Re: paleonet PDF PAPER AVAILABLE

[Charles Ciampaglio <chuck.ciampaglio@xxxxxxxxxx>]

Please send the PDF.


----- Original Message -----
From: Jean Guex <Jean.Guex@unil.ch>
Date: Thursday, September 21, 2006 6:53 am
Subject: paleonet PDF PAPER AVAILABLE
To: paleonet@nhm.ac.uk

> To anyone interested I can send the following paper in PDF form:
> 
> "Reinitialization of evolutionary clocks during sublethal 
> environmental stress in some invertebrates."
> 
> Abstract
> This paper describes the influence of high environmental stress on 
> evolutionary trends in some selected Mesozoic ammonite lineages 
> and 
> some protists. During extinction periods, many ammonoids are 
> affected 
> by drastic simplifications of their shell geometry, ornamentation 
> and 
> suture line. We observe that relatively tightly coiled ammonites 
> can 
> give rise to highly evolute forms or uncoiled heteromorphs with 
> simple ornamentation and almost ceratitic suture line - a 
> phenomenon 
> called "proteromorphosis". Such simplifications often correspond 
> to a 
> reappearance of ancestral geometries (primitive ornamentation, 
> evolute coiling or uncoiling) which suggest that the evolutionary 
> clock of these organisms can be reinitialized by extreme, 
> sublethal, 
> environmental stress such as giant volcanism (including its 
> consequences on diverse pollutions and on climatic changes) and 
> major 
> regressive events.
> 
> 
> 
>