I was on my raft with my ankylo trying to get metal but one of these was guarding the beach. It attacked my raft and destroyed a few of my storage boxes. After a long struggle to try to kill the guy with my bow (I forgot to bring my rifle) and almost dying, I decided to go all the way back to base and loaded my lvl 200 Rex on my tiny raft... long story short I now have a few extra cooked prime meat in my preserving bins. Tbh my ankylo was lvl 230 and could have easily destroyed the therizino but I decided to not risk it.