Re: sauropods

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

>The aproximate lineages are something like the following:
>
>Barapasaurids (early, fairly generalized forms, mostly Early Jurassic).
>    Cetiosaurids  (later, but still fairly generalized forms)
>    Brachiosaurids (very large, tall, forms, mostly Late Jurassic).

Actually, brachiosaurids are quite common in the Early Cretaceous (Astrodon
aka Pleurocoelus, Pelorosaurus, the Paluxey tracks, etc.)

>    Camarasaurids  (mid-sized forms, mostly Late Jurassic)
>    Euhelopodids  (forms from Asia, Late Jurassis and Early Cretaceous)
>    Diplodocids   (very long forms, mostly Late Jurassic)

If you include the Dicraeosaurinae in the Diplodocidae, then this group is
also common in the Cretaceous - Amargasaurus, Nemegtosaurus,
Quaesitosaurus, etc.

>        Titanosaurids (poorly known forms, mostly Late Cretaceous)

The primitive titanosaurian Janenschia (sometimes incorrectly called
Tornieria) is from the Late Jurassic, and there is abundant titanosaurian
material throughout the Cretaceous.

                                
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.