Sauropod Taphonomy

[Josh Smith <smithjb@sas.upenn.edu>]

Danvarner@aol.com wrote:

>  Another factor is the acidity of the paleosoils, and bugs. There are many 
> sauropod bones with traces of beetle infestation that would have destroyed a 
> smaller skeleton. Dan Varner.

        Insect turbation is definitely a probable significant taphonomic agent
with respect to bone preservation potential.  However, soil water
acidity must be treated with caution.  The rule of thumb that is usually
touted is that bones preserve where plants don't and vice-verca, but
a)., the phenomenon is not well studied at all and b)., there are plenty
of cases where the soil water chemistry should have put the bone
hydroxyapatite into solution but has not.  It is true that
hydroxyapatite is generally soluble in waters of pH 6.5 or lower, but it
doesn't always work that way.  Indeed, much of the research I have done
on this suggests that the real key is the rate at which ions are
delivered to the bone surface rather than the particular ions (Hydrogen
nuclei (protons) in the case of acidic soil waters) that contained
within the soil water solution.  However, what we found in the arctic
this summer blew some rather large holes in that nice tight rule of
thumb as well (plants preserved better than probably anywhere else in
the world in coarse. that had significant iron mobilization--but zero
iron replacement of the plant tissues...totally against current dogma). 
%%%%$$$!!## stinking complicated natural systems...
   The jury is definitely still out on the soil water acidity issue.

-Josh