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Re: Hell Creek (long)



 
----- Original Message -----
Sent: Wednesday, May 29, 2002 9:21 PM
 
Yes....... I have a thought...... 
Are you sure it isn't a dream instead? :-)
Fragile animals that by all accounts should have died out because of the massive climatic effects that should have taken place via the poisoning of the air and water (just like they die out today via industrial pollution).... didn't die out like they should have. The ones that did go bye byes were the ones that should have survived such an environmental holocaust.
Please tell which ones you mean. And remember that the impact didn't produce polychlorated biphenyls nor hormone analogs or suchlike. :-)
Too bad for the impactor lovers..... The blast wave apparently didn't make it to Montana.
Wrong. Somewhere else you write about the "global 3 mm layer"... that's wrong. Only in NA there is a double layer, 2 mm of ejecta with the shocked quartz + 1 mm "fireball layer" with the iridium. Elsewhere on the globe (except very close to the impact... Haiti, Belize...) there is only the 1 mm fallout layer.
What does this say about the rest of the globe?...... If North America wasn't hit as hard as it is theorized...... And it has been thought that the extinction rates on the rest of the earth were much less severe..... Well, you get the idea...
Already falsified. :-)
Now, the environmental perturbations caused after the initial impact, as dictated by numerous models and such, would have been world wide........ Nothing was safe...... Well, except for the salamanders, birds, and such, in Montana...... Once again..... I tend to think you get the idea.
Are you sure the Danian birds of Montana are direct descendants of Maastrichtian birds from the same place? The few known groups of LK Neornithes had very wide distributions. And one more time, all Cenozoic birds are Neornithes (if we ignore the problem of Lithornithiformes which has recently come out as their sister group), while a very small part of K birds are. Isn't Avisaurus from the Hell Creek?
Since I know that the majority have Paul's DA, I'll just refer you to his remarks on the KT extinction, that begin on page 293.... His writings basically sums it all up for me.
I'll have to wait for July. :-)
This chart shows where in time the major documented mass extinctions had taken place, while also plotting when in time massive volcanics are known to have occurred, along with when known impact events had taken place and their associated crater diameters.
Problem is... flood basalts are difficult to overlook. Craters are. Therefore the absence of a known crater tells nothing.
When I look at the chart, what I see for the Permian's Great Dying are the raging Siberian Traps spouting out nasties for a good deal of time before 2 coinciding impact craters (Confirmation on the largest one is still pending ).
Which ones are those? I only know of one in Argentina that's too small to have done it alone.
For the Triassic/Jurassic we have the Central Atlantic Volcanos and a single impact close to the extinction.
That depends on dating. There was that Nature paper in 1997 about a supposed crater chain at the Tr-J throughout NA and Europe... Manicouagan is apparently older, though, and may have caused the Carnian-Norian mass extinction (much less severe).
For the Mid-Jurassic we have massive volcanics and 2 impacts. For the Jurassic/Cretaceous we have big time volcanics a! ! nd a few impacts all after, but close to, the boundary.
Should depend on dating, too. Doesn't Morokweng fit?
To me, this equals malicious environmental effects caused by a volcanic onslaught stressing life before the impact(s) did its dirty work.
I still haven't understood how flood basalts are supposed to cause real problems. Sure, they must have released lots of gases, but they weren't explosive eruptions capable of blowing dust into the stratosphere and beyond. Are there any calculations about how much gas that must have been, and how far it got, and for how long it stayed?
The impacts could have increased or even stopped their outputs...
Stopped? How???
AFAIK there was no lava flow in Deccan right at the boundary. But I don't know the relevant literature.
as you approach the Trassic/Jurassic boundary, the Jurassic/Cretaceous boundary, and as you get closer to the KT boundary.... there is an apparent marked increase in impact events.
Is that true?
The Tertiary, though, is completely littered with impact and volcanic events.
You mean more are preserved. :-)
I know very little about Tertiary extinctions.
Well, there was the big Eocene-Oligocene event. At least 2 craters (Chesapeake Bay, Popigay) plus a big spike in helium-3 in marine sediments, indicating that there were more comets than usual buzzing around in the inner solar system.
A thing I should also mention.... as does Paul in DA.... is that all through the chart there are single impact events and multiple impact events that have NO associated mass extinctions.
Well how big are those craters? Of course an impact won't have global effects below a certain energy.
Factor in continental drifts and inland sea transgressions and regressions, and you get a canvas who's paints paint a picture that doesn't say impacts are the most important villains when it comes to mass extinctions.
Continental drift is too slow to cause global catastrophes. Most living things laugh about transgressions and regressions.
So....... I'm thinking that the environmental changes at the Triassic/Jurassic boundary before the impactor(s) were probably little, or were those not effecting [sic] the dinosaurs,  or were simply very nonexistent.
Looks like it.
As far as I know, we don't have a firm understanding of the weather patterns during this time which would have dictated the environmental effects caused be the volcanics and the impact(s).
Impacts above a certain energy won't care. Now I don't know what that energy is.
This means that the dinosaurs were not under stress before the impact. Thus, being as resilient a life-form they definitely appear to have been (and "still are" I should also say), they were able to walk right into the Jurassic (literally as according to the Science article) pretty much unscaved by the "disaster".

