Wikipedia:Featured article candidates/Cretaceous–Tertiary extinction event

Cretaceous–Tertiary extinction event

This article has been completely rewritten and brought to GA status recently. After reaching GA, further copy-edits, formatting, and general clean-up was accomplished. The article is a critical one for evolutionary biology, earth science, and dinosaurs. OrangeMarlin ^{Talk• Contributions} 22:27, 1 August 2007 (UTC)

Fixes needed, resolved. SandyGeorgia (Talk) 00:49, 3 August 2007 (UTC)

• Fixes needed to achieve FA status. I've included a list below; these are generally samples only, indicating attention needed throughout. Please leave this list intact and include any responses below the list, so that I can easily return to this list and strike items as they are addressed.

1. 1a, Copy edit needs (samples only, indicating need for a thorough prose audit):

   a) Please define mya on the first occurrence ... short period of time, approximately 65.5 million years ago (mya). MYA is used later in the article, but the Wikilink says it's mya. Please define on first occurrence and use consistently throughout.

   b) (Cause - cause): The cause of the event has centered on an large impact event, increased volcanic activity or other causes ...

   c) e.g. is used throughout (not followed by a comma). Pls refer to WP:MOS.

   d) Possible redundancies (see the exercises to identify redundancy at Tony1 (talk · contribs)): Many Other groups of animals and plants, including mosasaurs, ... in the Deccan traps have all been dated to the ... Stream communities tend to rely less on food from ...

2. 1c, 2d, referencing. The quality of the sources used is excellent, but there are a few book sources that don't include page numbers. Also, the cite web template is used for some journal and magazine sources, resulting in an inconsistent biblio style; pls use cite news or cite journal as appropriate for a consistent style throughout the article. Also, please use the parameter format = PDF as needed on the cite templates.

   I added cite tags to 3 uncited paragraphs. SandyGeorgia (Talk) 19:41, 2 August 2007 (UTC)

3. 2, MOS

   a) Wikilinking problems; see WP:CONTEXT and WP:MOSLINK. The first occurrence of relevant terms should be linked, common terms are not. I noticed in the first part of the article that plants is linked, while omnivore is not. Also, since there is no article for the red-linked coccolithophorids, the reader either needs a definition for the term, or a stub could be created. Also, the same word shouldn't be linked twice in two sentences (Organisms which depended on photosynthesis became extinct or suffered heavy losses due to reduced sunlight. Photosynthesizing organisms, from plankton ... ) Is "sea floor" different than ocean floor? Sea floor is used first, but not linked. There are technical terms throughout that aren't linked or defined (example, calcareous nanoplankton). These are samples only from the firt section: pls review linking throughout.

   b) See also, refer to WP:LAYOUT. Terms are ideally defined in the article and not repeated in See also. Several terms already well discussed in the article are repeated in See also. For example, Chicxulub Crater and Deccan Traps are daughter articles, linked with a main template, yet are repeated in See also. Pls review and prune See also.

   c) A similar situation exists for External links (see WP:EL and WP:NOT). Ideally, the text of an article will include or reference most relevant information on the topic, and a comprehensive article will have minimal external links. But again, there is information about Chicxulub and Deccan Traps, as examples only, in the Exernal links. Please review and prune the link farm. Some of the links may find more appropriate homes in the daughter articles.

   d) WP:DASH, no unspaced emdashes.

   e) Missing conversions on some units (see WP:UNITS) {{convert}} is very easy to use once you get used to it.

   f) Solo years should not linked (see WP:MOSNUM)

   g) Main articles: Paleocene dinosaurs It's only one article, so it could be handled correctly in the singular by using the {{main}} template.

4. 2a, lead:

   a) Please refer to WP:MOSBOLD and WP:ITALICS. I believe "widely known as the K–T extinction event, ..." would be the requisite markup.

   b) More significantly, the lead should be a stand-alone summary of the article, preparing the reader for further detail later introduced in the article. The detail is in the article; the lead is a summary. Yet, the first sentence of the article begins, "Despite the severity of the K–T extinction event, ... " It discusses the severity of the event before it has discussed the severity of the event! I don't know how best to fix this, but some rearrangement of the order of sections/info presented might solve this problem.

(See the instructions at both WP:PR and WP:FAC; pls close the peer review.) Please keep responses below my sig so I can easily strike items as they are addressed. SandyGeorgia (Talk) 22:51, 1 August 2007 (UTC)

I can't figure out how to do this logically, so here goes:

• Fixed bolding of K-T extinction event. OrangeMarlin ^{Talk• Contributions} 23:07, 1 August 2007 (UTC)
  • Orange, it's not necessary to respond point by point (they're generally only samples anyway), and will just clutter the FAC; I'll revisit when you've done a chunk. SandyGeorgia (Talk) 23:09, 1 August 2007 (UTC)
• MYA should capitalized per WP:MOSNUM. Just thought you should know. OrangeMarlin ^{Talk• Contributions} 23:11, 1 August 2007 (UTC)
  • Then the inconsistency between WP:MOSNUM and mya (unit) needs to be addressed; I'll ping Tony. [1] SandyGeorgia (Talk) 23:12, 1 August 2007 (UTC)
    • If used, it is nearly always "mya" (lowercase) in my experience, but the more common format is "Ma" ("mega-annum") in the geological and paleontological literature. Dragons flight 23:56, 1 August 2007 (UTC)
      • I've noticed some inconsistencies in WP:MOS, but I always assumed that if I stick with one inconsistency consistently (hmmm), I'd be all right. As for Ma, I would say that's what written sometimes in geological literature. I've seen almost everything from BP to everything spelled out. The problem with Ma is that it might be too academic, and mya (or MYA) is clear to most readers. OrangeMarlin ^{Talk• Contributions} 03:28, 2 August 2007 (UTC)
        • Hopefully consensus will develop at MOSNUM; seems it's not straightforward. SandyGeorgia (Talk) 04:01, 2 August 2007 (UTC)

