You can find phiomas at the herbivore island. But it’s a pretty long way and off to the side. Another good spot is at South Province 1. There is a big stone platform which usually have one. That’s where I tamed my first (and only) phioma. But later I was bringing an ankly back from herb island and they made a bronto angry somehow. My phioma tried to fight but lost along with my raptor and parasaur.

-R.I.P Pyro you will be missed :(