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Re: A long post about DUMB METATHERIANS vs EVIL, SMART PLACENTALS




John,
I think Ronald has hit the nail on the head. Both raccoons and opossums are generalist scavengers who thrive in our rather wasteful North American society where discarded food is commonly found in the trash----not to mention so much pet food being left outside that raccoons and opossums have no need to compete. There's plenty for all. Even "predation" by fast-moving vehicles can't keep their numbers from growing.
But getting back to more relevant matters, I was surprised at your characterization of K-T as a low-end mass extinction. I wouldn't call ANY global extinction "low-end". A low-end mass extinction might be regional or even continental, but a global event like K-T can hardly be called low-end. And it wouldn't even come close to grading into background extinction.
And even fish didn't get by "unscathed". Several whole orders of fish went extinct, and I doubt that any fish order got through it without a significant culling of genera. One might charge that some people exaggerate just how bad K-T was, but I think you are going to the other extreme, as if to say "it wasn't so bad" if everything wasn't wiped out. Maybe it wasn't as bad as the end of the Permian, but it certainly was devastating on a global scale.
If 100% of enantis went extinct, and over 90% of neornithinean species went extinct worldwide, that easily qualifies as a mass extinction in my book. Even if all the enantis had already gone extinct before K-T (which I doubt), the neornithineans were still devastated.
---------Ken
******************************************************
From: Ronald Orenstein <ornstn@home.com>
Reply-To: ornstn@home.com
To: jbois@umd5.umd.edu, David Marjanovic <david.marjanovic@gmx.at>
CC: The Dinosaur Mailing List <dinosaur@usc.edu>
Subject: Re: A long post about DUMB METATHERIANS vs EVIL, SMART  PLACENTALS
Date: Sun, 20 May 2001 21:07:48 -0400

At 05:30 PM 20/05/01 -0400, John Bois wrote:
 How about an
hypothesis such as: possum radiation occurred more rapidly in the
20th. century possibly due to reduction in racoon numbers at the hands of
man.

Unfortunately for this hypothesis, raccoon numbers have RISEN at the hands
of man. Raccoons are human commensals, reaching densities in suburban
areas of 69 per sq km according to "The Smithsonian Book of North American
Mammals" -higher than their density in natural woodlands (roughly 50 / sq km)!


--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@home.com

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