Not by asteroid alone: Rethinking the Cretaceous mass extinction

Jan 19, 2012 by Stuart Mason Dambrot feature
Location map and changes in benthic foraminiferal diversity and infaunal morphogroups across the K/Pg boundary. Location of sections and drill sites discussed in the text. (A) Yellow circles indicate a decrease in food flux to the sea floor as estimated from benthic foraminiferal evidence, black circles an increase, and half black circles indicate no significant change. See SI Materials and Methods for construction of map. (B) Blue squares show the decrease in diversity from uppermost Maastrichtian (Cretaceous) to lowermost Danian (Paleogene) for locations shown in A, red triangles show the change in the percentage infaunal taxa, a productivity indicator; data sources are given in SI Materials and Methods. Copyright © PNAS, doi: 10.1073/pnas.1110601109

(PhysOrg.com) -- At the end of the Cretaceous period some 65 million years ago, an asteroid slammed into Mexico’s Yucatan Peninsula, causing severe but selective extinction. While that is widely accepted, it has remained unclear exactly what the mechanisms were that caused extinction of ocean-dwelling organisms. Proposed explanations include global darkness due to blocking of sunlight with resulting interruption of photosynthesis at the base of the food chain, deadly radiation due to ozone destruction, global cooling or warming, and ocean acidification). Various widely-accepted hypotheses focus on a collapse of the primary and export productivity in the oceans – such as the so-called Strangelove Ocean or Living Ocean hypotheses, respectively – but do not account for the finding that deep-sea floor dwelling phytoplankton-dependent benthic foraminifera did not undergo significant extinction. Recently, however, research conducted at Universidad Zaragoza in Spain compared benthic foraminiferal records with benthic and bulk stable carbon isotope records. The scientists concluded that decreased productivity was moderate, regional, and insufficient to explain marine mass extinction, suggesting instead that a temporary period of increased surface ocean acidity may have been the primary cause of extinction of calcifying plankton and ammonites, with recovery of primary productivity possibly being as fast in the oceans as on land.

Researchers Laia Alegret at Universidad Zaragoza, Ellen Thomas at Yale University, and Kyger C Lohmann at the University of Michigan faced a range of issues in comparing benthic foraminiferal records with benthic and bulk stable carbon isotope records. “One of the main challenges is always to obtain sufficient benthic foraminiferal specimens for a statistically valid analysis,” says Thomas. “In the deep sea, there is no light, and so no photosynthesis. Therefore, almost all food must come from photosynthesis in the surface waters kilometers above – and only a very small percentage of the primary material, produced by unicellular algae, ever reaches the sea bottom.”

Put simply, deep-sea benthic foraminifera and other deep-sea organisms1 live in a world where the limiting factor of life is food – because there is extremely little of it.2 This implies that in samples from the deep-sea floor, microscopic shells of the organisms the team studied – foraminifera, a group of unicellular eukaryotes – are dramatically outnumbered by the shells of their relatives that live floating in the sunlit surface waters, and whose shells also fall to the sea floor. “We need to collect at least 300 specimens of the deep-sea dwellers per sample, which takes a lot of time sitting behind the microscope and hand-picking the bottom dwellers from the much more abundant surface dwellers,” Thomas explains to PhysOrg.com. “Then the very highly diverse assemblages need to be sorted out, and all specimens assigned to species.” Thomas also emphasizes that this is complicated by the fact that there is not true international agreement on the taxonomy of these species.

The team addressed these issues in a number of ways. “First,” agrees Alegret, “the consistency of our data set is unprecedented: The same authors used the same procedures and the same taxonomic concepts for all sites. Another challenge,” Alegret adds, “was finding microfossils in sediment that is not strongly affected by diagenesis – the high pressure and temperatures that take place during the formation of hard rocks from initially soft clay and ooze, which may strongly affect isotopic results. Material in sediment from scientific ocean drilling sites,” she continues, “is commonly less affected by diagenesis than samples obtained from rocks in quarries and outcrops on land. This gave us good preservation of the calcium carbonate, ensuring accuracy of our isotope results.”

