Re: Hell Creek [VERY LONG]

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Allan Edels" <edels@msn.Com>
Sent: Tuesday, June 04, 2002 1:33 AM

> Note that I originally wrote most of that posting nearly 4 years ago.  I
> did very little editing before sending it out.  (Also, parts of it had
> originated 15 years ago!)

Sure. I tried to point out just what is outdated.

> Thanks.

For what? ~:-|

> _At_ 65 Ma ago, to be precise, at 64.98 +- 0.05 Ma ago.
>
> ===> There was some question of the precise dating when I originally
> wrote this.

I see.

> >     3)    Lots of things changed on earth around 65 mya - climate,
> > land vs. sea ratios, etc.
>
> "Around". I'll ask Rampino next Monday
> on the last word on those climate change issues;

I forgot. Next Monday :-]

> the (milder than thought for long) regression that's seen in
> the Western Interior Seaway may not have been a global phenomenon
> either, and cannot have lead to global extinctions in any case.
>
> ===> There were reports of some seas receding over 200 feet - rather
> quickly, by geological standards.

Lasted 4 Ma, and e. g. throughout the Pleistocene sea levels jumped up and
down by 150 m or so with every ice age -- took a few thousand years each
time. No mass extinction. Don't know how long it took in the Oligocene when
the water dropped 300 m and no mass extinction happened either. Don't know
in the first place why a few special regressions are supposed to have caused
severe global trouble.

> > 2)    There were a lot of different survivors, including birds,
>
> Hardly any birds.
>
> ===> Yes, but they made it!
> [...]
> ===> Once again, they had major groups survive.  I never said that any
> of these groups passed through the K-T boundary unscathed.

I think it sort of sounded that way.

> > 7)    The climate changed drastically (geological time) - from very
> > warm and humid to much cooler and drier.
>
> Isn't that an old factoid?
>
> ===> Actually, it is based on the changes in the Foraminifera -
> indicating global changes.  The only thing that might be old is the
> humid vs. drier.

So it's only based on the following? ~:-|

> > 8)    Foraminifera changed at the K-T, indicating the climate change
> > (They went from very complex forms, usually indicative of warm water,
> > to very, very simple forms, usually indicative of cold water).
>
> From a very _diverse_ array of simple and complex forms to a
> monoculture of small and simple forms --
> a part of the plankton extinction. Strangelove ocean.
>
> ===>Yes.

If this was the entire evidence for a climate cooling, I wonder why anyone
still believes it.

> What I've read in New Scientist 3 or 4 years ago --
>
> Carboniferous: 35 %
> then "normal" (around 21)
> Middle Jurassic -- Eocene: 28 %
> since then: "normal"
>
> ===>  I'm not sure where their figures come from.

I think amber, too :-)

>  They are similar to the percentages that I posted.

Don't think so -- no change across the K-T.

> ===> Actually, there were no grasslands before the end of the
> Cretaceous.  (Someone can check on this).  It may be that the K-T
> extinction not only fostered the growth of the mammals, but the grasses
> as well.  [This is speculation - with assumptions galore].

There were no grasslands before the end-Eocene, and no grasses at all before
IIRC the Paleocene or so.

> I don't know of any monster K insects, though, while the gigantic
> Permian insects are famous (not to mention the Carboniferous
> *Arthropleura* -- it also had trachaeae, right?).

Aaaah! Hypercorrectivism! Trach_e_ae!!! :-]

> ===>  I had thought that if the O2 level was higher during the Jurassic
> and Cretaceous, that it might help explain how some dinosaurs were able
> to grow to such enormous sizes.  (i.e. They were able to exploit the
> increased O2, by pushing the limits).

AFAIK there are still no calculations whether a birdlike respiration system
would suffice under today's atmosphere. (Would certainly help if we know how
much such a sauropod weighed.)

> HOWEVER - your mention of the
> lack of monster K insects would seem to argue against that.  (Although,
> maybe some of the dinosaurs were VERY effective insectivores).

I'd still expect some in Solnhofen and Sihetun, both stuffed with insects.

> ===> [...] Signor-Lipps effect [...] My understanding of
> the effect is that if you set an arbitrary boundary, then the closer to
> this boundary that you get, the less likely you are to find some
> particular fossil.

Yes, that's part of it.