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The P-T extinction (a.k.a. the Great Dying) tends to be considered the worst - for example, Wikipedia states:

It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

Presumably the "96% of all marine species" (which references two books, neither of which I have) is in terms of multicellular marine species or some similar subcategory that's easier to observe in the fossil record (I could be wrong).

My question is this: Would the Great Oxygenation Event not have killed a higher proportion of organisms (taking into account all organisms)?

I know that we don't have any records that can tell us how many died in the GOE and hence this question is necessarily speculative, but surely nearly all organisms pre-GOE would have been obligate anaerobes (and therefore found oxygen to be toxic)?

What I'm unsure about is how single-celled organisms fared in more recent (Phanerozoic) extinctions, as most discussion seems to be in terms of opisthokonts (i.e. animals + fungi) and archaeplastidans (i.e. plants + algae).

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  • $\begingroup$ Would the GOE have actually killed organisms? Seems to me that it was slow enough so that oxygen-favoring organisms just reproduced better. $\endgroup$ – jamesqf Aug 19 '17 at 6:31
  • $\begingroup$ I guess the nuclear war that happened in 2077 doesn't count? $\endgroup$ – John Dvorak Jan 11 '18 at 3:41
  • $\begingroup$ @2077: No, because that just killed off a lot of humans, allowing the biosphere to recover from the Anthropocene Extinction Event. $\endgroup$ – jamesqf Jan 11 '18 at 6:02
  • $\begingroup$ Do you actually mean "proportion of organisms", or "proportion of species including single-celled organisms"? Your title says the former but your text suggests you mean the latter. $\endgroup$ – arboviral Feb 10 '18 at 10:01
  • $\begingroup$ I'm voting to close this question as off-topic because this is SE Biology, not The Guiness Book of Records. $\endgroup$ – David Jun 10 '18 at 9:27
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This is a great question. I decided to research it and here is what I found. For some reason the GOE is not on lists of the "big 5" mass extinctions. The question is why?

I think it's due to the pace of the event. The event is described as happening 2.45–2.32 billion years ago.

enter image description here

This is a timescale in billions of years. So it isn't really a proper mass extinction. Little is known about the time scale of the evolution of cyanobacterial lineages.

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    $\begingroup$ The GOE is not in the Big Five because the Big Five were recognized based on Sepkoski's work on marine invertebrates from the Phanerozoic (i. e. the last half billion years). The "Big Five" refers only to the main five extinctions of the Phanerozoic. $\endgroup$ – plannapus Sep 20 '17 at 11:02

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