Talk:Late Ordovician mass extinction

Confusion

khhg

You aren't combining the End Ordovician and End Silurian extinctions are you?

Dragons flight 23:03, Sep 19, 2004 (UTC)

To address Dragons flight's question, the end Ordovician extinction event began with a major glaciation which resulted in a major sea level drop (as much as 80 meters according to some sources). This resulted in a major extinction as continental shelves dried up and habitats changed or disappeared. Later, the glaciers melted, sea levels rose as high or even higher than they were before the glaciation, and the survivors of the first event were hit by another extinction event as environments and habitats changed yet again. All of this occured during the 1.9 million years of the Hirnantian stage.

My sources for this are The Great Ordovician Biodiversification Event, Edited by Barry Webby and Mary Droser, 2004, Columbia University Press; and A Geologic Time Scale 2004, Edited by Felix Gradstein, James Ogg, and Alan Smith, 2004, Cambridge University Press.

Hope this helps.

--Lenn 03:00, Jun 24, 2005 (UTC)

The webpage on footnote 6 speaks of Gondwana passing under the NORTH pole, which is contradicted by every map I've seen elsewhere, plus the wikipedia article; this source should be tossed out of the article as unreliable. I haven't read the book sources, but several maps and a few text pieces I've seen suggest that Gondwana was under the south pole tens of millions of years *before* the extinction event, which makes it very unlikely to be the proximate cause.134.29.178.146 (talk) 14:52, 7 February 2012 (UTC)

Causes

Hmm messing through the extinction events i have two remarks, the first being why is not immediatly the option of extraterrestial impact(s) , tested? I suppose it is, but i have read older reports telling most major extinction events have a Sr-rich layer right under. It would be relatively easy to establish and a rather telling fact for ppl like me (wogohob eg. first focusses on oceanographic aspects). A period of 1.6 million year for restabilisation of the ecosphere is somewhat high but nothing really exceptional. A severe event, upsets speciation for at least a million years, several severe events, as apparently geologically , paleologically proven in this case, would prolong that from the first occurence of the event to 1 million years after the last occurance. Ice ages have not as far as i know had any severe impact on diversity mondially. Ofcourse they might locally lead to cambrian circumstances, my bet would be eg. under the ice of antartica one could find confusingly cambrian-like geologys.

Also if the effect was due 'natural' fluctuations of the earths circumstances several genera would hardly have been touched. Wich is according to the article not the case. Simple question, can we establish wether meteorite impact was the cause before hopefully shouting earths natural fluctuations may provide sufficient (lack of) CO2 for extinction? As an example , the broken up comet that hit jupiter, might have taken 2 passages before all parts hit jupiter(would that be 60ky or 600?).77.248.56.242 13:39, 2 July 2007 (UTC)

End of the Event

The end of the second event occurred when melting glaciers caused the sea level to rise and stabilize once more.

This information is nice, but what triggered it? It seems obvious that the extinction event ( in essence an ice age) ended when the ice melted, as is suggested above, but if a ceasing of vulcanism and continued weathering of the Appalachian Mountains decreased CO₂ and began the extinction through what can be inferred as a general cooling of the Earth due to the removal of this greenhouse gas from the atmosphere, then what caused the glaciers to melt? (The ice age to end?)

If the answer is something as simple as - the Appalachians stopped weathering... I believe it might yet be worth mentioning. More likely, the answer is much more complex and involved than this or what is currently written. Indeed, the article also mentions other contributing factors for the cooling of the earth, yet this sentence, read so soon after the previous section implies that potentially, the end of the weathering of the mountains alone was enough to replenish CO₂, reheat the earth, end the ice age, and caused life to flourish once more. And that's only if you stop and think about what was actually written.

Thanks for taking the time to read and respond, as necessary. Regards. — Preceding unsigned comment added by 173.56.60.219 (talk) 04:42, 30 November 2011 (UTC)

I'm sorry, speak into my good ear?

