They obsessively go after wild dinos. If you carry one one your flier they'll follow you to try and get the wild dino. Easily lead it to traps like this. Just make sure there's nothing else around to attract its attention.
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.