K-Pg Extinction... Or Not?

[amargasaurus cazaui]

I haven't really read most of this thread but rather skimmed the last few posts. 

"I do sometimes play the devils advocate, and avoid the "safe" and simple path purposely to provoke discussion and present a viewpoint that I myself may not fully accept so I can determine if it is in the least defensible. This has the effect of bringing more information to the table and improving everyone's understanding."

So before or during your playing the devil's advocate, do announce that you yourself don't fully accept the idea or do you just let them think that is indeed your understanding and belief of the matter to see their reactions?   

I generally preface such a discussion with....a comment along the lines of...I am not entirely convinced or I remain torn...so that it is clear I do not have a solid opinion. Either that or i ask...what is the basis for...or the idea behind such and such idea, to get the ball rolling, as I do not know or understand for sure myself. If the implication is that I am a chain yanker or button pusher, no , i generally do not subscribe to those tactics.
     If your question is about this or a particular thread, I can state for you, I do not accept the single impact , single cause for dinosaur extinction at any level. I am indeed stating valid or often voiced questions about the issue , in my own belief. When I questioned the Spinosaurs identification , I do feel that discussion as well had merit and continues to. I believe I raised many valid concerns that were reaffirmed in the paper that you posted towards the end of that discussion. So I would suggest my two most conetentious discussions here were @ or regarding matters I stated my beliefs in honestly.
    Hope that addresses your question Gryph, feel free to ask if anything else presents itself. Please make note I did apologize and request this thread be removed from your own. I do again apologize for inpinging on your discussion of the Hadrosaurs in Spain.

[wings]

No Wings you completely misunderstood what I was stating...

Sorry, my fault I thought you were trying to compare the papers...

[amargasaurus cazaui]

No Wings you completely misunderstood what I was stating...

Sorry, my fault I thought you were trying to compare the papers...

Not at all, and thanks for all the papers Wings. I appreciate them !! I did thank you up there somewhere above in the thread for the papers.

[Simon]

I haven't really read most of this thread but rather skimmed the last few posts. 

"I do sometimes play the devils advocate, and avoid the "safe" and simple path purposely to provoke discussion and present a viewpoint that I myself may not fully accept so I can determine if it is in the least defensible. This has the effect of bringing more information to the table and improving everyone's understanding."

So before or during your playing the devil's advocate, do announce that you yourself don't fully accept the idea or do you just let them think that is indeed your understanding and belief of the matter to see their reactions?   

Thank you Gryphoceratops, for pointing that quote out.  It does explain quite a lot.  I must have missed it.  People who enjoy "playing devil's advocate" for the fun of it are not my cup of tea. 

[amargasaurus cazaui]

I did respond to Gryph's baiting attempt and made it quite clear what I meant, for him. I am sure you are capable of reading my response as well. Sadly some cannot follow the intended purpose of a discussion and feel the need to insult, stereotype and attack others. And for the record I am not a lawyer.
    I did state for you previously Simon, that intelligent people raise their argument, and weak minds raise their voices. Your continued personnal attacks are rather suggestive of this.
  Now did you have anything further to offer on topic or just the insults and sterotyping?
   

[Simon]

Hmmm ... and what of those who raise worn cliches?

[amargasaurus cazaui]

So moving foward with the purpose of the thread, and ignoring the personnal attacks that are against forum rules......as well as attempts at derailment............

[Gryphoceratops]

I haven't really read most of this thread but rather skimmed the last few posts. 

"I do sometimes play the devils advocate, and avoid the "safe" and simple path purposely to provoke discussion and present a viewpoint that I myself may not fully accept so I can determine if it is in the least defensible. This has the effect of bringing more information to the table and improving everyone's understanding."

So before or during your playing the devil's advocate, do announce that you yourself don't fully accept the idea or do you just let them think that is indeed your understanding and belief of the matter to see their reactions?   

I generally preface such a discussion with....a comment along the lines of...I am not entirely convinced or I remain torn...so that it is clear I do not have a solid opinion. Either that or i ask...what is the basis for...or the idea behind such and such idea, to get the ball rolling, as I do not know or understand for sure myself. If the implication is that I am a chain yanker or button pusher, no , i generally do not subscribe to those tactics.
     If your question is about this or a particular thread, I can state for you, I do not accept the single impact , single cause for dinosaur extinction at any level. I am indeed stating valid or often voiced questions about the issue , in my own belief. When I questioned the Spinosaurs identification , I do feel that discussion as well had merit and continues to. I believe I raised many valid concerns that were reaffirmed in the paper that you posted towards the end of that discussion. So I would suggest my two most conetentious discussions here were @ or regarding matters I stated my beliefs in honestly.
    Hope that addresses your question Gryph, feel free to ask if anything else presents itself. Please make note I did apologize and request this thread be removed from your own. I do again apologize for inpinging on your discussion of the Hadrosaurs in Spain.

