If you're at full charge these guys are capable of killing rexes, I learned this when I was dropped into a battle by a quetzal and charged at a kaprosuchus, a Rex stepped in front of it, probably because the kapro had our tribe founder in it's mouth, and I hit the Rex on the leg, instakilling it, it was as a lower level than my rhino but still, we now have a rhino squad dropped in by our quetzal, titanslayer, I recommend a rhino squad for any raid, my rhino even earned his name after rhino squad was created, Rex Ripper.
If you are on a pvp server(pve works as well), and you're raiding someone, try to use the rhino's charge attack. If your opponent has a rex, and you hit it with a full charge meter, it will be an instakill.
At first I’d looked over the creature, assuming it was as useless. But after gathering some information, i decided maybe it’d be worth trying to tame.
It took about 30 tranq arrows for me to knock him out. I fed him several mejo berries and stuffed in a little soothing balm, and soon after he was tamed! I decided to test him out. Despite his low stamina, he was incredibly fast and had a great charge attack. (Rip Carbo he one-shotted ☹️)
Shortly after giving him the name Trak, we did a little gathering and ended up with like 500 of each berry, along with lots of carrots and seeds. We demolished the whole forest afterwards.