It would be fun if you could capture a baby fire gecko and teach it to be an attack animal. Bug-type creatures are over used; why not more unique creatures and robots and factions, too.
The Geckos went extinct because of JET. Why? Reasons. Writers are supposed to have fun, and I don't discuss logic/reason/realism in a fiction setting'n shits, ...
It's entirely likely that Geckos, being reptiles and hence cold-blooded, just never crossed the Rockies. I mean, it's a plausible explanation.
I don't think geckos and lizards and the like are anywhere in that area so it makes sense to me, but I could be mistaken.
Geckos don't appear in Boston because"Something something something geckos". Everyone keeps forgetting that it's Bethesda, they don't need explanations and logic in a world with "talking ghouls". It just works.
