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>>PS. I'll believe dinosaurs survived into the Palaeocene when someone
>>finds>>ARTICULATED bones, IN-SITU in a RELIABLY DATED Palaeocene deposit.
Excuse the interruption on the tail-end of this discussion, but I would
think that if such a situation was discovered, it would more than likely
force a 10-year-long debate on the context of the deposit in
the first place. If we use as the hypothetical example the Hell
Creek-Tullock Fm. contact, the scenario might go something like the
First, the new hypothetical find would force a re-assignment of the strata
to the Hell Creek Formation.
The definition of the top of the Hell Creek Formation is (paraphrasing):
"Strata near the base of the lowest laterally continuous lignite _that
contains dinosaurs_". (Barnum Brown, 1907).
This re-assignment wouldn't pose any great problems, since the K-T boundary
is not considered to be "formation-dependent" anyway. However, the
re-assignment would throw out the two Z-coal layers as part of the
lithologic definition. Messy for field geologists...
I suppose there are provisions in the rules of stratigraphic nomenclature
that allow "redefinitions", or ammendments, or revisions, so I guess in the
long-run, little damage would be done to the formal definition, provided the
reference to dinosaurs is thrown out.
Second, the biostratigraphy debates might get messy. Because land mammals are,
presently, the most accurate way to distiguish Cretaceous from Tertiary
faunas land verts. in NA, a check of the mammal fauna at the site
would indicate a Puercan age for the articulated dinosaur (although it is
important to note that the North American Land Mammal Ages
only are _correlative_ with Cret. and Tert. periods; they don't define
them). The European Danian Stage would be correlative (but, again, not
definative). To actually claim a post Cretaceous dinosaur, one would have
to place it in the time context of the _definition_ of base of the Tertiary.
If memory serves, that definition is not based on anything in North America.
I am not down-playing the interest that a Puercan-stage dinosaur would
generate. But it would re-open the hornet's nest of what "Puercan" really
means regarding correlation with time-units. The Bug Creek problem (i.e.,
"Cretaceous-aspect mammal faunas" vs. "Bug Creek mammal faunas") would pale
in comparison to this. But, since the hypothetical dinosaur was
articulated, at least reworking wouldn't be an issue as it is at Bug Creek.
I hope I don't have too many factual errors written
here, but it's my $0.00023 on the issue. Now, if that dino is found above an
iridium spike, _then_ you have my attention. (Maybe Brownie Butte will come
through for us! :)