Note: I believe I've caught all the e.g.'s. I've done a search, and I can't find anymore. OrangeMarlin ^{Talk• Contributions} 03:51, 2 August 2007 (UTC)

With regards to 3f, this rule indicates it is editor's choice as to whether single years are wikilinked or not. I don't like them, especially since clicking on the year 2000 will not be at all helpful with this article. Any opinion?OrangeMarlin ^{Talk• Contributions} 04:24, 2 August 2007 (UTC)

Generally, on every FAC I've read, consensus is that solo years aren't linked unless something in our article about that year provides particular context to the article. The idea is that there's no need to distract the reader from the high-value links. SandyGeorgia (Talk) 04:28, 2 August 2007 (UTC)

Always thought they were silly, so I'm agreeing and removing the wikilinks!!! OrangeMarlin ^{Talk• Contributions} 04:36, 2 August 2007 (UTC)

Wikilinking is looking better, but some reviewers object to linking of any words commonly known to English speakers; for example, Australia and South America unless the country article provides specific context to this article. SandyGeorgia (Talk) 05:25, 2 August 2007 (UTC)

The wikilinking is looking good; I've not struck it yet because, in the event you decide the article sections need to be re-ordered to explain the severity/causes of the event before discussing the Extinction patterns, the links may need to be revisited so that the first occurrence of relevant terms is linked. I'm still confused about the section ordering, as it seems strange to dive straight into the different rates of extinction before setting the framework of the event. SandyGeorgia (Talk) 12:55, 2 August 2007 (UTC)

• Regarding references. The only journals that use the cite web template are three online journals, that do not use the standard "journal, volume, issue, page" format. I think cite web is preferable to cite journal in this particular case. OrangeMarlin ^{Talk• Contributions} 18:42, 2 August 2007 (UTC)
  • The Astrobiology sources (Mullen) are hard-print sources (preferable to web sources for a science article), so I converted them to cite journal. One of the links was dead (pls check that I updated it correctly), and I added the correct publication dates. [2] Striking that above. SandyGeorgia (Talk) 19:38, 2 August 2007 (UTC)

• Regarding Wikilinks. I think I've wikilnked everything. I wish there was a bot that did this work, it's hard on the eyes. OrangeMarlin ^{Talk• Contributions} 23:42, 2 August 2007 (UTC)
  • A bot wouldn't have known that someone didn't know what lasso meant in the context of Chicago Board of Trade Building :-) I haven't struck the wikilinking yet because, if you have to reorganize some section ordering, that affects wikilinking. Great progress ! SandyGeorgia (Talk) 23:45, 2 August 2007 (UTC)

One note in passing, please recheck the DOIs, I got 2 errors in 5 tries. Dragons flight 23:56, 1 August 2007 (UTC)

One journal seems to give out bad doi's--I know the two cases. I posted to the Village Pump, and I think we've all given up. I'll delete the bad doi's, even though the references are fine.OrangeMarlin ^{Talk• Contributions} 03:28, 2 August 2007 (UTC)

• Support en.wiki have lots of excellent preistoric-articles and this is one. --A cool night green owl 07:24, 2 August 2007 (UTC)

Only a minor point, but does the line "the most powerful thermonuclear bomb ever tested", where tested links to Tsar Bomba, constitute an easter egg link and if so should it be reworded? Hammer Raccoon 10:52, 2 August 2007 (UTC)

I'm not sure what you mean. The link does go to the largest thermonuclear bomb tested, so that makes sense to me. OrangeMarlin ^{Talk• Contributions} 18:33, 2 August 2007 (UTC)

Its just one wouldn't normally expect "tested" to link to "Tsar Bomba". No matter, its hardly important. Hammer Raccoon 18:37, 3 August 2007 (UTC)

• For the external link section: a quick analysis:

1. "Chicxulub": Greta Keller on Chicxulub as a "debate" (not much of a debate, since it's all her stuff)

2. "Dinosaur dust-up": Princeton article on Keller's work

3. "The Deccan Traps Volcanism-Greenhouse Dinosaur Extinction Theory": does what it says on the box

4. "Deccan traps": Link to a site that discusses the Deccan as not a mantle plume; doesn't talk about the extinction

5. "Understanding the K–T Boundary" - seems like a pretty good complement

6. "Shiva crater: Chatterjee et al. 2002 Volcanism, India–Seychelles Rifting, Dinosaur Extinction, and Petroleum Entrapment at the KT Boundary (GSA abstract)": it's the source on Shiva; your mileage may vary as to how germane you find it, but it seems useful

7. "List of 172+ impact craters in Earth Impact Database with Crater name, Diameter, Age, Country, Latitude, Longitude, etc.": indiscriminate list of impacts

8. "Earth Impact Database": Same thing as the previous

9. "The KT Boundary": BBC radio broadcast, looks all right

10. "Chicxulub impact predates the K–T boundary mass extinction": Greta Keller's 2004 abstract

11. "The Deccan Traps Volcanism-Greenhouse Dinosaur Extinction Theory": intro page to "The Deccan Traps Volcanism-Greenhouse Dinosaur Extinction Theory"

12. "Tom Holtz' lecture notes": doesn't seem helpful, as it's more or less redundant with this page except for some off-the-wall old extinction hypotheses

13. "Richard Cowen's analysis of the K–T extinction": essay, favors multiple factors, seems all right

14. "UC Berkeley's survey of theories": does what it says; UC Berkeley does a good job

