The Asteroid That Killed the Dinosaurs Created the Amazon Rain Forest

https://www.scientificamerican.com/article/the-asteroid-that-killed-the-dinosaurs-created-the-amazon-rain-forest/

by hheikinh • 5 years ago

106 79 5 years ago

scientificamerican.com

nnx• 5 years ago

Creative destruction at its finest.

rrdharan2• 5 years ago

Out of curiosity, when did the asteroid extinction theory cement as the scientific consensus?

I seem to recall that in my childhood (1980s, Canadian elementary schools) it was still treated as only one of several competing explanations, but now it’s pretty much an accepted fact.

Which makes sense given all the evidence, but I still have this odd sensation making me feel like I missed the memo! Am I the only one who feels this way?

rrdharan2• 5 years ago

Answering my own question: https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...

So I guess it was indeed proposed around the time I was born and “proven” by the time I had outgrown dinosaurs as an interest/hobby...

JohnJamesRambo• 5 years ago

With the exception of some ectothermic species such as the sea turtles and crocodilians, no tetrapods weighing more than 25 kilograms (55 pounds) survived.[5]

I wish we could unite and start forming a plan to survive the next one. I wonder what that would entail?

ip263• 5 years ago

This part in particular:

https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...

I think was around when consensus shifted from "Yeah this is probably what happened" to "This is it"

jacobolus• 5 years ago

Check out this 2-year-old New Yorker article, https://www.newyorker.com/magazine/2019/04/08/the-day-the-di...

scolson• 5 years ago

The Chicxulub crater off the top of the Yucatan peninsula is attributed for that particular event. It wasn't really known until the early/mid 90s I don't think.

ghaff• 5 years ago

Right. Although even after the discoveries related to the K-t boundary and the crater, there was a school of thought that it was just a contributing factor to a pre-existing general decline. My understanding is that there's now a general consensus that it was much more of a singular cataclysmic event.

Symmetry3• 5 years ago

The crater was well known to oil and gas people long before that, but the knowledge didn't make its way to academic geology until the 90s.

chiefalchemist• 5 years ago

I don't know. A couple of years ago I read a piece in (I believe) The Atlantic that proposed it was a massive volcanic eruption that did the dinos in. The sub-plot of the article was how science gets attached to an idea (i.e., it was an asteroid) and more or less self-fulfills that idea despite plenty of evidence that calls it into question.

Found it!

https://www.theatlantic.com/magazine/archive/2018/09/dinosau...

plank_time7• 5 years ago

The idea that we can know with any degree of certainty that an event tens of millions of years ago was the single cause of dinosaur extinction is absurd. It’s bad science.

Case in point, a pandemic could have wiped out all the dinosaurs 1 million years before the asteroid hit and we would have no fossil evidence of that.

The asteroid theory is still just a theory and for anyone to be arrogant enough to say that it is fact doesn’t deserve to teach science in any capacity.

Jabbles3• 5 years ago

Adding in additional events that we have no evidence for would also be bad science.

https://en.wikipedia.org/wiki/Extinction_event#Other_hypothe...

Symmetry3• 5 years ago

There's a big difference between "with perfect certainty" and "with any degree of certainty". We can't be pefectly sure that the scenario you outline didn't happen but the timing and the idea of a virus acting like that are so improbable that we can be almost entirely certain it didn't play out like that. We're not perfectly certain it was the impact, but we are very certain with all the evidence that has built up.

quesera3• 5 years ago

OK, but most of what we consider fact about any era (including the present) is a consensus understanding/belief based on the best available evidence -- if we're lucky.

Everything we are told or taught is a simplification, or a model.

The distinction between "fact" and "theory" is not always as clear as you imply.

yongjik• 5 years ago

Paleontologists have a much more detailed view of the past than you think. There are fossils of fish and trees killed by the asteroid impact itself, buried by the tsunami.[1]

In the deposit, the team discovered an ancient freshwater pond whose occupants had been quickly cemented together by waves of sediment and debris. The fossils include sturgeon and six-foot-long paddlefish, their scales intact but their bodies ripped and smashed; marine mollusks; leaves and tree fronds, and the burned trunks of trees. The fish carcasses were not bloated, decayed, or scavenged, suggesting that they were buried quickly — and that few animals were left alive after the cataclysm to come digging.
The fossil deposit also teems with tektites, tiny glass beads that are the telltale fallout of planetary-scale impacts. Fifty percent of the fossilized fish were found with tektites in their gills, as if the fish had inhaled the material. Also recovered were tektites trapped in amber. Their chemical composition was unchanged in 66 million years, and it closely matched the unique chemical signature of other tektites associated with the Chicxulub event.

[1] https://www.nytimes.com/2019/03/29/science/dinosaurs-extinct...

jmchuster• 5 years ago

It took six million years for the forests to return to the level of diversity they had before the meteorite, and the species that slowly grew back were completely different than what came before.

