What if the Permian extinction never occured?

[Chomper98]

What do you think would have happened had the Permian extinction never occurred? It occurred at a time when mammal like reptiles, Gorgonopsians, Dycynodonts, and Cynodonts were at their height. The dinosaurs would probably still evolve, though they would probably be small animals, maybe they would evolve alongside them, and mammals would arise and rule until the asteroid hit the earth.

The asteroid would have hit regardless of the Permian extinction, so the only difference are the big animals that go extinct, probably large mammals, though a few tiny ones would survive.

If that occurred, then perhaps the dinosaurs would become the dominant species, but with the lower oxygen level, animals would probably be similar in size to the animals of today.

If the ancestors of primates survived, then perhaps humans would evolve, and become the dominant animal, though instead of lions, there'd be animals like Allosaurus or T-rex. Of course this is just a guess, as alternate history gets harder to predict the further back. What do you think?

[Dosu2Dinner]

Hm, its an interesting thought...if the Permian extinction never happened, its probably safe to say that the biodiversity today would be immense, as every lifeform alive today is descended from the 4% or so that survived this cataclysm.

If the larger synapsid groups survived, I'm fairly sure the mammal lineage may not be the same as we know today (though admittedly my knowledge on such areas in amateur at best   ) If dinosaurs were cast to the shadows however, who's to say they couldn't have been outcompeted by other archosaur groups, rendering them extinct before the K-T event. Dinosaurs, for all their fame today, would just be footnotes, and birds certainly wouldn't exist...

[DarkHououmon]

You're not the only one who has thought of a what-if involving the permian extinction. One story I have been working on for years, Dinosarcus, actually deals with this very idea. The world it exists in is a world where the permian extinction never happened. There are other major differences, but that is an example.

[Kor]

The synapsids may have evolved into mammals.  Maybe a later sentient race, if there was any, would have called it instead of the age of dinosaurs may have been the age of mammals.  With mammals maybe still around, similar to how birds are what's left of dinosaurs.

[Chomper98]

I agree the mammals would likely have been far more diverse, as of course, the animals of today are descended from the 5% that made it. Perhaps mammals that looked like gorgonopsians or lystrosaurs alongside animals like andrewsarchus.

Proterosuchus and other archosaurs probably might have assumed the role once filled by many amphibians like the labrynthodonts. Dinosaurs were the most advanced archosaurs of their time, so I believe that they would have lived much like cynodonts in the Triassic, hunting at night, living in burrows, and living in the shadow.

However their evolution probably would be slow, as mammals didn't change much until the KT extinction. Many small mammals might have survived, and if proto-primates and primates lived, they might have lived as dominant animals until the dinosaurs assumed their status as dominant animals. Perhaps animals like allosaurs would have become dominant until more advanced predators appeared.

Raptors might not have evolved until over 100 million years after the extinction, as they didn't appear until the early cretaceous. It would have been a strange world indeed.

[Petrie85]

I think it would be very cool if that never happened. We will be living among all kinds of interesting life forms.