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.