Talk:Cretaceous-Tertiary extinction event

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Someone may want to place a link page for KT boundry to this site.

I removed a list of explanations. This appears to have been shamelessly ripped off from this page. --LMS

Can anyone tell me exactly (ok, roughly will do!) how long the dino-extinction took please? Deni.

"K-T" is on most of the redirects to Cretaceous-Tertiary extinction event, and that seems logical since it is abbreviating something hyphenated. (It's the head of what i used in my attempt to find the article.)

Yet "KT" is used twice in the first 'graph. Is that bcz the pros use KT, or is it just a guess that no one has fixed? --Jerzy 22:26, 2004 Feb 20 (UTC)

Actually, i now see that "K-T" is used in the 4th- and 3rd-to-last 'graphs, which sound more knowledgable. I'll change the KT references soon if no one responds, since the article is self-contradictory. --Jerzy 22:32, 2004 Feb 20 (UTC)

Didn't the orignal Alvarez paper concern specifically Gubbio, Italy? IIRC, the evidence became "worldwide" at a later date. --Jerzy(t) 05:42, 2004 Apr 29 (UTC)

Use of the Alvarez K-T extinction model as de facto is not warranted. The same mechanism would need to be invoked to explain other mass extinctions such as the Permian (whose process profiles do not so easily accord with an impact diagnosis). Presumably, those disappearing species which heralded the extinction process several million years prior to the K-T boundary must have used sophisticated astrometric instrumentation to see the asteroid coming, frightening themselves out of existence. Occam’s razor should dictate the more likely probability of gradual but heavy volcanism and subsequent environmental change. Evidence for this prosaic alternative is much easier to come by than a largely transatlantic led indulgence for a Hollywoodised disaster scenario. Work on other external impositions on the terrestrial environment, by MacClean and others, also deserve more merit - despite the lack of the PR machine afforded the Alvarez clan.

It is also no accident that an asteroidal impact theory prospers in a nation keen on indulging strategic defence on an industrial scale.

Steve Ringwood

Well said, indeed, Steve. The problem is that whereas you have sound reasoning on your side, you are opposed by tons of lurid magazine covers showing asteroids hitting the earth with dinosaurs in the foreground plus a dozen films with the same premise. The real science got lost in this a long time ago - which forgive me seemed to happen on a regular basis in any undertaking where Gould was involved.

If people wonder why this issue was so important to clarify instead of obfuscating, it is that our planet seems to be undergoing similar climate changes right now directly related to magnetic fields and volcanism, especially on the deepest part of the ocean floor. The Alvarez-Gould circus of Lysenkian proportions may very well have left mankind stunned like mullets when they should have been preparing themselves for the possible onset of a second Ice Age.

I'm sure Steven J. Gould would be happy that his legacy will consist not only of derailing anthropology for the past thirty years but also being instrumental in the deaths of millions of people in the Northern hemisphere who were watching the skies for theatrical cosmic intruders when they should have been keeping their eyes right down here on the planet around them instead, where the real action was.

(effeminate crypto communist edited these comments to make them more thought neutral) 13 Nov 2004

- Cleve Blakemore

Whence the K?

Geologists' abbreviating of the Cretaceous period by "K" reflects the need to avoid ambiguity: the more obvious "C" would also be the natural first choice for the "Carboniferous" period.

That makes no sense: K is just as ambiguous as C. Actually, the K stands for Kreide, the German term for Cretaceous. Geology was happening in Germany when the term was coined back in the 19th century.
—Herbee 12:50, 12 Nov 2004 (UTC)

Others attribute the K to the Greek "Kreta" which was a natural alternative to the Latin "Creta". Both of which mean chalk and latin/greek were still all the rage at the time. Incidentally, the name Cretaceous was first proposed by Jean-Baptiste-Julien d'Omalius d'Halloy in 1822 in relation to sections in France.
Dragons flight 15:17, Nov 12, 2004 (UTC)

Deleted long uneeded footnote quote about Shiva crater. The reference is there as a link for those interested. Also deleted slanderous garbage from previous discussion comment above. We can be civil here. -Vsmith 18:26, 13 Nov 2004 (UTC)

Contents

[edit] Deccan Traps section

"Other scientists think the extensive volcanic activity in India known as the Deccan Traps may have been responsible for, or contributed to, the extinction. However, paleontologists remained skeptical, as their reading of the fossil record suggested that the mass extinctions did not take place over a period as short as a few years, but instead occurred gradually over about ten million years, a time frame more consistent with massive volcanism. There was also a certain general distrust of a group of physicists intruding into their domain of expertise."

