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Re: Rapetosaurus stuff



[quoting rbi@dana.ucc.nau.edu]
>With Nemegtosaurus now looking firmly entrenched in the Titanosauria, does
>this open up the possibility that Alamosaurus is of Asian origin instead of
>one from South America?

That is a really interesting hypothesis, but I don't know enough about
sauropod phylogeny and Southwestern US paleofaunas to make a statement. A
little bit of research brings the following information to light, from a
recently published paper:

Lucas, S. G., and R. M. Sullivan. 2000. The sauropod dinosaur _Alamosaurus_
from the Upper Cretaceous of the San Juan Basin, New Mexico. In: S. G. Lucas
and A. B. Heckert, eds., 2000, Dinosaurs of New Mexico. New Mexico Museum of
Natural History and Science Bulletin No. 17., pp. 147-156.

(BTW, I highly recommend getting the _Dinosaurs of New Mexico_ volume if you
already haven't--many interesting papers on all sorts of dinos, from
theropods to ankylosaurs to ceratopsians).

In their abstract, Lucas and Sullivan state that, "_Alamosaurus_ may be
related to the Asian titanosaur _Opisthocoelicaudia_, so an Asian sauropod
immigration event to terminate the sauropod hiatus is consistent with the
introduction of other Asian dinosaur taxa to North America during Campanian
time."

Wilson and Sereno (1999, p. 61) also claim that no synapomorphies link
_Alamosaurus_ to any of the southern titanosaurs.

Wilson, J. A., and P. C. Sereno. 1999. Early evolution and higher-level
phylogeny of sauropod dinosaurs. Journal of Vertebrate Paleontology, Memoir
5, 68 pp.

>Also, we have much better evidence of
>faunal interchange between Asia and N. America than we do with S. America
in
>the Cretaceous.  Any thoughts?

I totally agree that we have better evidence of a faunal interchange between
North America and Asia than North America and South America, at least based
upon my (limited) dinosaur knowledge. I can't think of any North American
dinosaur taxa (besides _Alamosaurus_) that are of possible South American
origin. Does anyone else know what the lizards, mammals, crocodilians and
other animals indicate?

By the same token, I can't think of many (dinosaur) taxa that made it from
North America to South America. "Kritosaurus" australis is the only one--has
anybody published a hypothesis of its relationships to North American
gryposaurs? Is it a genuine gryposaur?

Best,

Andy
_______________________________
Andrew A. Farke
South Dakota School of Mines and Technology
501 East St. Joseph Street
Rapid City, SD  57701

andyfarke@hotmail.com