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RE: Rethinking What Caused the Last Mass Extinction



Interesting indeed.

The article mentions the top of the bed is missing so the Strangelove
deposit must be an unconformity.  Does not say what the Pinna bed is but
they do describe it as rock and soil!  I cant think how ammonites would get
into soil without being re-worked.

-----Original Message-----
From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf Of
David Marjanovic
Sent: 06 November 2007 12:22
To: DML
Subject: Re: Rethinking What Caused the Last Mass Extinction

>
http://www.nytimes.com/2007/11/06/science/06fossil.html?_r=1&ref=science&ore
f=slogin

Interesting. Is reworking ruled out? (Not from the condition of the 
specimens in the photo.)

Because... I don't see how it's possible to have a local extinction of 
ammonites. Ammonites had planktonic larvae. Either you kill them all 
worldwide at once, or the survivors fill the oceans again within a few 
generations, as happened after the Devonian-Carboniferous, the 
Permian-Triassic, and the Triassic-Jurassic mass extinctions. In other 
words, the fact that the ammonites are extinct is good evidence that they 
died out in a catastrophic mass extinction.

This is consistent with the last paragraph of the article, which describes a

Strangelove ocean above the supposed Paleocene ammonites.

Bringing up supposed gradual dinosaur extinctions doesn't earn the article 
any brownie points... (And "rethinking" is an extremely unfortunate word 
choice, IMHO.)