
What Caused the Dinosaur Extinction? - bkudria
https://www.theatlantic.com/magazine/archive/2018/09/dinosaur-extinction-debate/565769/?single_page=true
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pfdietz
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.

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vertline2
Is it possible for a meteor to cause a chain of volcanoes to blow? like all
the pressure under the crust gets rattled around?

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ridgeguy
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_cha...](https://en.wikipedia.org/wiki/Caloris_Planitia#Antipodal_chaotic_terrain_and_global_effects)

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flukus
> 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.

Could it be worked backwards, there a re a number of flood basalts, some as
recently as 10mya, is there any evidence of impacts for any others? Or is
there some reason the Deccan traps stand out compared to the others?

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ridgeguy
Good idea. There may be enough impact and vulcanism events with reasonably
good dating to search for the former as a cause of the latter.

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mordant
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
According to the article, the vulcanism starts two hundred thousand years
before the impact.

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EdwardDiego
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)

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BuckRogers
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.

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tokyodude
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?

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dannylandau
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.

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jhbadger
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
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.

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bethly
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.

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lkrubner
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.

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wild_preference
What’s with all the pretentious exposition? You could’ve shared your shower-
thought in 140 chars.

~~~
dang
Please don't be nasty here.

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

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apo
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?

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

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mr_toad
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
'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.

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woodandsteel
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.

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ncmncm
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.

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isoskeles
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.

