8 ms·

What Caused the Dinosaur Extinction?

88 points by bkudria 8y ago

dannylandau 8y ago
Extremely well written and fascinating story on a competing theory for the mass extinction. still not convinced that the generally accepted Alavarez Asteroid hypothesis is wrong. Worth a read nonetheless.
- jhbadger 8y ago
  That's the thing in pop science though. String theory is generally accepted -- so write about the iconoclasts who reject it. Asteroid accepted as the end of dinosaurs? Write about the iconoclasts there.
  - pfdietz 8y ago
    String theory is not generally accepted. It has not made a single successful prediction, or indeed any predictions at all. It's more correct to say most physicists view it with skepticism mixed with disdain.
mordant 8y ago
This is about the supervolcano hypothesis. Note that this and the Alvarez asteroid hypothesis aren't mutually-exclusive; a significant impact event could in fact trigger vulcanism on a massive scale. There's plenty of evidence that the K-T impactor was real and slammed into the Earth. It alone might've caused the massive die-offs, or it might've triggered vulcanism and/or venting of poisonous gas deposits from beneath the seabed.
- bryanlarsen 8y ago
  According to the article, the vulcanism starts two hundred thousand years before the impact.
  - EdwardDiego 8y ago
    Sure, started, but... http://science.sciencemag.org/content/350/6256/76 http://science.sciencemag.org/content/350/6256/76 > The existing Deccan Traps magmatic system underwent a state shift approximately coincident with the Chicxulub impact and the terminal-Cretaceous mass extinctions, after which ~70% of the Traps' total volume was extruded in more massive and more episodic eruptions. Initiation of this new regime occurred within ~50,000 years of the impact, which is consistent with transient effects of impact-induced seismic energy. Then there's the possibility of another impactor coincident in time to Chicxulub: https://en.wikipedia.org/wiki/Shiva_crater https://en.wikipedia.org/wiki/Shiva_crater
- Jedd 8y ago
  This was discussed in TFA.
pfdietz 8y ago
The evidence for a massive impact precisely at the K/T boundary is ironclad. Any alternate theory in which the impact was not causal has to explain how this incredible coincidence (the largest impact in the past 100 million years occurring in a layer deposited in just thousands of years, right at the boundary) occurred.
- vertline2 8y ago
  Is it possible for a meteor to cause a chain of volcanoes to blow? like all the pressure under the crust gets rattled around?
  - dmoy 8y ago
    Seems like yes? https://www.whitecoatinvestor.com/expense-ratios/ https://www.whitecoatinvestor.com/expense-ratios/
  - listenYou 8y ago
    I mean, this is definitely my goto theory. Everything tied up in one single package. But, unfortunately, just because we like something, doesn't mean it really went down that way. And rightfully so, a horde of nerds will come out of the woodwork, to inform us if we were to claim the validity of an event, without true evidence in hand. Either way, it won't stop me from harboring a deep suspicion that this is exactly what happened. Mostly, my own belief is founded in similar conceptual origins for the moon.
  - ridgeguy 8y ago
    Maybe. On Mercury, it seems the impact that created the Caloris basin [1] may also have created a seriously busted-up region at its antipode (opposite on the planet from the impact) [2]. This may have happened due to shock waves propagating through Mercury's interior, focused by reflection at the planet's surface onto an area opposite the impact. There are alternate theories. A few years ago, I looked into whether the Deccan Traps eruptions might have been either triggered or enhanced by similar antipodal seismic wave energy from the Chicxulub impact. Based on Earth's continental positions about 65M years ago, it seemed possible, maybe plausible. There were some papers discussing the possibility, but I don't have the data at hand. [1] https://en.wikipedia.org/wiki/Caloris_Planitia https://en.wikipedia.org/wiki/Caloris_Planitia [2] https://en.wikipedia.org/wiki/Caloris_Planitia#Antipodal_chaotic_terrain_and_global_effects https://en.wikipedia.org/wiki/Caloris_Planitia#Antipodal_cha...
apo 8y ago
Great article, but the ending made little sense: We all chuckled at this prediction—mass extinction, by this point, having become something of a macabre inside joke. Just past the spoil, we reached the end of the road, which was lined with piles of white dirt too tall to see over. Clambering over them in search of outcrops, we were confronted by a strange view on the other side: an enormous field of coal, pockmarked with holes. The black earth had been dug at regular intervals to create thousands of pits, all the size and depth of shallow graves. Each one had its own mound of white earth beside it, as if waiting to be filled. No one could explain what they were. This has little to do with the rest of the article, raises a whole slew of questions, and the phrase "no one could explain what they were" is uncharactersitically vague. It feels like I missed the punchline to a joke. I can imagine the kinds of debates about the origins of the pits might resemble the debate about the impact theory, but this indirection seems like an odd way to end an otherwise clearly written article. What am I missing?
- wtvanhest 8y ago
  The author seems to be talking about mining fossil fuels. And how they believe that fossil fuels will end humanity.
lkrubner 8y ago
