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Re: The timing of stegosaur extinction
Tim Donovan wrote-
> > Gurvan Eran, Tevsh, Undurukhin and Tsagantsab
> >formations of Mongolia. I don't know in which of
> >units or what other fossils show equivalence,
> >Tugulu turtles "seem little changed from the late
> The only dsungaripterid Unwin and Bakhurina (2000)
> report from anywhere in
> Mongolia is "Phobetor" parvus, which was previously
> named Dsungaripterus
> parvus. This does not mean it can be used to
> correlate stratigraphy with
> Dsungaripterus weii though.
> Your turtle statement is too vague to be useful.
AFAIK there are no stegosaurs in the c Barremian age
Mazongshan beds, nor in Mongolian or Chinese beds of
late early Cretaceous age, such as those which yielded
Chilantaisaurus. Is there any evidence that the
Lianmuqin is younger than Valanginian?
With all of ten or so stegosaur individuals known from anywhere in
Cretaceous Asia, I don't think their absence in particular formations means
Have the beds Chilantaisaurus was found in yielded any dinosaurs except
Chilantaisaurus itself, and a few indeterminate theropod elements?
My Lianmugin references are on campus, but Psittacosaurus xinjiangensis is
known from there, right? In Liaoning, Psittacosaurus is restricted to
Barremian-Albian, with Hongshanosaurus being present in the Late
Valanginian-Hauterivian beds, and Chaoyangsaurus in the early Valanginian.
> Ah, but his table 14.2 includes absolute dates which
> are as recent as Aptian
> (e.g. upper part of Tsagantsav Svita 120 +/- 5 Ma).
> The Aptian started 125
> Ma (Gradstein and Ogg, 2004).
That doesn't make much sense, since the youngest
putative Tsagantsabian dates overlap with those given
for the younger Huhteeg Gorizont. Shuvalov was aware
of those younger dates but evidently didn't take them
seriously. IGEM dates have big margins of error and
some are probably inaccurate. I note Lucas just used
130 Ma, apparently based on an average value.
They overlap in possible dates, but not definite ones. The youngest
Tsagantsav date is 120 +/- 5 Ma, compared to the Huhteeg value of 116 +/- 8
Ma. So the Huhteeg could be 108 Ma, and that part of the Tsagantsav 125 Ma,
for instance. The IGEM margins of error are comparable to the ARGI ones,
the latter of which include a date that's latest Hauterivian at earliest
(and mid Aptian at latest).
> I await this forwarded post.
Actually it wasn't put onlist but you should have it