Talk:Cretaceous–Paleogene extinction event/Archive 4

Error: Bad DOI specified
In the template for reference #56 (Agnolin, F. L. (2012), "Systematic reinterpretation of Piksi barbarulna Varricchio, 2002 from Two Medicine Formation (Upper Cretaceous) of Western USA (Montana) as a pterosaur rather than a bird))", Varricchio, D. (Muséum national d'histoire naturelle, Paris)) please change   to  . Thanks Illia Connell (talk) 03:53, 1 January 2013 (UTC)
 * Done. :) Firsfron of Ronchester  04:17, 1 January 2013 (UTC)
 * Thanks Illia Connell (talk) 04:59, 1 January 2013 (UTC)

Pterosaur

 * Starting discussion over
 * What about this disputed text? Sidelight 12 Talk 18:16, 31 December 2012 (UTC)
 * Recently, new pterosaur taxa have been discovered dating to the Maastrichtian, such as the ornithocheirids Piksi and "Ornithocheirus."(ref) This suggests that late Cretaceous pterosaur faunas were far more diverse than previously thought. (p.892)
 * Ref,:


 * this is not a primary source. It does not mention the KT boundary, but it does show that other pterosaurs were around during the Maastrichtian. This ref does have a lot to do with the existing paragraph. Sidelight 12 Talk 18:41, 31 December 2012 (UTC)
 * Quoting from the article (emphasis mine to facilitate reading):

"However, Campanian-Maastrichtian beds of Europe yielded isolated remains referable to Ornithocheirus (Ornithocheiroidea; see Wellnhofer 1991) and other non-azhdarchid taxa (Jianu et al. 1997; Barrett et al. 2008), and Campanian- Maastrichtian beds of USA and Brazil yielded fragmentary specimens of pteranodontid-like taxa and Nyctosauridae, respectively (see Company et al. 1999). Additionally, a nearly complete rostrum from the Maastrichtian of USA was recently assigned to the Tapejaridae (Kellner 2004). To these reports, here we add the non-azhdarchid Piksi barbarulna, also from USA. In conclusion, the current record of the Pterosauria is suggestive of a large diversity of Late Cretaceous pterosaurs, probably comparable to that of Early Cretaceous''' times"

Why people keep insisting in deliberately missing this part? — Preceding unsigned comment added by Chaoyangopterus (talk • contribs) 18:53, 31 December 2012 (UTC)

Emphasizing campanian doesn't help your case, since that is further from the Cretaceous–Paleogene extinction event which is why I avoided it. It is important to this subject, if a species is found dated to the Maastrichtian, but not the Campanian. I was trying to get your text inserted, and I didn't miss anything. Sidelight 12 Talk 19:36, 31 December 2012 (UTC)
 * Fair enough. But the Maastrichtian proper fossil reccord is minimal, and most of the content in the main page is equally speculation from late Campanian fossil sites. - Chaoyangopterus, 31 December 2012


 * I think this last addition can be deleted. It does, however, seem to clarify the paragraph before it. It would contradict it, except the part "Smaller pterosaur" is rather vague. Sidelight 12 Talk 18:07, 1 January 2013 (UTC)

K-T boundary or K-Pg boundary?
It seems strange to me that the article consistently uses 'K-T boundary'. Our article has been moved to Cretaceous-Paleogene boundary, so shouldn't we change all these instances to 'K-Pg boundary'? Mikenorton (talk) 19:17, 14 January 2013 (UTC)

Unconstructive new changes
IP 65.74.88.104, and new editor Chaoyangopterus appear to be single-use accounts who have been making major changes to the article that are disruptive. Discuss them here first before making the changes, otherwise these changes are going to RfC (and ANI if non-cooperative) for community review. - M0rphzone (talk) 09:04, 14 January 2013 (UTC)
 * I don't have a problem with most of the changes, which added sourced content to the article. The only one I would have reverted was the last one, which removed sourced content from peer-reviewed articles. The Ojo Alamo material is contentious, but it's not "pure nonsense". Firsfron of Ronchester  09:15, 14 January 2013 (UTC)


 * I added some things because I am familiar with the literature (but not how to use the talk pages). In my opinion, the page would benefit by updating it to reflect the latest literature. For example, studies published in the past few years show that both fish and lizards suffered major extinctions at the K-Pg boundary, and the article would benefit from updating it to reflect this. Likewise, the pterosaur edits (not mine) reflect new knowledge about pterosaur diversity. I think the author overstates the case, but their basic point- late Cretaceous pterosaur diversity is underestimated, so maybe more things go up to the K-Pg boundary than we thought- is valid. This is the kind of thing that improves the article.
 * Last- and perhaps more controversially- I think the article would benefit by presenting the evidence for the asteroid impact in more detail. This would include a brief summary of evidence for impact (iridium and other metals, spherules, shocked quartz, tsunami deposits), the proposed physical effects of the impact (darkening and cooling, wildfires, acid rain, etc.) and the logic linking the extinction to the impact: the Chicxulub event is the only event that has been shown to occur simultaneously with the extinctions (Deccan traps start before, final regression of the Western Interior Seaway happens after). 33 years ago, the asteroid impact would rightly have been considered a minority view with limited evidence, and (rightfully) given a paragraph or two. Now, it's the favored hypothesis (the Schulte et al. 2010 paper has several dozen authors, which was done deliberately to emphasize the broad support). Overall I focused on adding (including about 20 references, many recent) and re-organizing rather than deleting.
 * Concerning the deleted references, I did my best to preserve references. In several places, however, the cited papers aren't actually relevant to the point being made. For instance, reference 63 (Ryan et al.) does not refer to Late Cretaceous dinosaur diversity, but instead to Centrosaurus taphonomy (the relevant reference would actually be Sarjeant and Currie 2001). Likewise reference 62 refers to plant remains, not dinosaurs. Reference 56 refers to Early Cretaceous birds, not Late Cretaceous birds. Check the paper abstracts- these papers aren't relevant to the article. Either the correct reference needs to be located, or these need to be deleted. --- anonymous editor — Preceding unsigned comment added by 65.74.88.104 (talk) 10:50, 14 January 2013 (UTC)


