R: paleonet PDF PAPER AVAILABLE

["schilar@xxxxxx" <schilar@xxxxxx>]

Can you send a copy to me? 
Salvatore
----Messaggio originale----
Da: 
Jean.Guex@unil.ch
Data: 21-set-2006 10.37 AM
A: <paleonet@nhm.ac.uk>
Ogg: paleonet PDF PAPER AVAILABLE

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.