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Re: Re Pinacosaurus (was How Did Hadrosaurs Survive?)
Tim Donovan (email@example.com) wrote:
<Indeed it isn't present AFAIK, in the Barun Goyot sensu stricto, but some
authors -Lucas, Russell and Jerzykiewicz-consider the Djadokhta and Barun
Goyot the same faunachron. The absence of Pinacosaurus in the upper red
beds underlying exposed Nemegtian beds suggests it disappeared well before
the Nemegtian period, which therefore strengthens my case that the
Wangshi is older than the Nemegt.>
No, this just suggests that the Wangshi has some taxa that resemble or
may be the same as those of the Nemegt; this may correlate them somewhat,
or not, but it takes more than this to settle them laterally, as it were.
It may be of a slightly older, or younger level, and the Wangshi has
several taxa the Nemegt does not, as does the Barun Goyot, and the
Djadokhta. Its a regional variation, maybe. However, the bulk of the
Wangshi taxa are unique to it, even in terms of clades, anf this does not
support any supplantation despite age. If it is a Nemegt contemporary, it
is not a correlative level of Nemegtian taxa, and the relationship of the
beds is quite well-removed geographically. The Nanxiong Formation of
southeastern China is an even better corrolary with both *Tarbosaurus* and
a large therizinosaurid, *Nanshiungosaurus*, with a micro-hadrosaur,
*Microhadrosaurus nanshiungensis*, which is at present a nomen dubium and
likely a juvenile, based on gross number of tooth positions (similar to
baby hadros in the Two Medicine and Alaskan beds; Gangloff and Currie both
have recent papers on jaws for comparison, and the jaw is in _The
Dinosauria_ as well).
Jaime A. Headden
Little steps are often the hardest to take. We are too used to making leaps
in the face of adversity, that a simple skip is so hard to do. We should all
learn to walk soft, walk small, see the world around us rather than zoom by it.
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