These guys can be netted with a net gun. Tranq darts are affective but i knocked out a lvl 135 with about 15 shocking tranq darts. Great for boss fights cause of its courage roar ability. Pair with an army of rexes and you’ll be a force to be reckoned with.
It really is that simple though, they can't reach you or your flier on a big enough rock, so if you don't want to make a trap you can just shoot down from a rock or cliff once the carnos are dealt with. Be ready for a goose chase once it starts running.
If you're lucky, you can find one of these alone. I would recommend targeting one that is alone, unless it is too high of a level or too low. Therefore you don't have to worry about Carnotaurus trying to kill you. Kill off anything ot might try to pick a fight with, like mammoths (you can use the prime meat from them to tame it). It takes a good amount of arrows so best if you use tranq darts instead. Just be careful of its roaring because there could be Carnos nearby.