My recommendations: cut 4, 7, 8, 11, and 12 right off, then decide how much Keller you want; for essentially one voice that knows how to push the media and make it appear as if there is a giant controversy (I'm sure OrangeMarlin is familiar with how this works, given his experience with evolution articles), she's getting undue weight (all of the "News" links are to her as well). J. Spencer 16:16, 2 August 2007 (UTC)

Thanks for the suggestions. Evolution articles? I have no clue about them.  :) OrangeMarlin ^{Talk• Contributions} 18:27, 2 August 2007 (UTC)

BTW, I agree with your assessment of Keller. I was beginning to think she was a bit of a loudmouth, but I'm not "into" the field, so I wasn't sure. But I am not reading a lot of articles supporting her position. I'm concerned that her weight in this matter is approaching "undue." I'm doing a search later today on articles linking to hers, and I'll see what happens. OrangeMarlin ^{Talk• Contributions} 18:45, 2 August 2007 (UTC)

• I rewrote the first paragraph of the post-lead section. What do you think? OrangeMarlin ^{Talk• Contributions} 23:40, 2 August 2007 (UTC)
  • Well ... still concerned. That the text has to say "discussed below" is a tipoff that different article organization is needed. I don't like sending readers to and fro, and think the article would flow better if you'd tell us what it was before you tell us what it did. SandyGeorgia (Talk) 23:45, 2 August 2007 (UTC)
    • I tried something new. Here's the problem--the event is the extinction, which was complex. If you were like me, before I ever read this article, my image of the event was an asteroid hitting the earth, and there's a big T. rex burning up in the ensuing explosion. In other words, the extinction event is a biological or evolutionary event, less a geological one. I don't want to give undue weight to the impact event (or Deccan traps) or whatever. So I think my rewriting keeps to the biological nature of the event, keeping a discussion of the geological part until later. OrangeMarlin ^{Talk• Contributions} 23:57, 2 August 2007 (UTC)
      • Makes sense and it reads better now; hopefully we'll hear from others more familiar with the topic during the FAC. So, the only concerns I haven't struck are ce/redundancy reducing and this post-lead paragraph business and how it may relate to future wikilinking needs. I'll defer to others on those two (copyediting isn't a strength), but I'm generally satisfied with the structural elements of the article. SandyGeorgia (Talk) 00:27, 3 August 2007 (UTC)

• Oppose. You need to follow the MOS. Headers should not contain redundancy with article title; first mention of title should not be wikilinked. E.g. for headers, use "Patterns", "Evidence", "Duration", "Cause". Without prejudice towards raising further problems. 82.71.48.158 01:43, 3 August 2007 (UTC)
• Also, {{main}} is not the correct template to use. Check usage info, and compare with {{details}}, {{further}} and {{seealso}}. Alternatively, seek consensus to repurpose the templates according to what seems to have become common practice. (Hint: good karma.) 82.71.48.158 01:48, 3 August 2007 (UTC)

• Yes, per WP:LEAD the bolded title shouldn't be linked; those links should be worked in later. Cretaceous Period is mentioned and can be linked in the lead, but Tertiary Period isn't mentioned elsewhere in the lead, and needs to be worked in. The only redundant section heading I see per WP:MSH is Cause of K–T extinction event ... which could be shortened to just Cause. If this article doesn't summarize the other Main articles (using summary style), different templates should be used. SandyGeorgia (Talk) 02:24, 3 August 2007 (UTC)

• Yes, someone has now changed the instructions for {{main}} to be the opposite of what they were originally, and that's probably a good thing, seeing that the behaviour of the uninitiated proves this to be the more intuitive use of the template. 82.71.48.158 23:58, 3 August 2007 (UTC)

I believe I've repaired this problem. Sheep81 00:57, 4 August 2007 (UTC)

• Strong Support. The only suggestion I would have, is I did not see any reference to the Michael Rampino conjecture about the origin of the Deccan Traps associated with the convergence of surface seismic waves from the asteroid strike at the antipodal point.--Filll 14:19, 3 August 2007 (UTC)

• Not familiar with it. Can you add it in if it's got a decent reference? OrangeMarlin ^{Talk• Contributions} 14:46, 3 August 2007 (UTC)

Ok, I added a reference to it, but it was reverted. It appears that Rampino was not the first to wonder about this, but he did publish a poster about it at the 1993 AGU meeting. Does not seem to be a very substantial publication. I do wonder about the antipodal seismic focussing mechanism, but it must be remembered that we have essentially no data to look at. This all has to be done by computer simulation, which is plenty unreliable, especially when dealing with the continuum mechanical properties of material that we are unfamiliar with, in the mid and lower part of the crust, under extreme circumstances that we have never observed before. I would be less concerned about the paleogeography estimate that the antipodal point was "20% off" from the Deccan Traps, because of the lateral heterogeneity of the earth's crust, which can significantly alter travel times of seismic waves. In this case, we would be dealing with paleo lateral heterogeneities, which are even less certain than paleogeography. The current heterogeneous structure which has it largest components in the spherical harmonics of order 2 was only discovered in the last 20 years or so. And it has fairly large error bars. And other components of higher (and lower) order as well. What it might have been 65 million years ago is a bit speculative, to say the least. Also, it is not clear what the nature of the impact was. Was it a glancing blow? Was it a direct hit? These would excite different kinds of seismic waves, to be sure, and probably not seismic waves that are of uniform amplitude in all directions. The materials of the solid earth are not linear by any means, and there is no reason there is not some dispersive and amplitude-dependent effects involved here as well. So basically, the reversion I think is a bit naive, but I do not have any published studies to substantiate this comment at this point.--Filll 15:59, 3 August 2007 (UTC)

