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Re: Extinction

To: Dinosaur mailing list <dinosaur@usc.edu>
Subject: Re: Extinction
From: Jeff Hecht <jhecht@world.std.com>
Date: Fri, 24 Mar 2000 09:13:43 -0500
In-reply-to: <005301bf9593$c1da3ee0$2d093ccc@john>
References: <14.1e54df7.260c74ed@aol.com> <005301bf9593$c1da3ee0$2d093ccc@john>
Reply-to: jhecht@world.std.com
Sender: owner-dinosaur@usc.edu

At 8:20 AM -0500 3/24/00, philidor11 wrote:

 >>  Each mass extinction has its own cause, which need not be an
 asteroid impact at all. But the cause of the K-T mass extinction >is< an
 asteroid impact, beyond reasonable doubt.<<

Restating your assertion:  A mass extinction can have multiple causes, among
them an asteroid impact.  The K-T mass extinction occurred at approximately
the same time as an asteroid impact.  Therefore, the K-T mass extinction was
caused by an asteroid impact.

Watch out for the implicit assumption that the same causes lie behind all mass extinctions. Science teaches us to look for common causes behind similar-looking events, but one thing that seems clear to me from all the extinction debate so far is that the major mass extinctions have different underlying causes. It's also likely that multiple factors may be involved in many of them. For example massive volcanism might have made the biosphere vulnerable to another event which otherwise would not have caused the Permo-Triassic extinctions. -- Jeff Hecht

References:
- Re: Extinction
  - From: Dinogeorge@aol.com
- Re: Extinction
  - From: "philidor11" <philidor11@snet.net>