Many people aren't aware that the bronco is an easy early tame. It does take a lot of rocks but a slingshot works fairly well in knocking a bronto out. Bring supplies to repair your slingshot and find a low level bronto. As long as you walk straight backwards, it's tail can't hit you when it swings. Low levels typically don't need narcotics so you only have to worry about collecting berries but it's easy to do with a trike.