Its totally cool thanks for clarifying for me.  I figured you weren't trolling I just wanted to bring it to your attention that maybe it could have come off that way. 

[Gwangi]

Just to clear things up though and maybe calm some of the hostilities I figured I should share where exactly it is I stand on this. For starters, I acknowledged a long time ago that the Deccan Traps may have played a part in dinosaur extinction, you don't need to sell me on that one. Also while I do believe that a asteroid bolide is what ultimately killed off the non-avian dinosaurs I never once claimed that 1) It didn't do so in conjunction with something else (though I think it could of done the job itself) and 2) that there was only one object. My biggest concern here is the claim that dinosaurs were on their way to extinction anyway or were already extinct if not close.

No not whatever, Dinosaur Hunters is entirely a different book, I own them both, PLease do not place me in direct miscontext of my comments.It is not very polite nor appreciated . I do not misquote you, so please stop doing it.   I referred to the book "Hunting Dinosaurs " as it does provide the quotes i used. Thanks !!!

My apologies for claiming the wrong book as your source. In my defense the two titles are similar and if you had provided the name of the author this wouldn't have happened. Still, "Hunting Dinosaurs" by Louie Psihoyos (am I right this time?) was published in 1995 so I don't think it qualifies as current. I got the title wrong but the date is right and so my point is still valid. I won't address your other accusations as I don't feel that I was doing that (just a mis-type really) and it is not relevant. 

Yes you are correct, not new nor cutting edge, just accurate and generally accepted by most.  Lets follow your points one by one to their logical conclusions here.

That is not what my research has shown me. I'm not in the habit of ignoring good scientific evidence to cater to my own personal view points. If overwhelming evidence is accumulated that favors another means of extinction beside the Yucatan impact (and recall that I did acknowledge there may have been other factors at play) I will acknowledge it. Maybe I need to read "Dinosaur Hunters" but I'm not sure a 15 year old book could change my mind 

You did look up the Deccan traps apparently and then took the comments which were in favor of your argument out of context of the rest of the commentary sadly. Being fair, perhaps you should have posted them in entirety and allowed others to view the opposing viewpoint rather than condensing to meet your own criteria. Similar thing with the Shiva crater, the article clearly states the presence of iridium, shocked quartz and a rebound peak , the very same signatures being used to prove the Yucatan impact was a strike as well. Both articles present both pros and cons to the debate you failed to offer up.

That is not what I intended to do. I posted what seemed relevant to the conversion. What I posted was specific to our discussion and the point I was trying to make. I'm not about to re-post the entire article when the key point was right there. That is what the consensus is and for the sake of the argument that is what I shared. I don't even know if the Shiva Crater is an impact crater nor do I particularly care but if those in the majority who study these things say it is not than I will yield to their wisdom. You want me to go out of my way to present both sides of the debate? You're not doing that yourself are you? I haven't seen you post a link to...well...anything at all, nor very many references. If you want people to know your side of the argument than it is up to you to find the sources and share them as I have done. I haven't seen you post anything in favor of the prevailing theory nor anything against your own so if I'm guilty of what you're claiming than so are you. I've made an honest attempt to keep this discussion civil but in reading your last post you're offering up as many insults to my character as you are evidence of your theory.

why are no dinosaur remains found within a nine foot (3 meter) gape of the iridium analomy that supposedly caused their extinction.
The answer is simple, the dinosaurs were mostly long gone prior to the impact and the fossil record proves it quite well and thoroughly.

As others have pointed out, that is not true. You can come up with any excuses you want to dismiss that evidence but until a geologist or paleontologist or other professional in the these fields publishes their findings I'm going to side with those that have done the work to show us the remains within that gap. What I find strange is that you in one breath will mention the dinosaur remains younger than the K-P event and in the next claim that the 3 meter gap proves dinosaurs were already extinct if not close. Perhaps you can clear up your position on this? Don't dinosaur remains above the K-P event somehow throw a monkey wrench into your theory?

I am sorry, this is directly from Greg Paul's book and DOES state precisely what I said in almost identical words, it is right there in very simple elegant terms. The final line states, PRECISELY what I have said from the start of this wandering little narative, again stop mis-quoting me.

So you, the guy that claims dinosaurs were extinct before the impact are saying the exact same thing as Greg Paul? The man who says if dinosaurs were in decline it was only modest? Why don't you re-read that passage. What I see is this... "It is possible that nether the impact alone nor the Indian eruptions on their own would have proven so lethal, but the one-two punch may have done the job." But you seem to be suggesting the dinosaurs were dieing off before the impact? He also said in his last sentence..."It has been suggested that the seismic activity initiated by the impact could have set off the Indian eruption." But you don't think that do you? Because if that was the case then how could volcanic activity kill off the dinosaurs before the impact if that activity was caused by the impact? No, you're placing your cards in the second half of that claim which states..."some suggest the lava flows had already so severely damaged the dinosaur fauna that the impact was able to deliver the coup de grace." Okay, I get that but I said right at the beginning of this debate that I acknowledged the Deccan Traps may have played a part in the extinction, I just don't think enough work has been done to say that with as much confidence as "the rock did it". What that entire quote was doing was suggesting the various methods through which the dinosaurs went extinct. It was presenting both sides of the issue (which you claimed I wasn't doing).

