Phytoplankton at the K/T Boundary (from J. Young)

From
Date
Reply-To
>From: DEEJAM@aol.com
>Date: Wed, 19 Jul 1995 22:08:08 -0400
>To: paleonet-owner@nhm.ac.uk
>Subject: Re: Odd Observations at the K/T Boundary
>Status: O
>
>I greatly appreciate your reply on the K/T episode.  I have been troubled by
>the impact theory for some time.   As a marine biologist I have been put off
>by the reduction/elemination of photosynthesis by the impact since it would
>eliminate everything if it went on for several weeks.  It seems to me that
>the answer lies in a multiple condition scenerio.  Rapid climatic changes
>seems to me to be more realistic.  Dinosaurs, even warmblooded types, but
>large, might be more prone to disruption of ecological regimes than  mammals
>and birds(?).
>

On the other hand an argument for the impact/darkness theory is that cyst
forming phytoplankton (dinoflagellates - inc. calcareous dinoflagellates -
and diatoms) show only minor extinctions whilst non-cyst forming
phytoplankton (coccolithophorids, silicoflagellates) suffer very severely.
(P.S. this is a bit of an oversimplification since for many of the diatoms
and calc dinoflagellates I guess our knowledge of encystment is weak -
similarly among the coccolithophorids no-one knows if Braaurudosphaera,
which sails through the K/T boundary, is a vegetative or cyst stage).

Jeremy Young

-----------------------------
Dr. Jeremy R. Young           Tel: +44 (0)171 938 8996
Palaeontology Dept.           Fax: +44 (0)171 938 9277
The Natural History Museum    INTERNET: jy@nhm.ac.uk
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