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Re: Re Pinacosaurus (was How Did Hadrosaurs Survive?)



actually there is no unconformity between the Djadokhta and Barun Goyot, see 
for example discussion in Hayashibara Museum of Nat. Hist. Research Bul. 1.

Kenneth Carpenter, Ph.D.
Curator of Lower Vertebrate Paleontology &
Chief Preparator
Dept. of Earth Sciences
Denver Museum of Natural History 
2001 Colorado Blvd.
Denver, CO 80205

Fax: (303)331-6492
email: KCarpenter@DMNS.org
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>>> "Jaime A. Headden" <qilongia@yahoo.com> 03/Nov/02 >>>
Tim Donovan (msdonovan66@hotmail.com) wrote:

<Thanks a mint for this one, Ken. The presence of Pinacosaurus in the 
Wangshi series confirms a Barungoyotian age, or makes it most
parsimonious.>

  Just a note here, *Pinacosaurus* is the dominant and key taxon of the
Djadokhta Formation, and though *Protoceratops* is more prevalent in the
lower level, *Pinacosaurus* is not indicative or illustrative of a Barun
Goyot position. Djadokhta and Barun Goyot Formations possess an
unconformity and a gap that has puzzled geologists up to today, and the
only clear demarkation of the latter is with the Nemegt, making dating
relative to the lower of the three famous Mongol levels very questionable.
Baruungoyotian age, versus Nemegtian, is a time interval where we can only
reasonably suggest it ends, and thus makes a bad marker for estimated a
faunal "age," unlike the levels themselves. Areas where the Djadokhta and
Barun Goyot expose together are very rare, confounding the issue, as well
as the apparent absence of any conformity, prescence, or lack of either
between the levels where they expose.
 
  People should look at the literature regarding non-dinosaurs.
Lacertilians, turtles, placentals and multis, and ostracods/brachiopods
can be illustrative in other methods of creating biostratigraphical
theories, but these fall down sometimes.

  Cheers,

=====
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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