All of these people are stating the current consensus blah blah blah, but do you honestly believe they sat and did a person by person questionaire for each paleo-expert before writing that little line in the book? This is precisely what was done in the book "Hunting Dinosaurs" and why I chose to quote and cite the book. The author interviews most of the known names in the paleo field and offers their thoughts. Rather than copping out and using the cliche.....the general consensus is...I gave you specific names and quotes, not a cliche.

I presented the issue from two recent books (2009 and 2010) as well as two wikipedia entries. I included direct quotes and even links. If those sources claim that the general consensus is what it is I cannot really argue against it.

It is a much more endearing method of making a point, despite the efforts to undermine it giving the incorrect title, print date and so forth.

It was an honest mistake and I've admitted it. Instead of chastising me for it and accusing me of doing something I never intended to do why couldn't you just post the book's information yourself as I had done for my sources?

Here is your quote from the author you cited..make note NONE of it disagrees with my own interpretation of the evidence. I myself stated the ongoing catastrophes were reducing oxygen content and eliminating plant life, I already made this point myself. As for just below the layer, I think it might have been a good idea to elaborate just how far below. I somewhat doubt it is quite as close as being implied.

On the biological side, paleobotanists have documented a radical decimation of plant life at the end-Cretaceous boundary. Just below the iridium layer, fossil pollen and spores from many locations around the world indicate a diverse flora. Immediately above this layer, the pollen and spore evidence is heavily dominated by a single type-- ferns. Ferns are one of the first plants to recover after major environmental catastrophes, and this "fern spike", as it's been called, is cited as evidence of a sudden cataclysm--that is, death by silver bullet."

Actually it does because even if dinosaur remains were not found up to the iridium layer would not plant life have been so badly damaged that it would also not be within that gap? The author states that plant life was flourishing up until the impact which means the impact damaged the plant life. If the plant life was healthy up until that event then on what grounds can you state the extinction was gradual? That was why I posted that quote, I though you would see it as evidence for a devastating bolide collision which is what it was presented as in the book.

My information for crater sizes, impact sites and their dated occurrences was from information cited by Alvarez, and his sons, the authors of the impact theory. IF you use KNOWN impact Sites within the MESOZOIC period, the yucatan crater according to the study done by Alvarez places it in either fifth or sixth depending on Shiva and its status.

I don't know what to say because that is not what my source says. Do you have a source that you can share? Something that supports what you're saying? Surely you can understand why I would believe what I've read with my own eyes over what you're telling me someone said.

I already debunked the rather silly comment about exposed sites for the late creataceous earlier. If we dated dinosaur extinction to the actual event and not an unrelated impact, you would find that many of the sites already availible are closer to the tail of the dinosaurian reign than previously understood.

Sources?

Remember, there is a NINE foot gap between the last found dinosaur fossil and the analomy. The single known instances of this being in variance are a single triceratops horn, shown in the paper Wings posted....(which is somewhat debate worthy in itself...those horns are supposed to come in pairs right?) And the findings above the K-pg level in the San Juan basin. Outside that NOTHING. NOTHING within nine feet of the boundary event at all. That is a LOT of geologic time to contend with isnt it?

Nothing...until something else is found. The fact that something has been found seems to have no bearing on you despite a peer reviewed paper being published on it and NOT on what you're claiming.

And please make note, the author you are quoting stated...."The fossil record of dinosaurs is remarkably sparse for the final stage of the Mesozoic. Indeed, to date, only one place on Earth--- the Hell Creek Formation exposed most abundantly in eastern Montana and Dakotas--- has been investigated in detail."

He is NOT saying the sites do not exist, he is stating they have not been investigated in detail. Again , please do not misquote .

Yes, I know that. I didn't say otherwise did I? If I said other sites did not exist I meant to say were not known, a slip of the tongue really that I'm sure you can forgive.

As for Nanotyrannus and Dracorex, the last I read they were under discussion and nothing had been determined for certain wether juvenile or different species . Perhaps we should leave it that way until science can offer proof rather than playing armchair scientist?

What? Armchair scientist? I don't know if you're trying to insult me but is that not what we're both doing here?

I did state size matters...these dinosaurs that are being mentioned from the Cretaceous have far less oyxgen needs than a 100 foot long sauropod for instance.... or did you wish to revise that as well?

