What Caused the Dinosaur Extinction?

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.

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.

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.

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/

at about the 10 minute mark

or visual

https://www.youtube.com/watch?v=ZYoqtBEzuiQ#t=15m

Is that still a valid theory?

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.

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.

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.

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?

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.

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.

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.

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.