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Re: flowering plants




>>From: "Considine, Blaise" <bpc.apa@email.apa.org>
 >> What I 
 >> seemed to get out of it was the theory that the advent of flowering 
 >> plants in large part caused the extinction of the dinosaurs. Is this
 >> for  real, or was I hallucinating? 

>It was real, once upon a time.  Perhaps the show isn't as up-to-date
>as one would like.

>If this is the show I caught part of the other night, it had lots of
>out-of-date stuff.  For one thing it implied that the Morrison area
>(or even the whole of North America in the Late Jurassic) was covered
>with dense conferous forests.  This is false.  The Morrison formation
>was laid down in a semi-arid to arid climate (part of it is sand-dunes).

>And then there was the statement that the upland areas were devoid
>of vegetation during the Carboniferous (very questionable - at least
>moss and lichen would have been there).

>swf@elsegundoca.attgis.com             sarima@netcom.com

>The peace of God be with you.


I guess I will risk "de-lurking" to comment on this. The Morrison
is/was a big place. In Montana there is coal deposited during the
Morrison. In Wyoming there is lacustrine limestone with Equisetum
in it, as well as bits of conifers. Not to mention the Cycadeoid
trunks found there. In Colorado there are fern fronds from the
Morrison. The coal wasn't deposited under arid conditions, and the
Equisetum and the ferns absolutely require water for reproduction.
So I'd tend to pick a term like 'seasonally-arid' or
'strongly-monsoonal' (implying a big shift in the weather pattern
between different seasons). There's certainly lots of evidence for
arid times/areas, but there's also strong evidence for wetter
times/areas. "Dense coniferous forests"? I don't think so.

Dave Carlson
carlson@tellabs.com