Therizinos are very hard to tame since they are fast and very strong. Plus they aggro once close by it which we all know happens to us. So try to get a high ground which means no close combat only ranged. Meaning no fists and clubs. Only bows, cross, or a compound bow. With tranq arrows. Or darts if you can make a longneck. Once knocked it will take awhile with mejo or crops. But Have a lot of narcotics or narcoberries if you have a harvesting dino with you.