End of the "Lone Asteroid" Theory?

hussar writes "This BBC article reports on research that suggests the dinosaurs were not killed off by the Chicxulub asteroid's immediate effects but ultimately fell to evironmental stresses caused by a second asteroid that hit about 300,000 years later. The second impact may have been in the Indian Ocean."

Comments

Keller's Conclusions Strongly Refuted

[Punchinello]

Gerta Keller's conclusions are being strongly refuted by Jan Smits, one of the researchers that got funding for the core samples used in the study. He said in this NPR clip that he is really upset that Keller's research passed peer review without catching the obvious mistakes.

Re:Keller's Conclusions Strongly Refuted

[anantherous coward]

The significance of publication in a peer reviewed journal should not be overestimated as the press seems to do so often.

I remember from about 10 years ago that an article on letter on equidistant letter spacing in the Bible (I.e. Bible Codes) was published in "Statistical Science" -- a recongized peer reviewed journal. I also recall that those who approved the article did not agree with it. The reason for publishing it was because they could not refute the mathematics in it. It was a sufficiently interesting finding and methods to merit publication. The work was later effectively refuted, as most knew it would be -- the hypothesis was nutty.

The point here is that Keller's work may have merited publication even if we regard it likely that he is wrong. I don't know one way or the other myself. I guess I am reacting a little bit to the idea that Smits is upset that Keller was even published. It smells of censorship. But maybe he is right.

Less Violent End?

[ackthpt]

I caught this story on the BBC World News, Monday morning, along with the theories of the extinction of Aristide's presidency.

Back when I took astronomy the standard theories were carted out before us for our own inspection and consideration.

I've not been convinced climatic change did them in as most theories seemed predisposed to a direct impact on the dinosaurse themselves. i.e. the earth passed through the tail of a comet and the atmosphere cooled and they died off. I'm more inclined to some environmental change which impacted the low end of the food chain, plants in particular, but it still doesn't explain why aquatic dinos went, too.

I'm looking for a theory that says the earth was a warmer place with most of that fossil fuel carbon still on the surface (where we're presently putting it again, one study observed plants are taking up the extra carbondioxide in the air, what's the long term impact of that?) As the carbon became buried (ever think about how much green stuff it took to make pertroleum deposits or coal seams?) the food changed and those at the bottom of the chain adapted or perished. Perhaps dinosaurs were really hugely inefficient creatures and require large amounts of energy, whereas mammals and birds are quite efficient.

Anyway, that's my two cents. Anyone who can point me toward some theories which follow that logic, as opposed to the big-exciting-asteroid-or-comet theories much appreciated. I think in extinction theories, the ones involving some violent cataclysm get too much press, probably due to the sensational value.

Re:Less Violent End?

[Anonymous Coward]

Actually, "fossil fuels" did not come from plants or dinosaurs.... Nitrifying bacteria consumes rock and the byproduct is tar, oil etc. The bacteria uses the carbon in the soil/atmosphere to facilitate the reaction.
I can't believe they still teach that oil came from Dinos in our schools...

Re:Less Violent End?

[ackthpt]

Actually, "fossil fuels" did not come from plants or dinosaurs.... Nitrifying bacteria consumes rock and the byproduct is tar, oil etc. The bacteria uses the carbon in the soil/atmosphere to facilitate the reaction. I can't believe they still teach that oil came from Dinos in our schools...

Not dinos, but plant matter, the most prominent example of this process ongoing today are peat-bogs. North of where I lived in Michigan were muskegs, effectively small lakes which eventually filled in with mosses. Assmume this process continues for some time, building up a dense layer of dead moss at the bottom, as new moss continues to grow on top, then a glacier (like the ice age) deposits a cap of sand/gravel/clay on top of it and over successive millenia that layer continues to be overlayed by sediments, etc. Examination of coal often reveals the plant matter it was made from. Consider a 1 meter thick coal seam and the kind of pressure upon it, what was the original dept of this accumulation of plant matter?

Re:Less Violent End?

[Illserve]

Mammals aren't particularly efficient. In fact it's damned expensive to keep our homeostatic mechanisms in place.