They were the largest of their kinds at a time when you say the oxygen was depleting. Do you not see the problem here? Don't bother mentioning sauropods, the titanosaurs were represented all the way until the end of the Cretaceous and they were some of the largest animals ever to walk the planet. Argentinosaurus lived 95 million years ago. How does your gradual extinction that starts early in the late Cretaceous explain that one? Alamosaurus lived 65 million years ago, probably alongside Tyrannosaurus. It was over 100' long and was one of the largest dinosaurs from North America. Maybe now it is you who wish to revise what you've said?

I will request again very nicely, please refrain from misquoting me. I did NOT say what you posted. I said that the prevailing view is NOT that dinosaurs died by impact ....I never once stated there are NO scientists that subscribe to the hypothesis. I do not much care for character asassinations, and distortions, especially when connected to gross exaggerations of the worst and most inflammatory kind. I prefer you quote me at least somewhat accurately in the future PLEASE.  I did however state the dinosaurs were already in decline, but this is what the fossil record also shows, thanks.

I am not deliberately trying to misquote you so relax. This conversation has gone on for many days and hours and I'm going to make mistakes. I don't appreciate you publicly calling my character into question over these trivial things. You stated and I quote..."This is the modern paleontologist take as a whole that I get from practically every book I see. They too, no longer subscribe to the single killer mechanism , as it just does NOT hold up to scrutiny."
So no, perhaps you did not say that "no paleontologist supports the silver bullet hypothesis" but regardless by point still stands. Scott Sampson is a modern paleontologist that does support the silver bullet hypothesis. He wrote it in his own book. He thinks it holds up but also acknowledged something else may have been at play which is what any good scientist would do.

(This argument actually makes itself. He is stating entire lines of dinosaurs disappeared and he does not find it entirely persuasive?What of the many types that are not mentioned here? There were ENTIRE families of dinosaurs gone prior to the end of the Cretaceous that left nothing behind for a desendant. The North American Sauropod for instance? )

I cannot speak for Scott Sampson as he is a real life paleontologist whereas I am in your own words an armchair scientist. But no, sauropods were around all the way through the Cretaceous including Alamosaurus in North America.

So he is stating, I see no evidence and accept that the impact did the job.But, it seems questionable to argue for a lethal cascade of agents? Questionable to whom? Since we know they exist and have found the sites? ummm...

I will use him as a reference but I cannot speak for him. You can contact him here.

Finally I took the time to google the two terms I have used, Deccan traps, and the Shiva crater, and am going to post the actual related information, so everyone can see the actual information , in its completeness to topic, rather than the altered versions previously posted.

First Shiva.......
The proposed Shiva crater and other possible impact craters along with the Chicxulub has led to the hypothesis that multiple impacts caused the massive extinction event at the end of the Cretaceous period. Chatterjee is confident that Shiva was one of many impacts, stating that "the K-T extinction was definitely a multiple-impact scenario." However, other scientists remain unconvinced that the extinction event was caused by multiple impacts, or that the Shiva feature is even in fact a crater. Other theories have argued that since the Chicxulub impact is believed by some researchers to have occurred earlier than the extinction of the dinosaurs, Shiva's impact was enough to cause the mass extinction by itself.

I didn't alter anything. What I posted was from the wikipedia entry on the Deccan Traps "Suggested link to Shiva Crater", what you posted is from the entry on the Shiva Crater "Shiva and mass extinction" which until just now I don't think I had even read. The two are different sources and I did not alter anything. Again, stop with the assaults on my character. I have done nothing as malicious as what you're suggesting.

Unlike typical known extraterrestrial impact structures, Shiva is teardrop shaped, roughly 600 km × 400 km (370 mi × 250 mi). It is also unusually rectangular. Chatterjee argues that the low angle of an impact combined with boundary fault lines and unstable rock led to this unusual formation.Other researchers have noted that rock faults and impacts could modify the crater shape.[6] The crater also is reported to contain larger than average amounts of alkaline melt rocks, shocked quartz, and iron oxide laced with iridium. These types of rocks and features suggest an impact origin. The age of the crater is inferred from the Deccan traps, which contain relatively high amounts of iridium (an element extremely rare in the Earth's crust but more common in asteroids).

What does this prove? That Chatterjee thinks the Shiva crater is an impact crater? Good for him, he also thinks Protoavis is a bird from the Triassic. I don't share his view points. My point still stands... "the current consensus in the Earth science community is that this feature is unlikely to be an actual impact crater" from the wikipedia article I posted on the Deccan Traps.

