Well look around for one and then you find one that you want go to your base and get bout 75 tranq arrows (depends on the level of the big boi)if it's a level 25 then you need 50 tranqs if it's 100+ you need about 150 tranqs just to be on the safe side do not take it to your base if it's aggro on you it is pretty easy to tame just aim the head and run away from it as you tranq it then eventually it'll be down wait for the food to go down and then put in kibble or berries (torpor I good doesn't go down fast ).
I tamed mine with my carbo kibble that was gonna spoil from the carbo kibble quest, crops, and tranq arrows. pretty easy tame when you are prepared. I reccomend herbi island because of the tall cliff. Please ^ if this was helpful!
You will need: 50 tranq arrows, (sometimes you miss, and it's better to be safe than sorry) A flyer (a pteranodon will do) a bronto that spawned where they're is a high rock or cliff, where the bronto can't reach you and a crop plant of your choice. (If you just got two, use both, fifty of each.) Step 1: gather your stuff. Step 2: Get on your flyer and fly to the high rock or cliff, and land on it. (If it's a high rock, make sure its big enough so you can dismount and move a little bit.) Step 3: get your tranq arrows ready, and scan the area for danger. (Rexes, allo pack, spinos, basically anything that could harm you unconsious bronto.) Step 4: Shoot one tranq arrow at the bronto and get it's attention. Repeat until unconsious. Step 5: hop down. You should be at full health, and the fall damage won't kill you. Step 6: shove the crops in the bronto's inventory, and let it tame. Step 7: If your flyer is on a tall rock, whistle for it to follow and get it down. You can just whistle "follow all" and it'll come down. once its down, whistle "stop all", and mount it. if it's on a cliff, get up there and mount it. if you can't find a way up, repat the steps for high rocks. Do this if you need to make a quick getaway. if your flyer can't hover for long, just go back on the high rock/cliff, and wait until the bronto is tamed. Step 8: once the bronto is tamed, whistle "stop all" and fly back to your base. Step 9: request the bronto to your base, and name it. Step 10: If you're at lvl 63, you unlock the bronto saddle. if you tamed this at lvl 63+, i reccomend unlocking this engram. Once you get tame bronto, target your tamed bronto. You'll get the rewards! Please ^ if this was helpful!!!
These are the easiest tame ever, just get far away, shoot it with a crossbow repeatedly, when it gets close run and shoot, then boom u knocked out a brontosaurus (I literally have 5 of them that’s how easy they are to tame) please