Thomas notes that the team argues that a collapse of primary productivity by the unicellular algae in the surface waters as proposed in the Strangelove Ocean hypothesis, or continued productivity by such algae but a lack of transport of these algae into the deep bottom waters (also called a collapse of the biological pump) as proposed by the Living Ocean model, would both have resulted in an interruption of food supply to the bottom dwellers for hundreds of thousands of years. “Such an interruption of food supply should have had a serious influence on the bottom dwellers, which in the present oceans react even to changes in the seasonality of food supply. However, we didn’t see that. Rather, the bottom dwellers did not go extinct, indicating that they must have had access to food.”

In fact, Alegret notes, in some regions – for example, the Pacific Ocean – there they found an increase in the food supplied to the sea floor – which, she points out, “is incompatible with both the Strangelove Ocean and Living Ocean hypotheses.”

The scientists point out that their findings may impact other areas of research, from paleobiology to evaluating the effects of increasing atmospheric levels of carbon dioxide. “In many fields of paleontology it has been accepted that the main cause of such extinction was the collapse of primary productivity,” Thomas notes. “If that is not the case, one needs to look at other factors. If we’re correct in our speculation that a rapid pulse of oceanic acidification can have very severe effects on ocean life, then we need to take that into account when evaluating the potential effects of the very rapid anthropogenic ocean acidification, caused by a different type of acid – specifically, due to high carbon dioxide levels – on ocean life in the near future.”

The team is already looking forward to extending their research. However, Thomas cautions, what they’d like to do and what they’ll be able to do depends at least in part on funding. “We’re rather far along with a high resolution analysis of foraminifera and stable isotopes from a site close to one of our studied sites, but in shallower waters.” Once they have these data collected, they can better compare what happened at different depths in the water column in an expansion of their work at different geographic locations.

“It would be very exciting,” Thomas envisions, “to test whether we can indeed find direct and quantitative evidence, rather than evidence from extinction patterns of calcifying organisms, for the pH values of the surface waters of the oceans – for example, by trying to apply proxies for oceanic pH and carbonate saturation, such as measuring boron isotopes and/or boron/calcium values in the shells of planktic, or surface-dwelling, and benthic foraminifera across the extinction interval. This is not easy to do,” she points out, “because the planktic – also termed planktonic – foraminifera were so severely affected by the extinction – but it may be possible with the modern possibility to analyze very small amounts of calcite.”

“If we want to predict the future effects of the present acidification of the oceans,” Alegret concludes, “we should investigate and understand past acidification events by, for example, comparing the very rapid acidification event triggered by the end-Cretaceous impact ago with the much slower acidification during the extreme warming event which occurred 55 million years ago at the end of the Paleocene and caused severe extinction of benthic foraminifera.”

Explore further: TRMM Satellite calculates Hurricanes Fay and Gonzalo rainfall

More information: End-Cretaceous marine mass extinction not caused by productivity collapse. Published online before print December 29, 2011, doi: 10.1073/pnas.1110601109

1 Deep, diverse and definitely different: unique attributes of the world's largest ecosystem. Biogeosciences, 7, 2851-2899, 2010, doi:10.5194/bg-7-2851-2010

2 Phytoplankton: below the salt at the global table. Journal of Paleontology, May 1986, v. 60, p. 545-554

3.9 /5 (14 votes)

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User comments : 25

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Argiod
4 / 5 (12) Jan 19, 2012
This just goes to show that the Earth, and life in general, is much more resilliant than we give it credit for. While WE may not survive our own follies, the Earth will continue well past our lifetimes...
Henrik
1 / 5 (26) Jan 20, 2012
Proposed explanations include


How about a very simple one: a global flood destroyed most of earths life. Consistent with all the observed data, and does not need a flurry of ad hoc assumptions.
RealScience
5 / 5 (23) Jan 20, 2012
@henrik - How did 40 days and night of rain cover mountains thousands of feet tall - that's hundreds of feet of rain per day.
Where did all the water come from? The atmosphere doesn't hold even 0.1% of that amount, and if it came from the oceans then the sea level wouldn't rise?
Why do isotope ratios reflect that which would be expected from a much older earth?
Why can so many fossils be placed in a series as if they evolved?
Why do different species use similar biochemistry if they were individually created?