It's worth it of course, active temperature regulation lets us stay awake during the night and has let our neurons become more delicately tuned (and therefore we're smarter than cold blooded critters).

But it's a mistake to assume that we're more efficient from an energy perspective. You spend a huge chunk of you caloric input keeping your extremeties warm, and your brain cool. It's like your own personal environment suit built into your body. Lots of advantages, but very expensive to operate.

Now maybe their extreme size made dinosaurs less efficient, but I tend to think it's that being cold blooded they are less resistant to climactic change. A period of dynamic weather, with patterns changing faster than migration could handle, would tend to be very bad for anything cold blooded.

Also consider, before warm blooded things came about, nighttime must have been very safe and quiet in large areas of the world. All of a sudden warm blooded critters arrive on the scene and find this amazing niche, namely eating sleeping dinosaurs at night :)

Re:Less Violent End?

[cens0r]

I thought there was a lot of debate about whether or not dinosaurs were cold blooded? Most recent studies I've seen show that many of the dinosaurs had feathers, and most likely were closer to ostriches than reptiles. This means they were just as likely to be warm blooded as cold blooded.

Re:Less Violent End?

[ackthpt]

I thought there was a lot of debate about whether or not dinosaurs were cold blooded? Most recent studies I've seen show that many of the dinosaurs had feathers, and most likely were closer to ostriches than reptiles. This means they were just as likely to be warm blooded as cold blooded.

Based upon observation of like present day creatues I'm inclined to these argements:

Dinos were cold blooded and lived in a hothouse climate.

Dinos were warm blooded and required high caloric intake.

That some were found to nest suggests more than simply protecting the eggs, they were keeping them warm. These were not buried nests, but on the surface, exposed. How would a cold blooded animal keep an egg warm?

Ah, memories..

[grub]

This brings back memories.

I remember having a beer at my buddy Vijay's place in India (he was an outsourced Fern & Brush Maintainer for the Pangea Shrubbery Co. in the Late Cretaceous) Anyhow, I was working on my tan as the sun's light had only recently begun shining through to the Earth's surface thanks to the Chicxulub hit years before.

Vijay had just finished telling me a great joke about his dog having no nose when we saw a massive asteroid coming down. Vijay just muttered "Oh bugger, not again." The sad part of the whole thing was that I had tanned lying on my stomach that morning. My face and frontside were ghostly white for ages.

I was a laughing stock for most of the Tertiary period..

hmmm

[potaz]

"from the this-changes-everything-and-nobody-cares dept."

I'm thinking maybe the dinosaurs involved cared just a little...

Obviously...

[JackHart]

Obviously it was the second asteroid on the grassy knoll!

This was on NPR yesterday and they said . . .

[JustAnotherReader]

This was on NPR yesterday and they said that there were some pretty serious flaws in the theory. One scientist went so far as to say "I don't know how this got through peer review. It should never have been published"

It may just be scientist ruffling their feathers at a new theory, or there may very well be serious problems with the evidence. It's certainly not a final answer yet.

Re:Religious fanatics, unite! The end is very nigh

[Anonymous Coward]

Dont be a fool. Religious fanatics dont believe in dinosaurs.. first of all, to them earth is only 10,000 years old, second, dinos arent mentioned in the bible.. its all a conspiracy by satan.. the bones we find are just mixes of elephants and alligator bones.

Indian Ocean...

[cOdEgUru]

Indian Ocean eh?

I presume these Indians had something to do with the massive extinction of US Tech jobs as well?

First the poor dinosaurs, and now poor US geeks.. ............

And yes, I am Indian, the real deal, the kind Columbus went searching for..thankfully never found.

Re:Keller's Conclusions [weakly] Refuted

[H4x0r Jim Duggan]

Kellers findings are pretty well founded. The idea is that the Chicxulub impact occurred during this warming period with severe environmental effects but the extinction of the dinosaurs - When the second impact finally occurred, it hit an already stressed community which was the straw that broke the camel's back. Almost anything could have wiped them out at that point. Jan Smits doesn't refute this very clearly - but I would accept that the theory is less sensational that it appears from the headline.

Yet another theory?

[MissMarvel]

Ah.... The great K-T extinction debate continues....

