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Mass extinctions follow 27-million-year cycle

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Manwon Lender

This is very interesting subject, I have added a video that talks about the 27 million year cycle in your link.

Thank very much for sharing my friend.

 

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Jon the frog

Maybe it's the time needed for evolution to create a lots of dead ends. Just a subtile catastrophe or climate change would be needed to cleaver the overspecialized and the cycle restart.

Edited by Jon the frog

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Seti42

I wonder if this is another example of people finding a pattern where there isn't one. Something our brains love to do...

Then again, there's not enough data about mass-extinctions to say they definitively follow a cycle or not.

 

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quillius
35 minutes ago, Seti42 said:

I wonder if this is another example of people finding a pattern where there isn't one. Something our brains love to do...

Then again, there's not enough data about mass-extinctions to say they definitively follow a cycle or not.

 

more importantly.....this part:

 

Quote

It is worth noting of course that if the 27.5 million year figure is accurate - and given that the last mass extinction event happened 66 million years ago

that reads as a contradiction to me....if we are nearly 40 million years over due then that in itself says the 27m is not accurate?

 

 

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MysteryMike

Aren't we currently in one?

It's called the 6th mass extinction and we've been kn it once the beginning of the Holocene. It is our doing.

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Myles
3 hours ago, quillius said:

 

 

that reads as a contradiction to me....if we are nearly 40 million years over due then that in itself says the 27m is not accurate?

 

 

I thought the same thing.  They proved their own idea was wrong.

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pbarosso

well, ill go with: most of the asteroids that were in a position to be flung about have already done so and theres just not much out there (or far less) to cause any major damage. the solar system is settling down.

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Tom1200
17 hours ago, quillius said:

That reads as a contradiction to me....if we are nearly 40 million years over due then that in itself says the 27m is not accurate?

Agree 100%.  A quick search of extinction events throws up lots of graphics like this one: 

There have been five mass extinctions in Earth's history. Now we're facing  a sixth. - The Washington Post

I know those labelled are just the major ones, but I can't see any clear 27-million-year cycle here. 

Next consider what we (think we) know about these particular extinction events:

  • end-Ordovician: continental drift  Gondwanaland drifted across the South Pole  ice cap grew  sea levels fell  habitat loss
  • late Devonian: lasted up to 25 million years, so extremely difficult to pinpoint one cause
  • end-Permian: Siberian Traps volcanic activity  dust clouds  blocked sunlight  disrupt photosynthesis  collapse of food chain
  • end-Triassic: no clear consensus
  • end-Cretaceous: great big bloody rock falling from space

Wiki lists over a dozen possible causes, and it's very probable these mass extinction events were caused by multiple triggers.  Too many straws, and all that.  So I can't see how any one theory is going to explain this (apparent) cycle.  And I don't think we're going to find the answers in an unreferenced article in slashgear.com

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quillius
26 minutes ago, Tom1200 said:

Agree 100%.  A quick search of extinction events throws up lots of graphics like this one: 

There have been five mass extinctions in Earth's history. Now we're facing  a sixth. - The Washington Post

I know those labelled are just the major ones, but I can't see any clear 27-million-year cycle here. 

Next consider what we (think we) know about these particular extinction events:

  • end-Ordovician: continental drift  Gondwanaland drifted across the South Pole  ice cap grew  sea levels fell  habitat loss
  • late Devonian: lasted up to 25 million years, so extremely difficult to pinpoint one cause
  • end-Permian: Siberian Traps volcanic activity  dust clouds  blocked sunlight  disrupt photosynthesis  collapse of food chain
  • end-Triassic: no clear consensus
  • end-Cretaceous: great big bloody rock falling from space

Wiki lists over a dozen possible causes, and it's very probable these mass extinction events were caused by multiple triggers.  Too many straws, and all that.  So I can't see how any one theory is going to explain this (apparent) cycle.  And I don't think we're going to find the answers in an unreferenced article in slashgear.com

agreed, then throw in the simple fact its been 66m years since last 'suspected' extinction event.....proves there is no cycle..

Do people not bother to think before they type these days?

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Tom1200
2 hours ago, quillius said:

Do people not bother to think before they type these days?

That would take effort, and leave me no time for sitting on my fat **** watching telly.  ;)

Damn my failing eyesight - which emoji is that?

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quillius
1 hour ago, Tom1200 said:

That would take effort, and leave me no time for sitting on my fat **** watching telly.  ;)

Damn my failing eyesight - which emoji is that?

sorry just in case my post was lost in translation, I mean the journalist not you :)

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kartikg
23 hours ago, pbarosso said:

well, ill go with: most of the asteroids that were in a position to be flung about have already done so and theres just not much out there (or far less) to cause any major damage. the solar system is settling down.

Yeah that actually makes sense. Most of the bombardment is over. 

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Abramelin
On 12/14/2020 at 3:02 PM, Seti42 said:

I wonder if this is another example of people finding a pattern where there isn't one. Something our brains love to do...

Then again, there's not enough data about mass-extinctions to say they definitively follow a cycle or not.

 

I think there may be a cycle of impact events of around 27 million of years, but that 'only' a few of those impact events actually resulted in an extinction event.

Saying, these extinction events are points on the graph, but don't form a graph.

Edit:

The impact cycle, in its most simplistic form, can be displayed as a sinusoid:

 

image002.jpg

The crests are the impact events.

And what I meant was that only a few of those crests are extinction events.

So, the extinction events are part of a cycle  but don't form a cycle just by themselves.

 

Edited by Abramelin

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Carnoferox

There is no 27 or 26 million year cycle of mass extinctions. This is a claim that has been recycled for the past 30 or so years, and somehow still gets published. This particular study has selectively sampled mass extinctions in order to force this result. They only included extinctions that affected terrestrial tetrapods, so all mass extinctions from the Ediacaran-Devonian are excluded. They included at least one "mass extinction" (end Jurassic) that is no longer even thought to have been a significant extinction event. For some reason they also excluded the end Pleistocene extinction event. Cherrypicked data = worthless results.

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Carnoferox

I would also like to note that, as is typical for these studies, none of the authors are paleontologists. Understanding the different faunas of each time period is crucial to quantifying mass extinctions, so if there are no paleontologists on the team it should automatically ring alarm bells. The lead author Michael Rampino has been pushing this pet hypothesis since the 90's about how mass extinctions are on a 26-27 million year cycle and how it is all somehow related to dark matter. No real data to back this hypothesis of course, but it makes for a good story to keep selling to magazines and newspapers.

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