Because of its magnitude, scientists formerly speculated that the gases released during the formation of the Deccan Traps played a role in the Cretaceous–Paleogene extinction event (also known as the K-Pg extinction), which included the extinction of the non-avian dinosaurs. ]Sudden cooling due to sulfurous volcanic gases released by the formation of the traps and localised gas concentrations may have contributed significantly to mass extinctions.
However, the current consensus among the scientific community is that the extinction was triggered by the Chicxulub impact event in Central America (which would have produced a sunlight-blocking dust cloud that killed much of the plant life and reduced global temperature, called an impact winter).[5]

Did you miss the key parts there? "Scientists formerly speculated." and "The current consensus among the scientific community is that the extinction was triggered by the Chicxulub impact event."
You can post however much of the article you like, those points still stand regardless and in this discussion about what exactly the consensus is regarding the extinction are the parts of the entry that matter most. You want me to post the entire entry when the only point I'm trying to make is that the majority of scientists don't agree with your hypothesis? I'm not going to do that. Anyone reading this who wants to learn about the Deccan Traps and the Shiva Crater can do it themselves.

[amargasaurus cazaui]

In response to your post Gwangi, I will attempt to somewhat state my meanings and thoughts for you. I will keep this quite civilized and respectful to you, as I feel your last post was intended to me, and thanks for that. I felt quite good about your response as a whole and will address your points, and in one place I need to place some information and a formal apology.
  So, moving along. I did mean the Louis Psihoyos book, correct. You have the correct title book and date quite well cited this time and I appreciate the fact you did so. This was the book I was speaking of. I did not provide the name of the author as the book is on our book wall and is noted as a best read by many of the forum members despite its old and crippled age. I offered the book due to the specific quotes, of which i posted a miniscule amount ...from the most prominent minds in the field. I felt it was worth offering and yes I accept your criticism  of the books age.
  If you choose to read the book please do not do so for the extinction event alone, as it is only an ending to an otherwise voluminous narrative. The book of and in itself is stunning, and were I given the choice of the most updated and lavish book about dinosaurs to date, and that one, to have on an island as my only book I would choose it, over more updated works. Think what you will of that choice, it is a gorgeous and well done book, and I will not defend it further.
  My comments versus your postings about the Deccan traps as well as Shiva, were that you stated you had done some googling and this is what you found, at which point you only posted the things that were supportive of your viewpoint. Perhaps it was the wording used or phrasing, but to me at least it seemed you were implying the idea there was nothing further stated in those references which you chose not to post. As to posting an incomplete posting, or reference, the generally accepted practice is a series of dots posting the commentary to explain it was not posted in its completeness nor entirety, which I propose is rather misleading as your post did not contain such . When this method is used it demonstrates that while other data was availibe it was not copied or quoted and prods the researcher to then review the original source for a more definitive summary of the quote. I do not see those trailing points present in any of the work you posted, which suggested to me you were implying this was a complete reference. I do feel that is generally accepted literary practice in most public forums .So if you felt my reaction has impinged your character or unjustly tainted your reputation, this was the reason for my reaction and I hope you can somewhat understand the logic in my comment, and reason for my rather angry response.
     I disagree with the statement I have not posted any references. I posted the names of books, and online references as well. The need to crush and supress anything not written in the last 15 minutes not withstanding of course, as both books I named were published prior to the year 2000.
   You if I understood correctly in a previous thread mentioned you own the complete set of Jack Horner books. If I am wrong, please adjut my comment accordingly however I know you stated you owned some if not all of them at some point or fashion in your various postings. In the Book " Dinosaur Lives" -John R. Horner , a Harvest book, published by Harcourt and Brace company, Chapter 11 , title, "Extinction as a Way of Life" procedes to debunk much of the mythos about this impact theory, HOWEVER and perhaps more germaine to the next point he makes this direct Quote " Nowhere on earth has a dinosaur been found in association with the (K-T) K-P iridsum boundary , neither on the layer nor above it. The closest any remains have been found is about nine feet below it. That's where the T. Rex we found was located, for example:under nine feet of COMPRESSED sedimentary rock, representing many more times that width in actual sediment.............Since the impact event and its global consequences occcurred rapidly-ten years or less-it's very unlikely that evidence of the event will show up in the fossil record.Sound familiar? This looks like another instance of postulating the existence of something while at the same time asserting that it can't be pbserved.............     end quote, pages 211-212     Now, you can make what you want of the books age, and what you like of Jack Horner, but I am hesitant to call him a direct outright liar.  He states the same thing I have, in exact terms.
Wings provided us with a wonderful paper that showed a single dinosaur element that was located in association with the analomy, published I believe, this past year in fact.  What my issue there is, 200 years, people have discovered dinosaurs. All over the world, in every corner and place. Never once, till this one piece has something been found directly in association with the layer. You , yourself have said often to me, you take what the mass evidence most accurately reflects...that is not an exact quote , but you have told me something similar. The preponderance of evidence indicates no dinosaur remains associated with the layer. I will accept that.
   Remember we do not get to pick and choose the pieces that best reflect our viewpoints, it is what it IS. those are the facts Sir, correct?
