From that very same storyline that Thunderbird died in was the female mutate, Dragonfly. Along with the Ani-Men, she was put into lock-up (we learn later that it was on Muir Isle).
Well, in X-Men #104, during a battle on Muir Isle, two locked-up people escape. One, Mutant X, is addressed twenty issues later, in the Proteus fight. The secon, Dragonfly, is never mentioned again!
I do not know if Chris Claremont had a plot for her, but dropped it, but in any event, she was long known as one of the more prominent "dangling plotlines" in Marvel Comics, so noted stickler for details, Mark Gruenwald, resolved her story - THIRTEEN years later! - in the pages of Quasar.
In Quasar #15, we learn that right after she escaped, she was taken captive by the Stranger, which is where she's been ever since!
All wrapped up in a nice little bow!
Well, that's it for me this week!
Feel free to tell me some urban legends you have heard, and I will try to confirm or deny them!