Start with a 3 species model. Imagine a shallow, closed sea, in which there is a shark, a plesiosaur, and a bird. We need to explain why the shark and the bird survive, but the plesiosaur goes extinct. An asteroid hits somewhere, causing environmental change. For the rest of this comment, I'm going to refer to temperature as a short-hand way of referring to any environmental change. The shallow, closed sea is undergoing temperature change, so the environment for bacteria and viruses is rapidly changing, therefore new species of bacteria and viruses are emerging at a high speed. The shark is safe because the shark has general purpose macrophages which fights all pathogens with equal efficiency -- the shark does not care whether a pathogen is new or old, because the shark has a disease fighting system which does not rely on the principle of immunity. Sharks are 350 million years old -- they evolved long before immunity existed. The plesiosaur and the bird are both in danger, because they have a system of disease fighting that does rely on immunity -- they are efficient at fighting off pathogens they've already been exposed to, but they are inefficient at fighting off pathogens that they have never been exposed to. The birds see half the flock grow sick and die, so some instinctual fear of disease kicks in and the birds fly away from the shallow, closed sea. The plesiosaur has no escape. Their disease fighting system is inefficient when dealing with new diseases, and they are in a bath of new diseases, from which they can not escape. They go extinct. Immunity is the best model I've seen so far for explaining which species went extinct and which species survived.
- pfdietz 8y ago
  Yeah, no. There was massive extinction of single cell creatures (forams, for example) and also plants, which don't have immune systems. A good match for the extinction patterns is which species could survive a prolonged interruption of photosynthesis.
- frozenport 8y ago
  The animals you mentioned have active, as well as learned immunity. The systems in vertebrates are quite similiar. I'm not sure what your point is.
- wild_preference 8y ago
  What’s with all the pretentious exposition? You could’ve shared your shower-thought in 140 chars.
isoskeles 8y ago
I’m going to disagree that this was well written. I expected a factual article about dinosaur extinction and had to stop at the navel-gazing comment on a suicide attempt.
fredland 8y ago
Cigarettes.
ncmncm 8y ago
tl;dr: Stuff happened 65+ mya. Theories developed over past ~50 years. Human extinction due in 50 y to 0.5 my. Implication: there is no need to rush a conclusion. New evidence will continue to surface. We might be extinct before certainty arrives.
- Pica_soO 8y ago
  Where does that certainty arrive, that we will go out with a grandiose bang? Why not instead, shrink and shrivel to a rat thing, adapted to live on planet sized garbage dump, optimized for continuous fighting with its peers and survival in a toxic environment. No need to think about tomorrow- god unwills it. Occasionally, a head-albino is born, a demonic creature whos head is big enough to murder its mother and ask uncomfortable questions. Usually these are worshiped, then sacrificed and eaten to prevent the cycle from restarting a new. History of a species, is not about show business. There rarely is somebody before or after who will read it.
BuckRogers 8y ago
Excellent article that I thoroughly enjoyed. I had no idea there was any other compelling explanation for the dinosaurs' extinction other than an asteroid but it makes sense. It's definitely convincing enough that it shouldn't be dismissed outright and it sounds like about half of the scientific community is doing just that.
mr_toad 8y ago
This articles tone comes across as incredibly snide, sarcastic, and condescending. This is how it describes the impact theory: ‘Mystery solved’. ‘Scientists cheered’. ‘a heartwarming story about the integrity of the scientific method.’ It reads more like a snarky movie review than science journalism.
- chr1 8y ago
  'snide, sarcastic, and condescending' was not just the authors view, but the way involved scientists view theories of each other. So it's unfair to blame the article for that, which is an article about a scientist and not science in general.
woodandsteel 8y ago
From the article: "In 1997, hoping to reconcile disagreement over the speed of extinction, scientists organized a blind test in which they distributed fossil samples from the same site to six researchers. The researchers came back exactly split." Oh dear, that is bad.
tokyodude 8y ago
Is the Radiolab account off? That the impact basically fried the surface of the entire planet at > 1000 degrees? Wasn't that also kind of the premise of Seveneves? That a bunch of particulate matter gets into the atmosphere and rains down, on reentry it burns like the space shuttle but with so much of it around the entire planet it basically bakes the entire earth In the Radiolab episode they claimed the entire planet is covered in the baked layer. That you can dig anywhere on the planet and find it. https://www.wnycstudios.org/story/dinopocalypse/ https://www.wnycstudios.org/story/dinopocalypse/ at about the 10 minute mark or visual https://www.youtube.com/watch?v=ZYoqtBEzuiQ#t=15m https://www.youtube.com/watch?v=ZYoqtBEzuiQ#t=15m Is that still a valid theory?
bethly 8y ago
This is interesting less for the science and more for the conflicts between different camps of "rationalists" about what "science" means. Especially given that the "rockstar physicist shows up with a model, gets angry when everyone doesn't accept their conclusions" dynamic is hardly unique to paleontology.

