65-Million Year Old Mystery Resolved?

[Fnord]

According to this MSNBC article, the debate over cause of the mass extinction of the dinosaurs is settled.

Combining all available data from different science disciplines led us to conclude that a large asteroid impact 65 million years ago in modern day Mexico was the major cause of the mass extinctions ... with any extraordinary discovery there is a natural interest in confirming it. That's the scientific method.

I'm sold on the idea. Anyone else?

 

[coalesce]

I'm sold.

I look back on the leaps and bounds our collective knowledge of dinosaurs has grown over the last 25 years and am amazed. From thinking of them being lumbering, dim-witted long-dead beasts to nimble, feathered, their-descendants-walk/fly-among-us animals in one lifetime is enormous. Kind of like my grandparents who went from horse-drawn wagons to the Apollo missions in their lifetimes.

Michael

 

[blutoski]

According to this MSNBC article, the debate over cause of the mass extinction of the dinosaurs is settled.

I'm sold on the idea. Anyone else?

Basically. Given the information currently available, Chicxulub is the best candidate.

This is not a new hypothesis, though. I remember this from when I was in highschool in the 1980s. The thought at that time was about the geological support regarding the debris fallout. The 1990s provided good satellite imagery that convinced most remaining skeptics. I would have called this 'settled' at that time - 15 years ago.

The only debate at this point is whether the mechanism was extinction from darkness, or a global scale brushfire. Or both.

 

[cbish]

I too remember when I first heard about this as a college student in the mid-80's. It was the most preposterous thing I had ever heard.

 

[FreshHat]

According to this MSNBC article, the debate over cause of the mass extinction of the dinosaurs is settled.



I'm sold on the idea. Anyone else?

[palinmode]No room on the Ark?[/palinmode]

 

[KingMerv00]

I too remember when I first heard about this as a college student in the mid-80's. It was the most preposterous thing I had ever heard.

Large object strikes another large object at fantastic speed. Death ensues. What was preposterous about it?

 

[cbish]

I don't really know. Maybe because it was new. There wasn't any real evidence for it then as there is now other than the dino's died out rapidly. It seemed like a stab in the dark.

 

[Furcifer]

I thought this was pretty much settled as well. I didn't know there were any holdouts on the issue. Is there an alternate theory?

 

[The Fallen Serpent]

Versions of this article is popping up on most major news sites right now. The main competing theory for the KT extinction was of supervolcanic activity persisting for over a million years. The main debate appeared to be if the asteroid impact was itself enough to cause the widespread change or if it was one of many contributing factors in assisting rather than causing supervolcanic activity. I forget what it is called but that one line of inquiry suggested the impact was caused by supervolcanic activity launching a large part section of landmass and mantle into the air that then comes crashing down rather than an asteroid. If I remember correctly (which I might not, I do not even recall the name these type of hypothetical events have) geological studies showed more conclusively the impact area was clearly an extra terrestrial asteroid and not a bit of terrestial mass launched by a supervolcano.

It appears the recent studies were just final confirmations of the stronger KT extinction theory after investigating the competing lines of inquiry.

 

[Soapy Sam]

The Deccan eruptions in India probably didn't do a lot to help global ecology, but the Alvarez' (Walter & Luis) iridium layer findings was really the clincher that a bolide was involved.
Chixulub is the most likely known site, but there could still be others we don't know about. There's been a lot of erosion since then.

 

[geni]

I forget what it is called but that one line of inquiry suggested the impact was caused by supervolcanic activity launching a large part section of landmass and mantle into the air that then comes crashing down rather than an asteroid.

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

 

[blutoski]

I don't really know. Maybe because it was new. There wasn't any real evidence for it then as there is now other than the dino's died out rapidly. It seemed like a stab in the dark.

I think probably the reports you read just omitted the evidence that led them to this hypothesis.

Basically, the extinction period coincided with a geological layer (K–T boundary^WP) that became more dense toward the Yucatan, where there was evidence of a huge crater, and contained higher iridium concentrations than typical of the earth's crus, which was evidence of a large asteroid impact.

So, at that point, at least two strong lines of evidence pointed toward an extinction event caused by an asteroid impact in the Yucatan.

 

[The Fallen Serpent]

The Deccan eruptions in India probably didn't do a lot to help global ecology, but the Alvarez' (Walter & Luis) iridium layer findings was really the clincher that a bolide was involved.

