The following stats are taken from Famitsu's Official Guide Book. If critical values are not specified, guns firing this ammunition can not perform criticals.
EASY: Damage per bullet (Critical)
NORMAL: Damage per bullet (Critical)
They often hunt in pairs and are extremely tough. Therizinosaurus is something of an upgraded raptor, and will often be found in large corridors where raptors were more commonly found.
It should be noted that Therizinosaurus can sometimes follow Regina into other rooms if she runs away from them. Most notably, the corridor on floor B3 that leads into the room with the passageway to the docks or the Rest station area on B2.
If the player meets one, escaping is recommended because they have high resistance to many different weapons. However, if faced with an unavoidable fight, the player's best weapon choice is any kind of grenade round or darts (poison dart is a good choice hee). However, in the second corridor, the security laser shutters (in the area shown in the previous screenshot.) can bre used to trap them by tricking them into following Regina and running around the Therizinosaurs when they reach the other side and closing it behind them. This will get them stuck and they will be unable to attack Regina on the other side. They should remain there for the rest of the game or until Regina opens the shutters again.