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

This is actually fairly well thought out. However, there are a few points...

First, we need to establish what size Godzilla we're talking about. Smaller the better, so showa era would be idea. Next, I highly doubt we could outrun a T-Rex due to higher oxygen levels. In fact, I wouldn't step foot out of a time machine for fear of the radically different environment killing me on the spot, if not dooming me instantly. Also, this whole "feeds on radiation" thing certainly falls firmly on the fiction side of sci-fi. I don't claim to be an expert of any sort, but are there any examples of life (other than plants) that absorbs radiation anything like that? Sure, we get vitamin C from the sun, but we don't gain mass while tanning. (ok, maybe on a  quantum level, I dunno) That whole part just seems too far fetched.

As far as I'm concerned the biggest problem is energy/food. You propose he partially feeds on radioactivity, but I'm gonna assume he gets his go the old-fashioned way. Giant squid and whale do seem a logical choice, but if we had a breeding population of Godzilla's out there, the ecosystem would fall apart. The larger something gets, the energy required to power it increases exponentially, that's why we aren't giants and why larger creates are less practical. Hibernation would be a must obviously, but they'd have to munch out before that, their seafood dinners would empty the oceans.

Ok, 'nuff said for now...