Ah, cave-in dust. Such a blessing.
... when the beast doesn't also have wings.
I remember that scarab creature that was almost unkillable because it would always send any dwarf flying; if they didn't die in the repeated cave-ins, the syndrome itself would within a minute. Meanwhile, it would still hover without flinching. I hated that darn thing. HATE. SO MUCH HATE.
More on-topic, and in the same fort: a serpent FB with poisonous sting and a shell ate a few dwarfs after it appeared in the caverns. Bloodthirsty snake. It didn't try reaching my fort at first, nope... it was following civilians in the dark depths instead, staving off its hunger for hairy alcoholic meat. It gained quite the title within 5 minutes.
Then, once there wasn't any more worker unfortunate to have been stuck underground, it stalked a farmer up some long carved stairs. I had already sent my army, of course, but the serpent had been very quick at dismembering its victims, and the military very slow at remembering where they had put their xx(pig tail fiber socks)xx. It slithered upwards, faster than the farmer could run, and quick as the lightning, bit his left hand off. Shitting his pants and bleeding most of the beer in his veins, but having nothing left to lose, the dwarf awkwardly tried to punch the monster with his left - that is, right - hand, who dodged.
Did I mention they were 6-7 z-levels above the ground, and that the stairs were mostly uncovered?
So, the snake dodged the harmless punch. It didn't dodge the ground. More specifically, his brain, stuck inside its skull, didn't dodge the hard, humid, cold ground.
The farmer officially obtained the very nice title of Serpent Slayer.