Re: Paleocene dinos

[Peter Sheehan <sheehan@csd4.csd.uwm.edu>]

It needs to be above the impact layer.  Then there will be no problem
Peter

On Fri, 13 Jan 1995, Phillip Bigelow wrote:

> 
> >>PS.  I'll believe dinosaurs survived into the Palaeocene when someone 
> >>finds>>ARTICULATED bones, IN-SITU in a RELIABLY DATED Palaeocene deposit. 
> >>(I know:>>"dream-on").
> >
> >                  
>   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
> following: 
> 
> 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!  :)
>  
>