Permian is almost very likely for Dominion, and I can tell already this game aims to be very well based on all the Jurassic movies like the first, just in the next level this time. One rumored animal is the Dimetrodon (Though that's only based on "leaked" information & alleged "dino-appearing" merchandise. Only time will confidentially tell if it will officially appear in the film.), and the said Lystrosaurus, assuming it's not a Triassic species. I can see them (along with all other new on-screen species) being in the game via as a free update like the Fallen Kingdom and Battle at Big Rock updates, or maybe go in a different route as a Dominion based PDLC.
There are quite a few Permian creature ideas of my own for JWE2, but like all of my other ideas, I plan to save them until sometime after the game releases so that I know what is in it or not, just as I did with the first game "long" after every major update.