I don't see quite how this makes sense. Paleontologists are sceptical of the gradual-extinction massive volcanism theory caused by the Deccan Traps because their information points to a gradual extinction? It then goes on to say how they slowly came to accept a rapid extinction theory such as meteor impact instead of the slow-extinction Deccan Traps one. I'm not sure quite what whoever wrote this means to say, so I haven't changed it, but someone should make it clearer. --Orborde 05:20, 19 May 2005 (UTC)

[edit] Search Problem

Listening to Melvin Bragg's programme on Radio 4 (http://www.bbc.co.uk/radio4/history/inourtime/) today (23 June 2005), I wanted to read more on the discussion topic, 'KT Boundary'. On typing in 'KT Boundary' in the search box, I got nothing in the first four or five pages that would have taken me there, even though there's a 'Category:KT boundary'. Being still fairly new to Wikipedia, I don't know how to set up synonyms for the proper article. --MaxHund 08:42, 2005 Jun 23 (UTC)

Not sure why that wouldn't return the correct article, because KT boundary and K-T boundary both redirect to this page, and normally the search takes you directly to the relevant article if the title matches the search query.
If you want to make redirects, it's quite simple - if you want article A to redirect the reader to article B, then just type #REDIRECT [[article B]] in article A - you can see what I mean here. Worldtraveller 09:07, 23 Jun 2005 (UTC)

[edit] Supernova hypothesis section

Er, this section says, "The radiation from a supernova explosion should contain the plutonium isotope Pu-244," emphasis mine. This is kind of confusing. Are we saying that Pu-244 would be thrown off by the explosion and hit the planet, or are we saying the radiation would create Pu-244? Or is there some use of the word "radiation" that I'm confused about? -GregoryWeir 13:31, 26 July 2005 (UTC)

Pu-244 would be present in material ejected from a supernova; it is distinct from the supernova's radiation which would not include Pu; nor do I think such radiation would normally create it even at relatively near proximity to a supernova. The sentence was probably meant to read "The fallout from a supernova explosion should contain the plutonium isotope Pu-244," and I've changed the article to reflect that. --User:Jeffmedkeff | Talk 22:46, 30 November 2005 (UTC)

[edit] Image

Perhaps a pointer could be added to the image of the KT boundary to assist the reader's non-geologist eye to what feature exactly we should be looking at here? --Deglr6328 18:41, 14 August 2005 (UTC)

It would also be nice to know the geographic location of the photo. Vsmith 23:05, 14 August 2005 (UTC)
Sorry, taken in badlands near Drumheller, and will add that; however, I can not recall which black mark is the KT Boundary, and don't have enough skill to identify. Need someone of greater skill to put arrow line to identify.Glenlarson (UTC)

(also written in the pertinent image discussion page) I'm a closet geologist, but I strongly think that the KT boundary does not appear in drumheller. This picture does appear to be possibly from drumheller or dinosaur provincial park, however both areas contain older sediments (where dinosaur bones would be common). Eastend saskatchewan, 400 or so km southeast, has a perfect roadside view of the boundary. Much of that area was spared glaciation and the more superficial KT boundary remains. I suggest a picture of this be uploaded in place of the current picture. (Which is a beautiful badlands shot but does not show the KT boundary). If this picture does include the KT boundary, it isn't from drumheller and the caption should say so

[edit] Layout

Should we change the layout to more accurately organize the page? I suggest the page be layed out like this:

1 Casualties of the extinction
2 Theories
2.1 Impact event and iridium
2.2 Chicxulub crater
2.3 Deccan traps
2.4 Multiple impact event
2.5 Supernova hypothesis
3 Further skepticism
4 Other mass extinctions
5 References and external links

Phaldo 18:47, 2 January 2006 (UTC)

I have gone ahead and modified the headers to how I was suggesting. I saw the KT event article on the Portuguese wikipedia site and noticed that page was done how I was thinking, so I went ahead and made the necessary changes. Phaldo 00:31, 5 January 2006 (UTC)

[edit] Small flaw in the KT event being caused by an impact

I would guess that an impact crater, such as the one in the Yucatan, would send tsunamis onto any adjoining or possibly distant landmasses. Wouldn't that landmass exhibit some unusual fossil formations, meaning aquatic animals (from large to small) showing up in what would be generally considered dry areas? I never know how good the fossil record is, so maybe we cannot know this, or maybe it just hasn't been discovered yet. I've got to say, if some credible source could show aquatic fossils inland by sever kilometers, that would be some strong proof of an impact event rather than some terrestrial event such as the Deccan Traps. OrangeMarlin 00:01, 2 May 2006 (UTC)

We do have tsunami deposits in North America. Dragons flight 04:05, 9 July 2006 (UTC)

I saw on a special on the Discover Channel where one of the scientist from the original team that found the Yucatan crater had made an interesting discovery about 100KM from the edge of that crater in Mexico. Between the KT boundary and the iridium layer was something like 10 feet of sandstone. In that sandstone were fossil remains of aquatic worms and crabs that were only found in the ocean. The theory was that the sand could have only come from the ocean and got there from the tsunami caused by the impact. once the water receeded, all that sand was left and then the "asteroid fallout" fell on top of that. I could be wrong on the details for I didn't exactly write it down while watching it, but that's pretty much how it was explained. Hope this helps. Buggsbuny 00:58, 12 September 2006 (UTC)

[edit] Global Firestorms?

