Re: Extinction

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

>> Current theories regarding dinosaur extinction do ignore the smaller
>> species that survived the extinction.  IMHO I think that the reason why
>> they suvived is a question of size.  When you look at the species that
>> perished in the K-T extinction, it appears that every species the size of a
>> housecat and larger perished; their larger bodies requiring more food than
>
>Is this all species of any animals of any kind larger than a cat, or
>just dinos? I though there were some smaller than that; where are
>they?

Where are they?  Flying around outside today!  Except for the birds, all
known Late Cretaceous dinosaurs were cat-sized or larger as adults.  The
smallest ones include troodontids, small velociraptorines,
hypsilophodontids, and Leptoceratops.  The really small nonavian dinosaurs,
such as Compsognathus, are not currently known from late Maastrichtian (or
even Late Cretaceous) communities.

Some continental animals bigger than a breadbox (or a cat) did survive:
champsosaurs, crocodilians, and turtles, for example.  However, these
particular creatures are a) tied into a predominantly aquatic, not
terrestrial nor marine, food webs and b) at least crocs and turtles can
hibernate (champsosaurus may have, but they died out long ago).

                                
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.