The biggest problem, as I pointed out in my suggested addition, is the uncertainty in the temporal coincidences. However, there are always difficulties and revisions to these temporal estimates, as indicated in the text of the article itself, and fairly large error bars, depending on the method that is used, the number and quality of samples tested, and so on. I do not think this is necessarily a show-stopper either, but I do not have a publication to demonstrate this at this point. The interesting part of this is the fact that the theory does exist and has been debated and has received considerable media attention. These are all verifiable. --Filll 16:03, 3 August 2007 (UTC)

It should be remembered, that when dealing with cutting edge science and theories, like this one, there will be loose ends. I think the value of WP compared to other encyclopediae is that it can go into detail on many more things, and at least provide links to alternative theories or interesting facts and debates that the reader can explore if they are interested. This makes WP far more valuable, since it suggests that science is not all neat and clean, particularly when it is fresh and new and not yet established firmly. Including this, with appropriate caveats, is exactly what WP should do.--Filll 16:07, 3 August 2007 (UTC)

Actually, it was suggested in the early 1990s and largely refuted since then. It's not cutting edge. When it was suggested, people didn't have access to the compelling geochemistry information showing that Deccan started first, or to the paleoreconstruction data showing that Deccan was thousands of kilometers from the actual antipode. You'd be hard pressed to find advocates that this is much more than coincidence now. At best, Chicxulub stirred up an already erupting province, but you'd need a more recent reference for that. Dragons flight 16:27, 3 August 2007 (UTC)

I have addressed this and other concerns at length at Talk:Cretaceous–Tertiary extinction event--Filll 21:34, 3 August 2007 (UTC)

• Comments—This is impressive, but I'd like to see an unfamiliar collaborator go through it to clean out the glitches. I picked up just a few to demonstrate that the whole text needs attention.
  • Opening sentence: The Cretaceous–Tertiary event was the catastrophic mass extinction of extant animal species in a comparatively short period of time, approximately 65.5 million years ago (mya). Remove "extant". Short compared with what?
  • "With some controversial exceptions"—Remove "some"; it adds absolutely nothing.
  • Fossils whose?
  • "The cause of the event has centered on a large asteroid impact, increased volcanic activity or other catastrophic geological event (in combination or separately)". Not "the cause", but "theories on" or "explanations of" the cause, or similar.
  • "organisms. Organisms"
  • "began dying" --> "died"?
  • "The largest air-breathing survivors of the event, crocodilians and champsosaurs, were semi-aquatic, and, therefore, had access to detritus." The comma fairy is working overtime. "... aquatic and therefore had ..."
  • "In addition, modern crocodilian young ...". Why are the first two words necessary? Remove, please.
  • "Extinction evidence"—"Evidence of extinction" (title)
  • Read MOS on captions that aren't complete sentences (remove dot in at least two; one, I think, needs a dot).Tony 14:35, 3 August 2007 (UTC)

Thanks for these comments. I took your test on your user page a few days ago, and I went back and did some massive edits to clean up the language. Apparently, I didn't find them all :) OrangeMarlin ^{Talk• Contributions} 14:46, 3 August 2007 (UTC)

As you run through again, pls watch out for some of the straggling wikilinking issues (some mentioned in my original post); for example, the double linking of photosynthesis within two sentences and the sea bed-ocean floor situation are still there. Is there a difference between sea bed and ocean floor? If not, stick with consistent terminology, and link the first occurrence. SandyGeorgia (Talk) 15:02, 3 August 2007 (UTC)

• Support Looks great, well written, well referenced, comprehensive and nicely presented. If I had to make any suggestions it would be a couple of fairly minor copyedits, that in no way disqualify the article from featured status. ornis (t) 15:26, 3 August 2007 (UTC)

• Oppose. I am concerned with structural and factual problems in the discussion on "Extinction patterns"
  1. "There was a progressive decline in the diversity of organisms during the Maastrichtian stage of the Cretaceous period prior to the K-T boundary" - The K-T boundary is literally defined by the iridium anomaly created by the impact event [3], so this sentence says there was progressive decline in diversity before the impact. If that's what you are intending to say, it needs to be a lot clearer about the implications and provide references.
  2. "The boundary resulted from an ecological crisis..." - Again, the geological community has adopted a standard that the boundary is literally defined by the impact. The ecological crisis is associated with it, but not the cause of the boundary.
  3. "Organisms which depended on photosynthesis became extinct or suffered heavy losses due to reduced sunlight" and in the lead "These geological events caused extensive weather disruptions which reduced sunlight and led to reduced photosynthesis" - There is an unreferenced assumption that loss of sunlight is the killing mechanism. This continues through the whole section and is poorly justified. In particular, the idea that "weather disruptions" caused loss of sunlight seems bizarre (as opposed to say dust kicked up by an impact). Also, how long was it dark? If the whole section presumes darkness as the primary cause of the extinction patterns, this should be discussed more directly.
  4. "Herbivorous animals, which depended on plants and plankton as their food, died out as their food sources became scarce; consequently, top predators such as Tyrannosaurus rex also began dying." - The cause-effect chain is stated as fact here, when I doubt scientists who be so definitive. For example, if you blot out the sun it gets cold, which could just as easily doomed top predators before the food ran out.
  5. "Omnivores, insectivores and carrion-eaters survived the extinction event, because of the increased availability of their food sources." - unreferenced, stated as fact. Also, can we get some references less than 2 decades old for any of the "detritus" based food chain? A lot of thinking about K-T has changed since then. For example, they found Chixculub.
  6. There is also an unstated implication that if detritus feeding was key, then there must not have been any detritus feeding dinosaurs? Or put another way, what other factors were present that also influenced the extinction patterns? The section doesn't even consider other kill mechanisms, such as darkness induced cold, widespread fires, acid rain, anything else that could plausibly occur following an impact event. I have this sense that the text has bought into one interpretation to the exclusion of other factors.
• All together this introductory section leads off by discussing "Extinction patterns" in the context of a particular story of why things died that is poorly developed and in parts poorly referenced. I generally think the entire section either needs to focus more directly on the factual issue of what died (seperated from the question of why), or it needs to be clearer that it is providing an interpretation of the extinction patterns and develop that story more plainly. Dragons flight 20:44, 3 August 2007 (UTC)

