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.
A woolly rhino had one main ability it is the absolute best creature to collect thatch when you give it enough room to charge it can destroy tree like they are not even there collecting thousands of pieces of thatch
On a pvp server if you get 2 high levels and breed them if your lucky enough you can gethigh enough melee to rage a high health tamed giga in 1 hit with full charge the best counter for gigas in a raid
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.
Combined with a carnivore, this beast can destroy all the wild Dinos so that the carnivore can eat the bodies for an insane amount of meat. Sabertooth, Dire wolf or Carno may be best for this job as if you upgrade their speed they can easily catch up with the Rhino.