Dinosaur Extinction

Well, there is a movie where you might learn something about impact, dig though the nationalgeographic films in the nearest DVD store, i bet you will find something.

 

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This is what I wrote and part of it is paraphrased from Purves' biology book:

1) 65 million years ago: 76% of species disappeared from the meteor impact off the coast of the Yucatan Peninsula in Mexico.
2) about 206 million years ago: a large meteor crashed into Quebec, Canada wiping out 65% of the species on earth at the end of Triassic period.
3) about 250 million years ago: a large meteor crashed into Northwestern Australia, WITH a massive outflow of lava AND the extinction of about 96% of the world's animal species.
4) 355 million years ago: two large meteorites hit Nevada and Western Australia POSSIBLY causing the extinction of 75% of the world's species. Scientists are still uncertain about the exact cause.

I do believe beyond any reasonable doubt from everything that I have read, heard, and been taught that K-T was caused by a meteorite. To much evidence to say it wasn't.

I substantiated my 2nd statement by stating that we have found iridium deposits during the time of the extinction, and there was rapid recolonization of fern which usually occurs only over barren wasteland, as caused by a meteor impact.

I did not say in my 3rd statement that the extinctions was caused SOLELY by a meteor, but that during this extinction another meteor did strike, along with evidence of massive outpourings of lava.

In my 4th statement, I said "possibly" causing - we do not know.

I believe that we have sufficient proof that at least two out of the five mass extinctions were caused almost exclusively by meteors, and that is what I stated. I did not come right out and say that 4 out of the 5 extinctions were entirely caused by meteors, but meteors did strike Earth during the 3rd one as well.

 

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And yes, anytime such a large meteor like that strikes Earth, it's going to "have a role" in extinctions. This is not "wrong." Even the meteor that hit Siberia in 1908 might have wiped out certain subpecies that are only native to that region, like certain subspecies of wolves or insects or plants.

 

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Valich, it appears to me you are so wrapped up in posting that you don't properly read the responses. Why do I say that - well amongst many other examples you are still referring to the impact in Siberia as a meteor, when I have already explained to you that it was almost certainly a comet.
Read this very carefully: I am not discussing what you think. You are entitled to your opinion, right or wrong. I am stating that the current consensus on the matter of mass extinctions is 'undecided'. Yes, there is evidence for bolide impact being involved in several of the mass extinctions. Only in the case of the KT event is this widely accepted, and even here there are a number of authorities who vigorously dispute it.
The evidence you have cited re-iridium (which can also be derived from volcanic eruptions) and fern colonization (which only requires a wasteland, which might well be derived through climatic change) are suggestive, but nowhere near conclusive.

 

No, the current "scientific" concensus on the matter is that KT extinction was caused solely by the result of the meteor: the layman's consensus is what differs. The books refer to the Siberian meteor as a meteor and I am not in the position to change the wording which would be a misinterpretation of what is written: they know more than I do about it. By stating the facts as I read them, I am avoiding posting any "opinion" at all, but you are. You are of the "opinion" that the Siberian meteor was a comet. That's your "opinion." I'm not saying that it wasn't, but I'll stick to what I read so as to avoid any misinterpretations and confusions, and to avoid expressing my opinion, rather than change my wording just for the sake of conforming to your opinion.

I know what Iridium is but I've never heard of the element or the word "re-iridium." Are you now creating your own language too?

 

Valich - just exactly how are you determining that this is the current scientific consensus? There remain a significant number of geolgists who a) do not believe that the extinction was a rapid event, and/or b) believe it was brought about by the massive eruption of the Deccan traps.
Geol Rundsch. 1996 Jun;85(2):191-210. Related Articles, Links


Multiple factors in the origin of the Cretaceous/Tertiary boundary: the role of environmental stress and Deccan Trap volcanism.

Glasby GP, Kunzendorf H.

Department of Earth Sciences, University of Sheffield, England.

A review of the scenarios for the Cretaceous/ Tertiary (K/T) boundary event is presented and a coherent hypothesis for the origin of the event is formulated. Many scientists now accept that the event was caused by a meteorite impact at Chicxulub in the Yucatan Peninsula, Mexico. Our investigations show that the oceans were already stressed by the end of the Late Cretaceous as a result of the long-term drop in atmospheric CO2, the long-term drop in sea level and the frequent development of oceanic anoxia. Extinction of some marine species was already occurring several million years prior to the K/T boundary. The biota were therefore susceptible to change. The eruption of the Deccan Traps, which began at 66.2 Ma, coincides with the K/T boundary events. It erupted huge quantities of H2SO4, HCl, CO2, dust and soot into the atmosphere and led to a significant drop in sea level and marked changes in ocean temperature. The result was a major reduction in oceanic productivity and the creation of an almost dead ocean. The volcanism lasted almost 0.7 m.y. Extinction of biological species was graded and appeared to correlate with the main eruptive events. Elements such as Ir were incorporated into the volcanic ash, possibly on soot particles. This horizon accumulated under anoxic conditions in local depressions and became the marker horizon for the K/T boundary. An oxidation front penetrated this horizon leading to the redistribution of elements. The eruption of the Deccan Traps is the largest volcanic event since the Permian-Triassic event at 245 Ma. It followed a period of 36 m.y. in which the earth's magnetic field failed to reverse. Instabilities in the mantle are thought to be responsible for this eruption and therefore for the K/T event. We therefore believe that the K/T event can be explained in terms of the effects of the Deccan volcanism on an already stressed biosphere. The meteorite impact at Chicxulub took place after the onset of Deccan volcanism. It probably played a regional, rather than global, role in the K/T extinction