That is a very concise and clear summary of what I have come across, thank you.

Chixulub is the most likely known site, but there could still be others we don't know about. There's been a lot of erosion since then.

I am curious at looking into the iridium layer studies. I can see the evidence being spread about the globe from such an impact but I was under the impression the materials elsewhere matched the specific site as the crater. Elements left to solve!

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

That was it!

 

[Schrodinger's Cat]

I think it's probably true.

Side note:I lived in the Yucatan for a time and outside the crater's edge there are all these sinkholes called cenotes which are deep vertical caves in the ground that were caused by limestone dissolvng. They have underground ponds and lakes which are just amazing. I'd highly recommend the Yucatan as a travel destination. Gorgeous, filled with both human and natural history and cheap!

 

[KingMerv00]

Side note:I lived in the Yucatan for a time and outside the crater's edge there are all these sinkholes called cenotes which are deep vertical caves in the ground that were caused by limestone dissolvng. They have underground ponds and lakes which are just amazing. I'd highly recommend the Yucatan as a travel destination. Gorgeous, filled with both human and natural history and cheap!

http://www.tamug.edu/cavebiology/yucatan/images/KankirixchePhoto.jpg

Interesting but why did you post a picture from Avatar?

 

[Dorian Gray]

For a laugh, read the comments under the Yahoo version of that article.

 

[shadron]

Catastrophism runs counter to a lot of scientific training, particularly in the 20th century which opened on the thought that the Bible's use of catastrophism must be completely overcome with a secular uniformitarianism in which slow processes over long periods of time were the rule. It has been very hard to convince diehards that both processes have a place in science:

- The Big Bang
- Huge floods which scour square miles of land (glacial lakes in North America, and the Mediterranean)
- Meteors (it was often thought that meteor craters had been caused by volcanoes).

In this case, The Deccan Traps were built up by a 30,000 years series of huge outpourings of lava in western India, totaling half a million cukm of magma and covering about half of modern India. They started up about a million years before the Chixchulub meteor event. India has tried to hedge their bets, however, citing what might be an even larger meteor crater (perhaps; it could also be a volcanic feature!) in the Indian Ocean dated at about the same time as Chixchulub, called Shiva crater. Robert Baaker prefers a theory of dinosaur pandemics. It's been going back and forth since Chixchulub was pressed into the dinosaur elimination's service.

 

[Roboramma]

I thought one of the reasons that other causes were thought to have had an important impact on dinosaur extinctions was that the extinctions took place not all at once but actually over the course of millions of years, starting several million years before the K/T boundary. Which suggests that there was something else going on other than just an asteroid impact, and that the impact may have simply finished things off given an already weak ecology.

I always wondered if the idea that extinctions had accelerated slowly up to that point may have been an artifact of a poor fossil record, not having enough detail even at the level of millions of years, to show exactly when such extinctions took place.

Does anyone know what the current view is? Did the extinctions all take place at once, or were they spread out over several million years? Do we have evidence for the latter? What I've read on the subject is at this point at least a decade old.

 

[MG1962]

Does anyone know what the current view is? Did the extinctions all take place at once, or were they spread out over several million years? Do we have evidence for the latter? What I've read on the subject is at this point at least a decade old.

The most recent stuff (And I cant quote it) I have seen suggests that dinosaur bio diversity had been crashing for a while, however the biomass remained largely unchanged. It could very much be he action of the Deecan traps screwing with the environment.

In terms of the actual extinction event, it could well have been measured in days if not hours, depending which version you subscribe to

 

[samm]

Really? Nobody sees the silliness in science like this being decided by vote?

And, why does it matter?

Hypothesis: big rock hits earth, math of the physics follows, result... big trouble in little china. Check. thumbs up, good science.

Hypothesis: Dinosaurs existed, evidence of bones, tracks, etc. Proposed dating techniques that likely put it in a range of a really long time ago. Check, pretty good science. OK.

Ditto, dinosaurs cease to exist at some time. OK

Good possibility that one caused the other, OK. But why do you need to tell me this? And why does it need to be elevated beyond so simple a statement? Why does science need a college of cardinals?

IE
When you make a conclusion without a complete record or a complete slate of evidence, what is likely to happen to the effort to collect evidence?

What is gained by jumping to the conclusion (even if the gap is only two feet)? When did the voting step get added to the scientific method?