When did Godzilla's species exist?

I'm going to guess Paleozoic era, 500 million years ago. Before the dinosaurs, after plant life started.

Well, in the movie they say that Godzilla lived among the dinosaurs.

He exists in the Permian according to a couple of sources! 

In Godzilla Awakening, during the Permian era along with other giant monsters. They died out during the Permian Impact, but many either attapted to live in the deep oceans (like Godzilla) or deep beneath the Earth's crust (like the Shinomura from Godzilla Awakening)

It was apperantly a fully functioning ecosystem of giants like gojira, the mutos were a parasitic species who hunted godzillas in packs in order to lay their eggs in their radioactive dead bodies!

Permian? I don't seem to recall the Permian age to be dangerous and highly radioactive. Not saying your wrong, but in the movie they make them seem way older. They did consume nuclear energy and radiation, but that's what I recall the movie say anyway.

No, its definitely the Permian, I think it's towads the end of the period and the radiation levels rise because of some geographical issues.

That makes sense, but then where did the consume nuclear energy before the radiation levels spiked up?

I remember in the movie they said Gojira was the Alpha Predator. It is more likely the body was either something else or the body was dead when the parasites dug into it.

That didn't answer my question though.

i have a question regarding the fossil- who was it that laid the eggs in that fossil? and how big was the muto when it hatched? from the filipines