WI no Permian Extinction

For those of us who are biology nerds on this site:

A long time ago we had a thread discussing what if there was no K-T Extinction event.

Well, I am positing the question of what if there was no Permian Extinction, the largest dying of life in Earth's history. 90% of all life was destroyed in this event. The jury is still out on what actually caused this event, but it looks like it could have been caused by super-volcanic activity and the mass desertification of Pangaea.

So, what are some other routes life could have taken with these other species left living (longer). Would mammals evolve at all? Would Synapsids continue to dominate the planet, and how might they change over time? How will the precursors to Dinosaurs evolve? How will plant life change?

I know these are big questions, and there is certainly a lot of room to speculate, so let's have at it

Archosaurs were already present in late Permian, but most known post permian groups would be butterflied away. Sorry, no dinosaurs, birds, pterosaurs(?), crocodiles... It would be our world... Synapsid world!

I guess various neat beasties such as Gorgonopsids would still exist till jurassic, but they would eventually fade away and let other groups to fill their niches. Cynodonts looks particulary viable, I guess they would even without P-T manage to diversify in wide range of forms.

Dicynodonts were quite diverse in OTL mesozoic (mostly thanks to few surviving species, which afterwards reached so massive numbers, that they formed undoutable majority of vertebrate biomass) and I dont see why they couldnt repeat their success, as they were already on rise in late Permian.

But anything beyond later Triassic is hard to predict

This would require a massive geological PoD. The best explanation I have heard for the end-Permian extiction event(s) is that given by Peter Ward:

1. Massive flood basalt volcanism in what will become Siberia (the largest such eruptions in hundreds of millions of years).

2. Big spike in atmospheric CO2 levels.

3. As the polar regions warm and the temperature differential between the equatorial and polar regions reduces, global oceanic circulation slows and then comes to a halt.

4. Without aerated water reaching the ocean bottoms, the deep ocean becomes anoxic, like the Black Sea today. Mass extinction begins.

5. At the same time, surface water becomes much warmer and contains less dissolved oxygen (warm water is less capable of retaining dissolved gases).

6. Eventually, the deep ocean water's oxygen levels reach nearly zero, and sulfur-metabolizing bacteria begin to proliferate.

7. These bacteria release huge amounts of H2S into the ocean water.

8. Almost all oxygen-breathing life in the oceans dies, with the exception of a number of "refugia" that sustain oxygen-breathing life in isolated basins, cut off from the wider ocean, where the sulfur-metabolizing bacteria fail to become established. Mass extinction worsens.

9. Oceanic oxygen production plummets, and atmospheric oxygen levels drop, as most oceanic plant life is poisoned by dissolved H2S.

10. Land life is put under severe stress due to extreme heat and reduced atmospheric oxygen levels.

11. H2S starts to build up in the atmosphere, putting additional stress on the already suffering land life (and plant life, which also poorly tolerates H2S). Mass extinction at its worst.

12. Volcanism eventually subsides.

13. Atmospheric CO2 levels drop as CO2 is captured during chemical erosion.

14. Global temperatures drop.

15. Since polar temperatures drop further and more quickly than equatorial temperatures, temperature differential between equator and poles increases.

16. Oceanic circulation restarts and deep ocean becomes oxygenated.

17. Oxygen kills off sulfur-metabolizing bacteria.

18. Killing mechanisms (extreme heat plus lowered oxygen plus H2S poisoning) no longer operating. Mass extinction is over.

So if the Siberian flood basalts do not erupt, the end-Permian extinction could be avoided.

NOTE -- this mechanism would also help explain the end-Cretaceous extinction. This happened at the same time as the emplacement of the Deccan Traps, another massive flood basalt episode. I strongly believe that a similar, although less severe killing mechanism was operating (sulfur-metabolizing bacterial blooms probably did not happen during that mass extinction), which put the late-Cretaceous biosphere under heavy pressure. The Chicxulub impact merely provided the final blow. This also explains why other asteroid impacts that were almost as large did little damage to life on Earth -- the biosphere had been healthy when those impacts occurred.

Very hard to avoid, but of course one obvious result is no dinosaurs.

yourworstnightmare said:

Very hard to avoid, but of course one obvious result is no dinosaurs.

