Almost 100 percent certain that the skeleton is of another, non bombed Godzilla-- thus why it looked so different. But for those of you saying that the skeleton is of a snake like creature (the centipede monster) know that it'd have to have bones connecting about it to form junctions in which its many legs/arms would protrude.
If you look at the trailer, they are walking through what appears to be a hipbone, or something similar. I'm no expert on animal skeletons, but I'm pretty certain that skeleton is a Godzilla.
He is 350ft Tall people, those things on his neck ARE gills, and the Brazil photo is part of the final advertising design-- Deal with it.