 * okay... have discussed what I am up to. Since there's no commentary, I assume we have "consensus" and can add these edits back in? No explanation was given for why these edits or adding new, more up-to-date references and correcting inaccuracies is considered disruptive -anonymous — Preceding unsigned comment added by 65.74.88.104 (talk) 05:26, 15 January 2013 (UTC)


 * Thanks for your work. I haven't checked every source, but the material you've added looks reputable and well-sourced. I've gone ahead and added all of your edits back in, with the exception of the Ojo Alamo stuff, which you removed with the edit summary deleted stuff on Paleocene dinosaurs- this is considered nonsense. The paragraph actually discussed the claims made and countered them with more recent arguments, which seems pretty balanced and WP:NPOV to me. All three sources cited (Sloan et al (1986), Fassett et al (2001), Sullivan (2003)) in general support the material (though the measurements sourced to Sloan's work need fixed). Please continue with your good work, but be careful not to remove carefully-sourced material. Firsfron of Ronchester  06:03, 15 January 2013 (UTC)
 * Given that the newest official geological timescale defines the Paleocene beginning 66 Ma ago, and most recent sources consistently date the impact crater/upper Hell Creek/Lance etc. to about 65.5 (not sure if the margin of error is +/- 0.5 Ma), Paleocene dinosaurs may suddenly have been re-defined into existence! MMartyniuk (talk) 17:11, 15 January 2013 (UTC)

What the ever living….?
What happened to this great article? A bunch of opinion has been interjected (I've deleted)? Badly formatted citations? Nonexistent citations (I searched for one in Nature, which is not exactly a journal that hides it's articles deep in some Russian vault somewhere)? Uncited drivel. And then there's this pterosaur stuff based on ONE primary research article for which I could find no other supporting citation. Should we not at least pretend to be somewhat scientific and deprecate primary research?

Nevertheless, I'll accept consensus here (which appears to be four people, one of which is the SPA, and leave the silly Pterosaur section in there, even though giving weight to that one tiny clade is really odd. Shall we discuss every clade of mammal too? No, because the article would go on for 12 GB.

Anyways, I'm cleaning up this mess. It's typical of what's going on at Wikipedia. Experienced editors no longer are around, and amateurs can write whatever they want, and few care any more. Well, I care about this article, because I cite it a few times a day as an example of what Wikipedia does right. I don't want to be proved wrong. Ack. SkepticalRaptor (talk) 19:27, 17 January 2013 (UTC)


 * This deletion was because the citation was wrong. However, I finally found it as a "letter" to Nature, which indicates it was not peer-reviewed. No further publications were found, which means it never was sent in for publication and peer-review. I need to ask if anyone reviewed the citations from the recent massive changes? Because I'm not seeing it.SkepticalRaptor (talk) 19:36, 17 January 2013 (UTC)
 * I agree the pterosaur section seems out of place. One editor here is extremely persistent and for some strange reason has a huge vested interest in promoting any tenuous suggestion that the group was not in decline before the K/Pg (maybe thinking this would make them somehow inferior?). The details of whether or not the pterosaurs were in steep decline before the K/Pg seems irrelevant to the topic of the article, as the fact that they persisted to the boundary and died out for good in the extinction is not controversial. MMartyniuk (talk) 20:10, 17 January 2013 (UTC)
 * I have a problem with some of your removals, SR. In this edit, you remove cited content with the edit summary Deleting. Did anyone actually check the existence of these citations? So far, I'm finding that these cites are invented. A quick search pulls up the paper in question. Several other similar edits of this nature have been made today. It doesn't appear that you're checking before removing cited content. Firsfron of Ronchester  21:27, 17 January 2013 (UTC)

No longer Featured Article quality
I don't know when the article became like this (probably a couple years ago), but this is now far from being a featured article. The "Chicxulub Asteroid Impact" and "Alternative Hypotheses" sections are written in a synthesized, vague, and unsophisticated manner, and should be rewritten with all uncited claims removed or cited with reliable sources. For example, the second paragraph of the Evidence For Impact section is completely uncited and makes various vague claims in an inappropriate writing style. The paragraph starts off with "'The impact hypothesis was viewed as radical when first proposed. However, more evidence was soon uncovered.'" What the hell is this? Viewed by whom? Why aren't these sentences combined into longer sentences? What evidence? Where are the citations? A lot of sentences in this article can be combined or deleted altogether for being redundant.

The paragraph under the Alternative Hypotheses section is vague and full of weasel phrasing, and needs a citation. It looks like there originally wasn't a paragraph under the section, but someone added it in. Who the heck is managing/editing this article? Either clean it up, or I'm removing it.

All these paragraphs need to be rewritten in a more direct, specific, and more complex style. Also, why are the section headings not in title case? Look, I can fix some of these myself, but I'm just bringing up some of the numerous issues with this article. Maybe we should do a featured article review, and determine if this article is FA quality. I have a feeling that this will be speedy delisted at the state it's in now. - M0rphzone (talk) 03:17, 18 January 2013 (UTC)

evolution of animals based on the K-Pg "mass extinction" Wheller007 (talk) 04:58, 5 February 2013 (UTC)
I'd personally call it a mass death causing a mass evolution of what was left alive event.

Look at how animals left on islands dwarfed themselves as compared to the mainland animals of similar types. This is because the lack of sufficient food supplies to keep the large animal alive. Now imagine the same type of thing happening over millions of years to the dinosaurs and you'll see they didn't die out completely, they survived and dwarfed themselves. I personally have a flock of 50 dinosaurs that I feed daily. You would call them wrens but I call them "my kids".

