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Re: Sauropods



At 09:27 AM 7/10/97 -0400, Steve Tomporowski wrote:
>
>I remember reading from Uncle Bob's book that only one genus, Alamosaurus 
>(hope I spelled it right) existed in the Cretaceous (or was it Late 
>Cretaceous).  What's the current status of sauropods in the Cretaceous? 
> Have more species have been found?

(Ah, joys, not this again... :-S )

Well, Alamosaurus is the only known sauropod from the Late Cretaceous OF
WESTERN NORTH AMERICA.  (Okay, Dyslocosaurus *might* be from the Late K of
western North America, but it might instead be from the Late Jurassic).

However, Late Cretaceous sauropods are present in Asia (the titanosaurid? /
brachiosaurid? / diplodocoid? genera Nemegtosaurus and Quaesitosaurus), and
are a dime a dozen for the rest of the world.  Titanosaurid sauropods are
the most common dinosaurs in the Late Cretaceous of South America, India,
Africa, and Europe.  In fact, the largest known sauropods (barring the
possibly-mythical Amphicoelias fragillimus and the quite real Supersaurus)
are all Late Cretaceous South American forms: Argyrosaurus, Antarctosaurus
giganteus, and Argentinosaurus.

Sauropods are also very common in the Early Cretaceous worldwide, including
western North America (the famous Paluxey Tracksite of Texas, with the
Acrocanthosaurus footprints following the sauropod) are from the later part
of the Early Cretaceous.  Despite Bakker's publications to the contrary, I
do not know of any sauropod family which is present in the Late Jurassic
which is not also present in the Early Cretaceous.  Perhaps there is a
decline in within-family diversity for most of these groups, but the main
lineages are still present.

Hope this helps.

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