How does Wolf lose his mandible?

Acid is a safe bet given what the rest of his face looks like.

Acid spill. Broken off by a rogue hunter. A close scrape with a xenomorph inner jaw...

Plenty of possibilities, but not much back story to expand on his former adventures.

I think another pedator ripped it off his face during a fight.

1. A Xenomorph bit it off.

2. A Bad Blood ripped/sliced/or pulled it off.

3. An unknown accident.

Who knows?

It would be pretty safe to assume that it was from a xenomorph with a somewhat melted face where his mandible was. Acid blood, it's bitch :P

I don't think it was from acid. Although it is a dead, white eye, the eye is still intact. Any acid that was strong enough to cause that severe of a chemical burn on the skin would have completely destroyed the eye. There is no part of the exposed surface of the body that is more suceptible to acid and alkaline damage than the eye. I think it is more likely from some sort of explosion.

It's also possible that his race somehow evolved to have the effects of a Xenomorph's blood not harm them as much as it potentially could. But that's just me talking out of my ass, as I've never heard such a thing before.