Mothra / Rodan's 2018 Origins

A possible origin I have thought of for Mothra in the film is that she was originally a moth from the Carboniferous Period 300 million years ago, a time famous for high oxygen levels that allowed insects to grow to huge sizes. And as the 2014 film established in it's continuity, radiation was alot more common in prehistoric times. So if radiation was common during the Carboniferous, then a combination of it and the high oxygen levels could have resulted in Mothra's giant size and any special abilities the movie may give her. Plus, if the movie wishes to have her worshipped as she usually was in the Toho films, then she could have become irradiated on an island that would later become the home of primitive human natives, who would worship her as a god. The island could act as this series' equivalent of Infant Island.

As for Rodan, two origins I thought of are ones that recreate the scene with him flying out of the volcano in Ghidorah The Three Headed Monster as a sort of homage. Both also are suggesting that in prehistoric times volcanoes were hotspots for radioactivity. The first origin has Rodan as one of a species that thrived on radiation like Godzilla did, but particularly favoured volcanic radiation. Then as the radiation levels lowered, a single Rodan could have entered a form of suspended animation inside a volcano and awoken from it in the film, breaking out and flying out as the original Rodan did in the 1964 film. The other origin proposes that Rodan was originally a simple Pterosaur that hung around a volcano for too long and was mutated by it's radiation, growing in size, as well as gaining any abilities the movie wishes to give it, and entering a form of suspended animation within the volcano, before emerging in the movie and flying out as the first one did in Ghidorah The Three Headed Monster.

What do you think?