5 ms·

I thought that it still isn’t really known? Is is one common theory, but we have just probabilities to play with.

by nicce 1y ago

zamadatix 1y ago
Descartes would like a word as well, I'm sure. The big difference in the impact theory story is it's the first time we had enough evidence about any of the possibilities that widespread consensus (but not universal agreement it is the sole possible cause) was reached. Prior to that we weren't really sure if we'd even be able to get to that level about it. At least if the theory is replaced it'll be about something we see even clearer evidence of instead of "I dunno, could possibly have been...".
adastra22 1y ago
It'll be settled when the generation of researchers who fought over it retire/die off. The short TL;DR is that the guy who came up with the asteroid theory knew basically nothing about paleontology and paleoclimate, was way outside of his depth (he was a physicist that worked on the Manhattan project). He then made some pretty wild claims given the evidence that was available. When criticized by people who actually knew the field, he would personally attack them and drive public support against them as dinosaurs in a field of dinosaur research. Then the Chicxulub crater was found and dated to basically the exact same time as the K-T extinction event to within experimental error. So I guess the asshole was right? Except science doesn't work by smoking guns, as appealing as that would be. There are a lot of contradictory evidence. Better instruments and more careful data collection shows that in some places the fossil record stops prior to the impact layer. Also the fossils are of animals you would expect of an extinction event already ongoing. Oh, and coincidentally right before the Chicxulub impact India hit the continent of Asia and the Deccan Traps started spewing CO2 and other gasses into the atmosphere in volumes that put human-caused climate change to shame. The ocean was acidifying and ecosystems collapsing. Is it really fair to say an asteroid impact killed the dinosaurs, when they were already on the way out? IMHO the current best theory is the "one-two punch" that the Deccan traps eruptions basically put every large species on extinction watch, then the asteroid impact happened and finished the job. But it has become so political within that research community that people just aren't rational about the evidence, on either side.
- CamperBob2 1y ago
  The short TL;DR is that the guy who came up with the asteroid theory knew basically nothing about paleontology and paleoclimate, was way outside of his depth (he was a physicist that worked on the Manhattan project). Eh, that's underselling Luis Alvarez a bit. He wasn't just "a physicist," he was a Nobel laureate and arguably one of the twentieth century's few Renaissance men. My favorite Alvarez hack was when he used muon imaging to 'X-ray' the Great Pyramid. He didn't find any hidden chambers, but later researchers did. In the Alvarez mass-extinction hypothesis, he simply followed where the evidence led, unlike the supposed professionals in the field.
  - adastra22 1y ago
    Except the evidence didn't lead there. The fossil record is not consistent with sudden mass extinction. We have examples of sudden mass extinction events in Earth's history. The K-T boundary doesn't look like those. There were and still are many different lines of evidence pointing in incongruent directions. Alvarez pointed at layer of iridium and said "it must be a cosmic strike; it cannot be anything else" and derided anyone who still bothered publishing evidence to the contrary. Except.. there are a lot of iridium layers in the geologic record. These things tend to happen every 10-20m years. The most recent is probably the Eltanin impact about 2.5m years ago. The K-T impacter is definitely one of the largest, but not by as much of a margin as you might think. The mere presence of an impact within a million years or so of the mass extinction is neither surprising nor damning evidence, and Alvarez never bothered to make the case beyond that. And if you look at the history of mass extinctions, most of them are triggered by climate changes from geologic events. Pretty much every time there's massive vulcanism, most of the species on Earth die out. And hey, what do you know, there was a truly epic scale volcanic eruption going on for millions of years right at the same time! What a coincidence. The Chicxulub impact is certainly part of the story of the extinction event that killed off the dinosaurs. But the evidence isn't there to assert that it is the whole, or even the most important part of the story.
    - CamperBob2 1y ago
      I wouldn't be qualified to take sides in this particular pissing match, but still, the point stands. Alvarez was "directionally correct", and the existing researchers were not. He moved the field forward, while they did not.
mr_toad 1y ago
I think the majority of palaeontologists now accept the idea. Alternative ideas get disproportionate attention in popular articles.
joshmarinacci 1y ago
Finding the impact crater pretty much cemented it. It absolutely happened. The remaining questions are around if the impact was enough to trigger the extinction on its own or if other factors compounded the problem.
- marcosdumay 1y ago
  > The remaining questions are around if the impact was enough to trigger the extinction Well, in the sense that we can never be sure of anything, yeah. But it not being enough is a really extraordinary idea.
  - nicce 1y ago
    I believe the main question here is that whether they were doomed without asteroid regardless, and in that sense we can’t blame asteroid alone or primarily.
    - marcosdumay 1y ago
      Oh, yes, the point on the asteroid alone is possible, but a mass extinction at the same time an asteroid nearly destroys the wold being mainly caused by something other is a hell of a coincidence.
      - nicce 1y ago
        Not actually that big of coincidence. We tend to forgot the scale of these things. I remember reading that dinosaurs were already in decline for 2-3 million years. So if asteroids like that hit once per 100 million years, odds are not that small. Maybe 3% give or take.
- wang_li 1y ago
  There's a strong case to be made that the impact not only was enough to trigger the extinction, it happened in 1 day. The theory is that the ejecta from the impact was voluminous enough that it was sent into space and then spread around the Earth. On reentry it heated the atmosphere to thousands of degrees. So animals in New Zealand that likely didn't even feel the impact died when the air was too hot to breath. The only survivors were things in burrows or nests or under water.
IAmBroom 1y ago
Much like gravity, it is only a theory.
codeduck 1y ago
The geological record of the K-T boundary is very hard to argue with

I thought that it still isn’t really known? Is is one common theory, but we have just probabilities to play with.

by nicce 1y ago

I thought that it still isn’t really known? Is is one common theory, but we have just probabilities to play with.