I am unable to be part of a layman's consensus on this matter.
It is not my opinion that the Siberian bolide was a comet, it is the considered opinion of those who have researched the matter.
Brown JC, Hughes DW, Tunguska's comet and non-thermal (14)C production in the atmosphere.
Nature. 1977 Aug 11;268(5620):512-4.


Either english is not your native language, in which case trying to correct it in another's writing is risky, or you are being deliberately obtuse.

re-iridium - with respect to iridium - the evidence you have cited with respect to iridium - the evidence you have cited re-iridium.

Pause and think for a moment. Is it just possible that I have been studying these matters for slightly longer than you? Is it possible that I might have a degree in this area? Is it remotely possible that I have continued studying these and related topics after graduating? Is there the merest glimmer of a chance that on some of these issues I might just know a tiny bit more than you? Is there any ephemeral likelihood that I have been trying to share that knowledge with you in these posts, by correcting errors I have seen you make? And if any of these highly implausible, doubtless fictional speculations were actually true, do you think - faced with your reactions to such gentle corrections - that I might just be about to lapse into one of those mood swings you seem think I am prone to?

 

According to the consensus amongst the "scientific" community, the 1908 Siberian bolide was a meteor, not a comet, but the discussion about just what exactly it was is still being debated. Examine the much higher percentage of scientists that refer to it as a meteor in the journal list kept by the International Meteor Association www.imo.net/bib/mtitun0.html

Comets normally consist of consists chiefly of ammonia, methane, carbon dioxide, and water, and wouldn't have produced such a large explosion at that altitude: but there were iron and nickel fragments found.

"Sekanina admits the question is still open. "I tell you quite frankly that
there is a lot of handwaving in this. There isn't any quantitative theory
available that would give you so many tons of material at such and such a
height above the Earth's surface." Nevertheless, he is quick to add, the old
comet-tail hypothesis is untenable. Even the dustiest tail would not
contribute enough material to cause the glows seen.

While the finest particles drifted westward from Tunguska, some of the
vaporized remains of the meteorite condensed into particles a fraction of a
millimeter in size. They rained onto the devastated terrain, and microscopic
spheres of metal and glass were painstakingly sifted from the soil by
expeditions during the late 1950s and early 1960s. Lest there be any doubt of
their extraterrestial nature, Soviet researchers soon found abnormal
concentrations of nickel in the samples, indicative of meteoritic origin."

www.totse.com/en/technology/space_astronomy_nasa/tungusk2.html

"In 1993 researchers Chris Chyba, Paul Thomas, and Kevin Zahnle studied the Siberian explosion and concluded it was of this type -- a stone meteorite that exploded in the atmosphere. This conclusion was supported when Russian researchers found tiny stoney particles embedded in the trees at the collision site, matching the composition of common stone meteorites. The original asteroid fragment may have been roughly 50-60 meters (50-60 yards) in diameter." www.psi.edu/projects/siberia/siberia.html

You really are a very argumentatively-prone opinionated person.

 

As stated above in your quotation from one source, they offer another hypothesis, and I am not in disagreement with this. But what I said is basically what they are also saying, i.e., "the general consensus among the "scientific" community is that the KT extinction was caused by the Yucatan meteor." And your citation above reconfirms that. Many natural phenomena, and these mass extinctions, have other "contributing" causes, and I am not in disagreement with that. But that is not what I said.

You constantly keep subjectively misinterpreting my objectively cited quotations and comments.

 

Then I'll leave you to stew in your own ignorance then. Gooday to you.

 

You guys condemn me for posting quotes, wasting your's and everybody else's time with two days of senseless mudswinging, and now you call me ignorant. Had you posted or paraphrased or given some indication of the other reasons why the meteor should not be considered as the "consensus" explanation among scientists, as it is right now, then we would have been having a productive and progressive discussion.

The article you posted, "Multiple factors in the origin of the Cretaceous/Tertiary boundary: the role of environmental stress and Deccan Trap volcanism." is very interesting and now gives me something more to think about - and I will.

Thanks for posting it!

 

Valich,

I wasn't exactly getting on your case for using quotes. It was more the manner in which you were using them. As you see, we all use them from time to time. It just seemed that your use of them was not only excessive, but also... tangential.

The main thing that I was getting on you about was a certain sense of evasiveness that I'd gathered from reading you. Consider that this whole thing was about trying to get you to realize that your statement on meteoric impact being the cause of the extinction in most of those events.

Now. Appeal to authority is a logical fallacy, but Ophiolite is in his element here. I'm not saying that he's always right or that he's some kind of font of truth in this field, but he is right this time (that is, I agree with him.) You seem to fail to realize the tentative nature of the bolide theory for extinction events. Only the KT event has any kind of surety in this. And even it is disputed (quite strongly in some circles.)

