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Re: Bird and mammal K-T survival



From: "Ken Kinman" <kinman@hotmail.com>
Sent: Sunday, August 26, 2001 2:58 AM

>      We've been through this neornithine K-T survival discussion before,
so
> why is anyone still scratching their head for possible solutions?

Are you so convinced that the commonly-held theories are entirely correct,
especially given the holes in our knowledge about this period?


>     (3) burying your eggs like a megapode, preferable in alkaline soil
> (which would neutralize acid rain).
>      The third option was probably that which saved many crocodiles (and
not
> minding the ingestion of dead animals would have helped as well).

I seriously doubt that would have been a significant factor for reptiles,
birds or crocs. Croc eggs incubate for between 60 and 100 days - hardly long
enough to cope with the apparent effects this event had upon the world's
biodiversity. Eggs are one of the most (if not the most) vulnerable life
stages that oviparous vertebrates have, and young juveniles are either tops
or a close second. When it comes to crocs, long-lived adults with low
metabolic requirements seem far more equipped to survive, regardless of
their environment or shelter. Adults may go for 30 to 40 years without
producing a single surviving egg, yet given the opportunity and changing
conditions this situation can be reversed. This isn't wild speculation - we
know modern crocs do this, and we know just how resilient they are to
population pressure imposed by environmental factors. Some species certainly
survived this period like they survive any period - they have inherent
biological and/or ecological mechanisms to cope with adverse conditions.
Even if the causal mechanism was short-lived, species had to endure
longer-term changes to their environment.


>       I just don't think it is such a big mystery.  The survivors of the
K-T
> catastrophe were lucky enough to be in the right parts of the world, in
the
> right niches, and being a generalist feeder certainly was another plus.

Whether we concur or not, I do not agree that there's no value in
re-examining what little evidence we have.

Adam Britton