For those interested in reading about the supporting data and possible causes of the K-T extinction,
here's a good discussion" by Dewey M. McLean of the Department of Geological Sciences,
Virginia Polytechnic Institute and State University.

Re:Yet another theory?

[cluckshot]

First my compliments to the author of the previous post. Obviously a person interested in a learned discussion. Secondly I would like to throw in a few more observations.

At Mile 282 on US I-65 in Alabama the KT Boundary is exposed in a Road Cut about 1/2 way up the cut. It is exposed frequently across Alabama. The following facts are observable by anyone looking at these sites.

[1] The site has contigious deposition of strata from well below to well above the KT Boundary

[2] The site has a crumbly rock/clay consistancy for some 20 feet below the KT Boundary

[3] The Rock is Sandstone for about 20 feet above and then is Limestone for about 60 feet.

[4] Above that mapping contigious strata are layers of coal, shale, and again limestone

All of these layers represent a contiguious geologic layering as they are essentially like pages in a book and of fairly consistent thickness over great distances. The presence of Limestone which has sea bed fossils brings into question exactly what we are seeing at the site. The reasons for this are multiple including the geologic age of the Limestone (Very Old) and the means of deposition of it (Sea Bed activity). I believe it would be quite fair to question very nearly any theory regards the KT Boundary. It is clear that the area was under the Ocean for a substantial period after the KT Boundary and it would appear that the KT deposition was fairly consistent with that event and possibly just one of many depositions layered this way. The fossil and other data from the KT Boundary area is inconsistent with any existing theory. The Limestone for example dates from early life times per Geologic Estimates about 600 Million Years. Yet it is above the KT Boundary.

These inconsistencies with existing theories need investigation as the area is one with a very substantial amount of data and has a very stable history geologically allowing the story to be read in order of events.

It can be safely said that the presence of the rocks above the KT Boundary are consistent with the continent being sunk below the ocean. Many rocks below this level hold the same data. The strata being so stable in deposition process showing large fairly even deposition layers calls into question exactly what happened to deposit the soft material and the KT Boundary. The sandstones above are similar to volcanic ash depositions.

I knew it.

[hookedup]

See? The dinosaurs fell victim to outsourcing to india.

Re:Religious fanatics, unite! The end is very nigh

[maxwell demon]

Hmmm ... Kangaroos weren't mentioned in the bible as well. Nor was Australia. Probably the evil non-believers invented australia to hide the fact that earth really is flat :-)

Another suggestion

[TobiasSodergren]

... is that practically all dinosaurs that lived after the first impact were dead before the second hit earth ;)

Re:Why not a viral extinction?

[stratjakt]

There are many theories..

The ones presented on a Discovery Channel special (it was about Mammoths, but close enough for government work) were;

"The big Chill" - the Ice Age froze 'em all. Popular among scientists.

"The big Kill" - hunted to death by humans, little evidence exists for this, popular with the tree hugging set.

and

"The big Ill" - wiped out by some sort of disease. There was some sort of microbal evidence from frozen remains presented for this one.

I remember hearing a disease theory about the dinosaurs, basically it had to do with the rise of mammals, prehistoric rats as a vector to spread the virus - modeled after the spread of Black plague.

Frankly, I don't care. I'm just glad they're extinct. I've seen Jurassic Park.

Deccan Traps?

[Anonymous Coward]

The article doesn't seem to make any clear connection between the climatic stress - warming - supposedly caused by the eruptions that created the Deccan Traps and any meteorite. The accompanying graphs show a steady climatic cooling trend in the late Cretaceous and that curve doesn't appear to be affected by the iridium yeilding event. The biological diversity however correlates pretty muc exactly in geological time. So, where are the linking data that make sense of this article?

Re:Religious fanatics, unite! The end is very nigh

[back_pages]

I was only kidding about the Australians - forgot to add that as a PS on the last post. Kangaroos definitely do the bidding of the Prince of Darkness, though.

Conspiracy theory

[Anonymous Coward]

There must have been a second asteroid.

After all, everyone knows that the JFK 'Second Gunman' Theory is 100% accurate.;-)

My vote is...