Scientists from the University of Kansas and NASA have suggested that the initial extinctions could have been caused by a gamma ray burst originating from an exploding star within 6,000 light years of Earth (within a nearby arm of the Milky Way Galaxy). A ten-second burst would have stripped the Earth's atmosphere of half of its ozone almost immediately, causing surface-dwelling organisms, including those responsible for planetary photosynthesis, to be exposed to high levels of ultraviolet radiation. This would have killed many species and caused a drop in temperatures [2]. While plausible, there is no unambiguous evidence that such a nearby gamma ray burst has ever actually occurred.

This is a very creative use of the word "plausible" since in fact this is not plausible at all. You tell me how plausible it is that a GRB occurred at exactly the right distance that it happened to kill a significant percentage of life on Earth without killing absolutely all of it forever. Do you know what the margin of error is on those two alternatives, in terms of a gamma ray burst? Insignificantly little. So this is only plausible if you consider "deus ex machina" to be an equally plausible alternative. --75.63.48.18 (talk) 17:09, 20 January 2008 (UTC)

The sentence must be some kind of misrepresentation of the original text. A GRB 6,000 ly away will perhaps itch a fly on its back so that the fly actually experiences anything unusual ― however unlikely. A GRB must be nearby in order to make any substantial damage ― and then only on maximally 50% of the atmosphere, which doesn't seem a reasonable extinction cause to me. Personally I think this GRB hypothesis being pretty loony, wherever it comes from. Some unusual facts that cannot be explained in any other way than a GRB, use to be the usual prerequisites for such a speculative hypothesis even to be mentioned. Impacting comets and asteroids, ice ages and vulcanisms are much more conventional explanations that seems reasonable to prefer. ... said: Rursus (bork²) 17:18, 13 April 2009 (UTC)

I must correct myself: Melott's et al.'s article actually expresses a belief that a GRB at a distance of 2000 ly can actually make a significant damage on the atmosphere of Earth, if just the gamma beam, believed to be bipolar, happenstance is directed towards Earth. But in order to believe that, they speculate that a GRB emits cosmic rays... I don't believe them, however. ... said: Rursus (bork²) 17:42, 13 April 2009 (UTC)

These follow-up articles are of very much interest: "Gamma-Ray Bursts and the Earth: Exploration of Atmospheric, Biological, Climatic and Biogeochemical Effects" by Thomas, Melott and many others from 2005, explains that

1. the UBV emitting event (such as most likely a GRB) produces minute NO₂ which will instantly be devoured by microorganisms lusting for NO₂, as soon as possible,
2. that event will destroy most O₃ in one hemisphere in the stratosphere, only to produce a humungous amount of O₃ in the atmosphere layers under the stratosphere,
3. the extinction pattern at the time fits with if the GRB sprinkled UBV on the south pole, more southern than 75°S,

"Late Ordovician geographic patterns of extinction compared with simulations of astrophysical ionizing radiation damage" by Melott and Thomas from 2009, could thereafter be read, which supports the notion that this GRB is a giant what-if computation, needed to theoretically explore Gamma Ray Bursts, rather than actually making a plausible explanation on the Ordovician–Silurian extinction event. ... said: Rursus (bork²) 18:26, 13 April 2009 (UTC)

The latest thinking is that gamma ray bursts happen often enough that there is little likelihood of finding a planet with any sort of life on it anywhere near the center of the galaxy. The farther away you get from the center, the greater the chances that your planet can avoid destruction for a few billion years, or however long it takes for life to evolve. Our own solar system seems to be at about the 0.45 mark, or 65% chance that we're not here because our biosphere got destroyed, 45% that we're here because we missed getting destroyed. However, the implication is that, on average, there should have been about one mass extinction in the last 500 million years caused by a gamma ray burst. The next step is to look and see if any mass extinctions fit the expected profile. [article] Zyxwv99 (talk) 22:31, 20 August 2015 (UTC)

