If there’s no cliffs nearby and you’re at a high enough level, you can build a small stone house using 1 foundation 3 window frames and 5 door frames then a door (preferably reinforced door). The window frames and one door frame go on the foundation then the other 4 door frames go on top of those walls. Place the door in the bottom doorframe so you can leave and enter while still protected. Then you can shoot away at the bronto without getting hit- you may also want to crouch. Then leave the house when it starts to flee.