Having a pack of Dilos is a good way to combat one early on: they can slow it down with their spit attack, they can be generally hard for it to consistently hit, and carnos focus more on dinos than humans so if you get ambushed chances are it might change focus to your dilos. It can be possible to kill a carno with just 2 dilos if they can take a hit and you provide cover fire with any ranged option.
Large bear traps are the most under used thing in the game. Get like 7 or 8 of the large variety and when you see a carno put one down between you and it, agro it, shoot transfer and rinse and repeat till he's down.
A Very under rated tame. High lvl Carno with a decent rider is capable of huge destruction. My Carno Hugo can take 3 theri and multiple troodons at once and not even bat an eye. Hes even took low lvl rex. A must have early game and even mid/end game is still a reliable mount.
When you encounter a wild Carnotaurus in or near a forest, walk towards him, so that he is between you and the trees. He will go away from you to attack you with his charge run attack. By doing so he has a high chance of getting stuck between the trees. Now you can knock him out savely. But remember to chop down the trees when he is knocked out, because when he is tamed he will start running and bugging when the trees are still there.
I'm taming one right now actually they are very easy to tame even at lv 50 just use a platform higher than they and you should be good lol I use my neighbors boat XD it takes along time to tame but worth it you need meat to tame at least or get special items for after tame