   Regarding and pretaining to my comments centering about the dinosaurs in the San Juan basin, i asked Wings if he could locate the paper for said find and he did post it for all to review. In reading the paper, which i did completely and end to end, i learned that the remains described as unworked dinosaur fossils found above paleocene levels, were indeed found just as stated. HOWEVER, this was caused by two incomformities, that had uplifted layers of Cretaceous materials over Paleocene strata. The entire issus has roughly a one hundred year history of error, mistakes and controvery to sort through. So while the elements found were not reworked , the layers they were fossilized within had in a sense been, entirely. The conclusion of the authors was that no dinosaur remains from the location were dateable beyond the boundary event .
  There were a few finds in the paper that are somewhat arguable, and I did point the most valid one out upthread. However I do accept the conclusion of the paper that the remains were mistakenly dated and are pre boundary fossils.
   So , establishing that, my stand or take on this has been and remains. Dinosaurs were in decline the last ten million years of their existence. I had given causes, the marine regression, dropping of the sea level and various other factors all assigned as "change" and labeled a lazy answer. Fair enough...lazy then.
The known fossil record indicates the loss of massive quantities of dinosaur families, genera and types during the last marine transgression dating to around 75 million years ago. From that point forward the dinosaurs increased in overall population , but declined in species numbers. Many families and types of dinosaurs simply disappeared. At some point in that ten million year bubble we also lost Triceratops and Tyrannosaurus and many other species. The fossil record indicates, from study none of them were alive except the lone tricertaop that lost a horn at the boundary as shown in the so far published paper. Thats it. nothing more.
  I also shared with you the deccan traps scenario, and its known implications. What most people also do not quite yet comprehend, is you can get an iridium signature and shocked quartz from a volcanic event. BEFORE anyone jumps the gun, on that comment , make note, the level produced of iridium is miniscule compared to a bolide impact and is stated as such here for the record. So you have many scenarios occurring far before the dinosaurs vanished, never to be seen again. It is my contention they were in slow decline from a date of ten million years before the impact, until the impact itself. I had previously felt the finds in the San Juan reflected an isolated grouping that had survived post impact as that was the translation of the evidence until publication of previously noted paper. I do believe they were badly stressed and in decline far before any impacting agent ever splashed down. This has been corroborrated in many ways throughout the fossil record previously from egg shell thinning to the lack of specciation ocurring. Indeed there were many millions of dinosaur eggs from the late Cretaceous that never hatched, for some unknown reason. The one constant that they seem to share is much thinner shell than they had previously been associated with. I can relate some of that myself , as i own an set of four dinosaur eggs and many types of dinosaur egg shell. As I have stated before in a dozen ways, the bolide did likely kill off the last of the dinosaurs, all three or four of them. That is a figurative comment, but I do feel that most of them were gone or headed out far before the impacting agent.
  You seem very angry that I called you out for misquoting, and for partial referencing, however I did explain the issue with trailing punctuation above in the case of partial reference quoting.It might have very easily been an innocent mistake and I can accept that , fair enough.  As to mis-quoting my own comments and words, I do find it offensive. I am quite careful not to ever willingly do that to you , and Do again request you avoid it. I do not find such terribly scientific, fair or even well considered. If you can copy and paste other references, I can be given that same respect, or not quoted. If you find that harsh or unfair, I am sorry. I feel very strongly about this matter.
    And now I do owe a sincere apology Mr. Gwangi. My information I felt I was citing accurately about crater sizes cannot be established nor referenced fairly to state I was using anything accurate. I visited the site , the Earth impact and global database , and researched quite carefully known impact craters and their sizes.
      It clearly demonstrates Shiva, as an uncertain impact at 500 km, followed by the Yucatan impact (170 km)as second, and demonstrates quite clearly I was utterly wrong. I do apologize and admit my mistake here for you. I seldom do that or place myself in a position to do so. I hope that is acceptable to you.
Here is a listing for the craters made during the points in time  that would correspond with the dinosaur rule, and also the given crater sizes in kilometers I believe.
Largest to smallest with dating

chicxulub       170               64.98 million
kara                120 km         70.3
Manicouagan    100 km    215
Puchezh           80              167 million
Morokweng      70               145
Tookoonooka    55              112-133
Araguaunha      40               244
Saint martin       40               220
Mjolnir               40               142
steen river         24-40            91
carswell             39                115
Manson              35                74
Guarda               35               200
Boltysh                24              65.17
Lappajarvi           23              73.3
Rochefourt          21              201
Obolon                20             169
vista alegre        9.5                         65
eagle butte         10                   65.17
Vargeao dome         12                  70
tin bider                  6                    70
Ouarkziz                 3.5                     70
chukcha                   6                    70
maple creek             6                     75
zeleny gai                  3.5                   80
wetumpka                6.5                     81
dellen                    19                       89
avak                       12                        95
kentland                 13                        97
deep bay                13                        99
sierra madera           13                     100
mount toondina          4                    110
carswell               39                           115
oasis                         18                       120
bp structure                         2              1200
rotmistrovoka                2.7                   120
mien                       9                          121
gosses buff                  22                     142
tabun khara obo           1.3                    150
liverpool                       1.6                     150
vepriai                        8                                160
zapadnaya               3.2                            165
upheaval dome       10                              170
kgagodi                  3.5                               190
viewfield                2.5                                190
cloud creek              7                              190
riacho ring         4.5                                     200
red wing               9                                   200
wells creek          12                                     200