88 points by bkudria 8y ago

Extremely well written and fascinating story on a competing theory for the mass extinction. still not convinced that the generally accepted Alavarez Asteroid hypothesis is wrong. Worth a read nonetheless.

jhbadger 8y ago
That's the thing in pop science though. String theory is generally accepted -- so write about the iconoclasts who reject it. Asteroid accepted as the end of dinosaurs? Write about the iconoclasts there.
- pfdietz 8y ago
  String theory is not generally accepted. It has not made a single successful prediction, or indeed any predictions at all. It's more correct to say most physicists view it with skepticism mixed with disdain.

mordant 8y ago

This is about the supervolcano hypothesis. Note that this and the Alvarez asteroid hypothesis aren't mutually-exclusive; a significant impact event could in fact trigger vulcanism on a massive scale. There's plenty of evidence that the K-T impactor was real and slammed into the Earth. It alone might've caused the massive die-offs, or it might've triggered vulcanism and/or venting of poisonous gas deposits from beneath the seabed.

bryanlarsen 8y ago
According to the article, the vulcanism starts two hundred thousand years before the impact.
- EdwardDiego 8y ago
  Sure, started, but... http://science.sciencemag.org/content/350/6256/76 http://science.sciencemag.org/content/350/6256/76 > The existing Deccan Traps magmatic system underwent a state shift approximately coincident with the Chicxulub impact and the terminal-Cretaceous mass extinctions, after which ~70% of the Traps' total volume was extruded in more massive and more episodic eruptions. Initiation of this new regime occurred within ~50,000 years of the impact, which is consistent with transient effects of impact-induced seismic energy. Then there's the possibility of another impactor coincident in time to Chicxulub: https://en.wikipedia.org/wiki/Shiva_crater https://en.wikipedia.org/wiki/Shiva_crater
Jedd 8y ago
This was discussed in TFA.

