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



Tim Donovan (uwrk2@yahoo.com) wrote:

<Age estimates are again, based on more than that.>

  Yes, based on so much more data that is being presented. Yet for some reason
we are discussing a *Mesolimnetes* index age, or absence thereof, to cite an
age for a formation? Indeed, bunk.

<Absolute nonsense.>

  And if it wasn't clear to begin with, as it was before, I was not only being
facetious but invented these theories based on an absolute yet narrow reading
of a single particular datum. Which is what we've been reading from Tim
Donovan. I hope given the reply of "absolute nonsense,"  that it's finally
clear what kind of reception such strawmen theories give.

<WTF ??? Do you think the Kaiparowits and De-na-zin are of Maastrichtian age?
ALL known North American parasaurolophines are of Campanian age. Williamson has
repeatedly pointed out that Parasaurolophus does NOT occur in the Naashoibito.>

  I do admit a singular confusion of using Maastrichtian rather than Campanian.
The post is still worthy despite this error.

<In fact, the apparent restriction of North American parasaurolophines to the
Campanian, coupled with biogeographic links between Asia and America, is one
reason I doubt Godefroit's age estimate for the Tsagayan.>

  I would like to point out that for over a hundred years, triconodonts were
not known from the Cretaceous. Will it take a hundred years to stop shoehorning
formations based on narrow interpretations of time-ranges?

<Buffetaut considered Tsintaosaurus a parasaurolophine, and it occurs in
Djadokhta equivalent beds (Campanian).>

  So it's amazing I was pointing at it as an ancestral (i.e., derived EARLIER)
taxon? This means even MORE relict lineages for "parasaurolophines" which may,
or may not, be monophyletic or be a single taxon, or that the NA
*Parasaurolophus* could be multiple genera. Using the handy-dandy
genericometer.

At the end of his post, Tim Donovan wrote:

<Btw isn't it about time somebody corrected the temporal order of the Asian
units in the title of this thread as well as the spelling? :)>

  I would like to point out that there is not ONE single consistent spelling
for Mongolian place names, and while formation nomenclature is more strict in
spelling, I tend to be more or less plastic because I don't have the original
references, at least in regards to Djadokhta/Djadochta. Note that during
Mongolian geologic and palaeontologic investigations, Mongolia was controlled
by China, Russia, and then on it's own, with a shift towards various spelling
systems as placenames were translated from Mandarin, Pinyin, Russian,
Mongolian, and English interpretations. So give this bit a little latittude.
But I bring the following quote out of order to make another point that Donovan
refuses to stop:

<No, see above, they apparently existed in the Djadokhtan period, which I
suspect was also the age of the Tsagayan.>

  There is no such thing as a "Djadokhtan period". I have noticed that Donovan
(and I've said this before which has been ignored) that he will mix up land
mammal age names, land vertebrate age names, and formation and group geological
names with geological stages and periods. The Cretaceous Period, for example,
is a WHOLE lot larger than the Djadokhta (Djadochtah or Djadochta) Formation.
So if we want to quibble about consistency of useage or spelling, let's get
right particular.

  Incidentally, I also notice that Donovan has yet to address either my point
about using genera to predicate an age assaignment (e.g., *Saurolophus*) but it
is only to use related genera (*Tyrannosaurus* and *Tarbosaurus*) to do the
same, while similar to identical taxa throughout the Mongolian, NorthAmerican
Campano-Maastrichtian are not being use to collapse the ages for these
respective formations? This being my main problem with using alpha taxonomy as
biostrat markers. Convenient, but as a scapegoat, and it narrows thinking.
Also, I am curious why Donovan has not replied to Mickey Mortimer?

<Godefroit suggested a NA origin.>

  And if the data backs up any interpretation, then we'll see. But this will
require ALL of the data, not some of it; and in this case, all of the data
should be equal, not some "better" than others. So far, that data is leading me
away from thinking that taxonomy and thus index taxa have any reality regarding
biogeography. There do not seem to be any absolute boundaries in regards to
taxonomic distribution, even among island taxa today, except regarding mass
extinctions and other environmental factors. And since taxa MUST derived from
older taxa, we cannot argue that the first time a taxon appears is the first
time that taxon existed. As if the fossil record is perfect....

  Cheers,

Jaime A. Headden

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


                
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