Re: Improper question re. extinction

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

>Bob Myers (and others) replied to my posting re specific extinction
>info, and pointed out that it was much too general.
>
>My apologies to everyone...I did, infact, want to deal at a much
>broader level than species.  Families, would probably have been a much
>better choice.
>
>When discussing the "bang or whimper" question of extiction, I wanted
>to point out to them that dinosaurs were becoming less abundant and
>less diverse by the end of the Cretaceous, and merely wanted to flesh
>out the remarks with some specific information.

Actually, since you were interested in showning the decrease in diversity,
then "Family" is an inappropriate rank to show.  All the common families of
dinosaurs that were around in the late Campanian made it to the end of the
Cretaceous.

The decrease in diversity occured below the level of traditional "families".

To put it another way: the family Elephantidae is still doing fine at the
family level, but such a statement doesn't reflect the fact that half a
dozen species or more of elephantids have died off in the last half million
years (and the remaining two aren't in too good a shape, either).

                                
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.