I can see it in my own mind what happened once I thought of it and due to the lack of a space to suggest ideas like this, I'm suggesting them now. As far as not finding anything at all to prove anything, I come back with this challenge "find me proof that there was enough of a population that a certain breed of dinosaur that they were able to survive instead of being a simple fluke of nature here and there". The idea is they can't prove there was enough to make a breeding area (except in China and only one species of raptor) and under the same conditions they can't even prove my theory but mine actually makes perfect sense.

signed... Wheller007 (talk) 04:58, 5 February 2013 (UTC)

Science (journal)

 * Asteroiden-Einschlag gab den Dinosauriern den Rest
 * High-resolution dating technique: Chicxulub impact (c. 66,038,000 ya) and argon-argon dating of volcanic ash samples unearthed above the iridium-rich layer (c. 66,043,000 ya, error is now down to 0.1% (32,000 years)) (US-geologist Paul Renne, Geochronology Center, University of California, Berkeley)
 * --Chris.urs-o (talk) 20:22, 7 February 2013 (UTC)
 * High-resolution dating technique: Chicxulub impact (c. 66,038,000 ya) and argon-argon dating of volcanic ash samples unearthed above the iridium-rich layer (c. 66,043,000 ya, error is now down to 0.1% (32,000 years)) (US-geologist Paul Renne, Geochronology Center, University of California, Berkeley)
 * --Chris.urs-o (talk) 20:22, 7 February 2013 (UTC)

Iridium
The boundary clay shows high levels of the metal iridium, which is rare on Earth but abundant in asteroids

Is this true? As I recall Iridium is a trace metal in both asteroids and the Earth. In asteroids it is many times more common, but still a trace amount?

I suggest this be restated. Jokem (talk) 02:54, 20 February 2013 (UTC)

Impactor a comet
current Nature has this as a featured article, claims errors in measurement of global iridium layer. 76.180.168.166 (talk) 00:15, 24 March 2013 (UTC)

Common ambiguity in earth science texts
'75% of animals and plants went extinct". Individuals, species, families? — Preceding unsigned comment added by 84.120.150.177 (talk) 18:58, 11 April 2013 (UTC)

Vandalism: Deletion Without Explanation
The section, "The Simplest Model and the Rule of Occam's Razor", which is "probably" the solution to the entire K-Tr mystery, is being deleted without explanation. This defines Vandalism. DO NOT delete unless you can state your JUSTIFIED reasons!

Remember: No matter who you may think you are, or what position you have managed to secure -- you are a VANDAL by NATURE if you delete without civilized explanation. No doubt, in your true capacity, you cannot think of one.

206.45.229.10 (talk) 22:50, 11 June 2013 (UTC)


 * The "uncited" bit is certainly well-founded: there are only three citations, none of which are particularly helpful for the main thrust of the section. The first appears to be a personal site with as much interest in selling posters and books as putting up any useful information about ammonites, the second is the definition of Occam's Razor, and the third concerns coelacanths. The "speculative" charge is not entirely fair, because the basic idea, at least for vertebrates, is part of Robertson et al. (2004)'s work, albeit certainly not described as done here. Long thoughts short: to be included here, the passage should include more relevant citations and should have a less melodramatic tone.


 * Cited: Robertson DS, McKenna MC, Toon OB, Hope S, Lillegraven JA (2004). "Survival in the first hours of the Cenozoic" (PDF). GSA Bulletin 116 (5–6): 760–768. J. Spencer (talk) 00:10, 12 June 2013 (UTC)


 * Nevertheless it would be unprofessional in the extreme to delete a model which explains the entire event down to the last known species and yet retains the utmost simplicity! However it is expressed, the proper way ahead here would be to edit in order to address any expressional (and referential) shortcomings -- but never to delete!! For as long as there in common sense in science, (the model which explains all is also the simplest), the probability will be too great that you just deleted the correct solution! 206.45.229.10 (talk) 01:18, 12 June 2013 (UTC)


 * Removed again, please read WP:OR, WP:SYN, WP:RS and WP:BRD. Vsmith (talk) 01:34, 12 June 2013 (UTC)
 * A Wikipedia article should report and cite academic research using a neutral tone. Giving your own views without relevant citations is original research, which is forbidden. Dudley Miles (talk) 10:53, 12 June 2013 (UTC)

Contradiction over acid rain
The article says both that the acid rain produced was minor, based on a 2003 source, and that a 2008 paper argues the acid raid was worse than previously thought due to refined impact location and ocean depth calculations. Has this since been resolved? Either way, this could be phrased a lot more smoothly. -- Beland (talk) 19:15, 27 December 2013 (UTC)

Conflicting Info Over Mammalian Diversification Post Extinction
Under the "Extinction Patterns - Mammals" section, it states that "Current research indicates that mammals did not explosively diversify across the K–Pg boundary, despite the environment niches made available by the extinction of dinosaurs.[93]". However, in the "Recovery and Radiation" section, it states that "After the K–Pg extinction, mammals evolved rapidly to fill the niches left vacant by the dinosaurs."

The information seems conflicting, while stating both as absolute fact.