"Ordovician extinction"

On

<ref>{{Cite Sm|History Channel's Mega Disasters program, "Gamma Ray Burst", 2007, rebroadcast: 2008-11-13. |q=The program attributes the "Ordovician extinction" (sic) explicitly as the second most grievously large extinction event after the Permian extinction.}}&#lt;/ref>

... as an edit. (just made this date)

Despite the above section's disclaimer, the theory of a sudden ice age triggered by gamma radiation striping part of the ozone layer is out there, as this program repeated, bringing me to check the terms and our coverage...

• The program, definitely differs as to it boldly states it was the second most serious. Unfortunately, wasn't recording so can't recheck context.

I actually believe it's sense was in terms of percentage of biota species lost... but hacked together a smoke and mirrors spin phrase to include both numbers

... so you all could figure out how to adjudicate and write about such disputes. (Hey, I was just watching some tube! <g>) Experts, wake up! <g> // FrankB 21:36, 13 November 2008 (UTC)

Image

Something's wrong with the image, it is placed in the upper left corner withing a screen-wide frame now.. --CopperKettle 18:08, 18 December 2009 (UTC)

Copyright problem removed

One or more portions of this article duplicated other source(s). The material was copied from: (see below). Infringing material has been rewritten or removed and must not be restored, unless it is duly released under a compatible license. (For more information, please see "using copyrighted works from others" if you are not the copyright holder of this material, or "donating copyrighted materials" if you are.) For legal reasons, we cannot accept copyrighted text or images borrowed from other web sites or published material; such additions will be deleted. Contributors may use copyrighted publications as a source of information, but not as a source of sentences or phrases. Accordingly, the material may be rewritten, but only if it does not infringe on the copyright of the original or plagiarize from that source. Please see our guideline on non-free text for how to properly implement limited quotations of copyrighted text. Wikipedia takes copyright violations very seriously, and persistent violators will be blocked from editing. While we appreciate contributions, we must require all contributors to understand and comply with these policies. Thank you. J. Spencer (talk) 00:53, 21 October 2010 (UTC)

As discussed on Talk:Permian–Triassic extinction event, this page unwittingly received material copied from other sources during a merge in September 2008. The sources were http://math.ucr.edu/home/baez/extinction/, http://hannover.park.org/Canada/Museum/extinction/ordcause.html, and http://www.santafe.edu/media/workingpapers/99-12-079.pdf. Because this article was not as extensive as the PT article, I tried to rewrite the text to not lose the legitimate information. I have no prejudice if someone opts to remove the material altogether. J. Spencer (talk) 00:53, 21 October 2010 (UTC)

Impact / Fifth Mass Extinction

I changed section title to "Impact." While the list of mass extinctions at Extinction_event#Major_extinction_events positions the Ordovician–Silurian fifth in the list, that list is in reverse chronological order, with the most recent at the top of the list. If the list were in chronological order, this would have been first. I thought it best to change the title to one that doesn't reference an ordinal. I chose "Impact" for now. SlowJog (talk) 02:04, 31 January 2016 (UTC)

Critique of this Article

1. Is the title of the article appropriate and clear? Starting with the title, the Wikipedia page states that these events are categorized as Ordovician-Siluarian events but in the first sentence of the article, it states that it is known as the Ordovician extinction event. This was our first warning sign because we want to ensure that the reader knows what this extinction event is distinguished as but this article is not clear in its distinction which may result in misinformation being presented in the article. In order for this article to be valid and reliable, we will expand on this distinction for out final Wikipedia edit by finding scholarly sources that tell us whether or not the Ordovician-silurian extinction events are to be categorized together or just as Ordovician extinction events.

