Re: K/T impact (was Re: [for some reason] Tim's theory)

["Tim Williams" <twilliams_alpha@hotmail.com>]

John Bois wrote:


> Since there is _no record_ of the extinction of enantiornithines, this
> statement cannot be made.

Enantiornithines are found in the Late Cretaceous, but not in the Paleocene. 
 That's good enough for me.

> Marsupial extinctions are also consistent with placental replacement
> hypothesis.  How to choose between the two?

How indeed.


> Hypotheses should not be confused with facts.

It was phrased as a hypothetical scenario; I perhaps should have been more 
explicit on that point.  After all, I wasn't actually there.  Here's the 
hypothesis: Impact causes drop in sunlight and temperature globally, 
effecting (in a negative way) photosynthesis.  First plants/phytoplankton 
started to die off, then herbivores/planktonivores, then carnivores.  It 
wasn't all as neat and tidy as that (e.g. for a short period, scavengers 
would have had a wonderful time), but that's the thrust of the hypothesis.



Tim

------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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