How many years did it take ecosystems to recover from K-Pg Extinction event (Chicxulub asteroid)?

Submitted by virgoing t3_10xjlx4 in askscience

Hi, I'm doing research for fun stuff.

From my understanding of this article from Nature, the impact winter after the K-Pg meteor was caused by soot (and/or sulfur) in the atmosphere reducing sunlight penetration. And that the 10-ish years of the impact winter was much more responsible for the extinction event than the impact itself (ie. the sonic waves and tsunamis and heat and magnitude 11 earthquake and stuff).

I would like to figure out exactly what the timeline was for the world's recovery after K-Pg. This stuff is surprisingly hard to find, I swear.

I found a figure that said it took 30,000 years for the first microbes to start showing back up again. That feels weird. Why did the article say that the climate would be returned to normal after 10ish years but it still took 30,000 years for microbe life to return?

How long was it before the first big trees? How long until everything was more or less "back to normal" in terms of the presence of flora? Are we talking, like, 200 years or 200,000? At what point after K-Pg could I walk outside and see a green landscape?

Is this number different for fauna? Like, what's the earliest we saw animals thriving again?

I'm going crazy. If you're an expert I'd appreciate book recommendations or articles and whatnot. Point me in the right direction so I don't have to keep hasslin' you :)

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komatiitic t1_j7tj3vg wrote

The very unsatisfying answer is that nobody really knows. There aren't a lot of fossil beds immediately on either side of the K-Pg boundary, which means we don't really know how long the overall extinction took, let alone how long the recovery was, at least not on a global scale. There are estimates for the length of the extinction ranging from a few years to over 100,000.

Part of the problem is that you're dealing with an incredibly incomplete record. Preservation of fossils is rare, and finding them is difficult, so often researchers are trying to draw conclusions from very narrow sets of data and extrapolate it to the rest of the ecosystem. Like this one drawing conclusions from insect bites on fossilized leaves. They're making a lot of reasonable assumptions, but it's not exactly definitive even on a local scale.

It's also very difficult to narrow things down in geology/palaeontology to less than a few thousand years, so any numbers you find that are more precise than that aren't going to be based on actual data collected from the rocks. There's the convenient Iridium layer that generally lets you know which side of the K-Pg boundary you're on, but beyond that the most precise rock dates you can probably find would be +/-10,000 years.

So yeah. Any numbers you can get out of this are probably going to be large ranges, possibly overlapping each other.

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virgoing OP t1_j7uf0ro wrote

Replying to komatiitic (#1,760,176)

Thanks for taking the time to reply. This is still great to know! I'm glad to know that I'm looking at a scientific-community-wide blank in knowledge, and not just the blank in knowledge of my own research, which sometimes looks identical. Have a great day :)

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dittybopper_05H t1_j7v472g wrote

I found a figure that said it took 30,000 years for the first microbes to start showing back up again. That feels weird. Why did the article say that the climate would be returned to normal after 10ish years but it still took 30,000 years for microbe life to return?

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I think you're misinterpreting the article. It mentions that it took a long time for life to come back in the area adjacent or in the crater formed by the impact. That's to be expected, as that area was essentially sterilized by the impact

That that's not what would have happened all over the Earth. If *ALL* the microbes had died, all life would have also died. But we know it didn't. We know that plenty of animals survived the impact and the subsequent climate upheaval. After all, if they hadn't, we wouldn't exist!

So yeah, 10 years sounds like a reasonable figure for the soot and other debris launched into the stratosphere to fall out, and while 30,000 years sounds like a lot of time for life to return to the area of crater, I wouldn't dismiss it out of hand.

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pds314 t1_j82y4jj wrote

It's not really a properly defined question because there's no single good definition we can apply for "back to normal" if you mean "when did fern spores get more common than fungi and the light levels return to normal again" (a few years) the result is very different than "when did the 80 tonne herbivores and 8 tonne predators re-evolve?" (66 million years and counting).

IIRC it took something like 5-10 million years to get any mammalian herbivores over 500 kg coming back.

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electric_ionland t1_j83r256 wrote

Replying to virgoing (#1,778,440)

Sorry this looks like it was a bot answer that slipped through the cracks. Chat GPT and other similar tools are well known to simply make up believable facts. Do not take this answer as factual.

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