Late K sauropods, Trachodon

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

>>But remember that T. rex was a late Cretaceous character, and - if my
>>memory serves me - all the big sauropds were long gone by the time he
>>rolled in.  I think the situation would be more like T. rex facing a
>>ceratopsian, and it'd be a pretty even battle in terms of size.
>Is it really the case the big saurians were gone?  It was my
>impression that the number of _species_ had declined greatly,
>but that says little about absolute numbers.  Somebody jump
>in here.

[JUMP!]
With regards to sauropod diversity - it depends on where you are in the
Late Cretaceous.  In western North America, there were no sauropods until
Alamosaurus migrated back in (probably from South America, probably in the
Maastrichtian).  In Asia, sauropods were present but fairly rare.  In the
rest of the world, sauropods were as common as ever.

However, since the topic was T. rex (which as far as we know was only in
western North America), or broadly tyrannosaurids (which only occur in
North America and Asia), sauropods were not [for the most part] on the
menu.

>That's "Larry" with _two_ "r"s.  :)

Whoops!  Sorry.

>Interesting.  Hmmmmmm.  While I can't see loan-rex versus tricer or even
>a medium-large sauropod, I guess I can see one versus a "duck-bill".  If
>they were the primary prey, then we can imagine a loan t-rex stalking a
>herd of edmontosaurusii (God, how I miss "trachodon")

BTW, the reason "Trachodon" was abandoned was that the type material
included both hadrosaurid and ceratopsid teeth.  So, actually, Leidy
described five major components of Late Cretaceous western North American
fauna with just four teeth! - tyrannosaurids (Deinodon), troodontids
(Troodon), ankylosaurians (Paleoscincus), and hadrosaurids & ceratopsids
(Trachodon).

                                
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.