I've seen those in blackforest; I don't recall seeing them in meadows. And I never see live skeletons there, only the bone piles. I only recall live skeletons outside during the day at burial chambers and stone ruins, and pretty much everywhere in the swamp (and of course, the "skeleton surprises" where you get swarmed). I've only seen bone piles at those little stone formations and at entrances to troll caves. Hmmmm... well maybe after ~300 hours and seeing all the finished biomes, there are still things I haven't seen!