• Later points:
  1. "Iridium is extremely rare in the earth's crust because it is very dense, and therefore most of it sank into the earth's core while the earth was still molten" - This is factually wrong. Iridium is dense, but that's not the controlling factor. Iridium left because it is a siderophile and chemically alloys with iron readily. Some densier elements, e.g. uranium and thorium, are nonetheless concentrated in the crust because they bind into crust forming rocks in preference to dissolving into iron solution. Also, numbers should be given for the Alvarez Ir concentration and normal background.
  2. The high angle impact is disputed. The persistence of the Ir in the environment argues for a close to vertical impact as the momentum in an oblique impact would carry much of the impactor back into space.
• Dragons flight 21:03, 3 August 2007 (UTC)

Is there a reference that conclusively demonstrates this impact at a normal incidence? The reason is, that a totally orthogonal collision seems highly unlikely, given the speeds at which these objects approach and the putative mass of this object. If they were just drifting and fell into the earth's gravity field, then an orthogonal totally-inelastic collision is possible. However, given the tiny fraction of steradians relative to 4 pi for which one could expect such a collision, it strikes me as a bit strange to postulate it. An oblique/obtuse impact is far more likely, and if the mass was sufficient, there would still be plenty of mass ablated in the atmosphere and dispersed even on a glancing blow that would result in an Iridium layer. Of course, sufficiently oblique angles and momentum ranges would result in a "skipping phenomenon", or even a slingshot effect with minimal physical contact and associated mass and energy transfer, if any. Basically, I am saying on this issue and a number of others, lets not settle on same baby version of the science, but make it clear that there are some open ended questions here and issues in dispute or not yet settled conclusively. The current state of the science is definitely not final, by any means.--Filll 21:16, 3 August 2007 (UTC)

I'm sure there is discussion of this somewhere, but I don't know the iridium reference off hand. However, Morgan et al. 2006 (currently, ref. #41 in the article) concludes that the angle had to be greater than 45 degrees from horizontal, in contrast to the 20-30 degrees of horizontal which is presently stated as undisputed fact in the text. For the record, by "close to vertical" I meant something like within 30 degrees of vertical. Not ridiculously close, but not high angle either. Dragons flight 22:45, 3 August 2007 (UTC)

• Also, the K-T boundary was not always defined by the iridium layer. Perhaps the definitions have changed, but the K-T boundary was a well known geochronological feature long before the discovery of a worldwide iridium layer near the K-T boundary.
• The original definition of the boundary was the extinction event, literally, the ecological crisis. It has been changed? Do we have a reference for that?

  Yes it changed, or more correctly no official standard existed before the International Commission on Stratigraphy adopted the iridium layer as the standard in 1991. The reference was given above. Dragons flight 22:26, 3 August 2007 (UTC)

• There are multiple killing mechanisms that might be associated with an impact, such as a nuclear winter from the dust kicked up into the upper atmosphere, combustion of a large fraction of the vegetation on the planet (if I remember correctly, are there not carbon particles/soot associated with this layer in many places throughout the earth?), change of the ocean chemistry, change of atmospheric chemistry, and so on. Perhaps they should be described, with references, but I this is a minor point since no one really knows. I do not think this is a reason to deny eventually FA status to this article. I argue strongly that these minor deficiencies should be corrected, and then the article move on to FA status. To do otherwise is to discourage good editors who have put a substantial amount of work into a project from continuing to improve the article to FA status. The entire purpose of the FA should be to encourage better articles, not to hand out gold stars. So let's examine honestly and carefully the deficiencies, correct them together, and move forward to an article we can all be proud of.--Filll 21:31, 3 August 2007 (UTC)

• I'd like to see some reference that associates Eagle Butte or Vista Allegre with the K-T. Saying they are less than 65 Myr in age is not informative, since 35 Ma is after all less than 65 Ma, and crater ages really can have 10s of Myr uncertainties. Please provide something to show people (other than Wikipedia) associate these with the K-T. Dragons flight 23:11, 3 August 2007 (UTC)

Well please then provide the references and material you feel appropriate for the article.--Filll 23:35, 3 August 2007 (UTC)

• Oppose - This article needs to provide critiques of the different theories, not just list them. There is a significant body of research which concludes that many of the extinctions were not the result of an "event" but more gradual processes. For instance, how do extinction theorists reconcile the survival of so many pH-sensitive amphibian species with worldwide acid rainfall? Why was diversity declining in so many vertebrate taxa well before the boundary? How can you draw conclusions about worldwide terrestrial extinction patterns when the only well-sampled region is northwestern North America? These critiques and others are in the literature and would provide an important balance to the article. The debate is not just about which massive geological event killed off all those species, but also whether it was the result of an "event" in the first place. Sheep81 00:51, 4 August 2007 (UTC)

On second and third reading, some of these things are mentioned in passing but not connected to anything really. I still would like to see more critique but I do not oppose quite as strongly. Sheep81 01:50, 4 August 2007 (UTC)

• Can someone find a way to reword the lead to avoid i.e.? "With controversial exceptions (i.e. "Paleocene dinosaurs"), all non-avian dinosaurs ... " (See WP:MOS on the use of i.e. and e.g.) SandyGeorgia (Talk) 01:07, 4 August 2007 (UTC)
  • "With controversial exceptions, termed by some "Paleocene dinosaurs".... ornis (t) 02:50, 4 August 2007 (UTC)
    • Why not just delete the whole phrase? Sheep81 04:20, 4 August 2007 (UTC)
      • I guess it really depends on just how fringy the notion of palocene dinos is. Another option would be to footnote the link, with a short description. ornis (t) 04:49, 4 August 2007 (UTC)
        • It is also worth noting that it has a section at the end of the article. Dragons flight 04:53, 4 August 2007 (UTC)

