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Effect of a giant meteorite impact on Paleoarchean environment and life

chemistryworld.com

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Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#51

Post by jvanderbot »

Timwi wrote: post #46

The article perpetuates the widespread misconception that dinosaurs are extinct. In reality, (some) dinosaurs survived and evolved into modern birds. Everything from penguins to ostriches, hummingbirds to albatrosses and woodpeckers to eagles is a dinosaur. Science communication should do better and clear up this misunderstanding. It would be so much cooler to say that the asteroid killed the pterosaurs . Not only is…

This is fascinating. Although I'm having trouble mapping your comment onto this: https://opengeology.org/historicalgeology/case-studies/dinos...

What is the complete set and which are extinct?

Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#52

Post by datameta »

kevinkeller wrote: post #6

I love this type of articles where we can reconstruct what happened so long ago just based on careful observations. Some other instances I've come across: * The K-Pg extinction event that wiped off dinosaurs had the impact it did because the asteroid happened to impact a shallow water region. This kicked up a lot of sulfur (in gypsum) that further affected global climate: https://en.wikipedia.org/wiki/Chicxulub_crate…

Here is the Chixculub impact effect in realtime simulated as happening in today's world: https://youtu.be/ya3w1bvaxaQ?si=S-jmFegMo63HKzID

Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#53

Post by datameta »

rcyeh wrote: post #38
iambateman wrote: post #29

Earlier quoted context omitted.

The article claims that 363 billion tons of phosphorous were dropped on earth 3.26 billion years ago during a decade of darkness. I’m completely incapable of making sense of that claim because it’s so far outside of my expertise. But my fundamental problem is that I don’t trust the source’s incentives to deliver reliable information and I want someone independent to help me understand if this is a how strong or weak…

Just going through the numbers: 363 BB tons / (1 ton / cu m) / (1 BB cu m / cu km) is the mass of a 9-km-diameter ice ball, smaller for rockier materials. 363 BB tons / 10 years = 100 MM tons / day. By comparison, Mount St Helens (1980) and Eyjafjallajökull (2010) each produced 500 MM tons of ash. So the amount of material is about equivalent to having a similarly-sized volcano eruption every few days for ten years s…

We're assuming an even average distribution, and comparing ash to spherules - which would have different patterns of sedimentation depending on how far from epicenter one is. Although, for a large enough impact, the distribution radii overlap around the planet so there may be quite a bit of averaging as the sun+atmosphere provides a mixing medium and the energy to do so.

Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#55

Post by addaon »

jvanderbot wrote: post #51
Timwi wrote: post #46

The article perpetuates the widespread misconception that dinosaurs are extinct. In reality, (some) dinosaurs survived and evolved into modern birds. Everything from penguins to ostriches, hummingbirds to albatrosses and woodpeckers to eagles is a dinosaur. Science communication should do better and clear up this misunderstanding. It would be so much cooler to say that the asteroid killed the pterosaurs . Not only is…

This is fascinating. Although I'm having trouble mapping your comment onto this: https://opengeology.org/historicalgeology/case-studies/dinos... What is the complete set and which are extinct?

> What is the complete set and which are extinct?

That's as good a complete tree as you're likely to get, down to the class level. Some species in the class Aves survived, and progenitor species with Aves are still around today. There's no significant evidence of species in other classes of the clade Dinosauria surviving much past the impact boundary.

You can push this up one level to the clade Avemetatarsalia (including Pterosaurs along with Dinosaurs) and the statement above would still be true; but pushing it further to Archosauria would not be valid, because crocodilians survived (and survive) as well.

Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#56

Post by chiefalchemist »

Arech wrote: post #43
chiefalchemist wrote: post #31

Earlier quoted context omitted.

Not to nitpick but the dinosaurs were on already on the way out, the asteroid merely finished them off early. https://www.theatlantic.com/magazine/archive/2018/09/dinosau...

To the best of my knowledge not everyone agrees to that hypothesis. One of the strongest arguments against it is that paleontological evidence is always incomplete. Holes in it that are treated in favor of the hypothesis are actually smaller or comparable to holes that appear just due to incompleteness.

Read the article. That's the subplot. We get to see just how non-scientific science really is. The true and current evidence points to an asteroid being the final blow to an already declining environment. But the status quo narrative so strong that egos and biases override facts.

Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#57

Post by Timwi »

jvanderbot wrote: post #51
Timwi wrote: post #46

The article perpetuates the widespread misconception that dinosaurs are extinct. In reality, (some) dinosaurs survived and evolved into modern birds. Everything from penguins to ostriches, hummingbirds to albatrosses and woodpeckers to eagles is a dinosaur. Science communication should do better and clear up this misunderstanding. It would be so much cooler to say that the asteroid killed the pterosaurs . Not only is…

This is fascinating. Although I'm having trouble mapping your comment onto this: https://opengeology.org/historicalgeology/case-studies/dinos... What is the complete set and which are extinct?

The diagram in your link only shows the dinosaurs, not the entire tree of animals alive at the time. Within that diagram, everything except Aves (which, incidentally, is the Latin word for birds) is believed to be extinct.

The article makes no mention of other clades that lived during the Cretaceous, such as the pterosaurs, or indeed the mammals. Just as birds are descendants of the few surviving dinosaurs, we are descendants of the few surviving mammals.

Re: Effect of a giant meteorite impact on Paleoarchean environment and life

#58

Post by Timwi »

Qem wrote: post #48
Timwi wrote: post #45

Earlier quoted context omitted.

The dinosaurs were not “wiped off”, by which I mean they are not extinct. This is an extremely widespread misconception that popular science articles like this one keep perpetuating. We should do better and help people understand that (some) dinosaurs survived and evolved into modern birds. Birds are dinosaurs. Dinosaurs are alive today.

When referring to dinosaurs, most people are thinking about non-avian, teethed dinosaurs anyway.

I get that, but most people don't know that birds evolved from dinosaurs that survived the asteroid (which I think is both interesting and important to know) and I think it's the responsibility of science communicators to... communicate that.
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