Descartes would like a word as well, I'm sure. The big difference in the impact theory story is it's the first time we had enough evidence about any of the possibilities that widespread consensus (but not universal agreement it is the sole possible cause) was reached. Prior to that we weren't really sure if we'd even be able to get to that level about it. At least if the theory is replaced it'll be about something we see even clearer evidence of instead of "I dunno, could possibly have been...".

adastra22 1y ago

It'll be settled when the generation of researchers who fought over it retire/die off. The short TL;DR is that the guy who came up with the asteroid theory knew basically nothing about paleontology and paleoclimate, was way outside of his depth (he was a physicist that worked on the Manhattan project). He then made some pretty wild claims given the evidence that was available. When criticized by people who actually knew the field, he would personally attack them and drive public support against them as dinosaurs in a field of dinosaur research. Then the Chicxulub crater was found and dated to basically the exact same time as the K-T extinction event to within experimental error. So I guess the asshole was right? Except science doesn't work by smoking guns, as appealing as that would be. There are a lot of contradictory evidence. Better instruments and more careful data collection shows that in some places the fossil record stops prior to the impact layer. Also the fossils are of animals you would expect of an extinction event already ongoing. Oh, and coincidentally right before the Chicxulub impact India hit the continent of Asia and the Deccan Traps started spewing CO2 and other gasses into the atmosphere in volumes that put human-caused climate change to shame. The ocean was acidifying and ecosystems collapsing. Is it really fair to say an asteroid impact killed the dinosaurs, when they were already on the way out? IMHO the current best theory is the "one-two punch" that the Deccan traps eruptions basically put every large species on extinction watch, then the asteroid impact happened and finished the job. But it has become so political within that research community that people just aren't rational about the evidence, on either side.

CamperBob2 1y ago
The short TL;DR is that the guy who came up with the asteroid theory knew basically nothing about paleontology and paleoclimate, was way outside of his depth (he was a physicist that worked on the Manhattan project). Eh, that's underselling Luis Alvarez a bit. He wasn't just "a physicist," he was a Nobel laureate and arguably one of the twentieth century's few Renaissance men. My favorite Alvarez hack was when he used muon imaging to 'X-ray' the Great Pyramid. He didn't find any hidden chambers, but later researchers did. In the Alvarez mass-extinction hypothesis, he simply followed where the evidence led, unlike the supposed professionals in the field.
- adastra22 1y ago
  Except the evidence didn't lead there. The fossil record is not consistent with sudden mass extinction. We have examples of sudden mass extinction events in Earth's history. The K-T boundary doesn't look like those. There were and still are many different lines of evidence pointing in incongruent directions. Alvarez pointed at layer of iridium and said "it must be a cosmic strike; it cannot be anything else" and derided anyone who still bothered publishing evidence to the contrary. Except.. there are a lot of iridium layers in the geologic record. These things tend to happen every 10-20m years. The most recent is probably the Eltanin impact about 2.5m years ago. The K-T impacter is definitely one of the largest, but not by as much of a margin as you might think. The mere presence of an impact within a million years or so of the mass extinction is neither surprising nor damning evidence, and Alvarez never bothered to make the case beyond that. And if you look at the history of mass extinctions, most of them are triggered by climate changes from geologic events. Pretty much every time there's massive vulcanism, most of the species on Earth die out. And hey, what do you know, there was a truly epic scale volcanic eruption going on for millions of years right at the same time! What a coincidence. The Chicxulub impact is certainly part of the story of the extinction event that killed off the dinosaurs. But the evidence isn't there to assert that it is the whole, or even the most important part of the story.
  - CamperBob2 1y ago
    I wouldn't be qualified to take sides in this particular pissing match, but still, the point stands. Alvarez was "directionally correct", and the existing researchers were not. He moved the field forward, while they did not.

mr_toad 1y ago

I think the majority of palaeontologists now accept the idea. Alternative ideas get disproportionate attention in popular articles.

joshmarinacci 1y ago

Finding the impact crater pretty much cemented it. It absolutely happened. The remaining questions are around if the impact was enough to trigger the extinction on its own or if other factors compounded the problem.

marcosdumay 1y ago
> The remaining questions are around if the impact was enough to trigger the extinction Well, in the sense that we can never be sure of anything, yeah. But it not being enough is a really extraordinary idea.
- nicce 1y ago
  I believe the main question here is that whether they were doomed without asteroid regardless, and in that sense we can’t blame asteroid alone or primarily.
  - marcosdumay 1y ago
    Oh, yes, the point on the asteroid alone is possible, but a mass extinction at the same time an asteroid nearly destroys the wold being mainly caused by something other is a hell of a coincidence.
    - nicce 1y ago
      Not actually that big of coincidence. We tend to forgot the scale of these things. I remember reading that dinosaurs were already in decline for 2-3 million years. So if asteroids like that hit once per 100 million years, odds are not that small. Maybe 3% give or take.
wang_li 1y ago
There's a strong case to be made that the impact not only was enough to trigger the extinction, it happened in 1 day. The theory is that the ejecta from the impact was voluminous enough that it was sent into space and then spread around the Earth. On reentry it heated the atmosphere to thousands of degrees. So animals in New Zealand that likely didn't even feel the impact died when the air was too hot to breath. The only survivors were things in burrows or nests or under water.

IAmBroom 1y ago

Much like gravity, it is only a theory.

codeduck 1y ago

The geological record of the K-T boundary is very hard to argue with