146.1.1.3 (talk) 19:49, 14 March 2014 (UTC)

Bias towards asteroid theory
When this article was given FA status in 2007, it was cautious about the cause of the extinction, but it has now been changed to "it is now generally believed that the K–Pg extinction was triggered by a massive comet/asteroid impact". My impression from my reading is that scientific opinion has moved the other way since 2007, towards multiple causes. What do other editors think? Dudley Miles (talk) 10:38, 28 February 2014 (UTC)

Different editors think different things, but since 2010, they believed a meteor shower killed the dinosaurs, because now, 2 massive craters have been found, both in Ukraine and Mexico. This means even when Hateg Island had animals, the top predators also died out.Jk41293 (talk) 17:04, 1 July 2014 (UTC)


 * To preserve a NPOV, it's important that we are biased to the scientific consensus. Though respected scientists have proposed a an alternative hypothesis about the extinction of the dinosaurs, we need to remember two things. First, this article isn't about the extinction of the dinosaurs, although that's the popular reason why someone would read this article. Second, the numbers of scientists who support the alternative point of view are small in number. If the scientific consensus shifts towards other causes, this article should shift. But seriously, in the 7 years since this article became FA, the consensus has shifted much more strongly towards the bolide impact event. Dinosaurs were dying out prior to the extinction event, but they weren't extinct. the K-Pg event is a geological event after which we see a huge reduction in species, and it can be tied pretty directly to a bolide. SkepticalRaptor (talk) 18:57, 3 July 2014 (UTC)

65 million years ago or 66?
I found (ref) linked on the Chixculub crater page, claiming the impact and extinction event to be 66 million years ago. 65 million is certainly found in a plethora of articles outside wiki - probably more than 66 - but if it is in fact outdated and we have a more precise measurement (and I'm hardly an expert on the topic) I think the article should be updated. 209.6.166.24 (talk) 00:03, 1 October 2014 (UTC)
 * Ref.: http://www.bbc.com/news/uk-scotland-glasgow-west-21379024

Reptiles are non-avian
The intro says that the event "was a mass extinction of some three-quarters of plant and animal species on Earth — ***including all non-avian dinosaurs***" So, what about reptiles? Rui &#39;&#39;Gabriel&#39;&#39; Correia (talk) 20:41, 9 November 2014 (UTC)
 * Dinosaurs "are not lizards. Instead, they represent a separate group of reptiles that, like many extinct forms, did not exhibit characteristics traditionally seen as reptilian, such as a sprawling limb posture or ectothermy." So, a proportion of other reptiles survived, but non-avian dinosaurs didn't. . dave souza, talk 10:06, 10 November 2014 (UTC)
 * So, what you are saying is that dinosaurs are reptiles ("dinosaurs ... represent a separate group of reptiles", you said). Therefore "including all non-avian dinosaurs" would include (land/ water) reptiles (dinosaurs). I guess what needs to be made clear is that while all dinosaurs are reptiles, OTHER taxa (non-dinosaur) of reptiles survived the extinction. Rui &#39;&#39;Gabriel&#39;&#39; Correia (talk) 14:02, 10 November 2014 (UTC)

New impact theory
There is a new impact theory that is gaining a lot of traction as being more plausible than the dust cloud theory, it's not mentioned in this article, but definitely should be. I first learned of it on this epidosde of Radiolab. The theory goes that the asteroid that hit caused such a rapid rise in tempurature and subsequent acid and "glass" rain, that every dinosaur and plant on the surface, worldwide, died within a matter of hours. Only smaller dino's, deeper sea creatures and mammals, insects, etc, that were buried in the ground survived. -War wizard90 (talk) 03:13, 24 January 2015 (UTC)
 * The article already mentions both acid rain and global firestorms as possible extinction mechanisms. This new paper calls the firestorms into question. Mikenorton (talk) 13:10, 24 January 2015 (UTC)
 * I agree that the causes described above according to the Radiolab programme are already covered. As to the new paper, it only covers the heat pulse, not other suggested causes such as a rain of red hot ejecta. As it is only one paper, it would be premature to mention it. Dudley Miles (talk) 14:07, 24 January 2015 (UTC)
 * I agree that it's far too early to add such a new paper as a source in the article - I only mentioned it to show that what's new is changing all the time. Mikenorton (talk) 14:41, 24 January 2015 (UTC)
 * The article doesn't mention the "glass" rain, which is the major new point in this hypothesis. That the crater impact as it was driving into the earth became so hot that it caused the rock to become gaseous and was actually ejected out into space. In space it was then cooled into billions of tiny pieces of glass that were pulled back into the atmposphere by Earth's gravity. Most of this "glass rain" burned up in the atmosphere, causing the entire earth to become extremely heated (I believe in the epdisode it says something like 1200° F, but don't quote me on that) in a matter of hours, killing almost every living thing above ground, I don't see this theory mentioned anywhere, maybe I'm just missing it? -War wizard90 (talk) 23:47, 30 January 2015 (UTC)
 * Because it has not yet been accepted by the scientific community? Because it is only ONE paper, not yet "tested" via mathematical models by other scientists? It's not like this has not been considered before - I've read proposals like that for at least some 20 years in various paleo-forums, etc.68.19.5.35 (talk) 17:51, 8 July 2015 (UTC)

K-Pg extinctions occurred within hours of impact, not months, years, or decades?
This is my first interaction here. Please take it easy on me! Being brief and to the point: is there a reason why the ideas of H. Jay Melosh are not included in this article? He is apparently well respected and is an expert in impact cratering. His idea is that essentially all surface life died within HOURS of the impact. The normal view is that the impact lofted dirt, dust and ash into the atmosphere, stopping photosynthesis, and successively killing off the herbivores then the carnivores which depended on them, in a time period extending into months, years, or decades. Dr. Melosh's view is that the ejecta from the impact was a very hot gas (?) but cooled when it hit space. It condensed in space and fell back to earth (worldwide). The heat generated by its reentry raised the air temperature of the earth up to as much as 1200 degrees Fahrenheit, broiling all unprotected plants and animals. This process would have occurred within only a few hours of impact (I've heard between 2 and 6 hours). Burrowing animals and some cave dwellers could have survived, as well as plant roots, since dirt is a good insulator.

