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Sauropod extinctions

>I'm not sure that sauropods readdy we(try really went) extinct in the 
>Ve noted before, there are a slew (slough?) of sauropod remains
>in the Maastrichtian of West Texas, and I'm not convinced that they 
>re-emigrated from S. America.   The same taxa are common in N. Mexico and
>to a lesser extent in Wyoming.  Thus sauropod extinction is greatly

There does seem to be a real "sauropod hiatus" (to use Spencer Lucas'
phrase) in western North America in the Campanian and early Maastrichtian. 
We have huge samples of teeth, bones, and skeletons, and nary a sauropod. 
In the late Maastrichtian, there is the appearence of the sauropod
Alamosaurus, a titanosaurid which may (or may not) have immigrated from
South America.  Of course, we don't know enough about eastern North America
to say if the fragmentary late Late Cretaceous sauropods there are
immigrants or survivors.

Nevertheless, there are Campanian and Maastrichtian sauropods from South
America, Madagascar, Europe, and central and eastern Asia.  Therefore, the
sauropod hiatus is at best a North American, and probably only a western
North American, phenomenon.
Thomas R. Holtz, Jr.                            email: 
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