My titanosaur battle tactic (this version is drastically edited from bronto battle tactic and is posted on bronto's dododex page), if you're near a cliff

1. Put a cannon on the cliff and stock up on cannonballs

2. If the cliff isn't high enough, go further back from the cliff and build a thatch tower to size needed (supported by wood beams and such) for a better shot

Bonus round for defeat: Fire until KO and if you don't really mind rarity, especially earlier on before the saddle, go to unconscious titanosaur and kill. There will always be another after a while.

I'll have to test around with the tower method a bit more, so I will update on this topic later in these tips.

There's also always quetzalcoatlus platform saddle KO's and kills too so don't worry