Is this considered a "fringe" view and not worthy of inclusion in the article, or has no one gotten around to adding it? I'd consider working on it (if others considered it an acceptable addition), but I was hoping to start with something far simpler as my first edit in Wikipedia. Jharvey963 (talk) 17:36, 15 December 2013 (UTC)
 * Very fringe view. For one thing, stating "all surface life" is just preposterous. Down to the last microbe, eh?  Not likely.  :-)  — Preceding unsigned comment added by 68.19.5.35 (talk) 18:04, 8 July 2015 (UTC)
 * Totally wrong, extinction cannot be occurred within hours, the dust can not even disperse all over the earth within hours. Impact eject spherules or shock-minerals had very small size. In more than 1000 km away from crater, these ejecta are no more than 10 cm thick, and in more than 5000 km away from crater, the ejecta can not even formed a ejecta layer. But duration of extinction event or K-Pg event is short, probably no more than 10 or 5 ka (by calculating the sedimental rate of K-Pg clay). — Preceding unsigned comment added by Aleral Wei (talk • contribs) 04:51, 22 November 2015 (UTC)

added new important info
I'm kind of new here, and I added a sentence on the asteroid not being the primary cause of the extinction. Here is the source. Can someone add more info?Theyester (talk) 21:15, 1 February 2015 (UTC)


 * Actually what the source says is that firestorms were unlikely to be the main cause of extinction event - to quote from the source "multiple models have showed such an impact would have instantly caused devastating shock waves, tsunamis, and the release of large amounts of dust, debris and gases that would have led to a low light levels and a prolonged cooling of Earth’s surface. The darkness and a global winter would have decimated the planet life and the dependent animals." As with all brand new research, best to leave mentioning it until we see whether the results are accepted by other scientists. Mikenorton (talk) 21:21, 1 February 2015 (UTC)
 * Firestorm has never been regarded as the main cause, but 100~500 giga tons of sulfur released from impact is. There are many evidence indicate rapid and short-term global cooling at K-Pg boundary. — Preceding unsigned comment added by Aleral Wei (talk • contribs) 04:51, 22 November 2015 (UTC)

Extinguished? Comment
regarding: "...it is estimated that 75% or more of all species were extinguished by the K–Pg extinction"

Is there a better word than extinguished? like: Eliminated, Annihilated?

--CuriousMind01 (talk) 16:04, 22 December 2015 (UTC)
 * "Made extinct" would probably be adequate. Repetition for the sake of clarity is not a sin. Geogene (talk) 19:52, 22 December 2015 (UTC)

K-Pg boundary

 * Cretaceous-Paleogene boundary controversy
 * Deccan Traps: Gerta Keller, Vincent Courtillot, Blair Schoene and others
 * vs.
 * Chicxulub impact: Luis Walter Alvarez, Paul R. Renne and others
 * A secondary literature with an overview is needed


 * Summary
 * Note: K-Pg boundary with a value of 66.23 Ma
 * US-geologist Paul Renne, Berkeley Geochronology Center: Chicxulub impact (c. 66.038 Ma)
 * Deccan Traps: the main phase of eruptions initiated c. 250,000 years before of the K-Pg boundary
 * Deccan Traps: more than 1.1 million km3 of basalt erupted in 753,000 ±38,000 years
 * C29r/C29n magnetic reversal is at c. 65.552 Ma
 * Chicxulub impact ocurred after the K-Pg boundary
 * The Deccan Traps and the Chicxulub impact killed the nonavian dinosaurs and the ammonoids --Chris.urs-o (talk) 20:14, 16 December 2014 (UTC)
 * In this 2011 paper, Gerta Keller concludes that, "These data strongly show that the Chicxulub impact predates the KTB and caused no species extinctions at the KTB or at the earlier time of the impact." This is from Keller's site, which has quite a collection of papers refuting the asteroid-killed-off-the-dinosaurs nonsense. The K-T boundary is dated as either 65.59±0.07 Ma or as 66±0.07 Ma. Chicxulub was 300,000 years earlier. The Permian extinction is associated with the Siberian Traps. So the Deccan Traps are the logical suspect here, both for the mass extinction and for the iridium layer often cited as proof of the impact theory. H. Humbert (talk) 02:45, 6 July 2015 (UTC)
 * That's such a small minority viewpoint that even saying there's a controversy here is a stretch. Science rarely involves (or expects) complete consensus. Geogene (talk) 19:22, 6 July 2015 (UTC)
 * When I looked for books on this subject on Amazon, this was the first one that popped up: "Archibald refutes the widely accepted single-cause impact theory for dinosaur extinction." Vanished Ocean (2010) by Dorrick Stow has a chapter debunking the asteroid theory. I learned from Bob Sloan. The man seems to know everything there is to know about dinosaurs, and he certainly doesn't buy the asteroid theory. P.S. I just noticed this news article, which is based on research published only a few weeks ago. It argues that Chicxulub triggered a magna plume in Decca, which in turn led to the K-T extinctions. That certainly puts it all together nice and neat. H. Humbert (talk) 05:15, 7 July 2015 (UTC)
 * What rot. It may have convinced YOU, but the scientific community is another matter.68.19.5.35 (talk) 17:54, 8 July 2015 (UTC)
 * Do you realize that "the scientific community" includes many people who do not agree with you, whatever your opinion might be, and that you do not speak for it? H. Humbert (talk) 03:49, 9 July 2015 (UTC)
 * Keller's "evidence" are easily countered, but Keller et al consistently ignore these…… In, 2014, she published her summary paper on Geological Society of America Special Papers. She summed all the evidences that violate the Chicxulub impact theory, but these evidence are easily countered, noted that she changed the Chicxulub age to predate the K-Pg extinction about 100~150 ka, not 300 ka. In her paper, she concluded the upper spherules (El Penon section) layer had been reworked, and the original(oldest) spherules layer is blew the event deposit (sandstone that above upper spherules layer) 4~9 m, which means the impact is 100~150 ka before K-T extinction. However, the oldest spherules layer is strongly slumped,  ball-and-pillow-structure down from the upper spherules layer. The upper is reworked, because it transport by tsunami backwash. Also, Keller concluded that "the only evidence of disturbance is a small (<2 m) overturned gravity flow within a spherule layer sandwiched between more resistant marl layers along a slope at Loma Cerca"  There are plenty of evidence of disturbance published like 5 years ago, but Keller ignored. Another one of the cornerstones of her hypothesis is based on the impact eject is separated from the K-T boundary by 50 cm of limestone with five glauconite clay layers, common burrows and a planktic foraminiferal. However, this just misidentifications of dolomite crystals as forminifers, and limestone actually is cross-bedded dolomitic sandstone. Yet Keller has never offered to have her identifications tested, so she must be afraid the truth will come out. In 2013, Renne et al performed high-precision Ar/Ar dating on bentonites at K-Pg boundary and tektites from Chicxulub impact, and difference between their ages are only 5 +/- 27 ka. Thus, the hypothesis that the Chicxulub impact predated the KPB by ~150 ky is unsupported by Ar/Ar dating. Aleral Wei (talk) 04:11, 21 November 2015 (UTC)  — Preceding unsigned comment added by Aleral Wei (talk • contribs)
 * The sources of this article show that it's not just sole Gerta Keller who thinks that Chixculub impact can not be responsible for K/T extinction, nor that the dating it the only clue for that hypothesis. For me, it's actually enough evidence to make LIP hypothesis more credible than impact hypothesis. --David Jaša (talk) 16:16, 17 February 2016 (UTC)
 * Containing the runaway reference Geogene (talk) 20:44, 17 February 2016 (UTC)
 * I think you misunderstand what I'm tring to say. I do agree that Deccan can cause mass extinction, but I do not agree that Chicxulub impact predates the K-Pg boundary. Cretaceous asteroid impact would cause extinction but extinction magnitude would be lower if synergistic stressors had not already ‘primed the pump’ of extinction (Deccan volcanism).Aleral Wei (talk) 18:22, 17 February 2016 (UTC)
 * Containing the runaway reference Geogene (talk) 20:44, 17 February 2016 (UTC)
 * I think you misunderstand what I'm tring to say. I do agree that Deccan can cause mass extinction, but I do not agree that Chicxulub impact predates the K-Pg boundary. Cretaceous asteroid impact would cause extinction but extinction magnitude would be lower if synergistic stressors had not already ‘primed the pump’ of extinction (Deccan volcanism).Aleral Wei (talk) 18:22, 17 February 2016 (UTC)

