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Cretaceous sauropods (was Re: Sauropod extinction)



At 11:35 PM 7/27/98 -0400, Allan Edels wrote:
>    Actually Sherry wrote that particular question.  I attempted to answer
>the premise.  I assumed that sauropods, especially the really gigantic
>diplodocids and brachiosaurids disappeared fairly rapidly at the end of the
>Jurassic.

As discussed (ad nauseum) on the list before, we don't have evidence of
this.  Our sample size for Early Cretaceous sauropods isn't very good, and
indeed there has been very little in the way of articulated remains.
Nevertheless, the fragmentary material known is not dramatically different
in size from average Morrison material.

The reason we do have the remains of the Morrison giant individual may have
a lot more to do with the better preservation within that Formation relative
to overlying units: with a higher number of samples, the better chance we
sample the higher end of the size distribution curve.

Also, to remind folks, with the possible exception to the (never collected,
nor accessioned, only known from a line drawing) _Amphicoelias fragillimus_,
the largest skeletal remains of sauropods are all from the Cretaceous.
(Okay, they are South American, not North American, but they are still huge!).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661