Ok so I found out that you can easily so lo tame these guys at lv 27 and you put chests with trainq arrows in them and some in your inventory and put every level in speed and run shoot run restock and repeat then tame the other gender and boom a bronto farm at lv 27
Bronto are slow just shoot shocks or tranqs and walk backwards. Use large rocks to jam them they struggle to cross non flat terrain. Use EXCEPTIONAL kibble to tame high levels or you will be waiting 5-10 min even from starve using berries or veg.
Bronto can carry as many people as you like with or without platform saddle aslong as weight limit is not exceeded. (There is no seat for passangers to mount)