It's just very difficult to think in terms of these timescales, when all of human history is only a few thousand years.

cheschire2• 5 years ago

Just imagine you've only got to trace your lineage through a few hundred ancestors to reach the beginning of recorded history!

ip263• 5 years ago

Setting aside ancient history like Egypt, any sense of modern recording started something like 400 BC. At 20 years between generations, that's only ~120 generations.

With this accounting, the United States was founded ~12 generations ago.

vbezhenar• 5 years ago

I'd argue that Human history starts at lest 3.3 millions years ago, when first stone tools were found.

throwaway894345• 5 years ago

“History” is often used to mean “written history” as in the opposite of “pre-history”. That seems to be the sense in which the parent is using the term.

tremon4• 5 years ago

In general "human history" starts with the first written word, around 10,000 BC. Everything before that is considered prehistory. Of course, humans didn't simply come into existence 12,000 years ago, but we have very little conception of life before The Word (tm).

aasasd• 5 years ago

I recommend nursing half a glass of wine to get just a wee bit lightheaded, putting on some ethereal music like Dead Can Dance, and reading on Wikipedia through the history of continent movements and formation and breakup of supercontinents. After a while such reading evokes rather curious feelings, and six million years won't seem so long when continents are swimming this and that way.

(‘A Passage In Time’ is a great compilation from DCD. E.g.: https://youtu.be/ajfVT_uk6j4)

ip263• 5 years ago

Prior to 2013, it was commonly cited as having happened about 65 million years ago, but Renne and colleagues (2013) gave an updated value of 66 million years.

  -- https://en.wikipedia.org/wiki/Alvarez_hypothesis

My first thought reading this is, here they are casually adjusting the date by 1,000,000 years, and meanwhile homo sapiens is 200,000-300,000 years old. Helps illustrates the timescales a little.

del_operator• 5 years ago

Also cool: https://www.nasa.gov/content/goddard/nasa-satellite-reveals-...

mtrovo• 5 years ago

This is really cool but I find it very hard to believe that this has the effect they are supposing here. We're talking about an area that's ~50% of Europe, so I believe microclimates can help much more than the dust from the other side of the world. It would be like saying the Europe only exists the way it is because of the gulfstream, be it in Ireland or Romania.

Also keep in mind that rhe Amazon rainforest is much more dense on the area around the Equator line, which happens on all over the world at this latitude, so there's nothing unique about Amazon here.

Another intriguing thing about this is that if this dust is so fertile then it's hard to believe that it would not impact in a positive way the african coast line around the Sahara.

snurfer3• 5 years ago

When you consider that extinction events are cyclical and correlate with our solar system's oscillation through the galactic middle plane, you can bet life on this planet will get wiped out again and there's little we can do about it. The question is: how much time do we have left? (My guess is 20-30M years.)

JoeAltmaier• 5 years ago

Citation?

snurfer3• 5 years ago

I don't think the primary source is online, but it was referenced in the article "Defining Intelligence-Favoring Galactic Parameters for targeted SETI searches" in the 15 Feb 2021 issue of the "Journal of the British Interplanetary Society".

xaedes• 5 years ago

Here is another one which relates it to the passing of our solar system throught the galactic plane: "Sun's Movement Through Milky Way Regularly Sends Comets Hurtling, Coinciding With Mass Life Extinctions", 2008

https://www.sciencedaily.com/releases/2008/05/080502092145.h...

``The Cardiff team found that we pass through the galactic plane every 35 to 40 million years, increasing the chances of a comet collision tenfold. Evidence from craters on Earth also suggests we suffer more collisions approximately 36 million years. Professor William Napier, of the Cardiff Centre for Astrobiology, said: "It's a beautiful match between what we see on the ground and what is expected from the galactic record."

The periods of comet bombardment also coincide with mass extinctions, such as that of the dinosaurs 65 million years ago. Our present position in the galaxy suggests we are now very close to another such period.´´

----

Edit: There are also papers which relates it to passing through spiral arms (different cycle).

da39a3ee2• 5 years ago

Could someone post a link to a PDF of the original article please?

tylerchr• 5 years ago

Why not you?

da39a3ee2• 5 years ago

Because I couldn't get scihub to work; I think my ISP may be blocking it, or else my browser has over active security settings.

How is your question contributing to the discussion? Mine had the potential to give participants access to the primary source under discussion :)

TheMagicHorsey2• 5 years ago

It's terrifying to me that we still don't have a solution to prevent an asteroid of that size from wiping us out. I suppose they only come around every few million years, but still.

itisit• 5 years ago

It's not terrifying at all once you grasp how astronomically challenging it is to pulverize or divert an asteroid of such scale:

https://www.vox.com/science-and-health/2019/3/7/18251559/ast...

TheMagicHorsey2• 5 years ago

It's still terrifying.

Its just more understandable that we haven't solved the problem.

The Asteroid That Killed the Dinosaurs Created the Amazon Rain Forest

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