Those are some long-ass tusks, Mapusaurus is larger, but Zygo probably has the range advantage and could probably stab Mapusaurus on very important organs in Mapusaurus like the heart or lungs, but if Mapusaurus does get close to Zygo in biting range, it's over for Zygolophodon.

Could go either way but I'll vote for Mapusaurus to see votes.

Zygo the long tusked boi

Depends on terrain, climate, and circumstance.

Could go both ways

Mapusaurus would bite the tusks off