It's best to leave them alone unless you want to tame them. They act like spike walls, so you and your dino take damage when you melee it, and it's a lot of damage, even low level ones do a lot. If you want to kill one, it's best to use ranged attacks like a gun or a wyvern blast.
While battling a lone kentrosaurus or even a herd it is highly advised to use ranged weapons. Due to the kentrosaur’s slow movement speed and ability to reflect moderate melee damage using hand held weapons and attacks with smaller dinos can cause serious destruction to you and your tames.
Whatch out they are aggressive,but with a very small agro range (prob the size of a therzys agro) and if you are riding a parasuar in the begging of playing or a trike They can knock you off the dino and put it in its spikes where it cant move or fight back. I have lost lots of dinos because when riding parasuars and others you usually cant see them they are so small. BE AWARE-rip 250 tek parasuar
Short-tempered. Better to have someone like Reaper when killing these, as Reaper takes little damage from attacks due to it not being exposed to light. Being around these too long will agro them, try not to stay round Kentro for too long when of weak land dino.