There is no 'truth' in this. Not even close. You seem to blithely accept bolide impact as the cause when it is in only conjecture and can only ever be conjecture. Even with the conjectural basis of the theory in hand, one must realize that only the KT event has any kind of solid evidence. The evidence for the rest is lacking in the extreme.

One problem with the earlier events is that, while certain craters have been hypothesized to have been made at roughly the same time as the extinction event, the correlation is weak for several reasons.

One reason is that the time of the various impacts are only roughly synchronous with the extinction events. Some happen before. Some happen after. There can be no certainty as to dates. They only roughly match.

Another reason is that the extinction events themselves are not so coherent as they might appear in a text book. The period of time that the various events spanned are debated strongly. Some seem reasonably quick but most seem to have stretched over a vast span of time. And several are even broken down into sub-extinction events.

A direct cause for each event is not known.
There is no 'general consensus'. The only one that comes close to a 'general consensus' is the KT event and even that is still debated.

Do you see what I'm saying? I feel I'm repeating myself here.

The key point is that the tentative nature of these theories must be stressed when they are spoken of. If they are not stressed then we have a case just as we are dealing with here. You have taken them to be far more certain than they are.

Now. You can go ahead and think that we're just being opinionated assholes on this, but you'll find the same thing everywhere you go. These are hotly disputed topics. In all circles. There is no consensus.


As to Tunguska. Well. I've seen no scientific literature of this specifically. Only popular treatment of it. But, from what I know the comet theory is the leading theory over the meteor theory. The chief reason being absence of a crater and meteor remnant. I've seen documentaries showing how they drained the swamp and went through the mud with a fine tooth comb looking for evidence and found little to support a meteor theory.

Now. Evidence can often be interpreted in multiple ways. And in this light you'll likely be able to find papers saying all sorts of things. In fact, this is exactly the sort of thing that comes from picking your sources carefully. If you are discriminating enough in your resource search, then you can present an argument that seems strong but is biased.

I have no direct knowledge on the subject and am unable to say whether it was a meteor or comet. However, from everything I've read and heard, I thought the comet theory was in the lead. And the reasons given made sense to me.

However, it must be borne in mind that it took half a century before it was even understood what happened at Tunguska. It wasn't until after the atomic bomb and the understanding of the effects of mid-air detonation that the enigmatic butterfly shape of the blast zone was understood.

There is always more to be learned in any given field.
And the fact that even such a recent event as Tunguska is still debated shows how much more debate must be going on in topics that stretch back the eons to the extinction events.

Science is not about truth. It's about problem-solving. Theories come. Theories go. The crucial thing to keep in mind is that scientific theories solve problems. (And, in themselves, present us with more problems to solve....)

Have you read Popper, by any chance?

 

Does anyone know about how big dinosaur penises are?

 

You're right. You're repeating yourself a bit.

I read some of Popper many many years ago but doubt I could recall any specifics.

The problem with the meteor debate on this thread is that you guys never gave an opposing view to debate to begin with! Except if you want me to consider Jaxom's long proclamation on the first page that contained an endless list of numerous dubitable scenarios? As soon as I started quoting a source saying the meteor caused the extinctions, you two grabbed switchblades and axes and started hacking me to death without ever telling me why! You never presented any opposing views to counter it! All I kept hearing was: "Give me the proof," "Please cite a single source," "What does that have to do with the price of bread?," "You're disingenuous," "You're an ignorant asshole," etc. First you guys get on my case about quoting sources, then I'm being asked for "a single source," now, finally, both of you are quoting sources to provide and substantiate facts to form a basis for a forum to discuss and debate.

Only after Ophiolite quoted the article above with a differing explanation did I have any idea what you guys were talking about.

 

You might get an approximate idea by comparing your's to a horse?

 

So quite small then.

 

Ha ha. I said a horse, not a pony!

 

This was at the end of the Triassic Period (early dinosaurs); however, dinosaurs quickly diversified even more during the Jurassic, and did not become extinct until the end of the Cretaceous or early Tertiary.

 

The massive thick layer of ash that is found in a stratified geographic layer throught the entire world corresponds precisely to that particular time period. The thickness and pervasiveness of this thick ash layer is living proof that during that exact period of time when dinosaurs became extinct, the entire earth's atmosphere was blanketed from the sun' rays for months, causing a dramatic decrease in temperature and destroying massive plant life that relies on the sun for photosynthesis. This plant life is the source of food and energy for all herbivores. This is most probably not the only cause of the mass extinction, but beyond a doubt, it had to be a major contributary cause. Thus is the consensus of the scientific/biological/evolutionist community.

 

Refer to the above postings. There were two, and posibly even three, mass extinctions involving dinosaurs, so we're not talking about a spontaneous event or a precise mount in history, i.e., an exact moment in history when ALL dinosaurs became extinct.

 

Sounds reasonable to me. Can I ask you what your source was that explains the stages? You're bound to get some opposition feedback, and I hope you stand your ground in answering any, but I'd like to read where you got this from. Thanks.