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ysabetwordsmithThe Kotlin Crisis: Earth’s first mass extinction may have been far worse than previously believed
Fossils of the first sea creatures, long assumed to have vanished before a major mass extinction about 550 million years ago called the Kotlin Crisis, have now been found and are providing new details about that time period.
This discovery transforms what once looked like a routine species decline in Earth’s early history into what may be the first catastrophic extinction in animal history.
Second, actually, after the Great Farting Oxygen Event changed the atmosphere from reducing to oxydizing -- almost everything died, except a few archaea that found anoxic refuges and a few organisms that figured out how to use oxygen. But most people forget about that one.
Anyhow, look at the pattern:
* Ediacaran ecosystems had good diversity for that early in evolution. (They're not the first multicellular organisms, as they're way too developed for that. People forget this also.) There were mats, frond-like things, trefoil shapes, and so on. Clear niche partitioning was already underway. But they're almost totally unlike anything we see today. It's likely that some of them belonged to branches of life that aren't related to what survived.
* And then "something" happened.
* The Cambrian Explosion introduced much greater diversity, including clearly identifiable ancestors of modern organisms and a bunch of stuff that has since died out. Some of that is really wild, "throw spaghetti at the wall and see what sticks" innovation.
That's the pattern around a mass extinction. Regardless of the cause, that Ediacaran system collapsed. The few survivors, finding themselves faced with a lot of empty niches, underwent explosive radiation to fill those gaps. That's the Cambrian Explosion. Even without direct evidence of an extinction cause (e.g. massive volcanic activity), whenever you have Layer A that looks nothing like Layer B, a mass extinction is usually why. A glaciation event at the end of the Ediacaran period is one possible cause. So it's interesting to see someone else talking about this kind of extinction.
Earlier in the Ediacaran period, the normal trickle of extinctions seemed unusually low in the fossil record.
Instead of steady turnover, many lineages showed long stretches with little visible change until the Kotlin Crisis.
\o/
Chemical clues in rock layers from that interval have pointed to falling oxygen in ancient seas.
Lower oxygen levels would have squeezed animals into smaller livable zones, since oxygen-poor water limits breathing and feeding.
Changing seafloors may also have mattered, since early burrowers broke bacterial films and reshaped habitats for immobile forms.
Very often, a mass extinction doesn't come from a single cause, but rather a confluence of negative impacts that together overwhelm most species' ability to cope. Like what's happening now.
The fossils at Inner Meadow upend what once appeared to be a tidy progression of early life.
Instead of neatly replacing one another, these communities overlapped in time, linking the flourishing Avalon biota directly to the brink of extinction.
The discovery collapses the gap between stability and catastrophe – showing that the crisis struck not after a slow fade, but at the height of diversity. Now the question shifts from whether a major extinction occurred to why.
This is so exciting to follow. :D
Fossils of the first sea creatures, long assumed to have vanished before a major mass extinction about 550 million years ago called the Kotlin Crisis, have now been found and are providing new details about that time period.
This discovery transforms what once looked like a routine species decline in Earth’s early history into what may be the first catastrophic extinction in animal history.
Second, actually, after the Great Farting Oxygen Event changed the atmosphere from reducing to oxydizing -- almost everything died, except a few archaea that found anoxic refuges and a few organisms that figured out how to use oxygen. But most people forget about that one.
Anyhow, look at the pattern:
* Ediacaran ecosystems had good diversity for that early in evolution. (They're not the first multicellular organisms, as they're way too developed for that. People forget this also.) There were mats, frond-like things, trefoil shapes, and so on. Clear niche partitioning was already underway. But they're almost totally unlike anything we see today. It's likely that some of them belonged to branches of life that aren't related to what survived.
* And then "something" happened.
* The Cambrian Explosion introduced much greater diversity, including clearly identifiable ancestors of modern organisms and a bunch of stuff that has since died out. Some of that is really wild, "throw spaghetti at the wall and see what sticks" innovation.
That's the pattern around a mass extinction. Regardless of the cause, that Ediacaran system collapsed. The few survivors, finding themselves faced with a lot of empty niches, underwent explosive radiation to fill those gaps. That's the Cambrian Explosion. Even without direct evidence of an extinction cause (e.g. massive volcanic activity), whenever you have Layer A that looks nothing like Layer B, a mass extinction is usually why. A glaciation event at the end of the Ediacaran period is one possible cause. So it's interesting to see someone else talking about this kind of extinction.
Earlier in the Ediacaran period, the normal trickle of extinctions seemed unusually low in the fossil record.
Instead of steady turnover, many lineages showed long stretches with little visible change until the Kotlin Crisis.
\o/
Chemical clues in rock layers from that interval have pointed to falling oxygen in ancient seas.
Lower oxygen levels would have squeezed animals into smaller livable zones, since oxygen-poor water limits breathing and feeding.
Changing seafloors may also have mattered, since early burrowers broke bacterial films and reshaped habitats for immobile forms.
Very often, a mass extinction doesn't come from a single cause, but rather a confluence of negative impacts that together overwhelm most species' ability to cope. Like what's happening now.
The fossils at Inner Meadow upend what once appeared to be a tidy progression of early life.
Instead of neatly replacing one another, these communities overlapped in time, linking the flourishing Avalon biota directly to the brink of extinction.
The discovery collapses the gap between stability and catastrophe – showing that the crisis struck not after a slow fade, but at the height of diversity. Now the question shifts from whether a major extinction occurred to why.
This is so exciting to follow. :D
