Ok, so a mason of mine recently had a bit of a confrontation with a dragon...and lost... Dragon came and attacked while a few novice masons were building my road, as well as my triple legendary maxed stats mayor that was working on Masonry to pass the time. Dragon comes in as they were all heading back in from just finishing their work... Mayor hauls ass and makes it back in before the dragon gets to my entrance. Novice mason...didn't make it. The other two masons stayed back at the road and were safe, but the one that followed my mayor started getting chased. Instead of having him lead the dragon to the others, I activated him and watched him charge head first towards a swift fiery death.
The dragon promptly entered my fort and was struck down by my weapon traps.
But anyway, I was left with an extra crispy flaming dwarf corpse. I apparently had a spare coffin ready in my general dwarf tomb, when I thought I had none free. So while i'm busy assigning the task of building more, one of my dwarfs starts moving what's left of Tun Ducimcog's body to his tomb.
That's when I noticed smoke was billowing out of one of the coffins in my burial chamber. What threw me off was that checking outside, I could see that Tun's corpse was still there, and still on fire. Checking inside the coffin, however, revealed that someone had kindly already placed his flaming skull within the coffin, which was the source of the smoke.
The question here is obvious though. Should coffins be keeping out smoke as well as miasma? Also, wouldn't placing a burning corpse inside of a sealed stone coffin technicaly put the fire out due to lack of oxygen?