"A global firestorm may have resulted as incendiary fragments from the blast fell back to Earth. Analyses of fluid inclusions in ancient amber suggest that the oxygen content of the atmosphere was very high (30-35%) during the late Cretaceous [1]. This high O2 level would have supported intense combustion. The level of atmospheric O2 plummeted in the early Tertiary period."

I softened this from "A global firestorm" to "Global firestorms." Is this just speculation or is there some credible theory? If so I'd like to see some reference to it. I'm a layperson but I'm skeptical to the idea that the earth, due to high oxygen content, was like a powderkeg just waiting for a match to initiate a conflagration. There are plenty of natural firestarters: lightning storms in particular, plus lesser asteroid strikes, or spontaneous combustion of rotting material (which would be much more common back then, given 35% O2). These would cause natural fires and prevent things from reaching the point where flammable material was abundant enough to support a global firestorm. The high O2 level would simply lower the threshold between what's flammable and what's not. Lightning fires would burn off all the flammables, just as they do today if not prevented.

"Plummeted" is a relative term...it probably didn't happen overnight. The asteroid impact theory implies widespread reduction in living plants (food for the dinosaurs) due to the global dust cloud. Any such reduction must have been drastic to bring about extinctions, otherwise a few pockets of dinosaurs would survive and reproduce. This massive die-off in plant life would account for the oxygen level decrease, since plants are the primary source of atmospheric O2.

As I said I'm no expert. I have no idea whether Alvarez' theory is correct; but I'm not buying the global-firestorm idea. without a credible source. If there's no referencable discussion of this from a reputable source I think the paragraph should be removed. Shyland 03:40, 9 July 2006 (UTC)

It is a real theory, from some time in the late 80s. Aside from the fact that the impact definitely would have started fires and soot is found in a great many K/T boundary sections, I'm not aware of anyone who presently takes the rest of that (i.e. the oxygen bits) seriously. Dragons flight 04:10, 9 July 2006 (UTC)
OK good enough. Shyland 17:54, 9 July 2006 (UTC)

Saw it on one of the many Discover Channels I get with DirecTV. Sorry, but don't remember name or channel, but it was late August 06. Had Gerta (was that her name?), the scientist (also a professor at some Ivy league school) who originally challanged the whole asteroid theory and then the guy who actually came up the with theory and found the crater in Yucatan. These two just hammered at each other, it was quite comical. Anyway, being that these two were on the show, I can say it must be credible. There was also another femal professor on the show (British accent - sorry dont know her name) who dug in the KT boundary all over the world looking for charcoal. The theory was that if there was a large global firestorm, there would be charcoal all over the KT boundary throughout the world. They found some soot, but no charcoal. So in their opinion, their could not have been a mass burning for what happened to all the organic material if it didn't turn to charcoal? Maybe I am simplifying it, but this was the theory presented. Buggsbuny 00:51, 12 September 2006 (UTC)

[edit] Headline text

Though most likely, the Cretaceous-Tertiary extinction event wasn't necessarily caused by an asteroid. This article mentions scepticisms, but has few alternatives. On the website http://www.dinosaur.org/extinction.htm, they have a pie chart (http://www.dinosaur.org/extinction970404.jpg) showing possible reasons for the extinction event. I'd put that in this article, but I don't know where it would go, or what kind of copywrite it would have. Any ideas?

Birds are listed as being both significantly effected and minimally effected. Clarification? Coops71 15:54, 5 December 2006 (UTC)

The article says that Enantiornithes and Hesperornithiformes became extinct but the groups which were ancestral to modern birds seem to have survived reasonably well. Enantiornithes and Hesperornithiformes were not the ancestors of any modern birds. —The preceding unsigned comment was added by Philcha (talk • contribs) 23:51, 22 December 2006 (UTC).


[edit] 1.5 years on and still just as uninformative

Still the article (after my original complaint in Aug '05 above) gives no indication anywhere in the text, anywhere in the captions or anywhere in the talk or description pages of the images themselves as to just what in the heck the reader is looking at when he/she views these supposed images of the KT boundary at the top of the page. I argue now, that without indication of the KT boundary either in caption or within the image as an arrow or something, anything, that they are useless to the reader and merit removal from the article. The current images are equivalent to uploading this [1] image to the article on New York State without any further supplementary information and simply captioned it "New York". Its simply unacceptable. --Deglr6328 08:38, 25 December 2006 (UTC)

