WTF.... Schala isn't the entity. She's most likely a past arbiter.
I've started thinking about this, And I don't think that the Planet was actually the entity that created the gates. I'm starting to think now that it was the planets dream, but a greater force than it caused the gates to open up, and summon Dinopolis in from the other dimension.
The Planet was never stated as the entity in CT.... There is no stated entity in CC.... But we know that what's going on is as if it's the planets dream....
For one, in the time line that Crono is in, it should be impossible for the planet if it was the entity to create timegates or interfer in any way. Why? The planet had lost over 65,0000,000 years of energy thanks to Lavos, who used it up fighting Crono and co. The planet has no way of getting it back, but can regenerate over time into the future. Because it's a bit limp. I do not believe that the planet itself could have possibly summoned Dinopolis itself. It's like saying that the Earth is acctually sentinel, which would mean it would need some sort of incarnation, and it should have done that to stop Lavos itself. If the planet has enough energy to summon Dinopolis out of a dimension, causing it to be the missing piece for those dimension, the planet should have been able to handle Lavos by itself.
Lets say that Zurvan did it