pfdietz 8y ago

The evidence for a massive impact precisely at the K/T boundary is ironclad. Any alternate theory in which the impact was not causal has to explain how this incredible coincidence (the largest impact in the past 100 million years occurring in a layer deposited in just thousands of years, right at the boundary) occurred.

vertline2 8y ago
Is it possible for a meteor to cause a chain of volcanoes to blow? like all the pressure under the crust gets rattled around?
- dmoy 8y ago
  Seems like yes? https://www.whitecoatinvestor.com/expense-ratios/ https://www.whitecoatinvestor.com/expense-ratios/
- listenYou 8y ago
  I mean, this is definitely my goto theory. Everything tied up in one single package. But, unfortunately, just because we like something, doesn't mean it really went down that way. And rightfully so, a horde of nerds will come out of the woodwork, to inform us if we were to claim the validity of an event, without true evidence in hand. Either way, it won't stop me from harboring a deep suspicion that this is exactly what happened. Mostly, my own belief is founded in similar conceptual origins for the moon.
- ridgeguy 8y ago
  Maybe. On Mercury, it seems the impact that created the Caloris basin [1] may also have created a seriously busted-up region at its antipode (opposite on the planet from the impact) [2]. This may have happened due to shock waves propagating through Mercury's interior, focused by reflection at the planet's surface onto an area opposite the impact. There are alternate theories. A few years ago, I looked into whether the Deccan Traps eruptions might have been either triggered or enhanced by similar antipodal seismic wave energy from the Chicxulub impact. Based on Earth's continental positions about 65M years ago, it seemed possible, maybe plausible. There were some papers discussing the possibility, but I don't have the data at hand. [1] https://en.wikipedia.org/wiki/Caloris_Planitia https://en.wikipedia.org/wiki/Caloris_Planitia [2] https://en.wikipedia.org/wiki/Caloris_Planitia#Antipodal_chaotic_terrain_and_global_effects https://en.wikipedia.org/wiki/Caloris_Planitia#Antipodal_cha...

apo 8y ago

Great article, but the ending made little sense: We all chuckled at this prediction—mass extinction, by this point, having become something of a macabre inside joke. Just past the spoil, we reached the end of the road, which was lined with piles of white dirt too tall to see over. Clambering over them in search of outcrops, we were confronted by a strange view on the other side: an enormous field of coal, pockmarked with holes. The black earth had been dug at regular intervals to create thousands of pits, all the size and depth of shallow graves. Each one had its own mound of white earth beside it, as if waiting to be filled. No one could explain what they were. This has little to do with the rest of the article, raises a whole slew of questions, and the phrase "no one could explain what they were" is uncharactersitically vague. It feels like I missed the punchline to a joke. I can imagine the kinds of debates about the origins of the pits might resemble the debate about the impact theory, but this indirection seems like an odd way to end an otherwise clearly written article. What am I missing?

wtvanhest 8y ago
The author seems to be talking about mining fossil fuels. And how they believe that fossil fuels will end humanity.

lkrubner 8y ago

Start with a 3 species model. Imagine a shallow, closed sea, in which there is a shark, a plesiosaur, and a bird. We need to explain why the shark and the bird survive, but the plesiosaur goes extinct. An asteroid hits somewhere, causing environmental change. For the rest of this comment, I'm going to refer to temperature as a short-hand way of referring to any environmental change. The shallow, closed sea is undergoing temperature change, so the environment for bacteria and viruses is rapidly changing, therefore new species of bacteria and viruses are emerging at a high speed. The shark is safe because the shark has general purpose macrophages which fights all pathogens with equal efficiency -- the shark does not care whether a pathogen is new or old, because the shark has a disease fighting system which does not rely on the principle of immunity. Sharks are 350 million years old -- they evolved long before immunity existed. The plesiosaur and the bird are both in danger, because they have a system of disease fighting that does rely on immunity -- they are efficient at fighting off pathogens they've already been exposed to, but they are inefficient at fighting off pathogens that they have never been exposed to. The birds see half the flock grow sick and die, so some instinctual fear of disease kicks in and the birds fly away from the shallow, closed sea. The plesiosaur has no escape. Their disease fighting system is inefficient when dealing with new diseases, and they are in a bath of new diseases, from which they can not escape. They go extinct. Immunity is the best model I've seen so far for explaining which species went extinct and which species survived.