A Challenge for Dragons flight

You appear to be casting yourself as an expert on this issue, yet short of much sound and fury signifying nothing, you've not lifted a finger to actually improve the article. Instead of attempting to impress everyone on this FAC page with your geological knowledge, fix the damned aticle. OM came across a crappy article and fixed it up as best he could. Why don't you devote the same amount of time to correcting (with citations) those things you think are wrong rather than merely railing against them? •Jim62sch• 18:02, 6 August 2007 (UTC)

I would agree with this assessment. I have posed a large number of questions to Dragons flight, on this page and on the article talk page. Only a tiny fraction were addressed, and those with an air of general superiority and contempt, which frankly, is somewhat undeserved. I have also asked Dragons flight repeatedly to help us improve the article, if he feels it is so deficient. The goal here is NOT to just dump on the efforts of others, but to produce articles for WP we can all be proud of. That is, you either help in a productive manner, or you are just impeding the mission of Wikipedia, frankly. Do you want to be productive or not here? What in fact is your goal here? If you want to play an intellectual game of one-upmanship, as a "PhD candidate" at "Berkeley" in the earth sciences (which does NOT impress me at all, and in fact makes me laugh at how pathetic a gesture this is to brag about such a thing), believe me, you will have your head handed to you. So let's not play silly games which you will surely lose. Let's improve the article, shall we?--Filll 18:27, 6 August 2007 (UTC)

On this and other occassions, I have felt personally attacked by you. Please stop. Dragons flight 20:20, 6 August 2007 (UTC)

I have probed you on your claims. You have responded to only a few. I have tried to direct people to the talk page discussion. You removed it summarily. I am here to help improve the article. What are you here for? If you feel attacked, then you might want to consider another career path.--Filll 20:57, 6 August 2007 (UTC)

My time is limited. I had hoped that that there would be a subject matter expert among the contributors concerned with this article that could address my concerns, because even if I can recognize substantial weaknesses in the article it would still take me a great deal of time and considerable research to really fill in those gaps. The discussion of extinction patterns in particular is really a key part of the K-T extinction, but I could easily imagine spending several weeks worth of my Wikipedia time getting that up to a level that is scientifically rigorous and thorough. I don't mean to malign the efforts of OrangeMarlin and others who have put a good deal of time into this, as the article is clearly much improved for their efforts. However, I fear the article has suffered from a lack of detailed expertise in the subject matter, and is not yet ready to be featured. I had hoped that by posting here, it would attract someone with more free time to work on these issues. If it really falls to me to work on fleshing out the science content, then I'm sorry but it will take quite a while. Dragons flight 20:20, 6 August 2007 (UTC)

In other words you can't and won't be bothered. If you are an SME, as you have led us to believe, then you should be doing the editing. If you can't, then we must assume that the concerns you have raised are less valid than they might appear on the surface. •Jim62sch• 20:29, 6 August 2007 (UTC)

Others time is limited as well. We clearly do not have a "subject matter expert" among us, so we have to make do with what we have. It is easy to throw stones. But if you throw stones, expect to be challenged. And some of your behavior, like raising large numbers of issues, then ignoring the responses you choose not to respond to, and removing the link to the article talk page which I placed here, just start to give me pause. We are all trying to do our best here. Maybe the article is not ready for FA status. I am not a big fan of this rating system anyway, except as a mechanism to improve articles. If you see some huge defects and you have some references that answer some of the points, produce them. Making outlandish statements that are not backed up by any citations or reasoning really paints a certain image, however. And if having some of your outlandish claims challenged is uncomfortable for you, I am sorry, but that is how science is. If you can't take the heat, get out of the kitchen. Looking into your claims about osmium are raising a lot of questions in my mind about how firm those studies are. See, in science, things do not stay static. Studies that are 2 or 3 years old and not confirmed are not the final answer, by any means. The studies 10 years ago were not, even though at one time they were 2 or 3 years old as well...--Filll 20:40, 6 August 2007 (UTC)

About the link to the talk page: I'm very sorry about that. I'm not at all sure how it happened. It was never my intention to remove that link (which I've now put back). As it got wiped out when I was writing a reply to something else, I can only assume I accidentally editted an old version of the page. Dragons flight 21:12, 6 August 2007 (UTC)

Dammit Dragon's flight, I'm a doctor, not a geologist! Sorry, I never overlook an opportunity to utilize a good Star Trek quote. At any rate, we are all volunteering for this project, and most of us are quite busy. This is a critical article, one that that is currently a central link to a huge number of articles in the project. From my humble point of view, you almost can't talk about anything post-KT without linking to this article. I am not at the level of expert as you are, but many of scientists, and we need your level of assistance in making the article better. But if you start talking about the angle of the asteroid hitting or other type stuff, I'm lost, and I can't make this article better based on that information. You don't need to rewrite the whole thing. Give us some paragraphs, and we can clean it up, link it right, whatever. If you think the article need wholesale rewriting, then I'd disagree with you first, but agree that none of us have the time. This article sucked two months ago. It appears to be right near FA quality. If you can help me (or us, I hate violating WP:OWN, but I guess I own it for now), then please put in a couple of hours to get a critical article to the next level. OrangeMarlin ^{Talk• Contributions} 22:40, 6 August 2007 (UTC)

• Fixes needed - first some little things: cheers, Casliber (talk · contribs) 11:15, 7 August 2007 (UTC)

In Terrestrial plants, we're calling it "Cretaceous–Paleogene boundary" -I'm presuming this is not intentional and should be K-T as elsewhere..(?)

