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




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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