Uranium has a half life of 4,5 Billion years. Dinosaurs lived in an era (geologically speaking) that ended some 130 million years ago, way before man, but the levels of background radiation from Uranium deposits are largely the same as today.
Radioactive mutations are not dependent on environmental conditions, the DNA gets screwed producing many , many deviant organisms which may arise, but they simply cannot survive.
The premise from the article is that background radiation led to a huge variety of organisms achieving gigantism this is a fallacy, because Gigantism in this respect can only survive if there is sufficient protein resource to sustain it.
You need to be looking at other mechanisms for an answer to the Gigantism during the Jurassic, and cretaceous periods. Might be better to look at gas concentrations in the atmosphere, climatic conditions etc because high levels of radioactive particles would not affect each organism in the the same way and produce viable "giants" without other influences..
p.s. "Brontosaurus" became "Apatosaurus" many, many years ago because it was incorrect.
Edited by keithisco, 28 August 2012 - 05:11 PM.