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RE: Sauropod Survival

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Joe Cantrell
> I understand that sauropods(Antetonitrus and Isanosaurus) were already 
> present in the late Triassic. Large animals are
> considered most vulnerable to extinction because of relatively small 
> population size and large food requirements. How
> does the survival of sauropods across the Triassic-Jurassic boundary affect 
> our view of the severity of the end Triassic
> extinction and the agency/agencies responsible?
>     Can anyone answer this my question for me great intellectuals?

Hey, some of us don't check email everyday!!

In any case, the terrestrial Tr/J extinction event is a weird one. It seems as 
if many (if not all) the big non-dinosaurian
archosaurs and non-mammaliaform therapsids were actually extinct by the 
Norian-Rhaetian boundary, and didn't make it to the Tr/J
itself. (NOTE: this remains a subject of some debate). So the Tr/J on land may 
not be as catastrophic as the P/Tr or the K/T.

Regardless, the existence of Triassic sauropods does suggest (as you note) that 
large metabolically active creatures did survive the
event. It is perhaps noteworthy that (so far) the primary evidence for Late Tr 
sauropods is from the south, while coeval units in
the northern regions lack them. Perhaps there was a more regional element to 

Needs further study,

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796