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Re: Tyrannosaur Evolution
Btw, Tsintaosaurus may be dominant at Laiyang. If it
is a parasaurolophine, the apparently Djadokhtan or
Campanian beds there may have a faunal composition
quite similar to Jiayin. I think that is consistent
with a preNemegtian age for the latter. Jiayin may be
younger than Laiyang but not by very much-maybe
--- Tim Donovan <firstname.lastname@example.org> wrote:
> --- David Marjanovic <email@example.com>
> > > AFAIK, saurolophines are unknown from the
> > apparently
> > > Djadokhtan equivalent beds at Laiyang.
> > How many dinosaurs in total have been found there
> > far? Does that number
> > give us a reason to think that we'd already have
> > discovered saurolophines if
> > any were present?
> A fair number of specimens are known from at least
> three levels, indicating the presence of
> including Tsintaosaurus if a parasaurolophine,
> ankylosaurs, sauropods and theropods. You could have
> pointed out that at least two Udurchukan localities,
> and unit 2 of the Horseshoe Canyon, are dominated by
> one hadrosaur genus, yet much different types are
> known from geographically close localities of about
> the same age. At least one saurolophine,
> Kerberosaurus, did IMO exist in the preNemegtian
> period in Asia, albeit not at Laiyang AFAIK.
> > > It is likely IMO that the sauroloph niche was
> > already
> > > occupied in Asia by Keberosaurus to almost mid
> > > Maastrichtian, and the Tsagayan types were then
> > > supplanted by American immigrants.
> > What do you suggest that that niche was?
> I don't know what kind of vegetation saurolophs
> ate-presumably something fairly low which was
> in inland areas. It is noteworthy that any kind of
> hadrosaur could probably exist in the Amur area yet
> there is no evidence of Saurolophus or any other
> Maastrichtian American type in the supposedly late
> Maastrichtian Tsagayan despite the accessibility of
> remoter parts of Asia by c late early Maastrichtian.
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