Looks like you are the one who needs a flurry of ad-hoc 'magic' assumptions.
MarkyMark
5 / 5 (7) Jan 21, 2012
Proposed explanations include


How about a very simple one: a global flood destroyed most of earths life. Consistent with all the observed data, and does not need a flurry of ad hoc assumptions.

Seems your simple explanation is so full of holes its leaking like a sieve.

I would love to know where all that water came from and where it went? Of course if you replied i bet you would just avoid this by asking a question or by being satisfied with some deeply flawed theory passed on by some Quack!
foolspoo
1 / 5 (3) Jan 21, 2012
what happened to the volcanic theory that was supposed to squash this beloved asteroid theory...... noahs ark! HA!
jsa09
5 / 5 (1) Jan 22, 2012
The volcanic discharge in India that is supposed to correspond to the extinction event 65 mill years ago? the asteroid strike. Perhaps the combination of these?

Could be not enough evidence has been gathered yet to throw anything out. Then again volcanic discharge could be in gases that, instead of blocking sunlight, just poisoned the atmosphere.
ccr5Delta32
5 / 5 (6) Jan 23, 2012
@ Henrik I suppose your god sent a flood to drown all the fishes
He's not very bright is he ?
"Consistent with all the observed data" are you joking or just dishonest ?
RealScience
5 / 5 (6) Jan 23, 2012
@ccr5Delta32 - as far as I can see, Henrik, Kevinrtrs and a few other less-frequent young-earth-christian posters are neither joking nor dishonest, but are completely serious.
And what is even more astounding is that they think that their case is so strong, and all of the evidence of geology, biology, astronomy, physics and chemistry is so weak, that they'll actually convince people on a science website (but keep in mind that until a few hundred years ago science didn't know any better, either).

A few of the ones on this site have engaged in dialog and then realized the errors in their arguments, so it is worth responding with clean, simple reasoning.
Drowning the fishes is a great example!
weimin
not rated yet Jan 24, 2012
The Deccan Trap in India can also lead to the acidification of ocean waters.
Ethelred
4.6 / 5 (9) Jan 24, 2012
Somehow I had not seen this very relevant quote til the other day and have never seen it here.

"Debating creationists on the topic of evolution is rather like trying to play chess with a pigeon; it knocks the pieces over, craps on the board, and flies back to its flock to claim victory."

- Scott D. Weitzenhoffer


Which fits Kevin and Henrik stupefyingly well. Except that the way evades, dodges, pretends not to see and otherwise avoids questions he does not like makes it pretty clear that he knows his thinking has rather serious problems. There is so much that he has to avoid and he cannot do that if he didn't already know that the evidence is completely against him.

Well maybe not lets see if he pretends that this post and the next don't exist.

More>>
Ethelred
4.5 / 5 (10) Jan 24, 2012
How about a very simple one: a global flood destroyed most of earths life.
And when was that Flood?

Consistent with all the observed data, and does not need a flurry of ad hoc assumptions.
Completely false in every way. There is NO physical evidence for that flood and it should be everywhere. The reason it doesn't require ad hoc assumptions is because it only requires that you ignore the evidence and then about it.

Since you are so sure it happened when did it happen? The only source is Genesis, the original Sumerian myth was not claimed to be worldwide, and lots of people have run the numbers in the Bible so claims that it isn't Bible are just evasion so give us the date you think is real. Evasion on this constitutes you admitting you don't any real evidence AND you know the date shows it didn't happen.

Ethelred
MarkyMark
5 / 5 (1) Jan 26, 2012
It seems that Creationists and sarah Palin fantasists are at least consistant in there ninja post one troll post then run away.
drkim
1 / 5 (7) Jan 26, 2012
Regarding "proof"...submarine canyons.