Reading through the prose is good, but some subordinate clauses with parentheses I'd change to mdashes or commas. I always thought this was to be discouraged.

Overall I get a feeling of lack of coherency about the article. I hate to say this as a bucketload of work has gone into it and the effort is admirable so far. My feeling is there is a bit of mental confusion over whether the subject of the article is the extinction event or the boundary itself - and this impacts on the overall structure and flow of the article adversely. I tend to agree with Sheep81 on this above WRT listing causes. The LEAD really needs to summarise the article and contain the following:

Given it's about an extinction event, it really needs to succinctly summarise what became extinct and what survived - it focusses a bit on reptiles - mention bird/ammonite/mammal/amphibian surivivals/extinctions in lead- this should also occur right up there in para 1 of the lead - as launching into the boundary shifts the emphasis of the article.

The lead also needs to (after highlighting what became extinct) - succinctly summarise the causes and give some idea as to what consensus is - para 2 needs to be expanded to give an idea which theories are more widely held than others and at least touch on some theory of late Maastrichtian loss of diversity.

Then - given the article is about the Extinction rather than the boundary, it would be logical to have the section on what became extinct next, followed by causes. The evidence section should really be an intro bit of extinction patterns - I can't see any reason why it is separate. The Causes section has to be all-inclusive with an intro comment/summary on where/what consensus actually is and then go into all the geological stuff, as well as a section on the diversity argument and that ones strengths and weaknesses.

Overall this is doable though requires a step back and digest. I am happy to help if you agree this is a good way to go. cheers, Casliber (talk · contribs) 11:35, 7 August 2007 (UTC)

I went back and looked at the LEAD. I disagree with this editor. I think the current LEAD is already plenty detailed. If you want a longer LEAD, I would suggest another section called Introduction or Overview or Summary right after the LEAD. Although this kind of section is not standard on WP, it is very common in professional writing, and can be beneficial (for example, we often see sections such as Abstract, Introduction, Executive Summary, Overview, Summary, etc in a professional article, and usually an article will have 2 or 3 of these kinds of sections).

The reason for my preference is that it is helpful for more readers, and is more accessible. Most readers do not want a lot of detail. They want to quickly glance at the LEAD, and in a few sentences, know approximately what the topic is without reading a bunch of involved information. The vast majority is unlikely to read past the first paragraph (maybe 95% of the readers?). Probably 99% will not read past the LEAD. Only a tiny fraction will go beyond that and into the body.

The current LEAD is great. It is concise. It is succinct. It states what the K-T extinction event is. It states in a couple of sentences what the possible causes are thought to be and why. It states in a couple of sentences what went extinct. I can imagine some small tweaks to the LEAD. I would NOT suggest a massive rewrite of the LEAD, or some substantial expansion of the current LEAD.--Filll 12:27, 7 August 2007 (UTC)

(All it would require is shfting para 3 to para 2 and vice versa really, and emphasising what became extinct as that is the subject of the article) cheers, Casliber (talk · contribs) 22:40, 7 August 2007 (UTC)

Potentially part of the problem: Surveying the 100 or so editors who have contributed most to the current article, the person who has been editing the longest by far is Dragons Flight. Dragons Flight started editing the article in October of 2003. I wonder if we might be witnessing some WP:OWN problems here, since the article has been substantially rewritten by OrangeMarlin in the last few months.--Filll 12:59, 7 August 2007 (UTC)

Filll - I thought Overviews had been discouraged - all that such a section would do would be to rehash the lead and bloat the article. If one didn't want it in the lead then a Controversy section with succinct summary of wegihting of evidence of causes but this can be done under causes header.cheers, Casliber (talk · contribs) 22:40, 7 August 2007 (UTC)

PS:On a tangent I thought Schizophrenia had a good lead for a larger article - conceise but detailed. cheers, Casliber (talk · contribs) 22:46, 7 August 2007 (UTC)

Decision regarding structure

I've read over a lot of the comments herein, and I've come to a conclusion. First of all, ownership rules don't apply, because someone has to take the lead, which I have done. I will not take a personal stake in this article, because frankly I'm not an expert. I think what has become problematic is trying to make the article more than what it should be--it is about EXTINCTION of organisms, NOT a geological event. Although K-T boundary redirects to this article, it shouldn't. Many of the organisms were either becoming extinct prior to the K-T boundary or the K-T event itself pushed them to extinction. For example, Mammals did not radiate until well after the K-T event, yet seem to be unaffected by the event itself. So, we need to split off the boundary from the extinction. This FAC review has helped clean up the article from a structural and grammatical standpoint. This has been good. I think we need to hold on, while I clean it up. OrangeMarlin ^{Talk• Contributions} 18:08, 7 August 2007 (UTC)

I agree with Orange Marlin on the structure of the article. --Rocksanddirt 03:10, 8 August 2007 (UTC)