Suspected or likely crater sites
shiva crater       500               65
   
    As this is information I also cross confirmed from two other sources I accept and admit my mistake to you Mr Gwangi with my apologies, I stand corrected and well won Sir !!!!
Having done that and given what i felt was due, I do offer that when Alvarez proposed his theory there were a few other crater features that were considered as possible impacts which have since been relegated to the no can do list. In addition I also learned there is a tricky little thing that goes on with measuring either from the debris rim INSIDE the crater edge, or the outer edge of the Debris ring, and if this is alllowed, means the second choice actually is rather close if not surpassing the first. But devil his due, and no offense there to you Gwangi, your point is valid and proven, and admitted.
   I do wish to point out the extreme number of impacts of larger sizes the dinosaurs sailed through with no issue at all. Make note there are quite a few and some of them were rather large . In particular make note of the crater Kara, in Russia, at 70 million years, and almost the size of the crater at chicxulub. I would pose a question to those who do not feel the dinosaurs were stressed to the breaking point far before their extinction, what do you supposed that little impact did for their morning breakfast rituals?
I am uncertain how anyone can sit and argue definitely in favor of chicxulubas an extinction agent and in the same breathe say the impact at Kara had not placed their world in stress and perhaps partial extinction already, before the Deccan traps, before the marine regression and the loss of the North American inland sea.
In any event, my main point is dinosaurs survived a load of bolide impacts before  chicxulub and many were quite large enough to cause the same effect per se.
   I stated the oxygen levels were dropping, and with them fauna size. It was mentioned the titanosaurs survived, however it was not stated where they survived. The sauropods as a general lifeform practically vanished from most nothern latitudes prior to or during the low Cretaceous. You then find a centralized grouping of sauropods in the lower latitudes closer to the equatorial zone .It has been suggested, and offered a few times at least that closer to the tropical zone of the planet, the oxygen content would have been higher as well as the biomass to produce such. I myself am unsure and this is an area i am studying myself presently so by all means feel free to jump in and make any valid considerations that might help. I do think a strong case is made for an almost extinction of sauropods in northern areas, and only towards the southern areas of the landmass were they able to survive for whatever reason....I do know there are studies that suggest the oxygen level is higher at the equator than elsewhere in the world, but I admit I am not that far along studying the matter myself. Fair enough?
It is late and I am tired. I have not responsed to the rest of your points as they seem to center around who takes what from each quoted reference. I do feel that I seem to accept some lines of a valid point and you take the others. I think that is the nature of the debate generally.  I do not make issue with anything else here Gwangi. I have aplogized to you and posted the correct figures for my glaring error, which I think is more than most would do. Trust me when I say I am very proud, and seldom find myself in that place . Rather than defend my glaring mistake I did admit it and post it for all to see. I do ask in the future and please understand I am saying please...do not misquote my comments. It is a pet peeve. I will endeavor to respond to you in a more polite and proper fashion as well, fair enough?
  I felt it important after a nights sleep to revisit this post for comment I forgot to add in closing yesterday evening. I am NOT directing this last  towards you Gwangi, so please stand aside from this last remark .  When I was shown wrong in a point I had tried to make I did admit it. I apologized and accepted it. I think that is what someone that is mature and open to learn does. I did NOT attempt to then smear the issue by stating...well that part does not matter anyways because blah blah and summon other as equally difficult points to defend and try and paint over my mistake, as had been done upthread.I felt that should be stated, thanks

[wings]

Just saw the abstract (too bad I couldn't find the actual paper) of this paper today while web browsing, it's an article about dinosaur diversity during the mesozoic, please find link on http://publications.esc.cam.ac.uk:8080/2340/ and have a read through the abstract.

However, having said that, I've found a few more papers on this topic. While Lloyd et al. 2008 (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2603200/pdf/rspb20080715.pdf) also concluded that there is no gradual decline of the non-avian dinosaurs, and some actually thinks that the sauropod group diversity was increasing at the end of Cretaceous (Benson & Mannion, 2012 http://rsbl.royalsocietypublishing.org/content/8/1/127.full.pdf), on the other hand, studies of Lloyd (2012 http://rsbl.royalsocietypublishing.org/content/early/2011/04/14/rsbl.2011.0210.full.pdf), Barrett et al. (2009 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2686664/pdf/rspb20090352.pdf) and Brusatte et al. (2012 http://www.ncbi.nlm.nih.gov/pubmed/22549833) indicate at least some dinosaur groups have been declining for some time prior to the extinction. So it seems like there is still no consensus on this matter yet.

