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ZUNICERATOPS AND CRETACEOUS BIOGEOGRAPHY
Robert J. Meyerson wrote:
<<Thanks to all for the multiple corrections stating that _Psittacosaurus_ is
still the oldest ceratopian (perhaps we can call Zuni the "oldest known
quadrepedal ceratopian"; how many variations can we come up with?>>
I say we just call the blasted thing _Zuniceratops_.
<<Out of curiosity, is there any evidence for North American Psittacosaurs?>>
<<Also, is there any idea on how they got over here? With the earth having
high sea levels, it seems problematic to have a structural land bridge (or was
Alaska and Russia actually joined at that time?).>>
By this I am assuming you mean terrestrial vertebrates including ceratopians?
As far as I can tell, the only way they could have gotten to North America (or
vice versa) was by walking, and the only route that seems in any way resonable
was through Siberia and Alaska -- unless of course the walked through Asia,
then Africa, Antarctica, and South America, and miraculously left no carcasses
In all seriousness now, there seem to have been multiple cross-Bering faunal
exchanges in the later part of the Cretaceous. With ceratopians this happens
three or four times, with pachycephalosaurs, at least as many, as well as
numerous exchanges with hadrosaurs, ankylosaurs, tyrannosaurs,
ornithomimosaurs, and dromaeosaurs.
This is exemplified by the dinosaur fauna being found in the Da-na-zin Member
of the Kirtland Shale where a very Nemegt-ish fauna is being found in New
Mexico: the ankylosaur "Nodocephalosaurus" (Sullivin in press) which is most
similar to the Asian genera _Saichania_, _Shanxia_, _Tienzhenosaurus_ (sp?)
and _Tarchia_ and the pachy _Prenecephale_.