Easy way to tame it is to place 3 wooden foundations, 4 walls (2 on each side), and 2 doorways in the middle. (You can make this out of stone to make sure it doesn't break it). Run near it until it notices u and then run through the doorway. It will get stuck. Now proceed to shoot tranq arrows at it.
A simple way to get these guys is to simply distract them with something delicious. Command something tanky (Ex. Carbonemys) to attack them, then set them to passive so they don’t kill the Carno. Then, you can pelt it with a slingshot or bow and tranq arrow until it goes down. They don’t have the biggest torpor stat, so raising it to max won’t take many tranq arrows (5 if it is extremely low level)
Find one and stalk it from a good distance and wait for it to attack something with a good sized health pool such as a stego and while they're fighting pelt it with tranq arrows, it will probably kill the other dino then start to run away, keep up with it and keep hitting it until it's knocked out