https://cosmosmagazine.com/palaeontology/big-five-extinctions

"End Ordovician, 444 million years ago, 86% of species lost

"Graptolites, like most Ordovician life, were sea creatures. They were filter-feeding animals and colony builders. Their demise over about a million years was probably caused by a short, severe ice age that lowered sea levels, possibly triggered by the uplift of the Appalachians. The newly exposed silicate rock sucked CO2 out of the atmosphere, chilling the planet.

"Late Devonian, 375 million years ago, 75% of species lost

"Trilobites were the most diverse and abundant of the animals that appeared in the Cambrian explosion 550 million years ago. Their great success was helped by their spiky armour and multifaceted eyes. They survived the first great extinction but were nearly wiped out in the second. The likely culprit was the newly evolved land plants that emerged, covering the planet during the Devonian period. Their deep roots stirred up the earth, releasing nutrients into the ocean. This might have triggered algal blooms which sucked oxygen out of the water, suffocating bottom dwellers like the trilobites.

"End Permian, 251 million years ago, 96% of species lost

"Known as “the great dying”, this was by far the worst extinction event ever seen; it nearly ended life on Earth. The tabulate corals were lost in this period – today’s corals are an entirely different group. What caused it? A perfect storm of natural catastrophes. A cataclysmic eruption near Siberia blasted CO2 into the atmosphere. Methanogenic bacteria responded by belching out methane, a potent greenhouse gas. Global temperatures surged while oceans acidified and stagnated, belching poisonous hydrogen sulfide. “It set life back 300 million years,” says Schmidt. Rocks after this period record no coral reefs or coal deposits.

"End Triassic, 200 million years ago, 80% of species lost

"Palaeontologists were baffled about the origin of these toothy fragments, mistaking them for bits of clams or sponges. But the discovery of an intact fossil in Scotland in the 1980s finally revealed their owner – a jawless eel-like vertebrate named the conodont which boasted this remarkable set of teeth lining its mouth and throat. They were one of the first structures built from hydroxyapatite, a calcium-rich mineral that remains a key component of our own bones and teeth today. Of all the great extinctions, the one that ended the Triassic is the most enigmatic. No clear cause has been found.

"End Cretaceous, 66 million years ago, 76% of all species lost

"The delicate leafy sutures decorating this shell represent some advanced engineering, providing the fortification the squid-like ammonite required to withstand the pressure of deep dives in pursuit of its prey. Dinosaurs may have ruled the land during the Cretaceous period but the oceans belonged to the ammonites. But volcanic activity and climate change already placed the ammonites under stress. The asteroid impact that ended the dinosaurs’ reign provided the final blow. Only a few dwindling species of ammonites survived. Today, the ammonites’ oldest surviving relative is the nautilus. Will it survive the sixth great extinction?"

Comment: Raup claims in his book, all who lost had bad luck. The website has great pictures with a great artists version of a trilobite


> dhw: If I wear my theist hat, I can certainly see that a divinely designed mechanism producing all kinds of weird, platypussy wonders might serve the purpose of satisfying curiosity, providing relief from eternal boredom, having fun, learning new things etc. I can also see in all organisms, including the platypus, the purpose of survival. But what I cannot see is how the platypus - as unique in its way as homo sapiens, being the sole survivor of its wider family - can be part of your God's great plan to produce you and me. And you can multiply that example by all the other millions of extant and extinct natural wonders and evolutionary innovations which you insist also required God's personal intervention. - You wear two hats, so you must be two-headed. I still invoke the balance of nature to explain it, plus a drive to extreme inventiveness to see what evolves.

DAVID: If one looks for purpose one finds it.
> 
> dhw: I'm still waiting for a platypussy purpose, but thank you for this very honest assessment of your thought processes.-I'm sorry you can't see purpose.

dhw:I would suggest that evolution is the consequence of an in-built drive (possibly built in by your God) for survival and or improvement, and somewhere along the evolutionary line interbreeding may well have played a role in the production and survival of most new species (broad and narrow senses). - Agreed
> 
> dhw: If prediction was the art of looking retrospectively at what has already happened, we would all be infallible prophets! However, knowing what has happened does not mean that it had to happen that way - only that it did happen that way. - However, if a result is highly unusual, as in the production of human and their level of consciousness, one can strongly suggest something or somebody monkeyed with the works.
> 
> DAVID (under “Convoluted human evolution”) DNA has shown that our evolutionary tree is very bushy and more like a river delta with streams in every direction: - > https://aeon.co/ideas/human-evolution-is-more-a-muddy-delta-than-a-branching-tree?utm_s... 
> If your God specially wanted to create homo sapiens, why could he not simply have created homo sapiens (as he did in Genesis)? - Did you miss thee point? The other streams interbred with humans giving them immunity and other attributes the humans had not developed and were helped by. - > 
> DAVID's comment: Looks like a guided evolution to me since the pattern is so unusual compared to other primate species.
> 
> dhw; We should not ask such questions, should we? Whatever is here was meant to be here, so God must have guided it to be here. - If one looks for purpose one finds it.

