Re: K-T Theories

[Mikiel <Mikiel@ASU.Edu>]

> I went to Dr. Bakker's lecture last Friday here in Portland, Or.  He promotes
> the disease theory of the K-T boundary.

There is a letter to the editor in Nature (7 April, 1994) by Victor 
Buckwold concerning viral-induced extinctions.  He is 
specificly discussing phytoplankton-infecting viruses, but I 
think his point is relevant to dinosaurs as well:
"Viruses are obligate parasites, and their survival depends on the 
survival of the host.  If a virulent virus reduced the population of its 
host, the virus population would similarly be reduced until a balance 
(steady state) was achieved...A virulent virus can only emiminate a host 
population if the virus can also live in another host which it does not 
kill."

        Eventually, the virus has reduced the population density of the 
host organism to levels where the hosts do not come into contact 
frequently, thus preventing continued rampant spread of the virus.
        Precluding a second host organism which is not killed by the virus
(and which would have to have a similar geographical range as the 
dinosaurs) it seems unlikely that a virus alone could cause actual
extinction of a species, much less a genera, and much much less the 
entire Dinosauria.
        And anyway, dinos weren't the only organisms that became extinct at 
the K/T.  The K/T extinctions seem too complex to be attributable to a virus.