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Definitely no primates. Which begs the question of what is writing the alternate history.

Errnge said:

For those of us who are biology nerds on this site:

A long time ago we had a thread discussing what if there was no K-T Extinction event.

Well, I am positing the question of what if there was no Permian Extinction, the largest dying of life in Earth's history. 90% of all life was destroyed in this event. The jury is still out on what actually caused this event, but it looks like it could have been caused by super-volcanic activity and the mass desertification of Pangaea.

So, what are some other routes life could have taken with these other species left living (longer). Would mammals evolve at all? Would Synapsids continue to dominate the planet, and how might they change over time? How will the precursors to Dinosaurs evolve? How will plant life change?

I know these are big questions, and there is certainly a lot of room to speculate, so let's have at it

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Actually, its worth noting that Synapsids DID survive the permain extinction:
Lystrosaurus is thought to have lived on well into, the early to mid triassic, not only surviving but THRIVING-up to 95% of all terrestrial land animals in the early triassic was a Lystrosaurus. This makes it the most succesful land animal in history.
http://en.wikipedia.org/wiki/Lystrosaurus#Dominance_of_the_Early_Triassic

With that in mind, it is fair to speculate that the synapsids could well have continued to thrive without a permain extinction and continued to evolve into mammals ( although most scientists agree that lystrosaurus is not in fact the direct ancestor to all mammals.) However, other lines of mammal like reptiles were also evolving alongside and, crucially the first dinosaurs. Now, whether or not dinosaurs could have evolved or not, i still think that the synapsids would eventually have been outcompeted and forced into extinction by another line of creatures due to several factors that also caused the lystrosaurus' extinction OTL:

Overly specialised diet makes it vulnerable to enviromental change-like we see at the end of the triassic.

Ecological competition from archosaurs.

However, even when it died out, it would still have an impact as its ancestors-now evolved a lower jaw as opposed to beak and evolved into shrew like animals to cope with less food would thrive sooner then OTL and become the uncontested rulers of earth-unless dinosaurs evolve.

Its also worth thinking about the ocean: 95-99% of all sealife died in the permain event, devastating the worlds ecology and wiping out the trilobites. These little critters had been previously highly succesful, so without a major extinction event invertabrates would continue to occupy more niches then fish or reptiles.

Also remember that if they dont die from this extinction, then another extinction event will. It's natures way of repeating itself.

To learn how i persieve and show how a group of animals evolve to reoccupy niches after a mass extinction, here's my TL:
A brave new world: Dinosaurs not quite wiped......

and watch a strange version of the eocene where Troodon still reignes supreme and terror birds and hominids never evolve.
Hope this helps!
My TL:
A brave new world: Dinosaurs not quite wiped......

Things might not be super-radically different. Assuming we do get our POD (which, as has been said, would involve butterflying away a massive amount of stuff,) we might actually get things ending up not too far away from IOTL. The P/T (boundary) extinction wasn't quite the Ultimate Doom for tetrapods, and the therapsid-domination-with-slow-encroaching-by-archosaurs scheme that was the regime for much of the Triassic was already established by the latest Permian. And archosaurs didn't beat out their synapsid competition until the ending of the Triassic, so even without a PTB extinction they still have a good shot.

Assuming that archosaurs still figure out their upright stance at the same time as OTL, there's a good chance they'll end up running the Mesozoic, though there's likely to be a greater diversity of synapsids for longer- in fact, you might even see a delayed appearance of true mammals (going on the view that dinosaur dominance forced synapsids into the small-marginal-nocturnal role.) However, mammals are almost guaranteed to crop up at some point.

Basically, we'd probably see a messier, more vibrant Triassic and less total dinosaur supremacy so soon (on land, anyway.)

As has been said, synapsids would probably continue to dominate however it is very unlikely given no permian extinction that the mammalian line of synapsids would develop

It's hard to predict what the world would be like other than saying that

Tycho343 said:

Things might not be super-radically different. Assuming we do get our POD (which, as has been said, would involve butterflying away a massive amount of stuff,) we might actually get things ending up not too far away from IOTL. The P/T (boundary) extinction wasn't quite the Ultimate Doom for tetrapods, and the therapsid-domination-with-slow-encroaching-by-archosaurs scheme that was the regime for much of the Triassic was already established by the latest Permian. And archosaurs didn't beat out their synapsid competition until the ending of the Triassic, so even without a PTB extinction they still have a good shot.