• Support. 57 peer-reviewed sources have been cited in this article. The writing appears clear and concise. I believe nearly every one of Sandy's and Tony's concerns have been addressed: copyedit to remove redundancies, removing ie. and eg., citations added, wikilinks fixed. J's suggestions on the External links section were incorporated. 82's issue with wikilinks in headings was addressed. Sheep's point, that the article needs to provide critiques of the theories, has also been addressed. For example, the sea level regression theory is critiqued by lines like "A severe regression would have greatly reduced the continental shelf area, which is the most species-rich part of the sea, and therefore could have been enough to cause a marine mass extinction. However research concludes that this change would have been insufficient to cause the observed level of ammonite extinction." The asteroid impact theory is critiqued by lines like "Most paleontologists now agree that an asteroid did hit the Earth about 65 mya, but there is an ongoing dispute whether the impact was the sole cause of the extinctions." and the decline in biodiversity prior to the K-T boundary is certainly discussed. Cas's observation has led OM to move portions of this article to K-T boundary. Since the 8th, OM has reworked the material, incorporating many suggestions. Firsfron of Ronchester 11:03, 18 August 2007 (UTC)
• Support. as restructured, the article looks excellent and very informative. .. dave souza, talk 22:46, 18 August 2007 (UTC)
• No support at present. Not sure if this discussion is still ongoing or not, but there are a few problems with this that could be resolved; some factual innacuracies, some stuff missing, some things unclear and overall I would not say that this piece is brilliantly written. It certainly is a decent article, but not quite up to FA status at present. If the debate is ongoing I will contribute a fuller point by point analysis over the weekend, but I just wanted to chip in in case the situation was time critical. Badgerpatrol 19:17, 24 August 2007 (UTC)
  • Well, let's start with "factual innacuracies". What specifically do you think is inaccurate about the article as it stands? ornis (t) 06:07, 25 August 2007 (UTC)

• I've flagged one interesting statement already, although seemingly flagging uncited statements is not currently acceptable for some reason. I have started a discussion on the talk page though. There are a few other misleading statements that spring to mind, e.g.:

• Photosynthesizing organisms....formed the primary part of the food chain in the late Cretaceous (so is this not the case now? I believe it is...);

• Most species of brachiopods, a small phylum of nearly extinct marine invertebrates, survived the K-T event and diversified during the early Paleocene. The numbers of ... brachiopod genera exhibited significant diminution after the K-T boundary. (Am I the only one that finds this confusing? So brach survivorship at the species level was high and they radiated in the early Palaeocene, but genus level diversity decreased? Huh?;

• A few orders of mammals did diversify right at the K-T boundary, including Chiroptera (bats) and Cetartiodactyla (whales and dolphins ... (This misleading suggests to me that whales and dolphins emerged coincident to the KT boundary. In fact the first fossil "proto whale" (actually more like a big dog) is found in the Eocene. Should be rephrased.

• I don't understand the significance of the "evidence" section - although North American dinosaur (i.e. terrestrial) deposits are significant, as is Brazos river, the type section for the KT is (I think) still at El Kef, the Alvarez work was done at Gubbio, and by far the best and most complete KT sections are from ODP cores, which I don't think are even mentioned. Why the focus on North America then? And the "marine fossils" subsection merely reiterates material already presented.

• "Impact Event" makes note of evidence for global fires coincident to the boundary - in fact, the most recent work refutes this, and should at least be mentioned by way of a counterpoint. This would have further reduced the sunlight reaching the earth's surface and then precipitated as acid rain, killing vegetation, plankton and organisms which build shells from calcium carbonate (coccolithophorids and molluscs). - I guess it's possible that some may have suggested this, but I'd like to see a reference. The buffering capacity of the open ocean is enormous- in order to acidify the waters sufficiently to negatively impact CaCo3 precipitation we would surely be talking about a LOT of acid rain. I don't dismiss this outright, but it should have a citation. (I would also point out that nannos and some molluscs are planktic, so the sentence is partially tautological).

• Any other craters that might have formed in the Tethys Ocean would have been obscured by tectonic events like... should read "destroyed by subduction".

• "Maastrichtian sea-level regression" - this is a really important section, and should be expanded, e.g. at the expense of the "evidence" section above. There are two elements to transgression-regression; a) the actual physical loss of habitat caused by sea level change (which is reasonably well covered) b) the loss of fossil bearing rocks, because trangressive-regressive cycles are associated with changes in the ratio of shallow water (high diversity, lots of fossils) to deep water (low diversity, not so many fossils) facies preserved. Mass extinction events tend to correlate very well with sequence stratigraphic cycles, according to recent research. It's possible therefore that perceived mass extinction events are not real - rather they simply reflect the fact that there is less rock available for study, and thus less fossils to be found and a lower probability of discovering a given taxa. This is important work which has received a great deal of attention recently and should be mentioned.

• Some have also suggested that the KT is coincident with a global sedimentary hiatus, which if true would also artificially truncate species' ranges (a fuller explanation of Signor-Lipps could cover this hypothesis). Anyway, those are some of the problems; not a complete list but an indicative selection. Again, I must reiterate that the article is not bad, and I hope nobody takes offence. But it's not, in my view, currently up to FA standard, and I think there are some fairly significant problems in style and content to be resolved. Note that I'm enjoying my bank holiday weekend at the moment so I may not be online much to respond, but I will do my best. Badgerpatrol 14:09, 25 August 2007 (UTC)

Flagging cited statements as unreferenced is not acceptable no, and your query on the talk page has been answered. As for the rest, I'm not going to bother reading that until you learn how to use paragraphs. ornis (t) 14:16, 25 August 2007 (UTC)

The statement (which is wrong) was not referenced. The next one was however. See talk. As for your attitude - lose it, chum. It is totally unwarranted. Badgerpatrol 14:31, 25 August 2007 (UTC)

No, actually the more you talk the more it becomes apparent that it is indeed warranted. We don't have to cite every sentence if a ref at the end of a paragraph covers that paragraph. Common sense. Use it. ornis (t) 14:48, 25 August 2007 (UTC)

• Oppose per User:Dragons flight. --Hornet35 14:37, 25 August 2007 (UTC)

I haven't digested the entire discussion, but I should chip in and say I do agree with Dragon's Flight that a lot of statements are treated as definitve fact when they should in fact be qualified. Geologists rarely deal in umambiguous facts. The other thing I would say is that the boundary is defined by the iridium layer, not by the impact per se. The iridium is a physical observation, the impact is a genetic interpretation of that observation (and one which is almost certainly true). You can believe in the KT boundary without believing in the impact hypothesis (although almost everyone now does). Badgerpatrol 14:46, 25 August 2007 (UTC)