pfdietz 8y ago
Yeah, no. There was massive extinction of single cell creatures (forams, for example) and also plants, which don't have immune systems. A good match for the extinction patterns is which species could survive a prolonged interruption of photosynthesis.
frozenport 8y ago
The animals you mentioned have active, as well as learned immunity. The systems in vertebrates are quite similiar. I'm not sure what your point is.
wild_preference 8y ago
What’s with all the pretentious exposition? You could’ve shared your shower-thought in 140 chars.

isoskeles 8y ago

I’m going to disagree that this was well written. I expected a factual article about dinosaur extinction and had to stop at the navel-gazing comment on a suicide attempt.

fredland 8y ago

Cigarettes.

ncmncm 8y ago

tl;dr: Stuff happened 65+ mya. Theories developed over past ~50 years. Human extinction due in 50 y to 0.5 my. Implication: there is no need to rush a conclusion. New evidence will continue to surface. We might be extinct before certainty arrives.

Pica_soO 8y ago
Where does that certainty arrive, that we will go out with a grandiose bang? Why not instead, shrink and shrivel to a rat thing, adapted to live on planet sized garbage dump, optimized for continuous fighting with its peers and survival in a toxic environment. No need to think about tomorrow- god unwills it. Occasionally, a head-albino is born, a demonic creature whos head is big enough to murder its mother and ask uncomfortable questions. Usually these are worshiped, then sacrificed and eaten to prevent the cycle from restarting a new. History of a species, is not about show business. There rarely is somebody before or after who will read it.

BuckRogers 8y ago

Excellent article that I thoroughly enjoyed. I had no idea there was any other compelling explanation for the dinosaurs' extinction other than an asteroid but it makes sense. It's definitely convincing enough that it shouldn't be dismissed outright and it sounds like about half of the scientific community is doing just that.

mr_toad 8y ago

This articles tone comes across as incredibly snide, sarcastic, and condescending. This is how it describes the impact theory: ‘Mystery solved’. ‘Scientists cheered’. ‘a heartwarming story about the integrity of the scientific method.’ It reads more like a snarky movie review than science journalism.

chr1 8y ago
'snide, sarcastic, and condescending' was not just the authors view, but the way involved scientists view theories of each other. So it's unfair to blame the article for that, which is an article about a scientist and not science in general.

woodandsteel 8y ago

From the article: "In 1997, hoping to reconcile disagreement over the speed of extinction, scientists organized a blind test in which they distributed fossil samples from the same site to six researchers. The researchers came back exactly split." Oh dear, that is bad.

tokyodude 8y ago

Is the Radiolab account off? That the impact basically fried the surface of the entire planet at > 1000 degrees? Wasn't that also kind of the premise of Seveneves? That a bunch of particulate matter gets into the atmosphere and rains down, on reentry it burns like the space shuttle but with so much of it around the entire planet it basically bakes the entire earth In the Radiolab episode they claimed the entire planet is covered in the baked layer. That you can dig anywhere on the planet and find it. https://www.wnycstudios.org/story/dinopocalypse/ https://www.wnycstudios.org/story/dinopocalypse/ at about the 10 minute mark or visual https://www.youtube.com/watch?v=ZYoqtBEzuiQ#t=15m https://www.youtube.com/watch?v=ZYoqtBEzuiQ#t=15m Is that still a valid theory?

bethly 8y ago

This is interesting less for the science and more for the conflicts between different camps of "rationalists" about what "science" means. Especially given that the "rockstar physicist shows up with a model, gets angry when everyone doesn't accept their conclusions" dynamic is hardly unique to paleontology.