Assuming that archosaurs still figure out their upright stance at the same time as OTL, there's a good chance they'll end up running the Mesozoic, though there's likely to be a greater diversity of synapsids for longer- in fact, you might even see a delayed appearance of true mammals (going on the view that dinosaur dominance forced synapsids into the small-marginal-nocturnal role.) However, mammals are almost guaranteed to crop up at some point.

Basically, we'd probably see a messier, more vibrant Triassic and less total dinosaur supremacy so soon (on land, anyway.)

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As it is, i'm afraid even small changes in prehistoric terms usually means massive repuccusians. One species of dinosaur surviing butterflies away mankind-and many lines of mammals and birds. Yes, mammals will almost certainly still evolve, but the presence of synapsids will influence how they evolve and the consequent evolution of other creatures as well ( an example of how relient animals are on each other.)

Dinosaurs may well evolve, but they will definatly-as you said-be in less of a position to occupy many niches that will instead be occupied by mammals and synapsids. No saurapods, no tyranosaurus, proibly limited to smaller herbivors like Hypsolophodon and therapods like Troodon. Huge repucussians.

I think that the more primitive therapsids became extinct after a certain period of time (eg Gorgonopsia and perhaps Therocephalia). Their place could take some Cynodontia line, which can develop larger predators. By analogy, we know from the Cenozoic, during extinction Creodonta and Mesonychia, rapidly develop new lines of order Carnivora. Here it is possible analogous situation. After the extinction of Dinocephalia Gorgonopsia increased in size.

Shall I rename myself Grimm Trilobite for this thread?

Archon of Thessaly said:

As it is, i'm afraid even small changes in prehistoric terms usually means massive repuccusians. One species of dinosaur surviing butterflies away mankind-and many lines of mammals and birds. Yes, mammals will almost certainly still evolve, but the presence of synapsids will influence how they evolve and the consequent evolution of other creatures as well ( an example of how relient animals are on each other.)

Dinosaurs may well evolve, but they will definatly-as you said-be in less of a position to occupy many niches that will instead be occupied by mammals and synapsids. No saurapods, no tyranosaurus, proibly limited to smaller herbivors like Hypsolophodon and therapods like Troodon. Huge repucussians.

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i don't think he's talking about still having a british empire, or even having the continents the same but i find that there is a chance some mammal-like reptile ends up going into the cold and start growing hair, their probably won't be mammals as we know them; but there could still probably will be some form of a mammal analogue, whether it comes to dominate the world or not can't be known is and is probably a 1 in a billion chance, but we're not talking about similar in a recorded history kind of way but in a prehistoric way, so a world with with mammals and giant lizards is pretty damn close to the one we live in.

But of course the POD is way back so its possible that in 20-30 million years another extinction event happens and kills of all reptile and mammalian reptiles leading to a world so different as other forms of life fill the niche once dominated.

But I think there's a good chance the world could be "similar" tho of course very different.

Grimm Reaper said:

Shall I rename myself Grimm Trilobite for this thread?

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Definitely.

As it is said:

Not exactly. Things aren't so fine that one species of non-avian dinosaur butterflies away the Cenozoic's mammal/bird diversity, including humanity (no matter how badass Tyrannosaurus was, which is to say extremely.) Basically, the seeds of the Mesozoic are already in place before the PTB, and it's going to be pretty hard (outside of the scope of this POD) to avert the broad strokes of OTL. And a key part of archosaur success was their upright stance; they were doing well before they discovered it, but once they did they had a huge leg up on synapsids (no pun intended; there's also some speculation about glands and urea vs. uric acid, but that's another story.) So dinosaurs would have likely still become the dominant (large) land animals by lifehacking around Carrier's constant, as OTL ([insert speculation about metabolisms here].) Synapsids will respond by producing mammals (as they did OTL,) though with more synapsid diversity to play with, we could see an early synapsid return to the ocean (hey, the ichthyosaurs were doing it.) THAT would be nifty.

