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Re: Word from the sole "non-stealthy egg" believer.



Dinosaur ListAt 12:02 17/11/96 +1030, John Bois wrote:

>   What is left?  Set up an egg mountain.  Lay
>your eggs in some  scrubby terrain where not many small things can
>travel.  Move to the highlands.  Create egg-protecting societies.
>Dinosaurs were increasingly  forced to develope strategies of defence
>rather than strategies of  stealth.

Sigh....  I thought we had been through this one.  Mr Bois, please provide
me with one shred of genuine evidence that dinosaurs were unable to protect
their eggs adequately.  Please provide me with one new egg predator
appearing close enough to the K-T that beat mechanisms that had kept
dinosaurs going in the presence of mammals for well over 100 million years.
 Please explain to me why, in a much more diverse mammalian environment,
ratite birds such as emus, rheas and ostriches manage to survive with
"non-stealthy" eggs if a much less diverse mammalian fauna in the
Cretaceous managed to knock off all of the surviving dinosaurs.  Please
explain what dinosaur nesting habits could possibly have had to do with the
extinction of mosasaurs, enantiornithine birds, belemnites, ammonites,
large numbers of foraminiferan taxa and others at the K-T.

And if you can't do this, Mr Bois, please stop stating your hypotheses as
though they were proven facts.


  This was expensive.  How much better
>to carry your babies away  (like mammals), or to hide your eggs in
>out-of-the-way-places such as  offshore islands

How do we know that dinosaurs did not do exactly that?  Is there any reason
to assume that the maiasaur "egg mountains" could not have been on lake
islets out of reach of many egg predators?

, inaccessible locations
>(like birds and snakes), or to lay  and forget (like turtles).  Dinosaurs
>made a tremendous gambit for the  open-field, big animal niche.  And for
>a while (a long while) they were  successful.  But their life style had a
>fatal flaw: while their body architecture was fit, their reproductive mode
>was not.  Too bad they don't award partial credit in evolutionary stakes.

You have absolutely no evidence on which to base this statement.  How do
you know how much physiological effort dinosaurs invested in their
clutches?  Dinosaur eggs are remarkably small for the size of the adult.
Can you be sure that  dinosaurs did not have the strategy (as some tropical
birds apparently do) of laying small clutches so that if these failed in
the early stages another clutch could be laid with minor physiological
consequences?  Can you provide figures for the energetics of egg brooding
in dinosaurs?  Can you assure us that the amount of incubation and guarding
time necessary (if any) could not have been provided by a single parent who
could afford to live for some time on accumulated food reserves and devote
100% of its time and energy to the job (again, as some modern birds (eg
penguins) do quite nicely)?

You have simply assumed that no such strategic mechanisms could have
existed, or that if they did that they failed for some reason at the end of
the K-T - but if we know anything from the study of modern birds it is that
the range of possible adaptations, physiological and behavioural, to
breeding and nest protection is immense.  Assuming that it was not in
dinosaurs is questionable at best and, when it leads to statements like the
last one quoted, totally misleading and a trifle arrogant at worst.
--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2          Internet: ornstn@inforamp.net