cheers

Tim