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intresting thought, my knowledge on permian critters is not really good however.
were archosaurs even existing in late permian ?

if i remember correctly didn't they recently find mammalian fossils that date from the permian?

Anyways due to the fact that the origins of the mammals lays in the permian they would still evolve, they would look rather different than otl though.

The other question is birds?? no permian extinction would likely butterfly away many (or all) of the dinosaurs. so less prominent dinosaurs available,would it also mean no bird evolution?(after all birds stem from the dinosaurs)

wietze said:

if i remember correctly didn't they recently find mammalian fossils that date from the permian?

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sorry, you dont remember correctly, mammals are mesozoic thing. Back in Permian, even cynodonts were rather primitive, for a cynodonts

wietze said:

if i remember correctly didn't they recently find mammalian fossils that date from the permian?

Anyways due to the fact that the origins of the mammals lays in the permian they would still evolve, they would look rather different than otl though.

The other question is birds?? no permian extinction would likely butterfly away many (or all) of the dinosaurs. so less prominent dinosaurs available,would it also mean no bird evolution?(after all birds stem from the dinosaurs)

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which makes you wonder, who is likely to take to the skies?

Pterosaurs! (in a short answer.) Long answer: pterosaurs, probably. Pterosaur ancestry isn't well-known or understood, though the first representatives show up during the Triassic. It's likely that they would show up as OTL; no obvious reason for them not to.

And although I don't subscribe to the idea that no PTB extinction=no dinosaurs, it might complicate the evolution of birds, as there would likely be more synapsids (and/or synapsid kin/derivatives) occupying the small, highly-active animal niches, thus providing stiffer resistance to 'birdy' dinosaurs. However, I'll freely admit that the ecological/morphological dynamics of the evolution of birds vis-a-vis mammals is outside my purview.

Actually, the mammals could quite thrive even if there are dinosaurs..remember the Multituberculates, they were thriving and Afrotheria and Condylarths were starting to evolve in the Late Cretaceous when some dinosaur genera declined, I think that the K-T extinction contributed to the fall of Multituberculates, perhaps they could increase their size along with some of their fellow mammals and occupy the small and medium size herbivore niche.

I think Mammals and other Synapsids would have less stress if the P-T extinction never happened.

Tycho343 said:

Definitely.



Not exactly. Things aren't so fine that one species of non-avian dinosaur butterflies away the Cenozoic's mammal/bird diversity, including humanity (no matter how badass Tyrannosaurus was, which is to say extremely.) Basically, the seeds of the Mesozoic are already in place before the PTB, and it's going to be pretty hard (outside of the scope of this POD) to avert the broad strokes of OTL. And a key part of archosaur success was their upright stance; they were doing well before they discovered it, but once they did they had a huge leg up on synapsids (no pun intended; there's also some speculation about glands and urea vs. uric acid, but that's another story.) So dinosaurs would have likely still become the dominant (large) land animals by lifehacking around Carrier's constant, as OTL ([insert speculation about metabolisms here].) Synapsids will respond by producing mammals (as they did OTL,) though with more synapsid diversity to play with, we could see an early synapsid return to the ocean (hey, the ichthyosaurs were doing it.) THAT would be nifty.

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It would be NIFTY-and likely. You are right to point out that yes, dinosaur dominence is almost certain, but its worth noting that the synapsids will still hold a huge hold in the world-after all, if one species holds 95% of all large land animal population, its pretty clear that that it will be hugely succesful-especally without a mass extinction and will be difficult to replace. Yes the Archosaurs are destined to outcompete them, but the lystrosaur or placerias will be able to evolve a wider range of ancestors and continue to dominate the land scape for some time. So mammals may be able to develop and dominate sooner then OTL.

As the ocean, the Ichthyosaur and plesiosaur only really come the forfront of because the ocean ecosystem and all the previous lines of animals that dominated it had been wiped out-up to 99%. So the synapsids may well be able to occupy thoes niches, therefore, the changes will be more massive then you, me-anyone could really predict. Lets just say that our world would be unrecognisable.