I agree. The pics are useless to non-geologists, while geologists would need much more detailed pics.Philcha 13:14, 9 January 2007 (UTC)
I made a modified image (added a line marking the boundary, based on the info and photos here, but I can't seem to get it to display - can someone who is smarter with images than I am help? Many thanks - Geologyguy 16:20, 9 January 2007 (UTC)
I see the changes you made to my pic; they are showing up here. Thanks for doing that! Nationalparks 18:30, 9 January 2007 (UTC)
Great, must be my cache or something. Thanks for the original photo - I hope I credited the original correctly and adequately in the modified one, if not please fix it in whatever way you would want it to be - I definitely don't claim anything for just putting that line on it!! cheers Geologyguy 18:49, 9 January 2007 (UTC)
Yeah, you can try clearing your cache. I updated the new image's page so that the old image doesn't have to show full size, reducing server load. Nationalparks 19:37, 9 January 2007 (UTC)
The extra line in the Trinidad Lake pic doesn't help - it looks artificial and there's no explanation. I suggest: (a) drop the Trinidad Lake pic as it's just too small; (b) use the left half of the Drumheller pic and replace the right side with a set of labels pointing to the "normal" latest Cretaceous sediments, the boundary clay, the iridium and / or charcoal layer at the boundary, and the earliest Tertiary sediments. I expect (b) can only be done by a geologist - any volunteers?Philcha 19:47, 9 January 2007 (UTC)
I added an explanation for the line on the caption. On the full-size image, it is easy to see the thin white bed that marks the break - that was how I figured out where it must be, by comparing to the pics in the USGS site referenced above (and also why I didn't draw the line all the way across, so that one could see the rocks there). I don't know anything about the Drumheller area, can't help there... Anyway, if y'all decide the pics are still uninformative, do what you will. (Maybe lift some of the images from that USGS site? I think they are all black & white, but maybe useful) Cheers, Geologyguy 20:08, 9 January 2007 (UTC)
2560x1920 should be plenty big (that's how big the Trinidad Lake pic is, if you click on it to show full-res). Nationalparks 20:58, 9 January 2007 (UTC)

[edit] K-T Boundary

Hej! On the picture KT_boundary_054, is the K-T boundary the "gray" area between the "black" and the "green"? Ljohank 19:11, 18 January 2007 (UTC)

Per the discussion above, we don't know - that's why some suggested that this image should be deleted. We need either the original photographer, or someone familiar with the boundary in the area where the photo was taken, to help. Geologyguy 19:41, 18 January 2007 (UTC)
Oopps! I should have read it. Thanks anyway! Ljohank 19:46, 18 January 2007 (UTC)

I am the original photographer of the Trinidad picture. The white line was marked by User:Geologyguy based on this page, especially on this picture. Nationalparks 20:59, 18 January 2007 (UTC)

Hi Nationalparks, I thought he was referring to the other pic, from Alberta, which still needs some indication of the K-T position. Is that one yours too? Cheers Geologyguy 21:15, 18 January 2007 (UTC)
Sorry, that one isn't mine... Nationalparks 22:33, 18 January 2007 (UTC)

[edit] A sentence

According to the article, one of the extinction patterns is that: "Organisms which depended on photosynthesis became extinct or suffered heavy losses. And so did organisms whose food chain depended on photosynthesising organisms."

Am I missing something? Just how many types of organisms do not ultimately depend on photosynthesising organisms? Apart from chemoautotrophic bacteria, that is :). --91.148.159.4 17:22, 9 February 2007 (UTC)

Maybe "Organisms which directly depended on..." woluld help a bit. This excludes the detritus-based species, as their food was photosynthesised many years, decades (or even more) befor the event. --193.16.218.66 13:53, 21 March 2007 (UTC)

[edit] Small Predatory Dinosaurs Missing

Has it ever been suggested that large dinosaurs, both carnivorous and herbivorous, became cannibalistic due to a lack of vegetation? Would it explain the lack of fossils and presence of teeth if they became the last food source of large dying reptiles? War machine09 06:42, 17 February 2007 (UTC)

[edit] Misleading asteroid impact illustration

The 'Artistic depiction of asteroidal impact' shows an asteroid that is much too big, compared to the estimated size given in the article. In the illustration, the asteroid is about 200 km in diameter, roughly 20 times too wide. An impact of such a large asteroid would cause a lot more damage than the one that caused the K-T extinction event: assuming the impact still occured at the same speed, the energy released would be 8000 times as much (20x20x20), probably causing an extinction of all life on earth (even destroying the entire bacterial population, since the crust of the whole planet would be nearly liquified). I understand it's only an illustration, so maybe I'm just being picky? Pierre Rioux 17:28, 21 March 2007 (UTC)

[edit] Alvarez Hypothesis=Impact Event?

Is the section titled 'Alvarez Hypothesis' a summary of Impact event? ~Sushi 06:12, 22 March 2007 (UTC)

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