What Caused the Dinosaur Extinction?
theatlantic.com
What Caused the Dinosaur Extinction?
1–10 of 47 posts
Re: What Caused the Dinosaur Extinction?
#2Extremely 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.
Re: What Caused the Dinosaur Extinction?
#3This 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.
Re: What Caused the Dinosaur Extinction?
#4The 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.
Re: What Caused the Dinosaur Extinction?
#5Great 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?
Re: What Caused the Dinosaur Extinction?
#6Great 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…
The author seems to be talking about mining fossil fuels. And how they believe that fossil fuels will end humanity.
Re: What Caused the Dinosaur Extinction?
#7This 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 beneat…
According to the article, the vulcanism starts two hundred thousand years before the impact.
Re: What Caused the Dinosaur Extinction?
#8This 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 beneat…
According to the article, the vulcanism starts two hundred thousand years before the impact.
Sure, started, but...
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
Re: What Caused the Dinosaur Extinction?
#9This 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 beneat…
This was discussed in TFA.
Re: What Caused the Dinosaur Extinction?
#10Start 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.