Extinction inaccuracy - update needed
The text below indicates that monstersaurians are extinct, but the associated link shows that at least one species is currently extant.

"Many families of terrestrial squamates became extinct at the boundary, such as monstersaurians and polyglyphanodonts, and fossil evidence indicates they suffered very heavy losses in the KT event, only recovering 10 million years after it.[70]" — Preceding unsigned comment added by 50.234.120.74 (talk) 17:17, 15 March 2016 (UTC)

"More recent research, however, suggests that one or more non-avian ornithuromorph species may have survived the extinction event"
Somebody needs to re-examine the extremely tenuous claim that "More recent research, however, suggests that one or more non-avian ornithuromorph species may have survived the extinction event". I don't believe this is an accurate representation of the cited reference, and find no such suggestion. They state conclusively, "Nonavian dinosaurs and pterosaurs became extinct". They make no reference whatsoever to "non-avian ornithuromorph species", concluding only that "Archaic birds (i.e., outside the crown clade Neornithes), such as Enantiornithes and basal ornithurines, failed to persist beyond the Cretaceous...." and "Definitive fossils of archaic birds have never been reported from the Paleogene (7), and our examination of Paleocene fossils from North America (SI Appendix) failed to identify any archaic birds." 160.111.253.35 (talk) 14:19, 22 March 2016 (UTC)

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New contributing factor ID'd?
"Now, a paper just published in Scientific Reports has named another possible conspirator: crude oil. According to Kunio Kaiho and his colleagues at Tohoku University, in Sendai, Japan, the sudden ignition of underground oil at the Yucatán impact site could have jetted into the upper atmosphere a mass of fine black carbon, also known as soot. Human-made black carbon, the bane of Beijing, remains in the lower atmosphere for only a matter of days before falling back to the surface, where it warms the planet by absorbing heat. But black carbon injected into the stratosphere would have the opposite effect, acting as a long-lived sunshade that could abruptly cool Earth and inhibit photosynthesis over a period of years. Kaiho’s team suggests that the asteroid may have sent up as much as three billion tons of soot, hundreds of times more than the world’s industries release each year. Petroleum—the ectoplasm of ancient organisms, our shameful Anthropocene addiction—may have come back to haunt the dinosaurs, too." -- Darkness Falls on the Dinosaurs, By Marcia Bjornerud, New Yorker Elements, July 14, 2016

To be considered for our article, if the idea is well-received in the field. It sounds reasonable.... aside from the purple prose. --Pete Tillman (talk) 15:16, 6 August 2016 (UTC)


 * Here's the full text version of the paper, for anyone interested. Mikenorton (talk) 16:05, 6 August 2016 (UTC)

10,000 years plus?
So this theory is seriously suggesting that a comet/asteroid impact took at least 10,000 years to kill off a huge proportion of the dinosaurs? What, was death caught in traffic or something? LeapUK (talk) 21:22, 5 April 2016 (UTC)
 * Says: The duration of event was less than 10 ky, and the time span is too short to be explained by Deccan volcanism. Geogene (talk) 21:24, 5 April 2016 (UTC)

These species took thousands of years to die though. To link that to one event is truly bizarre; like blaming the fall of the British Empire on the Ice-Age. LeapUK (talk) 06:16, 6 April 2016 (UTC)
 * Only to the scientifically ignorant and/or the tin-foil hat crowd. Sorry. 50.111.199.0 (talk) 02:13, 5 November 2016 (UTC)

Reinserted my deleted passage
Can the person who deleted my post regarding evidence of multiple causes please explain their reason for the deletion. I have reinserted it.John D. Croft (talk) 02:44, 21 November 2016 (UTC)

