Re: disease theory of dinosaur extinction

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

> I'm not sure what the ramifications of this are on Bakker's theory of dinosaur
>extinction, but this idea cannot explain the simultaneous extinction of
>plesiosaurs, mosasaurs, ichthyosaurs, etc. to which a land bridge would be a
>barrier, if anything, to the spread of disease.

Bakker's explanation for the simultaneity (or near-so) between terrestrial
and marine extinctions is this - the same draining of the seaways which
opened land bridges greatly altered the food chain in the seas (a likely
event of removing vast regions of warm, shallow water).  Decrease in marine
productivity, he reasons, was sufficient to drive the large predatory
marine reptiles to extinction.

Actually, this is one of the aspects of Bakker's theory which appeals to me
- it shows that marine and terrestrial extinctions may have the same
ultimate cause, but radically different proximate causes.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.