"How did they get there? What forces could gouge out canyons that are sometimes 15,000 feet below sea level? Was the ocean floor raised or the ocean surface lowered by this amount so ancient rives could cut these canyons? If so, how? Canyons on the continents were supposedly formed by the cutting of fast flowing rivers and surface drainage. However, the flows measured in submarine canyons are much too slow--generally less than one mile per hour. Frequently the flow is in the wrong direction. Submarine landslides or currents of dense, muddy water sometimes occur. However, they would not form the long, branching (or dendritic) patterns that are common to river systems and submarine canyons. Besides, experiments with mud-ladened water in actual submarine canyons have not demonstrated any canyon-cutting ability." *Walter T. Brown, In the Beginning (1989), p. 63.
drkim
1 / 5 (6) Jan 26, 2012
While creationism cannot be scientifically tested, it seeks to use the scientific process to show why evolutionary theories are false. Thus, don't ask creationists to prove what is a matter of faith. Rather, accept our criticisms and observations as motivation to seek stronger evidence to prove that evolutionary mechanisms are true.

All we are saying is that evolutionists have not shown conclusively that evolutionary theory, as a whole or in part, is persuasive enough to change our minds.

Before you accuse me of being impervious to change my mind in the face of absolute proof, how many evolutionists would accept creationism if Noah's ark were indeed found to support the Biblical count, at least in regards to testable issues such as dimension?

Incredible claims require incredible evidence, or else it is a matter of faith (evidence of things unseen).

Respectfully,

Joseph Kim, DDS, FAGD, FICOI
drkim
1 / 5 (4) Jan 26, 2012
Ethelred,

I appreciate your observations. You definitely know how to cut to the chase. I imagine the questions you asked were rhetorical, as those who believe in a global flood tend to be Young Earth Creationists. The generally accepted date of the flood amongst YEC adherents is roughly 2304 BC.
drkim
1 / 5 (5) Jan 26, 2012
@Realscience
>How did 40 days and night of rain cover mountains thousands of feet tall - that's hundreds of feet of rain per day.

YEC tend to believe that mountains were created/raised during and after the flood, thus much less height to cover.

>Where did all the water come from?

YECs believe from the "fountains of the deep." See http://www.physor...847.html

>The atmosphere doesn't hold even 0.1% of that amount, and if it came from the oceans then the sea level wouldn't rise?

Levels did rise. "The difficulties encountered in explaining the lowering of sea level necessary for the canyons to have been cut by streams [with a volume of water such as we have today] seem insurmountable.. If Tolstoy's conclusion that Hudson Canyon extends down to a depth of 15,000 feet [4572 ml [!] is correct, the magnitude of lowering of sea level to permit subaerial canyon cutting seems beyond any possibility of realization." *William D. Thombury, Principles of Geomorphology, (1954), p. 47
Ethelred
4.5 / 5 (8) Jan 26, 2012
*Walter T. Brown, In the Beginning (1989), p. 63.
Walter don't run the numbers Brown is the worst engineer ever.

His attempts to patch up geology are beyond silly. They are just plain ludicrous. Race track continents, fountains from the deep, a deep 10 miles down where the water is above boiling. His ideas have continents that would slam into mountain ranges leaving them molten for centuries, Noah and the Big Assed Boat boiled, and water sprayed at escape velocity.

What forces could gouge out canyons that are sometimes 15,000 feet below sea level?
Turbidity currents for millions of years.

Frequently the flow is in the wrong direction. Submarine landslides or currents of dense, muddy water sometimes occur.
Indeed they do. And have done so for many millions of years and we have only been looking for a couple of decades yet we found it happening.>>
Ethelred
4.3 / 5 (6) Jan 26, 2012
However, they would not form the long, branching (or dendritic) patterns that are common to river systems and submarine canyons.
Sure they would. Its that Grand Canyon that wouldn't form in the Race Track Idiocy of Brown.

Besides, experiments with mud-ladened water in actual submarine canyons have not demonstrated any canyon-cutting ability."
Except for that paragraph above where you showed they do it. Don't you read what you write?

