Preservational bias revisited

[John Bois <jbois@umd5.umd.edu>]

About a month or so ago there was a brief thread which started out
wondering why there was an absence of plant material around dino finds.
The question followed: Was this an example of preservational bias. 
Then it became apparent that this was simply not true, that there were
plenty of wood fossils etc. associated with dinosaur fossils.

Here is my question:  In my search of the literature I have been unable to
find a reference that reports vegetable matter _around_ dino nests (I know
there is matter _in_ some nests).  In fact, most nests seem to be sited in
sedimentary deposits.  First of all, is this true?  (I would greatly
appreciate any refs. contra this!)  Secondly, if it is true, is there any
reason why nests in, say, wooded areas would be any less well preserved?
If not, can't I interpret the absence of nests associated with vegetable
matter as meaning that dinos (most?...all?...some?) laid their eggs in the
open?