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Re: How Did Hadrosaurs Survive?

Rob Gay wrote:
>Isn't Charonosaurus Maastrichtian?

Yes, but probably not Late Maastrichtian. To be fair, it has been claimed to 
be "Lancian," based on palynological work. However, it does not appear to fly. 
As I recall, the "Lancian age" for the deposits is based on the presence of 
Wodehousia spinata, a palynomorph that lends its name to the North American 
pollen zone that corresponds to Lancian strata in the northern Great Plains of 
North America. However, the palynologist who worked with Bolotsky on the Amur 
region deposits had earlier established that this palynomorph is present at a 
much earlier time in Russia than it is in North America (I can't recall, for 
that matter, if the North American FAD W. spinata is in the W. spinata Zone or 
before it). So the "evidence" of "Lancian" lambeosaurines is thus far wanting. 
I'm sure someone will eventually come up with uncontrevertable evidence of 
these buggers eventually.

>   The Wangshi and later Tsagayan environments had diverse hadrosaurs but 
>wre supplanted by a Nemegtian fauna with essentially just Saurolophus.

I would caution you strongly to avoid the assumption that the Wangshi 
is "Campanian" and therefore not correlative with the Nemegt. The Wangshi fauna 
appears to be reasonably consistent with interpretation as a "lowland" 
correlate of the Nemegt fauna. North American "Campanian upland" faunas are 
arguably more similar to "Edmontonian" faunas than to contemporaneous lowland 
faunas, at least hadrosaur-wise. It is certainly plausible that a similar 
situation might hold for the "Edmontonian" of Asia. Do you know of a recent 
paper that actually provides some objective measure of the age of the Wangshi 
fauna? It certainly could have happened in the three years since I've been 
allowed to read primary literature.