All bog mummies show varying amounts of decay. They are simply in a slower state of decay than a body buried in dry earth eaten by worms etc. Most bog bodies are found already half rotted away, some are mere bones.

Archeologists are mostly guessing at the ages of petrified bodies. Clothing and minimal artifacts didn't make any great enough changes in short spans of time to actually determine how old any particular body is in most cases. Most of them are found wearing plain peasant dress (if cloth parts are found) or skins that would have been typical anywhere from 500 BC to 500-1500 AD or even later.

Too bad dinosaurs didn't wear clothes is all I can say. Bog bodies do present proof that petrification is possible in short spans of time, relatively speaking. Some may actually only be a couple or a few hundred years old, which may very well be the case of the more intact bodies.

None have been found that archeologists have pinned dates of 10,000 years on. Nor have petrified animals been found within the bogs of that age leading one to reason that either the bogs themselves did not exist for that length of time, there was no civilization or other animal life near them for that length of time, or anything that old within them has already reached a state of compression beyond recognition.

The peat bogs and everything within them are in a process of compression, the same as coal.