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Re: Tsagayan/Udurchukan age-Campanian?
Tim Donovan (firstname.lastname@example.org) wrote:
<Bolotsky and Godefroit (June 2004 JVP, page 351) cited research by
Markevich and Bugdaeva (and Godefroit) which indicated that all three
Tsagayan or Udurchukan localities-Blagoveschensk, Kundur and Jiayin-and
the Miho Group of Sakhalin Island, which yielded Nipponosaurus- are
synchronous and belong to the Aquilapollenites subtilis/Wodehousesia
spinata palynozone, spposedly indicative of a late Maastrichtian age.
But ammonite evidence indicates that the unit which yielded Nipponosaurus
is of early Campanian age, if not older!(March 2004 JVP, page 146)
Apparently the Aquilapollenites subtilis/Wodehousesia spinata palynozone,
the basis for a putative late Mastrichtian age, can be as old as basal
Campanian, perhaps even late Santonian, in Asia. In view of the primitive
state of Amurosaurus, an early Campanian age seems perfectly plausible,
far more so than the age currently given.>
>From Suzuki, Weishampel and Minoura (2004, _JVP_ 24(1): pg. 146):
"Since South Sakhalin no longer belongs to Japan, it is presently
impossible for additional geological research to be conducted at the
Kawakami colliery by Japanese researchers. Thus, the details of this
specific locality are no longer clear. Moreover, field notes made at
time of the excavation are missing. Nagao (1936), however, did note
the locality of the type specimen of *Nipponosaurus* also produced
fossils of *Puzosia japonica* (now *Parapuzosia japonica*) and
*Inoceramus schmidti* (now *Sphenoceramus schmidti*), both of which
belong to the middle of the Upper Ammonites beds (now Upper Yezo Group;
Matumoto, 1951b). Recent biostratigraphic studies indicate that the
range of *P. japonica* and *S. schmidti* are limited to the lower
Campanian (Takayanagi and Matsumoto, 1981; Tashiro et al., 1995).
Although *S. schmidti* is known only from the lower Campanian, dubious
referrals of *S. schmidti* to *S. sachalinensis* are often made
(Hayakawa, pers. comm.); the latter is also known from the upper
Santonian. Consequently, the age of *Nipponosaurus* probably ranges
the late Santonian to the early Campanian."
Matumoto T. 1942. Fundamentals in the Cretaceous stratigraphy of Japan.
_Memoirs of the Faculty of Science, Kyushu Imperial University, Series
D, Geology_ 1:129-280.
Matumoto T., and I. Obata. 1979. _in_ Obata, I. 1979 [The ages of the
fossil reptiles in Japan.] _Kaseki_ 29:5358. [in Japanese]
Nagao T. 1938. On the limb-bones of *Nipponosaurus sachalinensis* Nagao,
a Japanese hadrosaurian dinosaur. _Annotationes Zoologicae Japonenses_
Takayanagi Y., and T. Matsumoto. 1981. Recent advances in the Cretaceous
biostratigraphy of Japan by coordinating mega- and micro-fossils.
_Recent Progress of Natural Sciences in Japan_ 6:125-138.
Tashiro M., H. Maeda, S. Wako, K. Hayakawa, M. Kano, and N. Arakawa.
1995. On "*Sphenoceramus schmidti* (Michael, 1899)" from Upper
Cretaceous System from south-west Japan. _Research Report of Kochi
University (Natural Science)_ 44 27-46. [in Japanese]
Ah, my problem with this issue is that there doesn't appear to be any
clear stratigraphic or locality information. This is a problem, since at
some places, a single locality can span formations, stages, and even eras
of time, especially at sections comprising Cretaceous--Paleogene periods
in northern Europe, the Jurassic section in central Europe, the Early
Cretaceous at Isle of Wight, and all those lovely sections that expose the
K/T (now, I guess we may need comfiness with B-Pg, but K/T owes as much to
faunal veriation as to geology, so using Tertiary is just as easy if only
using "T" for the well-known label). Other, more relevant sections, are
the Hermiintsab locality, which exposes the Baruun Goyot Formation AND the
Nemegt Formation, as well as the Nemegetu locality, and that the locality
of Ukhaa Tolgod shows many stratigraphically arrayed sublocalities, not
all of which are isolated to the exact same period of time. So should we
expect a fossil that comes from a locality and all other specimens from
that locality to be the exact same age?
Why cannot pollen and foram fossils constrain a date while inverts like
ammonites expand it? Pollen and forams will be subject to more immediately
observable evidence of evolution in their "simple" anatomies, leading to
marked change at distinct times, carried in extant studies as well as
extinct forms, allowing them to be used for time constraint. So why should
we believe that such data as the above mean that the ammonite information
is MORE likely to be true than the foram/pollen data? And what does
*Amurosaurus* have to do with *Nipponsaurus,* especially if the Suzuki et
al. offer it is related to *Hypacrosaurus*?
<The Tsagayan/Udurchukan localities are not necessarily as old as early
Campanian, but I think they may all be Campanian, judging by their
parasaurolophines etc and definitely predate the Nemegtian. It was
probably only by the latter period-c mid Maastrichtian-that Wodehouseia
spinata, long established in east Asia, spread to America-via the same
Bering bridge which enabled Saurolophus to spread to Asia- and became
representative of the late Maastrichtian of NA.>
*Parasaurolophus* (*P. tubicen*) is known from the lower Maastrichtian
Kirtland Formation of New Mexico. This is contiguous with everyone else's
current research on the Nemegt Formation's allocation to the uppermost
Campanian or lower Maastrichtian (as it is equivalent in some respects to
both the upper Campanian Dinosaur Park Formation and the overlying lower
Maastrichtian Horsehoe Canyon Formation). Thus, Urduchukan may also
indicate some of its fossils derive from a lower Maastrichtian level,
perhaps even the holotype of the "parasaurolophine" *Charonosaurus*
itself. If the palynology shows a long-lived *Wodehousia,* long held to be
a Maastrichtian fossil, or constrain beds containing it to the upper
Maastricthtian, it would show that many verts evolved to different areas
when they migrated across land bridges and became extinct in their endemic
regions (gosh, like that never happens).
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.
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
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