dhw: However, I take Raup's point and yours: it's bad luck either way on the organisms slaughtered either by chance or by God's choice. Not sure how such a comment helps us understand the process of evolution, though.-Getting rid of the old allows for new species to develop,i.e., dinosaurs, no more.-> dhw: If we believe in common descent, evolution only shows us that humans descended from apes, just as every other organism descended from preceding organisms. Or are you telling us that there was a strong drive for earlier organisms to produce weaverbirds, elephants and duckbilled platypuses?-The only strong drive I see is for humans. See today, convoluted human evolution entry.
> 
> DAVID: Their physical and mental capacities are different in kind from apes, and in this portion of known evolutionary history extinctions played no role unless one looks back 60+ million years ago to Chicxulub and goodbye dinos. 
> 
> dhw: So if they are different in kind, how does that make them predictable?-I'm looking retrospectively at how we appeared.

DAVID: We don't know if the Chicxulub asteroid was God's doing or not. The 'bad luck' quote is in the title of David Raup's highly regarded book. What seems to be true is that with each giant extinction, evolution advanced to more complex forms. If God is at work the process is working. Humans are here. Not at all unpredictable.
> 
> dhw: You obviously share Raup's view that most extinctions are bad luck, since you have stated it yourself. Bad luck and good luck are synonymous with chance. This means your God either couldn't or didn't want to control the environment, except for the occasional dabble. -Raup's 'bad luck' is his way of saying that sudden environmental changes caused extinctions. My interpretation and his is that this means the life that became extinct couldn't adapt fast enough to survive, no more. It does not imply God hurled Chicxulub or not. He may have.-> dhw: And if he couldn't or didn't control the environment, “most” of the consequences would also have been unpredictable (part of the great entertainment, perhaps). As for humans, leaving aside the question of who or what would have been capable of making predictions, I thought your whole “difference” campaign was based on your belief that they were NOT predictable, and it needed some really special dabbling from your God to produce them.-You are off on a tangent. Evolution shows us there was a strong drive to create humans out of apes. Their physical and mental capacities are different in kind from apes, and in this portion of known evolutionary history extinctions played no role unless one looks back 60+ million years ago to Chicxulub and goodbye dinos.

David's comment: This study shows the balance of nature is so important and current environment is part of that balance. Most extinctions are bad luck, described in previous entries.
> 
> dhw: Balance of nature simply means relations between living organisms and their environment. If the environment goes bust, the organisms go bust. And if extinctions are bad luck, it makes nonsense of the whole concept of divine planning and preprogramming. Your God carefully creates all these wonderful creatures, and then a bit of bad luck kills 99% of them! The whole process reeks of chance, and the only theistic explanation I can see is that this is how your God wanted it. In other words, he created all the conditions that would lead to an unpredictable ebb and flow of comings and goings (though he could do the occasional dabble if he felt like it). If you disagree, please give me an alternative theistic explanation for what you call “bad luck”.-We don't know if the Chicxulub asteroid was God's doing or not. The 'bad luck' quote is in the title of David Raup's highly regarded book. What seems to be true is that with each giant extinction, evolution advanced to more complex forms. If God is at work the process is working. Humans are here. Not at all unpredictable.


> "The culprit? Catastrophic volcanic eruptions that spewed enough lava to cover Australia led to the die-off at the end of the Permian era, the researchers found." [/i]
> 
> dhw: Preprogrammed by God, who had preprogrammed 10% of marine species and 25% of land dwellers to survive so that they could eventually create the innovations necessary to produce humans? Or a random catastrophe which some organisms were lucky enough to survive so that they were able to continue the higgledy-piggledy process of evolution?-Random catastrophe. The survivors had survival mechanisms responses which had been honed to a fine point through previous catastrophes, all guided by God. Theistic evolution solves all problems.

The Permian-Triassic extinction of 250 mya was the most severe. Up to 90% of all species lost (don't tell the EPA). The theory has always been a volcanic period, especially in Siberia. Now it appears to be verified:

http://blogs.scientificamerican.com/history-of-geology/2011/09/16/large-igneous-provinc...

New pinointing of the extinction:

http://www.sciencedaily.com/releases/2011/11/111117143955.htm