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Location of impact
A recent BBC TV programme argued that the location of the impact in an area rich in sulphur and gypsum was crucial, and if the impact had occurred a few minutes earlier or later it would have been in the deep ocean, and the effects would not have been catastrophic. The dinosaurs would have survived and humans would not have evolved. See. Does anyone know of an RS on this? Dudley Miles (talk) 09:36, 18 July 2017 (UTC)

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Paleogene?
The event is almost always called the Cretaceous–Tertiary extinction event. Geoffrey.landis (talk) 01:38, 4 October 2016 (UTC)
 * The early part of the Tertiary is now officially called the Paleogene. Older scientific texts did refer to "Cretaceous-Tertiary" but this would be regarded as obsolete/incorrect if it were to be used now. GeoWriter (talk) 12:19, 21 November 2016 (UTC)
 * Can we have a source for the fact that K-T would be incorrect, or obsolete? I heard a geology professor go on at great length about it just today. Thanks. BeenAroundAWhile (talk) 22:25, 11 December 2017 (UTC)
 * It is correct that ICS now discourages the use of the word Tertiary, but Cretaceous-Tertiary is not generally considered incorrect or obsolete. A search on Google Scholar for articles published in 2017 shows 1560 hits for "Cretaceous-Tertiary" and 1340 for "Cretaceous–Paleogene". The older term is thus still more popular even in scholarly sources. Dudley Miles (talk) 23:24, 11 December 2017 (UTC)

Size of the Impactor
See Talk:Chicxulub_impactor for a discussion.

Whatever you do, keep the two article in line with each other. 217.248.54.67 (talk) 10:26, 21 July 2017 (UTC)


 * I just updated the article Maastrichtian. All three articles should be kept in line with each other. Curious  Eric  14:25, 15 March 2018 (UTC)

Mammal info is dated
The section on mammals is badly dated. ' Diversification of mammals stalled across the boundary.[citation from 2007] Current research indicates that mammals did not explosively diversify across the K–Pg boundary, despite the environment niches made available by the extinction of dinosaurs.[citation from 2003].' This is no longer the consensus. Instead diversification rates increased to around 3 times pre-event levels: Halliday, Upchurch, and Goswamil, Proceedings Biological Science, 2016 Jun 29; 283(1833): 20153026. doi: 10.1098/rspb.2015.3026, "Eutherians experienced elevated evolutionary rates in the immediate aftermath of the Cretaceous–Palaeogene mass extinction". https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4936024/. Other evidence corroborates. The idea that the CT event had little impact on mammal evolution rates is no longer viable. — Preceding unsigned comment added by 208.80.117.214 (talk) 06:16, 6 July 2018 (UTC)

Celsius to Fahrenheit
At one point in the article it is said

> At Brazos section, the sea surface temperature dropped as much as 7 °C (45 °F) for decades after the impact.

While 7 °C equals 44.6 °F, a 7 °C drop does not mean a drop of 45° F. Obviously a drop of 7 °C when the temperature is 7 °C results in a change of 44.6-32 = 12.6 °F.

Therefore a 7 ° C drop should not be described as a 45 °F drop in temperature. It should be described as a 12 or 13 degree drop in °F. — Preceding unsigned comment added by 24.0.255.115 (talk) 02:00, 15 December 2018 (UTC)


 * Correct, but confusingly put. 0 °C = 32 °F and 100 °C = 212 °F; the difference between these temperatures is 180 degrees Fahrenheit or 100 degrees Celsius, so each Celsius degree is 180/100 or 1.8 Fahrenheit degrees.  7 × 1.8 = 12.6 so yes, a change of 7 degrees Celsius is a change of 12.6 degrees Fahrenheit.  Peter Brown (talk) 03:56, 15 December 2018 (UTC)

Short description: define or distinguish?
We have two proposed short descriptions for this article.

1. Mass extinction event ending the Mesozoic Era

2. Extinction of all non-avian dinosaurs

The whole short description system is very new, and may be changing, but I think this is where we are now.

Version #1 is a completely accurate definition of the subject. But defining the subject is not the purpose of the short description; its purpose is to distinguish this subject from others, especially as they come up in search results in mobile devices. (See Wikipedia_talk:Short_description) True, the short description shouldn't be incorrect, but making it precisely correct shouldn't override helping the readers realize which article they want. Also, Mezozoic won't be familiar to a good number of readers; we'd have to define Mesozoic itself in the description to make it work, which is a catch-22, since it is largely defined by this event.

Version #2 has the most notable feature of this event, and nothing else; it leaves off the great many other genera that were wiped out. But the end of the era of dinosaurs is the most notable thing about this event. I can't see how leaving out how this event is best known can be justified as helpful to the readers.

Maybe we can come up with something that better defines the event without leaving out its best known fact? Remember that short descriptions are supposed to be <=40 characters. --A&#8239;D&#8239;Monroe&#8239;III(talk) 23:22, 5 August 2019 (UTC)


 * I have another suggestion:


 * 3. End of the era of dinosaurs


 * This, like version 2, has what the subject is most known for. It might be better, since it doesn't duplicate the word "extinction" from the subject name.


 * Pinging User:Plantsurfer. --A&#8239;D&#8239;Monroe&#8239;III(talk)  21:24, 7 August 2019 (UTC)
 * As I indicated previously, there's much more to it than the end of the dinosaurs. 85% of all species died. I suggest that a better description would be "End-Cretaceous mass extinction" Plant surfer  11:06, 8 August 2019 (UTC)

I suggest "Event that killed the dinosaurs and other species". It's hard to think of a short description for this subject that's both short and descriptive, but I think that would be pretty good. Partly because it's suitable for the lay reader, such as someone who doesn't know what "Cretaceous" means. — Mudwater (Talk) 12:14, 8 August 2019 (UTC)


 * I'm re-presenting Plantsurfer's and Mudwater's suggestions in keeping with the format as the others:


 * 4. End-Cretaceous mass extinction
 * 5. Event that killed the dinosaurs and other species


 * For #4, I agree that using Cretaceous is as unhelpful as Mesozoic; both are technical terms largely defined by the subject of this article, so anyone not knowing this subject is likely to not know these terms either. Using "mass extinction" in the short description has some of the same problem, though it's not as technically opaque as either Cretaceous or Mesozoic.  It does fit the 40 character guideline.


