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Nemegt and Wangshi etc
Protoceratopsid remains are also known from the Wangshi; Bayan Mandahu-a
Djadokhta correlative- has them as well as Pinacosaurus in common.
The Nemegt fauna apparently extended well beyond the Nemegt basin, and
not just outer units like Gurilin Tsav. The Dinosauria mentioned an unnamed
unit in Heilongjiang i.e. not the Tsagayan, but very close, with Saurolophus
"kryschtofovici" and "A. periculosus", considered of Nemegtian age by Lucas.
This suggests the differences between the Nemegt and Tsagayan were the
result of time or succession, not distance.
Yes, Euoplocephalus and Edmontonia persisted from the Judithian to the
Edmontonian, despite obvious environmental changes as the area became more
inland with regression. (I don't think faunal changes were yet great;
generally there was continuity until the Lancian.)In contrast, I don't know
of any environmental changes in the Barungoyotian areas adjacent to
Nemegtian ones, by the time of the Nemegt deposition, but the once
ubiquitous Pinacosaurus is apparently absent in those habitats.
True, different NA hadrosaurs preferred different regions e.g. the near
marine Edmontosaurus and lambeosaurs farther inland. I note, however, that
Saurolophus and Hypacrosaurus? (=Barsboldia?) extended from NA all the way
to Asia. I can't understand why none of the Tsagayan hadrosaurs-probably
essentially those of the Wangshi series-were present in the Nemegtian areas.
Why just the American immigrants? After all, there were hadrosaurs in
Mongolia in the Barungoyotian period which preceded he c Edmontonian age of
Saurolophus. I get the impression the Asian hadrosaurs (which seem primitive
to Godefroit) must have been supplanted.
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