Re: Response to Orenstein's "explanation" of mammal success.

["JOHN C. ROBINSON" <jcrobin@welchlink.welch.jhu.edu>]

Gentlepersons:
        As I recall, this thread originated with John's contention
that dinosaurs were driven to extinction [by mammals] due to their
susceptibility to egg predation.  It is true that the vast majority of
modern "open-field, large-animal" niches are filled by mammals.  So?
What evidence is there that this is a result of the inherent relative
"lack-of-fitness" of ground-nesting egg-layers?  Certainly predation
on eggs and hatchlings of ground nesters is tremendous.  Is the
extinction of all (or even most) large ground-nesting egg-layers due
to this fact?  How long did the dinosaurs last?  Were there any egg
predators during that period comparable to raccoons, skunks, and etc.?
How long did Phorusrhacids (sp.?) and their ilk last?  How long have
mammalian equivalents lasted?  Can anything about this thread be
inferred from that information?  (I'm not suggesting anything, mind
you, just asking) Moas I understand to have been trashed by the
Maoris; a common result among island ground-nesters unaccustomed to
large predators.  Can this phenomenon be extended to mainland
communities?  What can present-day distributions tell us about
historical forces acting on populations (see Jared Diamond's work on
S. Pacific island bird distributions, with its subsequent rebuttals).
I don't wish to start more pyrogenics; I think that this topic has
reached the stage of more heat than light, and may be worth leaving
for the moment.
                        Regards,
                                JR