User blog comment:SolZen321/Could Godzilla actually exist/@comment-6810354-20140511181712/@comment-5527544-20140513234403

Firstly, the T-Rex thing is only about oxygen levels and is there to illustrate a point, it's not something you should be that focused on.

Also the best way to deal with something poisonous to you is to evolve a way to get rid of it, neutralize it or find a way to use it. Some animals don't produce poison but get poison from other organisms such as some caterpillars eating poisonous. If Godzilla's species evolved during a time (which we know never happened) when Earth's background radiation was ridiculously high then we are assuming his species could have evolved a way to deal with the radiation by using it to augment cellular respiration i.e. get energy. Is it that really that far-fetched, it is only recently that we developed thread that can surpass the strength of spider silk, there animal behaviors we don't understand, heck there are eels that don't just electrify prey but actually shoot out short electric bursts, there are tiny lifeforms (their name escapes me) that were discovered to regenerate so much they effectively don't age. Who is to say what the limits of biological evolution are? Also remember that larger bodies more readily absorb more radiation.

The size, the biggest problems with getting big are holding up your own weight, overheating and generating enough cellular respiration that you don't suffocate. If Godzilla's species evolved a way to use radiation to power cellular respiration to augment this process, that's one problem solved. So the grow bigger, obviously they would evolve ways of dealing with the other two problems, stronger bones for example, the Spines could also be used as temperature regulation system like some ancient dinosaurs. Also Godzilla spends a great deal of his time in the water which would help support his massive weight.

As for the growth, I never said it was instantaneous, eating being super charged, his body's cellular respiration rate would be over shot, the growth in mass would probably be a reaction to bring the release of energy under control, the mass would most likely come from it's other food source. As for a breeding population, Godzilla evolved when radiation levels were much higher, by modern times his species would've likely died out as the energy needed to maintain their size was becoming increasingly harder to find. I will agree with you, for a Godzilla I would go with the first one in the Showa would be the most realistic