Cahlicotherium are not necessarily aggressive, but we become EXTREMELY HOSTILE when approached by the player. I tamed two phiomias on Mobile and sat them outside my base on Passive. Then, I heard them getting attacked by one of these ugly behemoths. In the end, both my phiomias died to this thing, and it killed me and smashed one of the walls on my base. So, they may also become aggressive if they approach your tamed dinos too.

Rest in peace Pork Chop and Apple Sauce..you will never be forgotten..