Re: Preservational bias revisited

["John C. Robinson" <jcrobin@welchlink.welch.jhu.edu>]

For the most point, I've been ignoring this, but this sparked a few
thoughts:

John Bois wrote:
> 
> If memory serves, one of the points from the earlier thread on
> preservational bias was that occassionally there are events such as > 
> ashfalls , etc. which nevertheless inter forest dinosaurs.  So why not > any 
> eggs which may have been present?  I understand that this is a > rare 
> occurrence but why not _any_?

{FWIW, when dino eggs have been found, how many are from posited
solitary nesters, and how many from communal nesters?  Is this even
_known_ for most dinosaurs?  It may well be that this is just a
statistical artifact - the larger the number of nests in a site, the
more likely that some proportion of them get fossilized and survive to
get found.}

>         Also, one would think that forested riparian environments >might have 
> been subjected to preserving deposition.  I'm just now >reading Horner's 
> _Digging Dinosaurs_.  He describes an island >surrounded by trees, but the 
> nests are in the clear, not among the >cover!  They would have been 
> preserved, though, if they were in the >cover.

{Animals nesting in a group nowadays tend to cluster where they can see
each other or otherwise keep in touch; whether from social reasons,
defense against predators or 'anti-predator flocking' is kind of
immaterial.  Unless they were very small (insect-sized, say), woods or
even open brushland would be a poor choice over open ground.} 

<SNIP>
(quote from Judy Molnar)
> > Just as in birds, dinosaurs would not reuse a nest
> > the next season, or the parasite load would get intolerable.
> 
> Horner believes some dinosaurs at least revisited nest sites year after year.

{So do many birds and other animals; they just tend not to re-use the
actual nests (if those nests even exist in a usable form)}

<rest snipped>

{As always, note that isolated exceptions do not invalidate a general
statement...}

{Regards,
        JR}