The KT was a completely different story, as is being told by Horner's study.
Of course. The K-T was considerably worse. :-)
The dinosaur populations (at least in Montana) were having to deal with the environmental shockwaves being left behind and in front of the inland sea as it transgressed and regressed across the North American continent.
"Environmental shockwaves"... the end-Maastrichtian regression of the Western Interior Seaway began 2 Ma before the K-T and ended 2 Ma later AFAIK. That's a lot of time and no shockwave.
Making and/or removing such large bodies of water as inland seas woudl have disrupted with balance.
Well, more than half of the Western Interior Seaway was still present at the K-T. The north coast of the southern part was about there where the US-Canadian border is today, according to the paper with the last ammonite (recently mentioned onlist).
And from what I understand, North America is the only place where good multi-million year old chunks of life, before the KT and after the KT, are preserved directly atop one another..... How does one take the extinction record pre! ! served at only a few, little sites... all found in the same general area of the globe.... and apply the observations to the entire globe?????  I mean, I have always read of KT studies only from locations in the USA. This biased sampling has never sat very well with me.
Apparently you only read studies about the terrestrial extinctions. :-) There are lots of marine K-T sites all over the globe.
But anyway.... as I was saying..... The KT dinosaurs were being heavily stressed because of habitat shifts, faunal and floral die outs (as indicated in Horner's ongoing study),
now you present it as a fact?
What floral extinctions??? What about all the pollen dying out in the last 2 cm?
[...] and who knows what else....
That's it. Tell us what else. Evidence, please. :-)
As we have seen with a recent Nature article entitled "No 'Darkness at Noon' To Do in the Dinosaurs?"
That was in Nature. Wow. I've heard of it, but I managed to overlook it. :-o
the dust cloud might now have been less of a problem then was once thought.... [...] The article goes on to blame global wil! ! d fires and their resulting sun-blocking smoke clouds as the main culprit for the dinosaurs' demise. Only an impactor 10 kilometers and larger in diameter could throw up as much vapor that would be needed to cause these global fires.
That's the paper that says the boundary clay is a decay product of bigger, harder stones, so there was not enough dust for darkness at noon, isn't it? But these very stones, according to the same paper, caused the global -- NA, Japan, NZ -- wildfires that produced enough soot for darkness at noon! And that's ignoring the nitrogen dioxide! So all that paper says is the darkness came a few days later than originally thought. B-)
And this still does not explain why salamanders, birds, and other fragile animals in Montana, apparently went about their business as usual,
Most birds didn't. Salamanders... did that big Habrosaurus survive? Even if, when crocs can survive, why can't it, too.
while the non-avian dinosaurs lost their battle for survival.
Personally, I hate misquotes of Darwin, and even more so when they are -- probably -- totally out of place.
As I hinted before about weather.... How those high level winds were blowing and what weather patterns were in effect around the globe, and even the very seasons in place at the time of the impact, would have dictated the dissemination of the impact and volcanic effects around the globe.....
Depends on the size of the impact. Once the stuff is in or above the stratosphere, weather and other lowly earthly considerations are completely irrelevant. Calculations say stuff from Chicxulub entered even the mesosphere. The weather is interesting for the acid rain, though.
Some regions would have been hit hard, others effected [sic] just a bit...... while still other areas of the globe being completely unaffected.
Certainly nothing on the surface of the earth and nothing pretty deep into the oceans was completely unaffected. Remember the recent Science paper -- New Zealand burnt down completely.
I have always said that I expect us to find Laszarus Dinosaurs.....
Lazarus. :-)
I will be completely shocked if we don't.
I will be completely shocked if we do. Because then we get a huge problem to explain where the Lazarus ammonites, big foraminifera, zalambdalestids, even stagodontids and mosasaurs are -- and why they died out then. :-)