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Re: Age of the Djadok(ht)a, Barun Goyot and Nemegt Formations



Tim Donovan (uwrk2@yahoo.com) wrote:

<The figure of 78 Ma was apparently an error. Read the whole chapter. On pages
261 and 271 the age given for the Borzongiin Gobi locality, or Chuluut Uul, is
75 Ma. As I posted before, Shuvalov's view is strengthened by newer dating
indicating an age of 73 Ma for the Djadokhtan beds there, and the fact that
they are not "upper" Barungoyotian.>

  Which paper is this, and which paper shows that this locality is part of the
Baruun Goyot Formation to be "upper Baruungoyotian" (which one is this again, a
land funal age?)

<Not yours.>

  I have not presented positive data. I am criticizing it, but throwing in more
data (others' data, I might add, not mine) and looking for a resolution. it
doesn't seem to favor Donovan's theories at all, and in fact given his
dismissal of data, even apparently direct dating ones, due to a personal issue
with one of the authors (van Itterbeeck) I really must insist on waiting for
the data here to evaluate, instead of shoehorning pet theories. Again.

  If Donovan was referring to my three hypotheses of an earlier post
(http://dml.cmnh.org/2005Sep/msg00559.html) he should note these are
hypotheticals that, as I stated before, were parodying extreme views of
evidence. That I put *Parasaurolophus* in the Maastrichtian, though in error,
is fallacious to use as the base of laughing at the hypotheses, since the Bayan
Shiree skull that may be a "parasaurolophine" is still far predating any other
taxon described to this group, thus creating a similar ghost lineage that,
apparently so long as it's Campanian, can be ignored. Donovan is ignoring data
to support his own, and the responses he has given only support this.

<It is a nearly complete specimen in a good state of preservation.>

  If we treated all referrals in the literature as valid, paleontology and even
stratigraphy would be in a sorry, sorry state. And since it was referred to
*Alectrosaurus* over three decades ago, it has not been described since, nor
been photographed or viewed in publication by modern tyrannosaur systematics.
In the 70's and 80's, we saw a LOT of taxonomic changes including: 1)
Carnosaurs split and tyrannosaurs placed closer to birds, 2) ornithischians
radically reorganized, 3) over 100 new names coined, and 4) an explosion in
Mongolian genera named, including at least 10 new tyrannosaurs (not to mention
*Dryptosaurus* as described as one). So when this specimen is fully described,
we can determine what it is and what the utility of a genus to stratigraphy
really means. Otherwise, it's useless to us.

  BTW, Mike Keesey reminds me of a post a long time ago about the subjective
use of taxonomy, I would remind Donovan to read this carefully for the
implications of lumping taxonomically and it's effects on precious
biostratigraphic use of taxonomy: http://dml.cmnh.org/2003Apr/msg00030.html

  Cheers,

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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