I read so many studies and found so many contradictions and different results, there is definitely no consensus, the temperature of the water alone makes each case different.
The Texas study that I read used pigs in tanks in the Texas heat, protected from predators, so no fish or crabs to speed decomposition. Texas has that body farm out by San Marcus, between Austin and San Antonio. If you look at it on google maps, you can see the cages and faint outlines of human bodies and skeletons.
(I just looked through every one of our emoticons and there's not a skeleton or skull to be found)