 * I like that #5 is fully suitable for lay readers, and it does mention the non-dinosaur extinctions left out of #2. But it's less technically accurate, as avian dinosaurs survived.  And, as noted, it's a bit long.


 * So far, I'm leaning toward #3. The "era of the dinosaurs" isn't fully technical term, but readily understandable to all, especially lay readers.  I think it fulfills all we could ask of a short description. --A&#8239;D&#8239;Monroe&#8239;III(talk)  20:27, 8 August 2019 (UTC)


 * Yes, let's go with version 3. Version 5 won't do because the event did not kill the dinosaurs; the dinosaur extinction was part of the event, not an effect of it.  And "non-avian" is no more familiar than "Mesozoic" or "Cretaceous". Peter Brown (talk) 20:40, 8 August 2019 (UTC)


 * "End of the era of dinosaurs" (i.e. #3) would work for me too. — Mudwater (Talk) 22:52, 8 August 2019 (UTC)


 * Done. Thanks all.  --A&#8239;D&#8239;Monroe&#8239;III(talk)  16:11, 10 August 2019 (UTC)

Restate this?
I think this statement is misleading.

'The boundary clay shows high levels of the metal iridium, which is rare in the Earth's crust, but abundant in asteroids.'

I am not sure iridium is 'abundant' in asteroids. Isn't it measured in parts per million in asteroids, and parts per billion on the earth? Maybe restating this to say it is 'comparatively abundant' in asteroids might be a better way to say it. Jokem (talk) 04:13, 14 December 2020 (UTC)
 * The source says "Thirty years ago, the discovery of an anomalously high abundance of iridium and other platinum group elements (PGEs) in the K-Pg boundary clay led to the hypothesis that an asteroid ~10 km in diameter collided with Earth" Which makes no indication that iridium is "abundant in asteroids". At best we can say this asteroid had more iridium than what is commonly found on the Earths surface.  Hardyplants (talk) 04:26, 14 December 2020 (UTC)
 * How about "The boundary clay shows unusually high levels of the metal iridium, which is more common in asteroids than in the Earth's crust." Dudley Miles (talk) 10:27, 14 December 2020 (UTC)
 * That works. --Kent G. Budge (talk) 14:59, 14 December 2020 (UTC)

Tanis (fossil site)
§2601:246:4681:5CA0:55F7:2E68:9957:C0FE (talk) 20:05, 11 April 2021 (UTC)The Tanis fossil site article should be here and highlighted because it's the latest evidence of the extinction event and details.
 * I agree that Tanis (fossil site) deserves more than inclusion in a "See also" section. Should appear somewhere in the Evidences section. It need not be more than a paragraph, though, since the Tanis finds are still being evaluated. --Kent G. Budge (talk) 20:11, 11 April 2021 (UTC)
 * Done. --Kent G. Budge (talk) 20:22, 11 April 2021 (UTC)


 * . Thanks for adding Tanis, but it should have citation for the whole paragraph in this article. especially as the article is an FA. Dudley Miles (talk) 21:11, 11 April 2021 (UTC)
 * I've pulled over some additional cites from the Tanis article that should cover what's in the paragraph. I'll be adding some more shortly, including some for balance that mention skepticism by other geologists. --Kent G. Budge (talk) 21:40, 11 April 2021 (UTC)
 * See what you think now. Additional papers and a paper mentioning skepticism about the find. I think it's reasonably balanced and well-covered now, but will continue hunting cites. Meanwhile ... yeah, this guy raises a few red flags. Would still love to believe the site is all it is said to be. Sometimes even cranks are right. --Kent G. Budge (talk) 22:02, 11 April 2021 (UTC)


 * Thanks for your edits. They look fine to me apart from mentioning suspicion of DePalma because of his lack of a PhD and commercial activities. Some academics are jealous of success in anyone who does not have a PhD and stays in the ivory tower. I once read a book by a paleontologist who complained bitterly about the reputation of Richard Leakey even though he does not have a PhD. I think we should stick to substantive criticisms and not give publicity to ad hominem attacks.


 * There are a number of uncited comments added presumably since the article was promoted to FA in 2007. Could you take a look at them and add citations or delete them? You have a far better knowledge of the subject than me. Dudley Miles (talk) 09:51, 12 April 2021 (UTC)


 * At this point, since there are geologists who were willing to go record in Science expressing skepticism of DePalma (I know, one was anonymous. but the others are named), I think we need to at least mention it and their stated reasons for skepticism. I'm not sure I'd characterize these as ad hominem, a much misunderstood fallacy, though complaining about his lack of a Ph.D. comes close, and perhaps that should be removed. Let me look over the Science article again and think about it. Meanwhile, yeah, I can look for uncited material that has crept into the article and either find supporting cites or remove it. --Kent G. Budge (talk) 14:05, 12 April 2021 (UTC)

Meteorite vs. asteroid
re this I believe the IP is correct. It's more often heard of as an asteroid impact than a meteorite impact. Meteorites are generally thought of as small-ish rocks. Geogene (talk) 18:33, 31 May 2021 (UTC)
 * Fair enough, but there should be a source to support that because the current source mentions it as a meteorite. I'll see what I can do tomorrow. Wretchskull (talk) 18:35, 31 May 2021 (UTC)
 * Done. The reference erroneously said meteorite but it was later changed. Wretchskull (talk) 12:06, 1 June 2021 (UTC)