2. Is the purpose of this article made clear in the introduction? The first paragraph is clear as it gives an overall impact of the extinction and also ranks its relative importance to other events such as the Permian-Triassic extinction event. The second paragraph of the introduction starts to draw conclusions, as it states the immediate cause of extinction. Not only is this too soon to draw conclusions without documenting any supporting evidence, but this claim is also missing a citation. Once again, in order for us to strength the article we will need to first ensure that this claim is valid and true and then add a credible source and place this claim further down in the Wikipedia article where it can be further understood.

3. Do you find errors and facts of interpretation? Within the second opening paragraph, the Wikipedia article states “more than 60% of marine invertebrates died…” What I would want to know is what triggered this to happen? Also, this claim has 2 citations attached to it. When you click on the link that the author referenced, it brings you to NASA website which states that the cause of the extinction event could have been caused by gamma ray explosion or could have been an ice age. When you click on the second link that the author referenced for this claim, it references an article that was published in 2001. This is now out of date and needs to be updated which we will fix in our final wikipedia edit. Also, this reference states that 85% of marine invertebrates died during this event. Clearly, there is a misinterpretation of information and we will need to find a recent, credible source that can claim the approximate percentage of marine species affected from this event.

4. Has the author cited only relevant and current literature? The Wikipedia article states “a combination of lowering sea levels and glacially driven cooling are likely driving agents for the Ordovician mass extinction” This claim was not backed up with supporting evidence (i.e. studies conducted or research findings), rather it is referenced to a museum link that has rarely any factual information. Also, the Wikipedia article claims that this extinction event was the second largest of the 5 major extinction events but referenced a documentary made in 2007 (also video cannot be accessed- History Channel’s Mega Disasters Program-first citation in the article) This is a major claim being made and therefore needs to be supporting with a credible source that is up to date. Another example is that the Wikipedia article has a section that outlines a project that examines the potential chemical and physical causes of this extinction event but states that this project is currently being conducted. This project was done in 2004 and therefore this section needs to be updated which we will fix and examine the findings of this project in our final Wikipedia edit.

5. Should sections of the Wikipedia article be expanded or omitted? The Wikipedia article has a section on the End of the Event. This section only has 2 sentences and both sentences are without citations. This section definitely needs to be expanded and needs to draw on credible sources in order to conclude the end of this extinction event. Another section that needs to be expanded is the possible causes. The article did a good job by creating its own section of each possible cause (i.e. Gamma ray burst hypothesis, volcanism/weathering and metal poisoning) but only states a couple sentences for each potential cause. In order to strengthen these causes, we would need to draw on scholarly papers or research conducted on the potential causes. In general, the overall Wikipedia article needs to have updated sources which our group will ensure when completing our final Wikipedia edit.

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"Persistent global marine euxinia in the early Silurian"

Could you add information on this study to the article? Possibly to the sections "Impact" and "Possible causes". From the study:

This work extends the duration of anoxia to >3 Myrs–notably longer than well-studiedMesozoic ocean anoxic events

...

The correlation between the second pulse of the Late Ordovicianextinction4and the prolonged low-diversity interval3with the onsetand persistence of widespread global marine euxinia indicates amajor potential role for global ocean deoxygenation (and/or itsexternal drivers) in governing global marine biodiversity

...

Prolongedrecovery from the Late Ordovician mass extinction supports thenotion that ocean deoxygenation has repeatedly had prolongedimpacts on marine ecosystems at the timescales of geologicalstages/age

I added this to 2020 in science:

• A new study shows that the duration of anoxia approximately 444 million years ago was longer than 3 million years and affirms that the prolonged lack of oxygen in the oceans contributed to the Ordovician–Silurian mass extinction events at the time.

--Prototyperspective (talk) 17:01, 23 May 2020 (UTC)

References

Under “impact on life”

It’s claimed that species were “decimated”

That word has a specific meaning, and it’s not appropriate here. But I can’t think of a replacement term that fits here to indicate the species’ went extinct.

Please help! UsersLikeYou (talk) 09:01, 4 February 2022 (UTC)