[PhatKat]

There seems to be a popular opinion that humans are the most evolved of all species... that statement is totally bogus for a number of reasons, but if you define most evolved as best adapted to surviving whatever its environment throws at it (the galactic environment you could say), you just can't beat single celled organisms. The more adapted you are, the more you depend upon the situations and circumstances that make those adaptations beneficial. If we have a true Armageddon, I'm voting for the bacteria that live in deep sea volcanoes... it doesn't even need the Sun's light to survive.

Re:The Flat Earth Society

[jbrader]

I think it's incredibly ironic somewhere right now there is probably someone using a satellite link to look at the Flat Earth Society web site.

He deals with that

[Von Rex]

Check out his reply to the original article.

There's a picture of the soil sample he's talking about, too.

"The best evidence in favour of a single impact, I repeat, is in the K/T record from the US western interior. In numerous outcrops from Alberta in Canada, through Dogie Creek in Wyoming to the Raton Basin in New Mexico an iridium-enriched clay layer occurs in coal swamp deposits at the palynological K/T boundary. This clay layer has a dual nature (Izett, 1990), and consist of two layers: a lower layer that contains spherules (best seen in Dogie creek (Fig. 7) morphologicaly indistinguishable from the Chicxulub spherules from the Gulf.

The upper layer is strongly enriched in iridium and shocked minerals, such as quartz, feldspar and zircons. The shocked zircons are shown (Krogh, 1993) to have the isotopic properties (Sm/Nd) of the pan-African basement of the Chicxulub crater. In all the mentioned localities the two layers are in contact with each other, without an intervening layer. Not even a single layer of one fall season of leaves or plant material occurs between the two layers. If the upper, iridium-rich, layer is from another impact than the Chicxulub impact, they have to be simultaneous, and have to occur on the same pan-African basement - in itself highly unlikely, but not impossible. A 300Ka separation between the two layers in all the localities, as Keller posits for the separation between the Chicxulub impact and the iridium producing impact, is therefore excluded - barring a miracle."

Re:Religious fanatics, unite! The end is very nigh

[werfele]

I'd be the last to propound a literal interpretation of the Bible, but I believe the traditional interpretation of Genesis is that all of humanity is descended from Noah's children. Asians are presumed to be the descendants of Shem. You'll have to look for the origins of racism elsewhere.

That theory is still controversial

[Von Rex]

The abiotic theory on the origin of oil, while politically convenient to certain groups due to it's consequence of almost unlimited oil reserves, is still highly controversial. It is not reasonable to expect it to be taught as fact in textbooks for a long time, if ever.

Dutch radio interview

[Trestran]

For the Dutch slashdotters; Jan Smit said something about it on the Dutch radio(it's about 10 minutes into the stream), where he basicly called everything said by Kellar bullocks("a lott of mud throwing" and "facts that are verifiably wrong").

He has one of the samples of this study was based on (and (acording to above mentioned radioshow) the who divided up the original). In the end of the radiointerview he sugests letting all the original drill samples be tested by a third party for magnesium or calcium to prove if what Kellar has found are actual organism or just cristaline structures (as Smit seem to think). Sounds good to me, but then IANAPaleontologist.

Cause and Effect?

[boojum.cat]

What has bothered me for a long time about the Chicxulub theory is that nobody ever provides evidence linking the impact to the extinction. Every time new evidence appears indicating that there was an impact, it's reported as being new evidence that the dinosaurs were wiped out by it. Actually, all it shows is that there was an impact of some sort.

Years ago I read Robert Bakker's book, 'The Dinosaur Heresies". In it he claims that the fossil evidence shows that the dinosaurs were in decline long before the KT boundary and the appearance of its famed iridium layer. Furthermore, many species survived the extinction, and some of those species (such as amphibians) were ones that you might expect to be particularly susceptible. So although the impact might have contributed to the mass extinction, it's not likely to have been the root cause.

Misuse of Probability

[Winkhorst]

The only thing I really have trouble with is the Carl-Saganish misuse of probability. The fact that something happened once doesn't make it any less likely to happen the next day. The odds remain the same.

The second misuse of probability here is the assumption that there's no causal relation between the two events. They are simply treated as random occurrences, which fact is not in evidence. For all we know the two meteors could have been parts of the same original object on the same orbital path.