[DinoLord]

The ability of Frogs, Crocs and turtles to survive underground is well documented - there was a frog dug up in a mine that was estimated to be 2000 years old that awoke and lived another year or so - no joke - google it.

Do you have any link to this? Can't really find anything online about it, but it seems interesting.

[Gryphoceratops]

2,000 year old frog?  It was still alive?  Yes please show documentation.

[Simon]

*HARUMPH!*

I was repeating a story I read as a kid.  When I did a little research just now, it appears that there were a bunch of reports of frogs being found in British mines in the mid-1800s.  They all allegedly awoke when the rock or mud they were encased in was split open.

So ... it looks like an elaborate series of old hoaxes (he said, mortified  ).

However, in my Googling I did find some pretty amazing facts about hibernating frogs.  Like one species that freezes solid during the harsh Northern winter, the Wood Frog.  Here is the link:

http://en.wikipedia.org/wiki/Wood_Frog

[Gryphoceratops]

*HARUMPH!*

I was repeating a story I read as a kid.  When I did a little research just now, it appears that there were a bunch of reports of frogs being found in British mines in the mid-1800s.  They all allegedly awoke when the rock or mud they were encased in was split open.

So ... it looks like an elaborate series of old hoaxes (he said, mortified  ).

However, in my Googling I did find some pretty amazing facts about hibernating frogs.  Like one species that freezes solid during the harsh Northern winter, the Wood Frog.  Here is the link:

http://en.wikipedia.org/wiki/Wood_Frog

Yeah I was gonna say I think the oldest frog lives to be in its thirties or something.  2,000 is a little steep! 

[amargasaurus cazaui]

Gosh have to wonder where these people get their ideas huh? Why this almost sounds..well ..heretical !!

http://www.huffingtonpost.com/2012/12/08/volcanoes-killed-dinosaurs-india_n_2258395.html?icid=maing-grid10%7Chtmlws-main-nb%7Cdl4%7Csec3_lnk1%26pLid%3D243087

[amargasaurus cazaui]

http://www.huffingtonpost.com/2012/12/08/volcanoes-killed-dinosaurs-india_n_2258395.html?utm_hp_ref=dinosaurs

[HD-man]

Amarge, you keep mentioning the latest science and evidence and current thinking but despite all the claims you only reference the book "Dinosaur Hunters" which is 15 years old, perhaps an updated version of the book has been made? Searches on Amazon yield nothing. Actually if anyone knows of a recent book on dinosaur extinction I would appreciate knowing about it, it is a subject I would like to brush up on.

Archibald's Extinction and Radiation: How the Fall of Dinosaurs Led to the Rise of Mammals ( http://www.amazon.com/Extinction-Radiation-Fall-Dinosaurs-Mammals/dp/0801898056/ref=la_B004TLUKH4_1_1?s=books&ie=UTF8&qid=1381679910&sr=1-1 ) is the most recent book I know of about the K/T extinction in particular. I think it's for the specialist, though. For something less technical, I recommend Archibald's "Dinosaur Extinction: Changing Views" ( http://www.bio.sdsu.edu/faculty/archibald/Archibald02DinoExtiViews.pdf ). It's from Scotchmoor et al.'s Dinosaurs: The Science Behind the Stories ( http://www.amazon.com/Dinosaurs-Science-Judith-G-Scotchmoor/dp/0922152624/ref=sr_1_1?s=books&ie=UTF8&qid=1381680792&sr=1-1 ).

P.S. For more info about Scotchmoor et al.'s Dinosaurs: The Science Behind the Stories: http://vertpaleo.org/Publications/Dinosaurs--the-Science-Behind-the-Stories.aspx

[Gwangi]

http://www.huffingtonpost.com/2012/12/08/volcanoes-killed-dinosaurs-india_n_2258395.html?utm_hp_ref=dinosaurs

Just gotta try to keep this thread alive after an entire year has passed? Honestly, whatever science turns up is good enough for me. If it is was not a meteorite after all then so be it...science marches on. Still, I'm not convinced.

[amargasaurus cazaui]

Unsure what the little dig in your post was meant to suggest....science is the process of constantly re-examining the evidence and when new information presents itself, bringing that to the discussion and formulating more accurate and well considered conclusions. This new study does provide some new and conflicting evidence to the impact scenario so I posted it.
  The study does offer some answers to some of the questions I raised about the marine regression , and the Deccan traps. It deals with much of the evidence I originally questioned for the impact, in a very logical manner.