While creationism cannot be scientifically tested
Of course it can. It fails. The Universe is billions of years old. The Earth is billions. There is no evidence of the Great Flood. A flood that, if you use the numbers in the Bible, occurred during the middle of the Egyptian pyramid building era.

it seeks to use the scientific process to show why evolutionary theories are false.
It does no such thing. It ignores the evidence for evolution, the age of the Earth and the Universe and tries to obfuscate reality.>>
Ethelred
4.4 / 5 (7) Jan 26, 2012
IF the world was young we would know it. There would be no doubt just as there is no doubt that the world is old.

Thus, don't ask creationists to prove what is a matter of faith.
Right, don't ask for evidence. Just let them lie.

No. When do YOU think the Flood was?

Rather, accept our criticisms and observations as motivation to seek stronger evidence to prove that evolutionary mechanisms are true.
They have been proved within the limits of observation and those limits go back for billions of years of fossils.

All we are saying is that evolutionists have not shown conclusively that evolutionary theory, as a whole or in part, is persuasive enough to change our minds.
Being pigheaded doesn't even come close to making your fantasies real. The evidence is clear. You simply refuse to look at it.>>
Ethelred
4.2 / 5 (5) Jan 26, 2012
how many evolutionists would accept creationism if Noah's ark were indeed found to support the Biblical count, at least in regards to testable issues such as dimension?
It doesn't exist. It never existed and in Brown's Race Track foolishness he killed him by boiling. However if you find a 400 by 400 by 400 foot ship from 4400 year ago that would be interesting at the very least. Depends a bit on where it would be found. On the shore of the Black Sea and you don't have a world wide flood just the Black Sea flood.

The thing is that would only be ONE piece of evidence in comparison to

Megatons of fossils
Lab experiments
Field experiments
The age of the Earth
Egyptian history
Sumerian history
The City of Jericho
The City of Damascus
Bristle cone pines
Oh just the whole universe and planet

And you are refusing to with all of those.

What if apples were oranges and sand was silver. Let me know when the Big Ass Boat is found. It is just rocks and clearly so on Ararat.>>
Ethelred
4.3 / 5 (6) Jan 26, 2012
Incredible claims require incredible evidence, or else it is a matter of faith (evidence of things unseen).
Yes science has the evidence and you don't. So when are you going to go on the evidence?

The generally accepted date of the flood amongst YEC adherents is roughly 2304 BC.
Which is in the middle of the period that the Egyptians were building pyramids. The question was not rhetorical. The idea is to find out how do you deal with that major contradiction of reality. History does not have the Egyptians being drowned and replaced by new people with a new langauge and culture.

So how do you make that major problem go away. I recommend that you don't ask Dr. Brown. He is grossly incompetent in that he never even thought of running the numbers on his silly ideas. If an engineer doesn't check the numbers its because what they are already and they would kill all life on Earth. Yes even in the Big Ass Boat.>>
EverythingsJustATheory
3.7 / 5 (6) Jan 26, 2012
Yep, Noah somehow was able to find a male and female for each of the six to ten million species of insects on the earth, as well as all the bacteria and viruses, and put them on a wood boat bigger than any one built in history.
Ethelred
4.2 / 5 (5) Jan 26, 2012
YECs believe from the "fountains of the deep." See
They would be boiling hot AND the caverns seem to be supported only by wishful thinking. Sure isn't by water.

http://mypage.dir...dro.html

Ethelred
EverythingsJustATheory
3.7 / 5 (6) Jan 26, 2012
And even more ridiculous, after being inundated with water for 40 days, the foliage and plants that previously lived on the surface somehow reappeared.
Gawad
5 / 5 (1) Jan 27, 2012
Somehow I had not seen this very relevant quote til the other day and have never seen it here.

"Debating creationists on the topic of evolution is rather like trying to play chess with a pigeon; it knocks the pieces over, craps on the board, and flies back to its flock to claim victory."

- Scott D. Weitzenhoffer


Which fits Kevin and Henrik stupefyingly well.


Eth, please don't insult pigeons!