I think this is all very interesting and the ocean oxygen level theory is very believable. Well if were talking about giant insects and the like wat about those giant worms form Tremors? Could there existed worms like that? i mean they feed off the earth and since the high oxygen levels would benefit the plants alot and the plants would then make the earth even richer. Therefore making the food richer for these worms, im just want to hear everyone elses thoughts on this.

yes - there were massive trees, massive centipedes massive insects. yuk!!!! early formation of the earth apparantly.

i heard it was something to do with the earth's magnetic field that caused the size difference. saw a utube video where they created this effect in lab and got giant sized piranah fish. cant remember where link is... might have been about giantism or something.

if you look around, all insects, trees, mammals, reptiles and maybe even humans (if the stories of giants on the earth were real) have decreased significantly in size over time. possibly due to a deterioration in earth's magnetic field? or something like that?

[edit on 9-3-2009 by rapunzel222]