Forwarded on behalf of Mark Sumner: re Egged on

[rstephen@cswnet.com (Roger A. Stephenson)]

Hello all,

The following is forwarded from Mark Sumner, as it seems his server hates
list processors, or has a UNIX glitch only the gods can understand. Long
live Macintosh!

As I have told him, better said than my attempt, damned word smith!:-)

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I see several problems with the idea that egg predation was a
significant factor in dinosaur extinction.

1) Global Nature:  This is an extinction that took place worldwide,
and affected even unconnected landmasses.  Unless you are speculating
about some (unknown) globe-spanning egg predator, it seems unlikely
that species the world over would suddenly adopt this feeding habit
to any greater degree than it had already been practiced for the
preceeding 100 million years.

2) Trans-phyla extinction: The K-T boundary event doesn't spell the
end for dinosaurs only, but also for a broad number of species not
even vaguely related.  Surely egg-gnawing mammals could not have
affected ammonites, could they?

3) Cross-habitat extinction: Even if we restrict ourselves to
"reptilian" (please, God, note I did not say reptile) creatures, are
we to believe that there was a sudden increase in egg-predation that
affected creatures that must have had a broad range of nesting habits?
Surely there were dinosaurs that nested in all types of terrain and
practiced all sorts of nesting behavior.  And what of distant relatives
like the Plesiosaurs?  Did egg predators suddenly diversify to tackle
nests built in woodlands? In rocky terrain?  Eggs buried along the
beach?  We've only seen the nesting behavior of a handful (or less)
species.

4) Suddenness of onset: Whether we define the extinction event as
something that occured on a Sunday afternoon, or as a process
that took place through a period of a million years, it seems
unlikely that any species should be done in by egg predation over
such a short time.  And we're talking about hundreds, perhaps
thousands, of species in a world-wide ecology.  Yes, egg predation
can have a devistating effect for a handful of species locked in small
isolate populations, but this effect is not scalable.

5) Evidence: To suggest that egg-predation exploded like a bomb,
reaching devastating levels on a world-wide scale, is an extraordinary
theory, and requires extraordinary evidence. Any creature which preyed
upon dinosaur eggs to such an extint that it caused massive extinction
should be one of the most common creatures of the late Cretaceous.

Crocodilians and sea turtles today continue to face egg predation
without the death of species, much less entire orders.  In fact,
egg predation is much -less- of a threat to young alligators than
other factors which take their lives in the first two years.  Sea
birds nest along the beach in lound, obvious rookeries and face
an onslaught of oportunistic feeders.  But they survive.

The "egg-eating" theory seems to have a lot of the same problems as
the "disease" theory.  Vectors, distance, and variety.

Mark
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